Note: Descriptions are shown in the official language in which they were submitted.
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Title: METATHESIS CATALYSTS AND PROCESSES FOR USE THEREOF
FIELD OF THE INVENTION
This invention relates to metathesis catalyst compounds and processes for the
use
20 thereof.
BACKGROUND OF THE INVENTION
The cross-metathesis of two reactant olefins, where each reactant olefin
comprises at
least one unsaturation site, to produce new olefins which are different from
the reactant
olefins is of significant commercial importance. The cross-metathesis reaction
is usually
25 catalyzed by one OT more catalytic metals, usually one or more
transition metals.
One such commercially significant application is the cross-metathesis of
ethylene and
internal olefins to produce alpha-olefins, which is generally referred to as
ethenolysis. In
particular, the cross-metathesis of ethylene and an internal olefin to produce
linear alpha-
olefins (LAOS) is of particular commercial significance. LAOs are useful as
monomers or
30 comonomers in certain (co)polyiners (polyalphaolefins or PA0s) and/or as
intermediates in
the production of epoxides, amines, oxo alcohols, synthetic lubricants,
synthetic fatty acids
and alkylated aromatics. Olefins Conversion TechnologyTm, based upon the
Phillips Triolefin
Process, is an example of an ethenolysis reaction converting ethylene and 2-
butene into
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propylene. These processes use heterogeneous catalysts, such as tungsten and
rhenium
oxides, which have not proven effective for internal olefins containing
functional groups such
as cis-methyl oleate, a fatty acid methyl ester.
Methods for the production of polyalpha-olefins are typically multi-step
processes that
often create unwanted by-products and waste of reactants and energy. Full
range linear
alpha-olefins plants are petroleum-based, are inefficient, and result in
mixtures of
oligomerization products that typically yield Schulz-Flory distributions
producing large
quantities of undesirable materials. In recent years there have been new
technologies
implemented to produce "on purpose" linear alpha-olefins such 1-hexene and 1-
octene
through chromium-based selective ethylene trimerization or tetramerization
catalysts.
Alternatively, 1-octene has been produced via the telomerization of butadiene
and methanol.
Similar strategies are not currently available for the production of 1-decene.
1-decene is a co-product typically produced in the cross-metathesis of
ethylene and
methyl oleate. Alkyl oleates are fatty acid esters that can be major
components in biodiesel
produced by the transesterification of alcohol and vegetable oils or animal
fats. Vegetable
oils containing at least one site of unsaturation include canola, soybean,
palm, peanut,
mustard, sunflower, tung, tall, perilla, grapeseed, rapeseed, linseed,
safflower, pumpkin corn
and many other oils extracted from plant seeds. Alkyl erucates similarly are
fatty acid esters
that can be major components in biodiesel. Useful biodiesel compositions are
those which
typically have high concentrations of oleate and erucate esters. These fatty
acid esters
preferably have one site of unsaturation such that cross-metathesis with
ethylene yields 1-
decene as a co-product.
Biodiesel is a fuel prepared from renewable sources, such as plant oils or
animal fats.
To produce biodiesel, triacylglycerides ("TAG"), the major compound in plant
oils and
animal fats, are converted to fatty acid alkyl esters ("FAAE," i.e.,
biodiesel) and glycerol via
reaction with an alcohol in the presence of a base, acid, or enzyme catalyst.
Biodiesel fuel
can be used in diesel engines, either alone or in a blend with petroleum-based
diesel, or can
be further modified to produce other chemical products.
Cross-metathesis catalysts reported thus far for the ethenolysis of methyl
oleate are
typically ruthenium-based catalysts bearing phosphine or carbene ligands. Dow
researchers
in 2004 achieved catalysts turnovers of approximately 15,000 using the 1st
generation
Grubb's catalyst, bis(tricyclohexylphosphine)benzylidene ruthenium(IV)
dichloride,
(Organometallics 2004, 23, p. 2027). Researchers at Materia, Inc. have
reported turnover
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numbers up to 35,000 using a ruthenium catalyst containing a cyclic alkyl
amino carbene
ligand, (WO 2008/010961). These turnovers were obtained with a catalyst
reportedly too
expensive for industrial consideration due to high costs associated with the
catalysts being
derived from a low yielding synthesis (See, Final Technical Report entitled
"Platform
Chemicals from an Oilseed Biorefinery" grant number DE-FG36-04G014016 awarded
by the
Department of Energy). Additionally, the introduction of chelating
isopropoxybenzylidene
ligands has led to ruthenium catalysts with improved activities for metathesis
reactions (J. Am.
Chem. Soc. 1999, 121, p. 791). However, these ruthenium alkylidene catalysts
are usually
prepared by the reaction of ruthenium species with diazo compounds. The
concerns
associated with industrial scale reactions comprising diazo compounds have led
to increased
efforts to prepare ruthenium alkylidenes via alternate synthetic routes, such
as using terminal
alkynes or propargyl alcohols.
The synthesis of RuC12(PCy3)2(3-phenylindenylene) has proven useful in
providing
an easy route to ruthenium alkylidenes which avoids costly diazo preparations
(Platinum
Metals Rev. 2005, 49, p. 33). Also, Furstner et al., J. Org. Chem., 2000, 65,
pp. 2204-2207,
have prepared (N,N'-bis(mesityl)imidazol-2-ylidene)RuC12(3-phenylindenylene).
However
these types of complexes have not proven effective in ethenolysis reactions.
Unsymmetrical N-heterocyclic carbene ligands have been prepared by Blechert
and
coworkers and complexed to ruthenium alkylidenes to form active metathesis
catalysts
(Organometallics 2006, 25, pp. 25-28). It was hypothesized that these
complexes would give
improved activity to that of the symmetrical analogs previously prepared by
Grubbs and
coworkers (Org. Lett. 1999, 1, pp. 953-956). These complexes were tested for
catalytic
activity in ring closing and cross-metathesis reactions. However, the
catalysts were reported
to be similar in activity to the symmetrical analogs, namely the Grubbs
catalyst, 2nd
generation (1,3 -bis-(2,4,6-trimethylpheny1)-2-
(imidazolidinylidene)(dichlorophenylmethylene)(tricyclohexylphosphine)ruthenium
) and the
expected improved activities were not observed.
In order to obtain an economically viable process for 1-decene production via
the
cross-metathesis of ethylene and biodiesel (derived from animal or vegetable
oils), higher
activity catalysts must be discovered. Thus there is a need for higher
activity processes that
produce desired products and co-products in commercially desirable ratios.
There remains a need for catalysts which demonstrate high activity and
selectivity in
ethenolysis which are capable of being synthesized by both mild and affordable
synthetic
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routes. The instant invention's metathesis catalyst compounds provide both a
mild and
commercially economical and an "atom-economical" route to desirable olefins,
in particular
alpha-olefins, which in turn may be useful in the preparation of PAOs. More
particularly, the
instant invention's metathesis catalyst compounds demonstrate improved
activity and
selectivity towards ethenolysis products in ethylene cross-metathesis
reactions.
The inventors have found that symmetrically substituted N-heterocyclic carbene
ligands linked to ruthenium alkylidenes, though known to be cross-metathesis
catalysts, tend
to have low activity in the ethenolysis of methyl oleate. Surprisingly, an
asymmetrically
substituted N-heterocyclic carbene ligand linked to a ruthenium alkylidene
yielded a catalyst
that was more active than the symmetrical analog and very selective towards
the ethenolysis
of methyl oleate yielding 1-decene and methyl-9-decenoate.
Other references of interest include: US 7,119,216; US 7,205,424; US
2007/0043180;
WO 2006/138166; WO 2008/010961; US 2007/0043180; US 7,268,242; WO 2008/125568;
WO 2008/046106; WO 2008/095785; WO 2008/140468; US 7,312,331; and WO
2008/010961.
Other references of interest also include: a) "Synthesis and Reactivity of
Olefin
Metathesis Catalysts Bearing Cyclic (Alkyl)(Amino)Carbenes" Anderson et al.,
Angew.
Chem. Int. Ed. 2007, 46, pp. 7262-7265; b) "Intramolecular 'Hydroiminiumation'
of Alkenes:
Applications to the Synthesis of Conjugate Acids of Cyclic Alkyl Amino
Carbenes (CAACs)"
Jazzar et al., Angew. Chem. Int. Ed. 2007, 46, pp. 2899-2902; c) "Kinetic
Selectivity of
Olefin Metathesis Catalysts Bearing Cyclic (Alkyl)(Amino)Carbenes" Anderson et
al.,
Organometallics, 2008, 27, pp. 563-566; d) "A New Synthetic Method for the
Preparation of
Protonated-NHCs and Related Compounds" Jazzar et al., J. Organometallic
Chemistry 691,
2006, pp. 3201-3205; e) "A Rigid Cyclic (Alkyl)(Amino)carbene Ligand Leads to
Isolation of
Low-Coordinate Transition Metal Complexes" Lavallo et al., Angew. Chem. Int.
Ed., 2005,
44, pp. 7236-7239; f) "Stable Cyclic (Alkyl)(Amino)carbenes as Rigid or
Flexible, Bulky
Electron-Rich Ligands for Transition Metal Catalysts: A Quaternary Carbon Atom
Makes the
Difference" Angew. Chem. Int. Ed., 2007, 44, pp. 5705-5709; g) "Synthesis and
Activity of a
New Generation of Ruthenium-Based Olefin Metathesis Catalysts Coordinated with
1,3-
Dimesity1-4,5-dihydroimidazol-2-ylidene Ligands" Org. Letters, 1999, 1, pp.
953-956.
SUMMARY OF THE INVENTION
This invention relates to an asymmetrically substituted N-heterocyclic carbene
(NHC)
metathesis catalyst and process for use thereof in the production of olefins,
where the
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metathesis catalyst is represented by the following formula:
R5 R4
R6 )-(------rat
.,3
......,--.....,
Ri N N NV R2
Xr...
........---M
J_2
R7
L
where:
M is a Group 8 metal; preferably Ru or Os;
X1 and X2 are, independently, any anionic ligand, or X1 and X2 may be joined
to form a
dianionic group and may form a single ring of up to 30 non-hydrogen atoms or a
multinuclear
ring system of up to 30 non-hydrogen atoms;
L is a heteroatom or heteroatom-containing ligand; preferably the heteroatom
is N, 0, P, or S;
preferably P; optionally L may be joined to R7 and/or Rg;
and R1, R2, R3, R4, R5, R6, R7, and R8 are, independently, hydrogen or a C1 to
C30
substituted or unsubstituted hydrocarbyl;
wherein any two adjacent R groups may form a single ring of up to 8 non-
hydrogen atoms or
a multinuclear ring system of up to 30 non-hydrogen atoms; and
wherein R1 and R2 are dissimilar to each other.
In alternate embodiments, when R7 and R8 form an unsubstituted phenyl group
and
R1 is mesityl, then R2 is not methyl or ethyl, preferably R2 is hydrogen or C1
to C30
substituted hydrocarbyl, or a C3 to C30 unsubstituted hydrocarbyl (preferably
a C4 to C30
unsubstituted hydrocarbyl, preferably a C5 to C30 unsubstituted hydrocarbyl,
preferably a C6
to C30 unsubstituted hydrocarbyl).
DETAILED DESCRIPTION
The present invention comprises a novel metathesis catalyst compound useful
for the
cross-metathesis of olefins, and processes for the use thereof. More
particularly, the present
invention comprises a novel metathesis catalyst compound which comprises an
asymmetrically substituted N-heterocyclic carbene group. Even more
particularly, the
present invention comprises a novel metathesis catalyst compound which
demonstrates
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improved activity and selectivity towards ethenolysis products in ethylene
cross-metathesis
reactions.
This invention also relates to a process comprising contacting a feed oil
(typically a
triglyceride or seed oil) or derivative thereof (and optional alkene) with an
olefin metathesis
catalyst of the types described herein under conditions which yield an alpha-
olefin. The feed
oil may be esterified or transesterified with an alcohol prior to contacting
with the olefin
metathesis catalyst.
This invention also relates to a process comprising contacting a
triacylglyceride or a
derivative thereof with an optional alkene (such as ethylene) and an olefin
metathesis catalyst
of the types described herein under conditions which yield an alpha-olefin,
typically yielding
a linear alpha-olefin (such as 1-decene, 1-heptene, and/or 1-butene) and an
ester or acid
functionalized olefin.
This invention further relates to a process for producing alpha-olefins
(preferably
linear alpha-olefins) comprising contacting a triacylglyceride with an alcohol
(such as
methanol) to produce a fatty acid alkyl ester and thereafter contacting the
fatty acid alkyl ester
with an olefin metathesis catalyst of the types described herein (and optional
alkene, such as
ethylene) under conditions which yield an alpha-olefin (preferably a linear
alpha-olefin,
preferably 1-decene, 1-heptene, and/or 1-butene) and an ester or acid
functionalized olefin.
This invention further relates to a process for producing alpha-olefins
(preferably
linear alpha-olefins) comprising contacting a triacylglyceride with water
and/or an alkaline
reactant (such as sodium hydroxide) to produce a fatty acid and thereafter
contacting the fatty
acid with an olefin metathesis catalyst of the types described herein (and
optional alkene,
such as ethylene) under conditions which yield an alpha-olefin (preferably a
linear alpha-
olefin, preferably 1-decene, 1-heptene, and/or 1-butene) and an acid
functionalized olefin.
This invention further relates to contacting unsaturated fatty acids with an
alkene
(such as ethylene) in the presence of an olefin metathesis catalyst of the
types described
herein under conditions which yield an alpha-olefin (preferably a linear alpha-
olefin,
preferably 1-decene, 1-heptene, and/or 1-butene) and an acid functionalized
olefin.
This invention further relates to contacting an unsaturated fatty acid ester
with an
alkene (such as ethylene) in the presence of an olefin metathesis catalyst of
the types
described herein under conditions which yield an alpha-olefin (preferably a
linear alpha-
olefin, preferably 1-decene, 1-heptene, and/or 1-butene) and an ester
functionalized olefin.
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This invention further relates to contacting an unsaturated fatty acid alkyl
ester with
an alkene (such as ethylene) in the presence of an olefin metathesis catalyst
of the types
described herein under conditions which yield an alpha-olefin (preferably a
linear alpha-
olefin, preferably 1-decene, 1-heptene, and/or 1-butene) and an ester
functionalized olefin.
This invention also relates to a process to produce alpha olefins (preferably
linear
alpha olefins, preferably 1-decene, 1-heptene, and/or 1-butene) comprising
contacting a
metathesis catalyst of the types described herein with an alkene (preferably
ethylene), and one
or more fatty acid esters (preferably fatty acid methyl esters, preferably
methyl oleate).
In a preferred embodiment, this invention relates to a process to produce
alpha olefin
(preferably linear alpha olefin, preferably 1-decene, 1-heptene, and/or 1-
butene) comprising
contacting a metathesis catalyst of the types described herein with an alkene
(preferably
ethylene), and one or more fatty acid esters (preferably fatty acid methyl
esters, preferably
methyl oleate) derived from biodiesel.
In a preferred embodiment, the olefin metathesis catalysts described herein
may be
combined directly with triacylglycerides, biodiesel, fatty acids, fatty acid
esters, and/or fatty
acid alkyl esters to produce alpha-olefins, preferably linear alpha olefins,
preferably C4 to C24
alpha-olefins, preferably 1-decene, 1-heptene, and/or 1-butene.
In a preferred embodiment, a mixture of one or more triacylglyceride,
biodiesel, fatty
acids, and/or fatty acid esters is used to produce alpha-olefins, preferably
linear alpha olefins,
preferably C4 to C24 alpha-olefins, preferably C4 to C24 linear alpha-olefins.
In a preferred
embodiment, a mixture of alpha olefins, preferably linear alpha olefins,
preferably 1-decene,
1-heptene, and/or 1-butene is produced.
Metathesis Catalysts
This invention relates to an asymmetrically substituted NHC metathesis
catalyst
compound represented by the following formula:
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R5 R4
R6----)--E.R3
......,-
Ri N NV N -......_ R2
Xi........,
........--M K R8
' )_, R7
Formula (I)
where:
M is a Group 8 metal; preferably Ru or Os;
X1 and X2 are, independently, any anionic ligand, preferably a halogen (such
as chlorine or
bromine, preferably chlorine), an alkoxide or an alkyl sulfonate, or X1 and X2
may be joined
to form a dianionic group and may form a single ring of up to 30 non-hydrogen
atoms or a
multinuclear ring system of up to 30 non-hydrogen atoms;
L is a heteroatom or heteroatom-containing group; preferably the heteroatom is
N, 0, P, or S;
preferably P; optionally L may be joined to R7 and/or R8, preferably L is
L*(R)q_i when L is
not bound to R7 or R8 or L is L*(R)q_2 when L is bound to R7 or R8, where q is
1, 2, 3, or 4
depending on the valence of L* (which may be 2, 3, 4, or 5) and L* is N, 0, P,
or S,
preferably P and R is as defined for R3;
and R1, R2, R3, R4, R5, R6, R7, and R8 are, independently, hydrogen or a C1 to
C30
substituted or unsubstituted hydrocarbyl, preferably R1, R2, R3, R4, R5, R6,
R7, and R8 are
selected from the group consisting of methyl, ethyl, propyl butyl, hexyl,
octyl, nonyl, decyl,
undecyl, dodecyl, indenylene, substituted indenylene, phenyl, substituted
phenyl, and the
linear, branched and cyclic isomers thereof (including mesityl, 3,5,5-
trimethylhexyl,
cyclohexyl, methyl cyclohexyl, cyclododecyl, diisopropylphenyl, cyclopentyl,
and norbornyl;
wherein any two adjacent R groups may form a single ring of up to 8 non-
hydrogen atoms or
a multinuclear ring system of up to 30 non-hydrogen atoms;
and wherein R1 and R2 are dissimilar to each other.
Preferably, any two adjacent R groups may form a fused ring having from 5 to 8
non-
hydrogen atoms. Preferably, the non-hydrogen atoms are C and/or O. Preferably,
the
adjacent R groups form fused rings of 5 to 6 ring atoms, preferably 5 to 6
carbon atoms. By
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adjacent is meant any two R groups located next to each other, for example R7
and Rg, can
form a ring.
For purposes of this invention and claims thereto, a "Group 8 metal" is an
element
from Group 8 of the Periodic Table, as referenced by the IUPAC in Nomenclature
of
Inorganic Chemistry: Recommendations, G.J. Leigh, Editor, Blackwell Scientific
Publications, 1990.
For purposes of this invention and claims thereto, a "substituted hydrocarbyl"
is a
radical made of carbon and hydrogen where at least one hydrogen is replaced by
a heteroatom.
For purposes of this invention and claims thereto, a "substituted alkyl or
aryl" group is a
radical made of carbon and hydrogen where at least one hydrogen is replaced by
a heteroatom
or a linear, branched, or cyclic substituted or unsubstituted hydrocarbyl
group having 1 to 30
carbon atoms.
For purposes of this invention and claims thereto, "alkoxides" include those
where the
alkyl group is a C1 to Ci 0 hydrocarbyl. The alkyl group may be straight chain
or branched.
Preferred alkoxides include a C1 to C10 alkyl group, preferably methyl, ethyl,
propyl, butyl,
or isopropyl. Preferred alkoxides include those where the alkyl group is a
phenol, substituted
phenol (where the phenol may be substituted with up to 1, 2, 3, 4, or 5 C1 to
C12 hydrocarbyl
groups) or a C1 to C10 hydrocarbyl, preferably a C1 to C10 alkyl group,
preferably methyl,
ethyl, propyl, butyl, or phenyl.
Preferred alkyl sulfonates are represented by the Formula (II):
R9
0 = S-0-
11
0
Formula (II)
where R9 is a C1 to C30 hydrocarbyl group, fluoro-substituted hydrocarbyl
group, chloro-
substituted hydrocarbyl group, aryl group, or substituted aryl group,
preferably a C1 to C12
alkyl or aryl group, preferably trifluoromethyl, methyl, phenyl, or para-
methyl-phenyl.
In all embodiments herein, the invention relates to asymmetrically substituted
NHC
metathesis catalyst compounds wherein R1 and R2 are dissimilar to each other,
causing
asymmetry in the NHC ligand. For purposes of this invention and the claims
thereto,
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dissimilar means that R1 and R2 differ by at least 1 non-hydrogen atom
(preferably by at least
2, preferably at least 3, preferably by at least 4, preferably by at least 5
non-hydrogen atoms)
or if R1 and R2 have the same number of non-hydrogen atoms, then they differ
in structure or
saturation, e.g., if one is cyclic then the other is linear; or if one is
linear then the other is
branched; or if one is saturated (such as cyclohexyl) then the other is
aromatic (such as
phenyl), etc. In particular embodiments, where R1 and R2 are dissimilar to
each other, R1 is
an aromatic group, preferably phenyl, substituted phenyl, indenylenes, and
substituted
indenylenes; and R2 is an aliphatic group, preferably methyl, ethyl, propyl,
isopropyl, butyl,
tert-butyl, pentyl, hexyl, cyclohexyl, cyclohexylmethyl, and so on. For
example, in some
embodiments, R1 is a mesityl group and R2 is a methyl group. In another
embodiment, R1 is
a 2,6-diisopropylphenyl group and R2 is a cyclohexylmethyl group. In yet
another
embodiment, R1 is a 2,6-diisopropylphenyl group and R2 is a propyl group. In
alternate
embodiments, when R7 and R8 form an unsubstituted phenyl group and R1 is
mesityl, then R2
is not methyl or ethyl, preferably R2 is hydrogen or C1 to C30 substituted
hydrocarbyl, or a C3
to C30 unsubstituted hydrocarbyl (preferably a C4 to C30 unsubstituted
hydrocarbyl,
preferably a C5 to C30 unsubstituted hydrocarbyl, preferably a C6 to C30
unsubstituted
hydrocarbyl). In a preferred embodiment, both R1 and R2 are a C3 to C30
unsubstituted or
substituted hydrocarbyl (preferably a C4 to C30 unsubstituted or substituted
hydrocarbyl,
preferably a C5 to C30 unsubstituted or substituted hydrocarbyl, preferably a
C6 to C30
unsubstituted or substituted hydrocarbyl). In another embodiment, one of R1
and R2 is
aromatic (such as phenyl, mesityl, cyclopentyl, indenyl, norbornyl) and the
other is a C3 to
C30 unsubstituted or substituted hydrocarbyl (preferably a C4 to C30
unsubstituted or
substituted hydrocarbyl, preferably a C5 to C30 unsubstituted or substituted
hydrocarbyl,
preferably a C6 to C30 unsubstituted or substituted hydrocarbyl).
In particular embodiments, the invention relates to asymmetrically substituted
NHC
metathesis catalyst compounds wherein R7 or R8 is not joined to L. In
preferred
embodiments, R7 or R8 is at least one of a phenyl, substituted phenyl,
indenylene, and
substituted indenylene group. For example, catalysts of the type below in
Formula (III),
where R7 is not joined to L, where each G is independently, hydrogen, halogen,
or C1-C30
substituted or unsubstituted hydrocarbyl, and R1 and R2 are dissimilar to each
other are
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particularly useful herein. In a preferred embodiment, this invention relates
to a compound
represented by the formula:
R5 R4
R6--) __ E-R3
N
R2
R8
X1///4
M
X2 I
Formula (III)
where M, X1, X2, L, R1, R2, R3, R4, R5, R6, and R8 are as defined in Formula
(I) and G is
independently, hydrogen, halogen, or C1-C30 substituted or unsubstituted
hydrocarbyl.
Preferably any two adjacent G groups may form a fused ring having from 5 to 8
non-
hydrogen atoms. Preferably the non-hydrogen atoms are C and/or O. Preferably
the adjacent
G groups form fused rings of 5 to 6 ring atoms, preferably 5 to 6 carbon
atoms.
In other particular embodiments, R7 and R8 are fused such that the C(R7)(R8)
group is
a benzylidene, substituted benzylidene, indenylene, or substituted indenylene.
Even more particularly, a catalyst useful herein is (1-mesity1-3-methy1-2H-4,5-
dihydroimidazol-2 -ylidene)(tricyc lohexylpho sphine)-3 -phenyl- 1H-inden-1 -
ylidene ruthenium
(II) dichloride, shown below in Formula (IV), wherein R1 is a mesityl group,
R2 is a methyl
group, R7 and R8 are fused to form a phenyl-substituted indenylene group which
does not
join to L, L is a tricyclohexylphosphine group (represented as PCy3), and X1
and X2 are
chloride groups. Ph = phenyl.
NN
U%Ru .140
PCy3 Ph
Formula (IV)
In other particular embodiments, the invention relates to asymmetrically
substituted
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NHC metathesis catalyst compounds wherein a heteroatom of R7 or R8 is also
joined to L, as
represented below in Formula (V). In a preferred embodiment, this invention
relates to a
compound represented by the formula:
R5 R4
R6 -H------ R3
_....--.....,
R rN N NZ R2
X i .....
R8
v
yx2
L-....., ,
R' .
Formula (V)
where M, X1, X2, L, R1, R2, R3, R4, R5, R6, R7, and R8 are as defined in
Formula (I). In
preferred embodiments, R7 or R8 is at least one of a phenyl, substituted
phenyl, indenylene,
and substituted indenylene group. For example, catalysts of the type below in
Formula (VI),
where R7 is a phenyl group joined to L, where each G is independently,
hydrogen, halogen, or
C1-C30 substituted or unsubstituted hydrocarbyl, and R1 and R2 are dissimilar
to each other
are particularly useful herein.
R5
R4
R6 ----) _____________________________ (----- R3
_..---...õ
R rN N R2
R8
X i %.,,,,, G
'
...----
'M
X2 1
L 111
G G G
Formula (VI)
where M, X1, X2, L, R1, R2, R3, R4, R5, R6, and R8 are as defined in Formula
(I) and G is
independently, hydrogen, halogen, or C1-C30 substituted or unsubstituted
hydrocarbyl.
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Preferably any two adjacent G groups may form a fused ring having from 5 to 8
non-
hydrogen atoms. Preferably the non-hydrogen atoms are C and/or O. Preferably
the adjacent
G groups form fused rings of 5 to 6 ring atoms, preferably 5 to 6 carbon
atoms.
In other preferred embodiments, R7 and R8 are fused to form an indenylene
group
which is joined to L as shown in Formula (VII) below:
R6 _______________________________
R5 R4
H---- R3
RiN N ----R2
NV G
G
M," _116p
X2
L =G
G G
Formula (VII)
where M, X1, X2, L, R1, R2, R3, R4, R5, and R6 are as defined in Formula (I)
and G is
independently, hydrogen, halogen, or C1-C30 substituted or unsubstituted
hydrocarbyl.
Preferably any two adjacent G groups may form a fused ring having from 5 to 8
non-
hydrogen atoms. Preferably the non-hydrogen atoms are C and/or O. Preferably
the adjacent
G groups form fused rings of 5 to 6 ring atoms, preferably 5 to 6 carbon
atoms.
Even more particularly, a catalyst useful herein is 2-(i-propoxy)-5-(N,N-
dimethylaminosulfonyl)phenylmethylene(1-
cyclohexylmethy1-3 -(2 ,6- diisopropylpheny1)-
4,5-dihydro-1H-imidazole) ruthenium (II) chloride, shown below in Formula
(VIII), wherein
R1 is a 2,6-diisopropylphenyl group, R2 is a cyclohexylmethyl group, R7 is a
dimethylaminosulfonyl-substituted phenyl group which joins to L, L is an
isopropoxy group,
and X1 and X2 are chloride groups.
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/ ______________________________________ \
N J
C=j0 O
Clo=--Ru
¨
C I `"ss I
A =
SO2N(CH3)2
Formula (VIII)
Preferred metathesis catalysts useful herein include: 2-(i-propoxy)-5-(N,N-
dimethyl-
amino sulfonyl)phenylmethylene(1 - cyclohexylmethy1-3 -(2,6-diisopropylpheny1)-
4,5 -dihydro-
1H-imidazo le) ruthenium (II) chloride, (1 -mesity1-3 -methy1-2H-4,5 -
dihydroimidazol-2-
ylidene)(tricyclohexylpho sphine)-3 -phenyl-1H-inden-1 -ylidene ruthenium (II)
dichloride, and
mixtures thereof
The catalyst compounds described herein may be synthesized as follows. The NHC
precursor, as the imidazolium salt, can be synthesized as known in the art.
For example, 2,6-
diisopropylaniline (R1) is reacted with 2-bromoethylamine hydrobromide at
reflux for four
days. The resulting diamine is condensed with a suitable reagent such as
cyclohexylcarboxaldehyde (R2) to give the imine. The resulting imine is
reduced to the
corresponding diamine using any suitable reducing agent, such as sodium
borohydride.
Treatment with triethyl formate and ammonium chloride yields the imidazolium
salt. The
imidazolium salt upon deprotonation with the appropriate base such as lithium
bis(trimethylsilyl)amide generates the NHC ligand. This carbene can be reacted
with
ruthenium alkylidene complexes such as 2-(i-propoxy)-5-(N,N-dimethyl-
aminosulfonyl)phenylmethylene(tricyclohexylphosphine) ruthenium dichloride to
generate
the asymmetrically substituted NHC ruthenium complex, 2-(i-propoxy)-5-(N,N-
dimethyl-
amino sulfonyl)phenylmethylene(1 -cyclohexylmethy1-3 -(2,6-diisopropylpheny1)-
4,5 -dihydro-
1H-imidazole) ruthenium (II) chloride.
The resulting ruthenium alkylidene complex is an efficient catalyst or
catalyst
precursor towards for the cross-metathesis of ethylene and methyl oleate, a
component of
biodiesel, to generate with good selectivity 1-decene and methyl-9-decenoate.
Process
In a preferred embodiment, the metathesis catalysts described herein may be
combined directly with feed oils, seed oils, triacylglycerides, biodiesel,
fatty acids, fatty acid
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esters and/or fatty acid alkyl esters ("feed materials") to produce alpha-
olefins, preferably
linear alpha olefins, preferably C4 to C24 alpha-olefins, preferably C4 to C24
linear alpha-
olefins, such as preferably 1-decene, 1-heptene, and/or 1-butene.
Typically, the molar ratio of alkene to unsaturated feed material (such as
unsaturated
fatty acid or fatty acid ester) is greater than about 0.8/1.0, preferably,
greater than about
0.9/1Ø Typically, the molar ratio of alkene to feed material (such as
unsaturated fatty acid or
fatty acid ester) is less than about 3.0/1.0, preferably, less than about
2.0/1Ø Depending
upon the specific reagents, other molar ratios may also be suitable. With
ethylene, for
example, a significantly higher molar ratio can be used, because the self-
metathesis of
ethylene produces only ethylene again; no undesirable co-product olefins are
formed.
Accordingly, the molar ratio of ethylene to feed material (such as unsaturated
fatty acid or
fatty acid ester) may range from greater than about 0.8/1 to typically less
than about 20/1.
The quantity of metathesis catalyst that is employed in the process of this
invention is
any quantity that provides for an operable metathesis reaction. Preferably,
the ratio of moles
of feed material (preferably fatty acid ester and/or fatty acid alkyl ester)
to moles of
metathesis catalyst is typically greater than about 10:1, preferably greater
than about 100:1,
preferably greater than about 1000:1, preferably greater than about 10,000:1,
preferably
greater than about 25,000:1, preferably greater than about 50,000:1,
preferably greater than
about 100,000:1. Alternately, the molar ratio of feed material (preferably
fatty acid ester
and/or fatty acid alkyl ester) to metathesis catalyst is typically less than
about 10,000,000:1,
preferably less than about 1,000,000:1, and more preferably less than about
500,000:1.
The contacting time of the reagents and catalyst in a batch reactor can be any
duration,
provided that the desired olefin metathesis products are obtained. Generally,
the contacting
time in a reactor is greater than about 5 minutes, and preferably greater than
about 10 minutes.
Generally, the contacting time in a reactor is less than about 25 hours,
preferably less than
about 15 hours, and more preferably less than about 10 hours.
In a preferred embodiment, the reactants (for example, metathesis catalyst;
feed
materials; optional alkene, optional alcohol, optional water, etc.) are
combined in a reaction
vessel at a temperature of 20 to 300 C (preferably 20 to 200 C, preferably 30
to 100 C,
preferably 40 to 60 C) and an alkene (such as ethylene) at a pressure of 0.1
to 1000 psi (0.7
kPa to 6.9 MPa), preferably 20 to 400 psi (0.14 MPa to 2.8MPa), preferably 50
to 250 psi
(0.34 MPa to 1.7MPa), if the alkene is present, for a residence time of 0.5
seconds to 48 hours
(preferably 0.25 to 5 hours, preferably 30 minutes to 2 hours).
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In certain embodiments, where the alkene is a gaseous olefin, the olefin
pressure is
greater than about 5 psig (34.5 kPa), preferably, greater than about 10 psig
(68.9 kPa), and
more preferably, greater than about 45 psig (310 kPa). When a diluent is used
with the
gaseous alkene, the aforementioned pressure ranges may also be suitably
employed as the
total pressure of olefin and diluent. Likewise, when a liquid alkene is
employed and the
process is conducted under an inert gaseous atmosphere, then the
aforementioned pressure
ranges may be suitably employed for the inert gas pressure.
In a preferred embodiment, from about 0.005 nmoles to about 500 nmoles,
preferably
from about 0.1 to about 250 nmoles, and most preferably from about 1 to about
50 nmoles of
the metathesis catalyst are charged to the reactor per 3 mmoles of feed
material (such as
TAGs, biodiesel, fatty acids, fatty acid esters, and/or fatty acid alkyl
esters or mixtures
thereof, preferably fatty acid esters) charged.
In a preferred embodiment, the process is typically a solution process,
although it may
be a bulk or high pressure process. Homogeneous processes are preferred. (A
homogeneous
process is defined to be a process where at least 90 wt% of the product is
soluble in the
reaction media.) A bulk homogeneous process is particularly preferred. (A bulk
process is
defined to be a process where reactant concentration in all feeds to the
reactor is 70 volume %
or more.) Alternately, no solvent or diluent is present or added in the
reaction medium,
(except for the small amounts used as the carrier for the catalyst or other
additives, or
amounts typically found with the reactants, e.g., propane in propylene).
Suitable diluents/solvents for the process include non-coordinating, inert
liquids.
Examples include straight and branched-chain hydrocarbons such as isobutane,
butane,
pentane, isopentane, hexanes, isohexane, heptane, octane, dodecane, and
mixtures thereof;
cyclic and alicyclic hydrocarbons such as cyclohexane, cycloheptane,
methylcyclohexane,
methylcycloheptane, and mixtures thereof such as can be found commercially
(IsoparTm);
perhalogenated hydrocarbons such as perfluorinated C4_10 alkanes,
chlorobenzene, and
aromatic and alkylsubstituted aromatic compounds such as benzene, toluene,
mesitylene, and
xylene. Suitable diluents/solvents also include aromatic hydrocarbons, such as
toluene or
xylenes, and chlorinated solvents, such as dichloromethane. In a preferred
embodiment, the
feed concentration for the process is 60 volume % solvent or less, preferably
40 volume % or
less, preferably 20 volume % or less.
The process may be batch, semi-batch or continuous. As used herein, the term
continuous means a system that operates without interruption or cessation. For
example, a
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continuous process to produce a polymer would be one where the reactants are
continually
introduced into one or more reactors and polymer product is continually
withdrawn.
Useful reaction vessels include reactors (including continuous stirred tank
reactors,
batch reactors, reactive extruder, pipe, or pump.
The processes may be conducted in either glass lined, stainless steel, or
similar type
reaction equipment. Useful reaction vessels include reactors (including
continuous stirred
tank reactors, batch reactors, reactive extruder, pipe, or pump, continuous
flow fixed bed
reactors, slurry reactors, fluidized bed reactors, and catalytic distillation
reactors). The
reaction zone may be fitted with one or more internal and/or external heat
exchanger(s) in
order to control undue temperature fluctuations, or to prevent "runaway"
reaction
temperatures.
If the process is conducted in a continuous flow reactor, then the weight
hourly space
velocity, given in units of grams feed material (preferably fatty acid ester
and/or fatty acid
alkyl ester) per gram catalyst per hour (h-1), will determine the relative
quantities of feed
material to catalyst employed, as well as the residence time in the reactor of
the unsaturated
starting compound. In a flow reactor, the weight hourly space velocity of the
unsaturated
feed material (preferably fatty acid ester and/or fatty acid alkyl ester) is
typically greater than
about 0.04 g feed material (preferably fatty acid ester and/or fatty acid
alkyl ester) per g
catalyst per hour (h-1), and preferably, greater than about 0.1 h-1. In a flow
reactor, the
weight hourly space velocity of the feed material (preferably fatty acid ester
and/or fatty acid
alkyl ester) is typically less than about 100 h-1, and preferably, less than
about 20 h-1.
In certain embodiments, reactions utilizing the catalytic complexes of the
present
invention can be run in a biphasic mixture of solvents, in an emulsion or
suspension, or in a
lipid vesicle or bilayer.
The feed material is typically provided as a liquid phase, preferably neat. In
particular
embodiments, the feed material is provided in a liquid phase, preferably neat;
while the
alkene is provided as a gas that is dissolved in the liquid phase. In certain
embodiments, feed
material is an unsaturated fatty acid ester or unsaturated fatty acid and is
provided in a liquid
phase, preferably neat; while the alkene is a gaseous alpha-olefin, such as
for example,
ethylene, which is dissolved in the liquid phase.
Generally, the feed material is an unsaturated fatty acid ester or unsaturated
fatty acid
and is provided as a liquid at the process temperature, and it is generally
preferred to be used
neat, that is, without a diluent or solvent. The use of a solvent usually
increases recycle
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requirements and increases costs. Optionally, however, if desired, a solvent
can be employed
with the alkene and/or feed material. A solvent may be desirable, for
instance, where liquid
feed material and alkene are not entirely miscible, and both then can be
solubilized in a
suitable solvent.
In a preferred embodiment, the alkene and an unsaturated fatty acid ester or
unsaturated fatty acid are co-metathesized to form first and second product
olefins, preferably,
a reduced chain first product alpha-olefin and a second product reduced chain
terminal ester
or acid-functionalized alpha-olefin. As a preferred example, the metathesis of
methyloleate
with ethylene will yield cross-metathesis products of 1-decene and methyl-9-
decenoate. Both
products are alpha-olefins; the decenoate also terminates in an ester moiety
at the opposite
end of the chain from the carbon-carbon double bond. In addition to the
desired products, the
methyloleate may self-metathesize to produce small amounts of 9-octadecene, a
less desirable
product, and dimethy1-9-octadecene-1,18-dioate, CH30C(0) (CH2)7CH=CH(CH2)
7C(0)0
CH3, a second less desirable product.
In the process of this invention, the conversion of feed material (preferably
fatty acid
ester and/or fatty acid alkyl ester) can vary widely depending upon the
specific reagent
olefins, the specific catalyst, and specific process conditions employed. For
the purpose of
this invention, "conversion" is defined as the mole percentage of feed
material that is
converted or reacted to the cross-metathesis alpha-olefin products. Typically,
the conversion
of feed material (preferably fatty acid ester and/or fatty acid alkyl ester)
is greater than about
50 mole %, preferably, greater than about 60 mole %, and more preferably,
greater than about
70 mole %.
In the process of this invention, the yields of first product olefin and ester
or acid-
functionalized second product olefin can also vary depending upon the specific
reagent
olefins, catalyst, and process conditions employed. For the purposes of this
invention "yield"
will be defined as the mole percentage of cross-metathesis alpha-olefin
product olefin formed
relative to the initial moles of feed material (such as fatty acid ester
and/or fatty acid alkyl
ester) in the feed. Typically, the yield of alpha-olefin will be greater than
about 35 mole %,
preferably, greater than about 50 mole %. Typically, the yield of ester or
acid-functionalized
alpha-olefin will be 30% or more, preferably 40% or more, preferably 45% or
more,
preferably 50% or more, preferably 55% or more, preferably 60% or more.
In a preferred embodiment, the yield for reactions (when converting TAGs as
represented in the formula below), is defined as the moles of alpha olefin
formed divided by
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(the moles of unsaturated Ra + moles of unsaturated Rb + moles of unsaturated
RC) introduced
into the reactor is 30% or more, preferably 40% or more, preferably 45% or
more, preferably
50% or more, preferably 55% or more, preferably 60% or more.
0
II
H2C ¨ 0 ¨ C¨ Ra
0
ii
HC ¨O ¨ C¨ Rb
1 0
ii
H2C ¨ 0 ¨ C¨ Re
where Ra, Rb, and RC each, independently, represent a saturated or unsaturated
hydrocarbon
chain (preferably Ra, Rb, and RC each, independently, are a C12 to C28 alkyl
or alkene,
preferably C16 to C22 alkyl or alkene).
For the purposes of this invention, "productivity" is defined to be the amount
in grams
of linear alpha-olefin produced per mmol of catalyst introduced into the
reactor, per hour. In
a preferred embodiment, the productivity of the process is at least 200 g of
linear alpha-olefin
(such as decene-1) per mmol of catalyst per hour, preferably at least 5000
g/mmol/hour,
preferably at least 10,000 g/mmol/hour, preferably at least 300,000
g/mmol/hour.
For the purposes of this invention, "selectivity" is a measure of conversion
of alkene
and feed material to the cross-metathesis alpha-olefin product, and is defined
by the mole
percentage of product olefin formed relative to the initial moles of alkene or
feed material. In
a preferred embodiment, the selectivity of the process is at least 20 wt%
linear alpha-olefin,
based upon the weight to the material exiting the reactor, preferably at least
25 wt%,
preferably at least 30 wt%, preferably at least 35 wt%, preferably at least 40
wt%, preferably
at least 45 wt%, preferably at least 50 wt%, preferably at least 60 wt%,
preferably at least 70
wt%, preferably at least 80 wt%, preferably at least 85 wt%, preferably at
least 90 wt%,
preferably at least wt95%.
For the purpose of this invention, "catalyst turnover number" (TON) is a
measure of
how active the catalyst compound is and is defined as the number of moles of
cross-
metathesis alpha-olefin product formed per mole of catalyst compound. In a
preferred
embodiment, the (TON), of the process is at least 5,000, preferably at least
10,000, preferably
at least 50,000, preferably at least 100,000, preferably at least 1,000,000.
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Feed Materials
Feed materials useful in metathesis processes described herein include feed
oils, fatty
acids, fatty acid esters, triacylglycerides, and biodiesel.
Feed Oils
The fatty acid rich material useful in the processes described herein can be
derived
from plant, animal, microbial, or other sources (feed oil). Preferred feed
oils include
vegetable oils such as corn, soy, rapeseed, canola, sunflower, palm and other
oils that are
readily available; however, any vegetable oil or animal fat can be employed.
Raw or
unrefined oil can be used in certain embodiments; however, filtered and
refined oils are
typically preferred. Use of degummed and filtered feedstock minimizes the
potential for
emulsification and blockage in the reactors. Feedstock with high water content
can be dried
before basic catalyst processing. Feedstock with high free fatty acid content
can be passed
through an esterification process to reduce the free fatty acid content before
the process of
esterification to convert fatty acid glycerides to monoalkyl esters. The
reduction of free fatty
acids and the conversion of fatty acid glycerides can also in the same
processing step.
Feedstock containing other organic compounds (such as hexane, heptane,
isohexane, etc.) can
typically be processed without significant modifications to the reactor. Other
materials
containing fatty acid glycerides or other fatty acid esters can also be
employed, including
phospholipids, lysophospholipids, and fatty acid wax esters. The fatty acid
rich material
useful in the processes described herein typically includes a mixture of fatty
acids. For
example, the fatty acid profiles of several potential feedstocks are shown in
Table 1. The
feed oil can also include a mixture of fatty acid glycerides from different
sources. The free
fatty acid content of useful vegetable oils is preferably about 0.1 wt% or
less when employed
in a basic homogeneous catalyst esterification reaction. Higher levels can be
utilized as well,
and levels up to about 3 wt%, or even as high as 15 wt% or more can typically
be tolerated.
For purposes of this invention and the claims thereto the term "feed oil"
refers to one
or more vegetable or animal oils, such as canola oil, corn oil, soybean oil,
beef tallow, tall oil,
animal fats, waste oils/greases, rapeseed oil, algae oil, peanut oil, mustard
oil, sunflower oil,
tung oil, perilla oil, grapeseed oil, linseed oil, safflower oil, pumpkin oil,
palm oil, Jathropa
oil, high-oleic soybean oil, high-oleic safflower oil, high-oleic sunflower
oil, mixtures of
animal and/or vegetable fats and oils, castor bean oil, dehydrated castor bean
oil, cucumber
oil, poppyseed oil, flaxseed oil, lesquerella oil, walnut oil, cottonseed oil,
meadowfoam, tuna
oil, and sesame oils.
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Vegetable oils useful herein preferably contain at least one site of
unsaturation and
include, but are not limited to, canola, soybean, palm, peanut, mustard,
sunflower, tung, tall,
perilla, grapeseed, rapeseed, linseed, safflower, pumpkin corn and other oils
extracted from
plant seeds.
In a preferred embodiment, a combination of oils is used herein. Preferred
combinations include two (three or four) or more of tall oil, palm oil,
tallow, waste grease,
rapeseed oil, canola oil, soy oil and algae oil. Alternate useful combinations
include two
(three or four) or more of soy oil, canola oil, rapeseed oil, algae oil, and
tallow.
In certain embodiments, processed oils, such as blown oils, are the source of
fatty
acids useful herein. While vegetable oils are preferred sources of fatty acids
for practicing
disclosed embodiments of the present process, fatty acids also are available
from animal fats
including, without limitation, lard and fish oils, such as sardine oil and
herring oil, and the
like. As noted above, in certain embodiments, a desired fatty acid or fatty
acid precursor is
produced by a plant or animal found in nature. However, particular fatty acids
or fatty acid
precursors are advantageously available from genetically modified organisms,
such as a
genetically modified plants, particularly genetically modified algae. Such
genetically
modified organisms are designed to produce a desired fatty acid or fatty acid
precursor
biosynthetically or to produce increased amounts of such compounds.
TABLE 1
Fatty Acid Profile of Several Typical Feed Oils
Fatty Acid Palm Oil Soy Oil High Oleic Rapeseed Yellow Grease
0 wt% 0 wt% 0 wt% 0 wt%
C6:0 0 wt% 0 wt% 0 wt% 0 wt%
C8:0 0 wt% 0 wt% 0 wt% 0 wt%
C10:0 0 wt% 0 wt% 0 wt% 0 wt%
C12 :0 0 wt% 0 wt% 0 wt% 0 wt%
C14 :0 1 wt% 0 wt% 0 wt% 2 wt%
C16:0 44 wt% 7 wt% 4 wt% 23 wt%
C18:0 5 wt% 5 wt% 1 wt% 13 wt%
C18:1 39 wt% 28 wt% 60 wt% 44 wt%
C18:2 10 wt% 53 wt% 21 wt% 7 wt%
C18:3 0 wt% 0 wt% 13 wt% 1 wt%
C20:0 0 wt% 0 wt% 0 wt% 0 wt%
C22:1 0 wt% 0 wt% 0 wt% 0 wt%
Misc. 1 wt% 8 wt% 0 wt% 9 wt%
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Fatty Acids and Fatty Acid Esters
Fatty acids are carboxylic acids with a saturated or unsaturated aliphatic
tails that are
found naturally in many different fats and oils. Any unsaturated fatty acid
can be suitably
employed in the process of this invention, provided that the unsaturated fatty
acid can be
metathesized in the manner disclosed herein. An unsaturated fatty acid
comprises a long
carbon chain containing at least one carbon-carbon double bond and terminating
in a
carboxylic acid group. Typically, the unsaturated fatty acid will contain
greater than about 8
carbon atoms, preferably, greater than about 10 carbon atoms, and more
preferably, greater
than about 12 carbon atoms. Typically, the unsaturated fatty acid will contain
less than about
50 carbon atoms, preferably, less than about 35 carbon atoms, and more
preferably, less than
about 25 carbon atoms. At least one carbon-carbon double bond is present along
the carbon
chain, this double bond usually occurring about the middle of the chain, but
not necessarily.
The carbon-carbon double bond may also occur at any other internal location
along the chain.
A terminal carbon-carbon double bond, at the opposite end of the carbon chain
relative to the
terminal carboxylic acid group, is also suitably employed, although terminal
carbon-carbon
double bonds occur less commonly in fatty acids. Unsaturated fatty acids
containing the
terminal carboxylic acid functionality and two or more carbon-carbon double
bonds may also
be suitably employed in the process of this invention.
Because metathesis can occur at any of the carbon-carbon double bonds, a fatty
acid
having more than one double bond may produce a variety of metathesis products.
The
unsaturated fatty acid may be straight or branched and substituted along the
fatty acid chain
with one or more substituents, provided that the one or more substituents are
substantially
inert with respect to the metathesis process. Non-limiting examples of
suitable substituents
include alkyl moieties, preferably C1_10 alkyl moieties, including, for
example, methyl, ethyl,
propyl, butyl, and the like; cycloalkyl moieties, preferably, C4_8 cycloalkyl
moieties,
including for example, cyclopentyl and cyclohexyl; monocyclic aromatic
moieties, preferably,
C6 aromatic moieties, that is, phenyl; arylalkyl moieties, preferably, C7_16
arylalkyl moieties,
including, for example, benzyl; and alkylaryl moieties, preferably, C7_16
alkylaryl moieties,
including, for example, tolyl, ethylphenyl, xylyl, and the like; as well as
hydroxyl, ether, keto,
aldehyde, and halide, preferably, chloro and bromo, functionalities.
Non-limiting examples of suitable unsaturated fatty acids include 3-hexenoic
(hydrosorbic), trans-2-heptenoic, 2-octenoic, 2-nonenoic, cis-and trans-4-
decenoic, 9-
decenoic (caproleic), 10-undecenoic (undecylenic), trans-3-dodecenoic
(linderic), tridecenoic,
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cis-9-tetradeceonic (myristoleic), pentadecenoic, cis-9-hexadecenoic (cis-9-
palmitoelic),
trans-9-hexadecenoic (trans-9-palmitoleic), 9-heptadecenoic,
cis-6-octadecenoic
(petroselinic), trans-6-octadecenoic (petroselaidic), cis-9-octadecenoic
(oleic), trans-9-
o ctade cenoic (elaidic), cis- 11 -o ctadecenoic, trans- 11 -o ctadecenoic
(vaccenic), cis-5 -
eicosenoic, cis-9-eicosenoic (gadoleic), cis-11-docosenoic (cetoleic), cis-13-
docosenoic
(erucic), trans- 13 -docosenoic (brassidic), cis- 15 -tetracosenoic
(selacholeic), cis- 17-
hexacosenoic (ximenic), and cis-21-triacontenoic (lumequeic) acids, as well as
2,4-
hexadienoic (sorbic), cis-9-cis-12-octadecadienoic (lino leic),
cis-9-cis-12 -cis-15 -
octadecatrienoic (linolenic), eleostearic, 12-hydroxy-cis-9-octadecenoic
(ricinoleic), and like
acids. Oleic acid is most preferred. Unsaturated fatty acids can be obtained
commercially or
synthesized by saponifying fatty acid esters, this method being known to those
skilled in the
art.
Fatty acid esters are formed by condensation of a fatty acid and an alcohol.
Fatty acid
alkyl esters are fatty acids where the hydrogen of the -OH of the acid group
is replaced by a
hydrocarbyl group, typically a C1 to C30 alkyl group, preferably a C1 to C20
alkyl.
Fatty acid alkyl esters are fatty acids where the hydrogen of the -OH of the
acid group
is replaced by an alkyl group. Fatty acid alkyl esters useful herein are
typically represented
by the formula: RA-C(0)-0-R*, where RA is a C1 to C100 hydrocarbyl group,
preferably a C6
to C22 group, preferably a C6 to C14 1-alkene group, and R* is an alkyl group,
preferably a
C1 to C20 alkyl group, preferably methyl, ethyl, butyl, pentyl and hexyl.
Preferred fatty acid
alkyl esters useful herein are typically represented by the formula: RA-
CH2=CH2-RA-C(0)-
0-R*, where each RA is, independently a C1 to C100 alkyl group, preferably a
C6 to C20,
preferably a C8 to C14 alkyl group, preferably a C9 group and R* is an alkyl
group, preferably
a C1 to C20 alkyl group, preferably methyl, ethyl, butyl, pentyl and hexyl.
Particularly
preferred fatty acid alkyl esters useful herein are represented by the
formula:
CH3-(CH2)n-C=C-(CH2)m-C(0)-0-R*,
where and R* is an alkyl group, preferably a C1 to C20 alkyl group, preferably
methyl, ethyl,
butyl pentyl and hexyl, m and n are, independently 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14,
15, or 16, preferably 5, 7, 9, or 11, preferably 7.
Fatty acid methyl esters are fatty acids where the hydrogen of the -OH of the
acid
group is replaced by methyl group. Fatty acid methyl esters useful herein are
typically
represented by the formula: RA-C(0)-0-CH3, where RA is a C1 to C100
hydrocarbyl group,
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preferably a C6 to C22 group, preferably a C6 to C14 1-alkene group. Preferred
fatty acid
methyl esters useful herein are typically represented by the formula: RA-
CH2=CH2-RA-C(0)-
0-CH3, where each RA is, independently a C1 to C100 alkyl group, preferably a
C6 to C20,
preferably a C8 to C14 alkyl group, preferably a C9 group. Particularly
preferred fatty acid
methyl esters useful herein are represented by the formula: CH3-(CH2)n-C=C-
(CH2)m-C(0)-
0-CH3, where m and n are, independently 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, or 16,
preferably 5, 7, 9, or 11, preferably 7.
Preferred fatty acid methyl esters include methyl palmitoleate, methyl oleate,
methyl
gadoleate, methyl erucate, methyl linoleate, methyl linolenate, methyl soyate,
and mixtures of
methyl esters derived from soybean oil, beef tallow, tall oil, animal fats,
waste oils/greases,
rapeseed oil, algae oil, Canola oil, palm oil, Jathropa oil, high-oleic
soybean oil (e.g., 75
mole % or more, preferably 85 mole % or more, preferably 90 mole % or more),
high-oleic
safflower oil (e.g., 75 mole % or more, preferably 85 mole % or more,
preferably 90 mole %
or more), high-oleic sunflower oil (e.g., 75 mole % or more, preferably 85
mole % or more,
preferably 90 mole % or more), and other plant or animal derived sources
containing fatty
acids.
Alcohol (also referred to as Alkanols)
Fatty acid esters are formed by condensation of a fatty acid and an alcohol.
The
alcohol used herein can be any monohydric, dihydric, or polyhydric alcohol
that is capable of
condensing with the feed material (such as the unsaturated fatty acid) to form
the
corresponding unsaturated ester (such as the fatty acid ester). Typically, the
alcohol contains
at least one carbon atom. Typically, the alcohol contains less than about 20
carbon atoms,
preferably, less than about 12 carbon atoms, and more preferably, less than
about 8 carbon
atoms. The carbon atoms may be arranged in a straight-chain or branched
structure, and may
be substituted with a variety of substituents, such as those previously
disclosed hereinabove
in connection with the fatty acid, including the aforementioned alkyl,
cycloalkyl, monocyclic
aromatic, arylalkyl, alkylaryl, hydroxyl, halogen, ether, ester, aldehyde and
keto substituents.
Preferably, the alcohol is a straight-chain or a branched C1_12 alkanol. A
preferred alcohol is
the trihydric alcohol glycerol, the fatty acid esters of which are known as
"glycerides." Other
preferred alcohols include methanol and ethanol.
Preferably, the alcohol employed in the esterification and/or
transesterification
reactions is preferably a low molecular weight monohydric alcohol such as
methanol, ethanol,
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1-propanol, 2-propanol, 1-butanol, 2-butanol, or t-butanol. The alcohol is
preferably
anhydrous; however, a small amount of water in the alcohol may be present
(e.g., less than
about 2 wt%, preferably less than about 1 wt%, and most preferably less than
about 0.5 wt%;
however, in certain embodiments, higher amounts can be tolerated). Acid
esterification
reactions are more tolerant of the presence of small amounts of water in the
alcohol than are
basic transesterification reactions. While specific monohydric alcohols are
discussed herein
with reference to certain embodiments and examples, the preferred embodiments
are not
limited to such specific monohydric alcohols. Other suitable monohydric
alcohols can also
be employed in the preferred embodiments.
Preferred sources of fatty acid esters for use herein include TAGs and
biodiesel
sources.
Biodiesel
Biodiesel is a mono-alkyl ester derived from the processing of vegetable oils
and
alcohols. The processing is typically carried out by an esterification
reaction mechanism, and
typically is performed in an excess of alcohol to maximize conversion.
Esterification can
refer to direct esterification, such as between a free fatty acid and an
alcohol, as well as
transesterification, such as between an ester and an alcohol. While vegetable
oil and alcohols
are commonly employed as reactants in esterification reactions, a fatty acid
source such as
free fatty acids, soaps, esters, glycerides (mono-, di- tri-), phospholipids,
lysophospholipids,
or amides and a monohydric alcohol source, such as an alcohol or an ester, can
be esterified.
In addition, various combinations of these reagents can be employed in an
esterification
reaction.
Alkyl oleates and alkyl erucates are fatty acid esters that are often major
components
in biodiesel produced by the transesterification of alcohol and vegetable oils
(preferably the
alkyls are a C1 to C30 alkyl group, alternately a C1 to C20 alkyl group).
Biodiesel
compositions that are particularly useful in this invention are those which
have high
concentrations of alkyl oleate and alkyl erucate esters. These fatty acid
esters preferably have
one site of unsaturation such that cross-metathesis with ethylene yields 1-
decene as the
coproduct. Biodiesel compositions that are particularly useful are those
produced from
vegetable oils such as canola, rapeseed oil, palm oil, and other high oleate
oil, high erucate
oils. Particularly preferred vegetable oils include those having at least 50%
(on a molar basis)
combined oleic and erucic fatty acid chains of all fatty acid chains,
preferably 60%,
preferably 70%, preferably 80%, preferably 90%.
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In another embodiment, useful fatty acid ester containing mixtures include
those
having at least 50% (on a molar basis) alkyl oleate fatty acid esters,
preferably 60% of alkyl
oleate fatty acid esters, preferably 70% of alkyl oleate fatty acid esters,
preferably 80% of
alkyl oleate fatty acid esters, preferably 90% of alkyl oleate fatty acid
esters.
In another embodiment, useful fatty acid ester containing mixtures include
those
having at least 50% (on a molar basis) alkyl erucate fatty acid esters,
preferably 60% of alkyl
erucate fatty acid esters, preferably 70% of alkyl erucate fatty acid esters,
preferably 80% of
alkyl erucate fatty acid esters, preferably 90% of alkyl erucate fatty acid
esters.
In another embodiment, useful fatty acid ester containing mixtures include
those
having at least 50% (on a molar basis) combined oleic and erucic fatty acid
esters of all fatty
acid ester chains, preferably 60%, preferably 70%, preferably 80%, preferably
90%.
Triacylglycerides (TAGS)
Triacylglycerides (TAGs), also called triglycerides, are a naturally occurring
ester of
three fatty acids and glycerol that is the chief constituent of natural fats
and oils. The three
fatty acids can be all different, all the same, or only two the same, they can
be saturated or
unsaturated fatty acids, and the saturated fatty acids may have one or
multiple unsaturations.
Chain lengths of the fatty acids in naturally occurring triacylglycerides can
be of varying
lengths but 16, 18, and 20 carbons are the most common. Natural fatty acids
found in plants
and animals are typically composed only of even numbers of carbon atoms due to
the way
they are bio-synthesized. Most natural fats contain a complex mixture of
individual
triglycerides and because of this, they melt over a broad range of
temperatures.
Vegetable oils include triglycerides and neutral fats, such as
triacylglycerides, the
main energy storage form of fat in animals and plants. These typically have
the chemical
structure:
0
II
H2C ¨ 0 ¨ C¨ Ra
0
ii
HC ¨O ¨ C¨ Rb
1 0
ii
H2C ¨ 0 ¨ C¨ Re
where Ra, Rb, and RC each, independently, represent a saturated or non-
saturated hydrocarbon
chain (preferably Ra, Rb, and RC each, independently, are a C12 to C28 alkyl
or alkene,
preferably C16 to C22 alkyl or alkene). Different vegetable oils have
different fatty acid
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profiles, with the same or different fatty acids occurring on a single
glycerol. For example, an
oil can have linoleic, oleic, and stearic acids attached to the same glycerol,
with each of Ra,
Rb, and RC representing one of these three fatty acids. In another example,
there can be two
oleic acids and one stearic acid attached to the same glycerol, each of Ra,
Rb, and RC
representing one of these fatty acids. A particularly useful triglyceride
consists of three fatty
acids (e.g., saturated fatty acids of general structure of CH3(CH2)r,COOH,
wherein n is
typically an integer of from 4 to 28 or higher) attached to a glycerol
(C3H5(OH)3) backbone
by ester linkages.
Transesterification /Esterification Reactions
In the esterification process, vegetable oils and short chain alcohols are
reacted to
form mono-alkyl esters of the fatty acid and glycerol (also referred to as
glycerin). When the
alcohol used is methanol (CH3OH), a methyl ester is created with the general
form
CH3(CH2),-,COOCH3 for saturated fatty acids. Typically, but not always, the
length of the
carbon backbone chain is from 12 to 24 carbon atoms.
The esterification process can be catalyzed or non-catalyzed. Catalyzed
processes are
categorized into chemical and enzyme based processes. Chemical catalytic
methods can
employ acid and/or base catalyst mechanisms. The catalysts can be homogeneous
and/or
heterogeneous catalysts. Homogeneous catalysts are typically liquid phase
mixtures, whereas
heterogeneous catalysts are solid phase catalysts mixed with the liquid phase
reactants, oils
and alcohols.
In processes herein, the conversion of TAGs to fatty acid alkyl esters
("FAAE")
through transesterification of the TAG typically involves forming a reactant
stream, which
includes TAG (e.g., at least about 75 wt%), alkanol (e.g., about 5 to 20 wt%),
a
transesterification catalyst (e.g., about 0.05 to 1 wt%), and optionally,
glycerol (typically up
to about 10 wt%). Suitable alkanols may include C1-C6 alkanols and commonly
may include
methanol, ethanol, or mixtures thereof Suitable transesterification catalysts
may include
alkali metal alkoxides having from 1 to 6 carbon atoms and commonly may
include alkali
metal methoxide, such as sodium methoxide and/or potassium methoxide. The
basic catalyst
is desirably selected such that the alkali metal alkoxide may suitably contain
an alkoxide
group which is the counterpart of the alkanol employed in the reaction stream
(e.g., a
combination of methanol and an alkali metal methoxide such as sodium methoxide
and/or
potassium methoxide). The reactant stream may suitably include about 0.05 to
0.3 wt%
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sodium methoxide, at least about 75 wt% triacylglyceride, about 1 to 7 wt%
glycerol, and at
least about 10 wt% methanol. In some embodiments, the reactant stream may
desirably
include about 0.05 to 0.25 wt% sodium methoxide, at least about 75 wt%
triacylglyceride,
about 2 to 5 wt% glycerol, and about 10 to 15 wt% methanol.
The rate and extent of reaction for esterification of the fatty acid
glycerides or other
fatty acid derivates with monohydric alcohol in the presence of a catalyst
depends upon
factors including but not limited to the concentration of the reagents, the
concentration and
type of catalyst, and the temperature and pressure conditions, and time of
reaction. The
reaction generally proceeds at temperatures above about 50 C, preferably at
temperatures
above 65 C; however, the catalyst selected or the amount of catalyst employed
can affect this
temperature to some extent. Higher temperatures generally result in faster
reaction rates.
However, the use of very high temperatures, such as those in excess of about
300 C, or even
those in excess of 250 C, can lead to increased generation of side products,
which can be
undesirable as their presence can increase downstream purification costs.
Higher
temperatures can be advantageously employed; however, e.g., in situations
where the side
products do not present an issue.
The reaction temperature can be achieved by preheating one or more of the feed
materials or by heating a mixture of the feed materials. Heating can be
achieved using
apparatus known in the art, e.g., heat exchangers, jacketed vessels, submerged
coils, and the
like. While specific temperatures and methods of obtaining the specific
temperatures are
discussed herein with reference to certain embodiments and examples, the
preferred
embodiments are not limited to such specific temperatures and methods of
obtaining the
specific temperatures. Other temperatures and methods of obtaining
temperatures can also be
employed in the preferred embodiments.
The amount of alcohol employed in the reaction is preferably in excess of the
amount
of fatty acid present on a molar basis. The fatty acid can be free or
combined, such as to
alcohol, glycol, or glycerol, with up to three fatty acid moieties being
attached to a glycerol.
Additional amounts of alcohol above stoichiometric provide the advantage of
assisting in
driving the equilibrium of the reaction to produce more of the fatty acid
ester product.
However, greater excesses of alcohol can result in greater processing costs
and larger capital
investment for the larger volumes of reagents employed in the process, as well
as greater
energy costs associated with recovering, purifying, and recycling this excess
alcohol.
Accordingly, it is generally preferred to employ an amount of alcohol yielding
a molar ratio
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of alcohol to fatty acid of from about 15:1 to about 1:1 (stoichiometric), and
more preferably
from about 4:1 to about 2:1; however the process can operate over a much wider
range of
alcohol to fatty acid ratios, with nonreacted materials subjected to recycling
or other
processing steps. Generally, lower relative levels of alcohol to fatty acid
result in decreased
yield and higher relative levels of alcohol levels to fatty acid result in
increased capital and
operating expense. Some instances of operation at ratios of alcohol to fatty
acid over a wider
range include when first starting up the process or shutting down the process,
when balancing
the throughput of the reactor to other processing steps or other processing
facilities, such as
one that produces alcohol or utilizes a side stream, or when process upsets
occur. When a
molar ratio of 2:1 methanol to fatty acid is employed and a sodium hydroxide
concentration
of about 0.5 wt% of the total reaction mixture is employed, the ratio of
sodium hydroxide to
methanol is about 2 wt% entering the reactor and about 4 wt% at the exit
because about half
of the alcohol is consumed in the esterification reaction.
Similarly, higher amounts of catalyst generally result in faster reactions.
However,
higher amounts of catalyst can lead to higher downstream separation costs and
a different
profile of side reaction products. The amount of homogeneous catalyst is
preferably from
about 0.2 wt% to about 1.0 wt% of the reaction mixture when the catalyst is
sodium
hydroxide; at typical concentration of 0.5 wt% when a 2:1 molar ratio of
methanol to fatty
acid is used; however, in certain embodiments, higher or lower amounts can be
employed.
The amount of catalyst employed can also vary depending upon the nature of the
catalyst,
feed materials, operating conditions, and other factors. Specifically, the
temperature, pressure,
free fatty acid content of the feed, and degree of mixing can change the
amount of catalyst
preferably employed. While specific catalyst amounts are discussed herein with
reference to
certain embodiments and examples, the preferred embodiments are not limited to
such
specific catalyst amounts. Other suitable catalyst amounts can also be
employed in the
preferred embodiments.
The esterification reaction can be performed batchwise, such as in a stirred
tank, or it
can be performed continuously, such as in a continuous stirred tank reactor
(CSTR) or a plug
flow reactor (PFR). When operated in continuous mode, a series of continuous
reactors
(including CSTRs, PFRs, or combinations thereof) can advantageously operate in
series.
Alternatively, batch reactors can be arranged in parallel and/or series.
When the reactor is operated in a continuous fashion, one or more of the feed
materials is preferably metered into the process. Various techniques for
metering can be
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employed (e.g., metering pumps, positive displacement pumps, control valves,
flow meters,
and the like). While specific types of reactors are discussed herein with
reference to certain
embodiments and examples, the preferred embodiments are not limited to such
specific
reactors. Other suitable types of reactors can also be employed in the
preferred embodiments.
As described above, biodiesel refers to a transesterifled vegetable oil or
animal fat
based diesel fuel containing long-chain alkyl (typically methyl, propyl, or
ethyl) esters.
Biodiesel is typically made by chemically reacting lipids (such as vegetable
oil) with an
alcohol. Biodiesel, TAG's and derivatives thereof may be used in the processes
described
herein. Likewise, preferred fatty acid methyl esters useful herein may be
obtained by reacting
canola oil, corn oil, soybean oil, beef tallow, tall oil, animal fats, waste
oils/greases, rapeseed
oil, algae oil, Canola oil, palm oil, Jathropa oil, high-oleic soybean oil,
high-oleic safflower
oil, high-oleic sunflower oil, or mixtures of animal and/or vegetable fats,
and oils with one or
more alcohols (as described above), preferably methanol.
Isomerization
In another embodiment, the feed material is first isomerized, then combined
with a
metathesis catalyst as described herein. For example, the processes disclosed
herein may
comprise providing a feed material (typically a fatty acid or fatty acid
derivative), isomerizing
a site of unsaturation in the feed material (typically a fatty acid or fatty
acid derivative) to
produce an isomerized feed material (typically a fatty acid or fatty acid
derivative), and then
contacting the isomerized material with an alkene in the presence of a
metathesis catalyst.
The isomerized material can be produced by isomerization with or without
subsequent
esterification or transesterification. Isomerization can be catalyzed by known
biochemical or
chemical techniques. For example, an isomerase enzyme, such as a linoleate
isomerase, can
be used to isomerize linoleic acid from the cis 9, cis 12 isomer to the cis 9,
trans 11 isomer.
This isomerization process is stereospecific, however, nonstereospecific
processes can be
used because both cis and trans isomers are suitable for metathesis. For
example, an
alternative process employs a chemical isomerization catalyst, such as an
acidic or basic
catalyst, can be used to isomerize an unsaturated feed material (typically a
fatty acid or fatty
acid derivative) having a site of unsaturation at one location in the molecule
into an
isomerized, feed material (typically a fatty acid or fatty acid derivative)
having a site of
unsaturation at a different location in the molecule. Metal or organometallic
catalysts also
can be used to isomerize an unsaturated feed material (typically a fatty acid
or fatty acid
derivative). For example, nickel catalysts are known to catalyze positional
isomerization of
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unsaturated sites in fatty acid derivatives. Similarly, esterification,
transesterification,
reduction, oxidation, and/or other modifications of the starting compound or
products, such as
a fatty acid or fatty acid derivative, can be catalyzed by biochemical or
chemical techniques.
For example, a fatty acid or fatty acid derivative can be modified by a
lipase, esterase,
reductase or other enzyme before or after isomerization. In another
embodiment, the
isomerization described above may be practiced with any triacylglycerides,
biodiesel, fatty
acids, fatty acid esters, and/or fatty acid alkyl esters described herein,
typically before
contacting with the metathesis catalyst.
Alkenes
Besides the feed materials, the metathesis process of this invention may
require an
alkene as a reactant. The term "alkene" shall imply an organic compound
containing at least
one carbon-carbon double bond and typically having less than about 10 carbon
atoms. The
alkene may have one carbon-carbon unsaturated bond, or alternatively, two or
more carbon-
carbon unsaturated bonds. Since the metathesis reaction can occur at any
double bond,
alkenes having more than one double bond will produce more metathesis
products.
Accordingly, in some embodiments, it is preferred to employ an alkene having
only one
carbon-carbon double bond. The double bond may be, without limitation, a
terminal double
bond or an internal double bond. The alkene may also be substituted at any
position along the
carbon chain with one or more substituents, provided that the one or more
substituents are
essentially inert with respect to the metathesis process. Suitable
substituents include, without
limitation, alkyl, preferably, C1_6 alkyl; cycloalkyl, preferably, C3_6
cycloalkyl; as well as
hydroxy, ether, keto, aldehyde, and halogen functionalities. Non-limiting
examples of
suitable alkenes include ethylene, propylene, butene, butadiene, pentene,
hexene, the various
isomers thereof, as well as higher homologues thereof Preferably, the alkene
is a C2_8 alkene.
More preferably, the alkene is a C2_6 alkene, even more preferably, a C2_4
alkene, and most
preferably, ethylene.
Useful alkenes include those represented by the formula: R*-HC=CH-R*, wherein
each R* is independently, hydrogen or a C1 to C20 hydrocarbyl, preferably
hydrogen or a C1
to C6 hydrocarbyl, preferably hydrogen, methyl, ethyl, propyl or butyl, more
preferably R* is
hydrogen. In a preferred embodiment, both R* are the same, preferably both
R*are hydrogen.
Ethylene, propylene, butene, pentene, hexene, octane, nonene and decene
(preferably
ethylene) are alkenes useful herein.
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For purposes of this invention and the claims thereto, the term lower olefin
means an
alkene represented by the formula: R*-HC=CH-R*, wherein each R* is
independently,
hydrogen or a C1 to C6 hydrocarbyl, preferably hydrogen or a C1 to C3
hydrocarbyl,
preferably hydrogen, methyl, ethyl, propyl, or butyl, more preferably R* is
hydrogen. In a
preferred embodiment, both R* are the same, preferably both R* are hydrogen.
Ethylene,
propylene, butene, pentene, hexene, and octene (preferably ethylene) are lower
olefins useful
herein.
Alpha-Olefin Products of the Metathesis Reaction
In a preferred embodiment, the processes described herein produce a linear
alpha
olefin. The alpha-olefin, preferably linear alpha-olefin, produced herein
contains at least one
more carbon than the alkene used in the reaction to make the alpha-olefin.
In another embodiment, the processes described herein produce a blend of an
alpha
olefin and an ester-functionalized alpha olefin. Generally a mixture of non-
ester-containing
alpha olefins will be produced due to the presence of mono-, di-, and tri-
unsubstituted fatty
acid chains. The major alpha olefin products are expected to be 1-decene, 1-
heptene, and 1-
butene. The major ester-containing alpha olefin product is methyl dec-9-
enoate.
In a preferred embodiment, the alpha olefin produced herein is 1-decene.
Typically
the 1-decene is produced with an ester.
In a preferred embodiment, the major alpha olefin produced herein is 1-decene.
Typically the 1-decene is produced with an ester.
In a preferred embodiment, ethylene and methyl oleate are combined with the
metathesis catalysts described herein (such
as 2-(i-propoxy)-5-(N,N-
dimethylaminosulfonyl)phenylmethylene(1-
cyclohexylmethy1-3 -(2,6-diisopropylpheny1)-
4,5 -dihydro-1H-imidazo le) ruthenium (II)
chloride, (1 -mesity1-3 -methyl-2H-4,5 -
dihydroimidazol-2-ylidene)(tricyclohexylphosphine)-3-pheny1-1H-inden-1-ylidene
ruthenium
(II) dichloride, and mixtures thereof) to produce 1-decene and methyl dec-9-
enoate.
Separation of the 1-olefin (such as the 1-decene) from the ester may be by
means
typically known in the art such as distillation or filtration.
The linear alpha-olefin (such as 1-decene or a mixture of C8, C10, C12 linear
alpha
olefins) is then separated from any esters present and preferably used to make
poly-alpha-
olefins(PA05). Specifically, PAOs may be produced by the polymerization of
olefin feed in
the presence of a catalyst such as A1C13, BF3, or BF3 complexes. Processes for
the
production of PAOs are disclosed, for example, in the following patents: US
3,149,178;
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CA 02777176 2013-07-08
3,382,291; 3,742,082; 3,769363; 3,780,128; 4,172,855; and 4,956,122. PAOs are
also
discussed in: Will, J.G. Lubrication Fundamentals, Marcel Dekker: New York,
1980. Certain
high viscosity index PAOs may also be conveniently made by the polymerization
of an
alpha-olefin in the presence of a polymerization catalyst such as Friedel-
Crafts catalysts.
These include, for example, aluminum trichloride, boron trifluoride, aluminum
triehloride, or
boron trifluoride promoted with water, with alcohols such as ethanol,
propanol, or butanol,
with carboxylic acids, or with esters such as ethyl acetate or ethyl
propionate or ether such as
diethyl ether, diisopropyl ether, etc., see for example, the methods disclosed
by US
4,149,178; US 3,382,291; US 3,742,082; US 3,769,363 (Brennan); US 3,876,720;
US
4,239,930; US 4,367,352; US 4,413,156; US 4,434,408; US 4,910,355; US
4,956,122; US
5,068,487; US 4,827,073; US 4,827,064; US 4,967,032; US 4,926,004; and US
4,914,254.
PAOs can also be made using various metallocene catalyst systems. Examples
include US ,
6,706,828; WO 96/23751; EP 0 613 873; US 5,688,887; US 6,043,401; WO
03/020856; US
6,548,724; US 5,087,788; US 6,414,090; US 6,414,091; US 4,704,491; US
6,133,209; and
US 6,713.438.
PAOs are often used as additives and base stocks for lubricants, among other
things.
Additional information on the use of PAO's in the formulations of full
synthetic, semi-
synthetic or part synthetic lubricant or functional fluids can be found in
"Synthetic Lubricants
and High-Performance :Functional Fluids", 2nd Ed., L. Rudnick et al., Marcel
Dekker, Inc.,
N.Y. (1999). Additional information on additives used in product .formulation
can be found
in "Lubricants and Lubrications", Ed. By T. Mang and W. Dresel, by Wiley-VCH
GmbH,
Weinheim 2001.
In another embodiment, this invention relates to:
1. An asymmetrically substituted NHC metathesis catalyst compound
represented by the
formula:
R5
R4
R6 R3
---).--- .
Rg
X r.....,,
......-M --------
X2 I
L R.
where:
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M is a Group 8 metal; preferably Ru or Os, preferably Ru;
X1 and X2 are, independently, any anionic ligand (preferably halogen, an
alkoxide or an alkyl
sulfonate), or X1 and X2 may be joined to form a dianionic group and may form
a single ring
of up to 30 non-hydrogen atoms or a multinuclear ring system of up to 30 non-
hydrogen
atoms;
L is a heteroatom or heteroatom-containing ligand; preferably the heteroatom
is N, 0, P, or S;
preferably P, optionally L may be joined to R7 and/or R8, preferably L is
L*(R)q_i when L is
not bound to R7 or R8 or L is L*(R)q_2 when L is bound to R7 or R8, where q is
1, 2, 3, or 4
depending on the valence of L* (which may be 2, 3, 4, or 5) and L* is N, 0, P,
or S,
(preferably P) and R is as defined for R3;
and R1, R2, R3, R4, R5, R6, R7, and R8 are, independently, hydrogen or a C1 to
C30
substituted or unsubstituted hydrocarbyl;
wherein any two adjacent R groups may form a single ring of up to 8 non-
hydrogen atoms or
a multinuclear ring system of up to 30 non-hydrogen atoms; and
wherein R1 and R2 are dissimilar to each other.
2. The catalyst compound of paragraph 1, wherein M is ruthenium.
3. The catalyst compound of paragraph 1 or 2, wherein when R7 and R8 form
an
unsubstituted phenyl group and R1 is mesityl, then R2 is not methyl or ethyl,
preferably R2 is
hydrogen or C1 to C30 substituted hydrocarbyl, or a C3 to C30 unsubstituted
hydrocarbyl
(preferably a C4 to C30 unsubstituted hydrocarbyl, preferably a C5 to C30
unsubstituted
hydrocarbyl, preferably a C6 to C30 unsubstituted hydrocarbyl).
4. The catalyst compound of any of paragraphs 1 to 3, wherein X1 and X2 are
Cl.
5. The catalyst compound of any of paragraphs 1 to 4, wherein the
heteroatom in L is N,
0, or P.
6. The catalyst compound of any of paragraphs 1 to 5, wherein R1, R2, R7,
and R8 are,
independently, C1 to C30 hydrocarbyl.
7. The catalyst compound of any of paragraphs 1 to 6, wherein R3, R4, R5,
and R6 are,
independently, hydrogen.
8. The catalyst compound of any of paragraphs 1 to 7, wherein R1 is an
aromatic
hydrocarbyl or substituted hydrocarbyl and R2 is an aliphatic hydrocarbyl or
substituted
hydrocarbyl, (preferably R1 is a substituted or unsubstituted C6 to C30 aryl,
and R2 is a C1 to
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C30 substituted or unsubstituted alkyl, preferably C3 to C30 substituted or
unsubstituted alkyl,
preferably C4 to C30 substituted or unsubstituted alkyl, C5 to C30 substituted
or unsubstituted
alkyl, C6 to C30 substituted or unsubstituted alkyl).
9. The catalyst compound of paragraph 1, wherein the metathesis catalyst
compound
comprises one or more of: 2-(i-propoxy)-5-(N,N-
dimethylaminosulfonyl)phenylmethylene(1-
cyclohexylmethy1-3-(2,6-diisopropylpheny1)-4,5-dihydro-1H-imidazo le)
ruthenium (II)
chloride, (1 -mesity1-3 -methyl-2H-4,5 -dihydroimidazol-2-ylidene)(tricyc
lohexylpho sphine)-3 -
phenyl-1H-inden- 1 -ylidene ruthenium (II) dichloride, and mixtures thereof
10. A process to produce alpha-olefin comprising contacting a feed material
(such as a
feed oil) with the catalyst compound of any of paragraphs 1 to 9.
11. The process of paragraph 10, wherein the feed material is selected from
the group
consisting of canola oil, corn oil, soybean oil, rapeseed oil, algae oil,
peanut oil, mustard oil,
sunflower oil, tung oil, perilla oil, tall oil, grapeseed oil, linseed oil,
safflower oil, pumpkin
oil, palm oil, Jathropa oil, high-oleic soybean oil, high-oleic safflower oil,
high-oleic
sunflower oil, mixtures of animal and vegetable fats and oils, castor bean
oil, dehydrated
castor bean oil, cucumber oil, poppyseed oil, flaxseed oil, lesquerella oil,
walnut oil,
cottonseed oil, meadowfoam, tuna oil, sesame oils and mixtures thereof
12. The process of paragraph 10, wherein the feed material is selected from
the group
consisting of tall oil, palm oil and algae oil.
13. A process to produce alpha-olefin comprising contacting a
triacylglyceride with an
alkene and the catalyst compound of any of paragraphs 1 to 9, preferably
wherein the alpha
olefin produced has at least one more carbon atom than the alkene.
14. The process of paragraph 13, wherein the triacylglyceride is contacted
with alcohol
and converted to a fatty acid ester or fatty acid alkyl ester prior to
contacting with the catalyst
compound of any of paragraphs 1 to 9.
15. The process of paragraph 13, wherein the triacylglyceride is contacted
with water
and/or an alkaline reagent and converted to a fatty acid prior to contacting
with the catalyst
compound of any of paragraphs 1 to 9.
16. A process to produce alpha-olefin comprising contacting an unsaturated
fatty acid
with an alkene and the catalyst compound of any of paragraphs 1 to 9,
preferably wherein the
alpha olefin produced has at least one more carbon atom than the alkene.
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17. A process to produce alpha-olefin comprising contacting a
triacylglyceride with the
catalyst compound of any of paragraphs 1 to 9, preferably wherein the alpha
olefin produced
has at least one more carbon atom than the alkene.
18. A process to produce alpha-olefin comprising contacting an unsaturated
fatty acid
ester and or unsaturated fatty acid alkyl ester with an alkene and the
catalyst compound of
any of paragraphs 1 to 9, preferably wherein the alpha olefin produced has at
least one more
carbon atom than the alkene.
19. The process of any of paragraphs 11 to 18, wherein the alpha olefin is
a linear alpha-
olefin having 4 to 24 carbon atoms.
20. The process of any of paragraphs 11 to 19, wherein the alkene is
ethylene, propylene,
butene, hexene, or octene.
21. The process of any of paragraphs 19 to 20, wherein the fatty acid ester
is a fatty acid
methyl ester.
22. The process of any of paragraphs 13 to 21, wherein the
triacylglyceride, fatty acid,
fatty acid alkyl ester, fatty acid ester is derived from biodiesel.
23. The process of any of paragraphs 10 to 22, wherein the alpha-olefin is
butene-1,
decene-1, and/or heptene-1.
24. The process of any of paragraphs 10 to 23, wherein the productivity of
the process is
at least 200 g of linear alpha-olefin per mmol of catalyst per hour.
25. The process of any of paragraphs 10 to 24, wherein the selectivity of
the process is at
least 20 wt% linear alpha-olefin, based upon the weight to the material
exiting the reactor.
26. The process of any of paragraphs 10 to 25, wherein the turnover number
of the
process is at least 5,000.
27. The process of any of paragraphs 10 to 26, wherein the yield, when
converting
unsaturated fatty acids, unsaturated fatty acid esters, unsaturated fatty acid
alkyl esters, or
mixtures thereof, is 30% or more, said yield being defined as defined as the
moles of alpha
olefin formed per mol of unsaturated fatty acids, unsaturated fatty acid
esters, unsaturated
fatty acid alkyl esters, or mixtures thereof introduced into the reactor.
28. The process of any of paragraphs 10 to 26, wherein the yield, when
converting TAGs
as represented in the formula below, is 30% or more, said yield being defined
as defined as
the moles of alpha olefin formed divided by (the moles of unsaturated Ra +
moles of
unsaturated Rb + moles of unsaturated RC) introduced into the reactor,
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0
ll
H2C - 0 - C- Ra
0
ii
HC ¨O ¨ C¨ Rb
1 0
ii
H2C ¨ 0 ¨ C¨ Re
where Ra, Rb, and RC each, independently, represent a saturated or unsaturated
hydrocarbon
chain.
29. The process of paragraph 27, wherein the yield is 60% or more.
30. A process to produce C4 to C24 linear alpha-olefin comprising
contacting a feed
material with an alkene selected from the group consisting of ethylene,
propylene butene,
pentene, hexene, heptene, octene, nonene, decene, and mixtures thereof and a
metathesis
catalyst compound of any of paragraphs 1 to 10, wherein the feed material is a
triacylglyceride, fatty acid, fatty acid alkyl ester, and/or fatty acid ester
derived from seed oil.
31. The process of paragraph 30, wherein the alkene is ethylene, the alpha
olefin is 1-
butene, 1-heptene, and/or -decene, and the feed material is a fatty acid
methyl ester, and/or
fatty acid ester.
EXPERIMENTAL SECTION
Tests and Materials
All molecular weights are number average unless otherwise noted. All molecular
weights are reported in g/mol unless otherwise noted.
For purposes of this invention and the claims thereto, Et is ethyl, Me is
methyl, Ph is
phenyl, Cy is cyclohexyl, THF is tetrahydrofuran, Me0H is methanol, DCM is
dichloromethane, and TLC is thin layer chromatography.
Typical dry-box procedures for synthesis of air-sensitive compounds were
followed
including using dried glassware (90 C, 4 hours) and anhydrous solvents
purchased from
Sigma Aldrich (St. Louis, MO) which were further dried over 3 A sieves. All
reagents were
purchased from Sigma-Aldrich, unless otherwise noted. 1H, 13C, and 31P spectra
were
recorded on Bruker 250 and 500 spectrometers. IR data was recorded on Bruker
Tensor 27
FT-IR spectrometer. Yields of metathesis product and catalyst turnover numbers
were
calculated from data recorded on an Agilent 6890 GC spectrometer as shown
below.
Typically, a sample of the metathesis product will be taken and analyzed by
GC. An
internal standard, usually tetradecane, is used to derive the amount of
metathesis product that
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is obtained. The amount of metathesis product is calculated from the area
under the desired
peak on the GC trace, relative to the internal standard.
Yield is reported as a percentage and is generally calculated as 100 x
[micromoles of
metathesis products obtained by GC]/[micromoles of feed material weighed into
reactor].
Selectivity is reported as a percentage and was calculated as 100 x [area
under the
peak of desired metathesis products]/[sum of peak areas of cross-metathesis
and the
homometathesis products].
Catalyst turnovers (TON) for production of the metathesis products is defined
as the
[micromoles of metathesis product]/([micromoles of catalyst].
In a particular embodiment, the metathesis of methyl oleate with ethylene will
yield
cross-metathesis products of 1-decene and methyl-9-decenoate. In addition to
the desired
products, the methyl oleate may homometathesize to produce small amounts of 9-
octadecene,
a less desirable product, and 1,18-dimethy1-9-octadecenedioate, a second less
desirable
product. Yield was calculated as 100 x [micromoles of ethenolysis products
obtained from
the GC]/[micromoles of methyl oleate weighed into reactor]. 1-decene
selectivity is shown as
a percentage and was calculated as 100 x [GC peak area of 1-decene & methy1-9-
decenoate]/[sum of GC peak areas of 1-decene, methyl-9-decenoate, and the
homometathesis
products, 9-octadecene, and 1,18-dimethy1-9-octadecenedioate]. Catalyst
turnovers for
production of the 1-decene was calculated as the [micromoles of 1-decene
obtained from the
gas chromatograph]/([micromoles of catalyst].
Products were analyzed by gas chromatography (Agilent 6890N with auto-
injector)
using helium as a carrier gas at 38 cm/sec. A column having a length of 60 m(J
& W
Scientific DB-1, 60 m x 0.25 mm I.D.x 1.0 [tm film thickness) packed with a
flame ionization
detector (FID), an Injector temperature of 250 C, and a Detector temperature
of 250 C were
used. The sample injected into the column in an oven at 70 C, then heated to
275 C over 22
minutes (ramp rate 10 C/minute to 100 C, 30 C/minute to 275 C, hold).
EXAMPLES
EXAMPLE 1
Synthesis of Catalyst 1:
(1-mesity1-3-methy1-2H-4,5-dihydroimidazol-2-
ylidene)(tricyclohexylphosphine)-3-pheny1-1H-inden-1-ylideneruthenium(H)
dichloride:
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Pd2(dba)3
40 Br
( )-BNAP,
NaOtBu H A
F-1
triethyl r\N' KOtPn N,
orthoformate 1\1-/F
ni I
NH4BF4 PCy3
i
formic acid n1:7----1Zu
PCy3 ph
PCy3 ph Catalyst 1
Synthesis of Compound A: N-methyl-N'-mesity1-1,2-ethylenediamine:
In a 100 mL round-bottom flask tris(dibenzylideneacetone)dipalladium(0)
(Pd2(dba)3)
(110 mg, 0.120 mmol) and ( )-2,2'-Bis(diphenylphosphino)-1,1'-binaphthalene ((
)-BINAP)
(230 mg, 0.37 mmol) were added to 25 mL toluene and stirred for 20 minutes.
Next, 2-
bromomesitylene (2.45 g, 12.3 mmol), N-methylethylenediamine (1.01 g, 13.6
mmol) and
sodium t-butoxide (NaOtBu) (3.56 g, 37 mmol) were added along with 25 mL
toluene. This
was stirred for 72 hours at 80 C. The flask was then removed from heat, cooled
to room
temperature and diluted with 20 mL diethyl ether. The solution was then washed
with 5 x 30
mL water and 3 x 15 mL brine, and dried over magnesium sulfate. After
filtering and
vacuum removal of solvent, a dark red oil was recovered and used without
further purification.
Synthesis of Compound B: 1-Mesity1-3-methyl-2H-4,5-dihydroimidazolium
tetrafluoroborate:
Compound A (2.07 g, 10.8 mmol) oil was diluted in 10 mL toluene and stirred
with
triethylorthoformate (15.98 g, 108 mmol), ammonium tetrafluoroborate (NH4BF4)
(4.51 g, 43
mmol) and 5 drops of formic acid at 130 C for 18 hours. After cooling to room
temperature
the solution was filtered and solids were dissolved in dichloromethane and
precipitate filtered
off. The solvent was removed by purging with nitrogen and the residue was
recrystallized
from acetone/methyl tert-butyl ether. A total of 0.39 g (25.1%) of Compound B
was obtained.
Synthesis of Catalyst 1: (1-mesity1-3-methy1-2H-4,5-dihydroimidazol-2-
ylidene)(tricyclohexylphosphine)-3-phenyl-1H-inden-1-ylideneruthenium(II)
dichloride:
To a solution of Compound B (50 mg, 0.172 mmol) in 5 mL hexanes was added
potassium tert-pentoxide (KOtPn) (0.172 mmol) from a 15% solution in hexanes.
To this
solution was added bis(tricyclohexylphosphine)-3-pheny1-1H-inden-1-
ylideneruthenium (II)
dichloride (purchased from Strem Chemicals, (Newburyport, MA)) (145 mg, 0.156
mmol)
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and the solution then stirred for 12 hours at 50 C. After cooling to room
temperature, the
solution was concentrated to approximately 2 mL under a stream of nitrogen,
then filtered and
washed with hexanes, yielding 105 mg (79 %) of Catalyst 1 as a brown powder.
Methyl Oleate Ethynolysis (Cross-metathesis of methyl oleate with ethylene):
Catalyst 1: The ethynolysis of methyl oleate was used as a test to determine
the activity of
the
(1 -mesity1-3 -methyl-2H-4,5 -dihydroimidazol-2-ylidene)(tricyc lohexylpho
sphine)-3 -
pheny1-1H-inden-1-ylideneruthenium(II) dichloride complex (Catalyst 1). A
0.120 mM stock
solution was made by dissolving Catalyst 1 in dichloromethane. Methyl oleate
(0.87g, 1.0
mL), Catalyst 1 stock solution (125 nmol, 1.04 mL), dichloromethane (2.91 mL)
and of
tetradecane (0.152 g, used as an internal standard) were weighed out and then
placed in a
Fisher-Porter bottle equipped with a stir bar. The Fisher-Porter bottle was
then filled with
ethylene to 150 psig and placed in an oil bath heated to 40 C for 3 hours. The
vessel was
depressurized and 5 drops of ethyl vinyl ether was added to stop the reaction.
A sample was
removed and analyzed by GC.
Comparative Catalyst A: Tricyclohexylpho sphine [3 -phenyl-1H-inden-1 -
ylidene] [1,3 -
bis(2,4,6-trimethylpheny1)-4 ,5 -dihydroimidazo 1-2-ylidene]ruthenium(II)
dichloride
(Comparative Catalyst A) is a symmetrical annolog of Catalyst 1 and was
purchased from
Strem Chemicals. The structure of Comparative Catalyst A is shown below.
ii NN =
Ph
C1,,.
Ru 0
C11 1
PCy3 411
Comparative Catalyst A
A 0.139 mM solution of the Comparative Catalyst A complex in dichloromethane
was
prepared. Comparative Catalyst A stock solution (94.4 nmol, 0.679 mL),
dichloromethane
(3.12 mL), methyl oleate (0.87g, 1.0 mL) and tetradecane (0.152 g, used as an
internal
standard) were weighed out and then placed in a Fisher-Porter bottle equipped
with a stir bar.
The Fisher-Porter bottle was filled with 150 psig of ethylene and heated to 40
C for 3 hours.
A sample was removed and analyzed by GC.
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The results of the ethenolysis reactions are as follows:
Catalyst nmols % selectivity % yield TON (1-
Decene)
Catalyst
Catalyst 1 125 91.2 28.6 6700
Comparative Catalyst A 94.4 89.8 3.84 1200
In the ethenolysis of methyl oleate, symmetrically substituted NHC carbene
ligands
ligated to ruthenium alkylidenes, such as tricyclohexylphosphine[3-pheny1-1H-
inden-1-
ylidene] [1,3 -bis(2,4,6-trimethylpheny1)-4,5 -dihydroimidazol-2-ylidene]
ruthenium(II)
dichloride (Comparative Catalyst A), have displayed low activity resulting in
comparatively
low yields of 3.84% with correspondingly low turnover numbers of 1200.
The inventors have surprisingly discovered that by replacing one of the
mesityl groups
on the nitrogen of the NHC ligand ligated to the ruthenium alkylidene, as in
Catalyst 1 above,
the activity increased substantially as depicted by increased turnover numbers
in excess of
five-fold, with a corresponding increase in yield.
EXAMPLE 2:
Synthesis of Catalyst 2: 2-(i-propoxy)-5-(N,N-dimethylaminosulfonyl)phenyl]
methylene} (1-cyclohexylmethy1-3-(2,6-diisopropylpheny1)-4,5-dihydro-1H-
imidazole)
ruthenium (II) chloride
0
Br' NH2
Hj()
NH2 HB.rNH2 _________________________________________
NaBH4NN0
reflux benzene THF
triethyl
NNIcl orthoformateNNJ1:3 a) LiHMDS, C6D6
-
H
NH4C1
b) Zhan 1C
Cl`sµ I
SO2ks_ ..3,2
=,Tr,õ
Catalyst 2
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Synthesis of Compound C: M-(2,6-diisopropylphenyl)ethane-1,2-diamine:
2,6-Diisopropylaniline (12 mL, 63.6 mmol) and 2-bromoethylamine hydrobromide
(2.8 g, 14 mmol) were heated at reflux for 4 days. The liquid was cooled to
room temperature
and dissolved in ether. This solution was washed with 1N sodium hydroxide and
brine, then
dried over magnesium sulfate, filtered and concentrated under reduced
pressure. Unreacted
diisopropylaniline was removed by vacuum distillation, followed by column
chromatography
with 30% acetone/hexane eluent. The pure diamine product, Compound A, was
obtained as a
pale yellow oil in quantitative yield: Rf 0.31 (30:70 acetone/hexane); IR (cm-
1): 3359, 2961,
2868, 1667, 1458, 1364, 1252, 1113,755; 1H NMR (500 MHz, C6D6) 6 1.29(m, 12H),
1.79
(s, 2H), 3.14 (br s, 2H), 3.18 (m, 2H), 3.67 (qn, J = 10 Hz, 2H), 4.07 (br s,
1H), 7.14 (m, 3H);
13C NMR (125 MHz, C6D6) 24.5 (4C), 27.8 (2C), 51.2, 52.7, 123.8, 124.1, 143.0,
144.5,
166.8.
Synthesis of Compound D: M-cyclohexylmethylene-N2-(2,6-
diisopropylphenyl)ethane-
1,2-diamine:
Compound C (2.3 g, 10.4 mmol) and cyclohexylcarboxaldehyde (1.3 mL, 11 mmol)
were dissolved in 20 mL benzene and refluxed for 1.5 hours, as water was
collected in a
Dean-Stark trap. The reaction was cooled and benzene removed under reduced
pressure to
give Compound D as a pale yellow oil, which was carried on to the next step
without further
purification.
Synthesis of Compound E: M-cyclohexylmethyl-N2-(2,6-diisopropylphenyl)ethane-
1,2-
diamine:
Compound D was dissolved in 50 mL THF. Sodium borohydride (NaBH4) (1.9 g, 50
mmol) was added in portions. The reaction was allowed to reflux for 30
minutes, then cooled
and quenched with methanol. Water was added, and then the mixture was
concentrated and
extracted with 3 portions of dichloromethane. The combined organic layers were
washed
with brine, dried over magnesium sulfate, and concentrated under reduced
pressure. A crude
yellow oil (Compound E) was obtained in 65% yield: Rf 0.46 (30:70
acetone/hexane); IR
(cm-1): 3359, 2960, 2924, 2851, 1447, 1362, 1254, 1111, 754; 1H NMR (250 MHz,
C6D6) 6
1.23 (m, 20H), 1.67 (m, 5H), 2.30 (d, J = 6.5Hz, 2H), 2.60 (m, 2H), 2.92 (m,
2H), 3.54 (qn, J
= 6.8 Hz, 2H), 7.14 (m, 3H).
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Synthesis of Compound F: 1-cyclohexylmethy1-3-(2,6-diisopropylpheny1)-4,5-
dihydro-
1H-imidazol-3-ium chloride:
Compound E (2 g, 6.3 mmol) was dissolved in 20 mL triethylorthoformate.
Ammonium chloride (360 mg, 6.6 mmol) was added and the reaction heated at
reflux
overnight, during which, it turned dark red and a precipitate formed. The
mixture was cooled
and filtered. Washing the solid with ether gave Compound F as a tan powder in
52% yield:
1H NMR (250 MHz, CDC13/DMS0) 6 1.09 (m, 18H), 1.60 (m, 5H), 2.27 (qn, J = 6.8
Hz, 2H),
3.64 (d, J = 7.3 Hz, 2H), 4.09 (m, 4H), 7.08 (d, J = 7.5 Hz, 2H), 7.27 (m,
1H), 9.63 (s, 1H);
13C NMR (63 MHz, CDC13/DMS0) 23.5 ¨ 25.5 (7C), 28.5 (2C), 29.5 (2C), 34.5,
48.7, 53.0,
53.6, 124.4 (2C), 129.7, 130.6, 146.2 (2C), 159.5.
Synthesis of Catalyst 2: 2-(i-propoxy)-5-(N,N-dimethylaminosulfonyl)phenyl]
methylene} (1-cyclohexylmethy1-3-(2,6-diisopropylpheny1)-4,5-dihydro-1H-
imidazole)
ruthenium (II) chloride:
An oven dried 20 mL scintillation vial was charged with LiHMDS (lithium
bistrimethylsilylamide) (40 mg, 0.24 mmol) and dissolved in 4 mL C6D6.
Compound F (88
mg, 0.24 mmol) was then added portion wise over 5 minutes. This mixture was
allowed to
stir for about 30 minutes until the solid ligand was mostly dissolved. Zhan 1C
(2-(i-
propoxy)-5 -(N,N-dimethylamino sulfonyl)phenylmethylene(tricyclohexylpho
sphine)
ruthenium dichloride) (114 mg, 0.16mmol) was then added in one portion and the
mixture
was allowed to stir at room temperature. After 1 hour, CuCl (copper (I)
chloride) (160 mg,
1.6 mmol) was added and allowed to stir overnight. The reaction mixture was
loaded directly
onto a silica column (loaded in 50% DCM/hexane) and eluted with 1% Me0H/DCM.
The
pure fractions were concentrated in vacuo, yielding approximately 50 mg of
Catalyst 2.
EXAMPLE 3:
Synthesis of Catalyst 3:
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propionaldehyde
NH2 ________________________________ N_ N NaBH4
' 'N
CH2C12, MgSO4 THF
triethyl
orthoformate i(jfk N...
NH4C1
Synthesis of Compound G: M-2,6-diisopropylphenyl-N2-propylideneethane-1,2-
diamine:
Propionaldehyde (0.6 mL, 8.3 mmol) and 2,6-diisopropylphenylethane-1,2-diamine
(1.5 g, 6.8 mmol) were dissolved in 20 mL dichloromethane. Magnesium sulfate
was added
and the mixture stirred for 19 hours, then filtered and concentrated. Compound
G was
obtained as a crude yellow oil which was carried on to the next step without
further
purification.
Synthesis of Compound H: M-2,6-diisopropylphenyl-N2-propylethane-1,2-diamine:
Compound G was dissolved in 30 mL THF. Sodium borohydride (NaBH4) (1.3 g, 34
mmol) was added in portions. The reaction was allowed to reflux for 30
minutes, then cooled
and quenched with methanol. Water was added, and then the mixture was
concentrated and
extracted with 3 portions of dichloromethane. The combined organic layers were
washed
with brine, dried over magnesium sulfate, and concentrated under reduced
pressure.
Compound H was obtained as a crude pale yellow oil in 35% yield: 1H NMR (250
MHz,
C6D6) 6 0.85 (t, J = 7.3 Hz, 3H), 1.26 (m, 14H), 2.36 (t, J = 6.9 Hz, 2H),
2.58 (m, 2H), 2.90
(m, 2H), 3.52 (qn, J = 6.8 Hz, 2H), 7.12 (m, 3H).
Synthesis of Compound I: 3-(2,6-diisopropylpheny1)-1-propy1-4,5-dihydro-1H-
imidazol-
3-ium chloride:
Compound H (650 mg, 2.4 mmol) was dissolved in 7.9 mL triethylorthoformate.
Ammonium chloride (NH4C1) (141 mg, 2.64 mmol) was added and the reaction
heated at
reflux overnight. Removal of triethylorthoformate gave Compound I as a crude
reddish
brown oil in quantitative yield.
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As is apparent from the foregoing general description and the specific
embodiments,
while forms of the invention have been illustrated and described, various
modifications can
be made. Accordingly, it is not intended that the invention be limited
thereby. The scope of
the claims should not be limited by the embodiments set out herein but should
be given the
broadest interpretation consistent with the description as a whole.
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