Note: Descriptions are shown in the official language in which they were submitted.
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STABILIZATION OF OLEFIN METATHESIS PRODUCT MIXTURES
Background of the Invention
In a first aspect, this invention pertains to a process of stabilizing an
olefin metathesis product mixture, preferably, against double bond
isomerization and
thermal and chemical decomposition. In a second aspect, this invention
pertains to a
stabilized olefin metathesis product composition. In a third aspect, this
invention
pertains to methods for removing metals from an olefin metathesis product
mixture.
Olefin metathesis processes commonly involve the conversion of two
reactant olefins in the presence of a metathesis catalyst into one or more
product
olefins that are different from the reactant olefins. If the two reactant
olefins are
chemically different compounds, then the process is referred to as "hetero-
metathesis".
If the two reactant olefins are chemically identical compounds, then the
process is
referred to as "homo-metathesis". In a different, but yet related manner,
olefin
metathesis processes also include ring-opening metathesis polymerization
reactions
wherein an unsaturated cyclic compound is ring-opened and polymerized to form
an
unsaturated polymer. In yet another type of olefin metathesis process, a
reactant
alkene and reactant alkyne can be cross-metathesized to form a conjugated 1,3-
diene.
The prior art discloses homogeneous and heterogeneous metathesis catalysts
that
comprise at least one catalytically active metal, such as ruthenium,
molybdenum,
tungsten, or rhenium, and one or more ligands complexed to the metal(s).
Metathesis processes find utility in converting olefin feedstocks of low
commercial value into unsaturated products of higher commercial value. By way
of
example, a long chain internal olefin, such as methyl oleate, obtainable from
seed oils,
can be metathesized with a lower olefin, such as a C2-8 olefin, preferably
ethylene, in
the presence of a metathesis catalyst to yield two product olefins of
intermediate chain
length, for example, 1-decene and methyl 9-decenoate. Intermediate length a-
olefins,
such as 1-decene, are useful in the preparation of poly (olefin) polymers.
Alpha,
omega (a,00) ester-functionalized olefins, such as methyl 9-decenoate, can be
converted into polyester polyepoxides, polyester polyalcohols or polyester
polyamines,
all of which find utility in the preparation of thermoset polymers, such as
epoxy resins
and polyurethanes.
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Olefin metathesis product mixtures typically comprise one or more product
olefins, a
metal-ligand metathesis complex catalyst, optionally, metathesis catalyst
degradation
products, optionally, metathesis reaction by-products, and optionally,
unconverted reactant
olefins. As noted hereinabove, the metathesis catalyst comprises at least one
catalytically
15 Homogeneous catalysts, while particularly active and selective, present
a problem in
that for economical purposes, the catalyst (including catalytic metal) should
be recovered
from the olefin metathesis product mixture. More importantly, it has been
recognized that
metathesis catalysts and catalyst degradation products destabilize olefm
metathesis product
mixtures against isomerization (double bond migration), which produces
undesirable
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catalyst supports, heterogeneous catalysts, metallic reactors, pipes, and
conduits.
Accordingly, efforts have been made to stabilize olefin metathesis product
mixtures against
double bond isomerization and decomposition resulting from metal contaminants.
H. D. Maynard and R. H. Grubbs disclose in Tetrahedron Letters, 40 (1999),
4137-4140, purification of ring-closing metathesis products of metathesis
reactions utilizing
a ruthenium catalyst. The purification involves treating the metathesis
product mixture with
a water-soluble phosphine, specifically, tris(hydroxymethyl)phosphine,
followed by
extraction with water so as to remove ruthenium into an aqueous phase.
Disadvantageously,
this method reduces the concentration of ruthenium by only one order of
magnitude when an
excess of 10 equivalents of water soluble phosphine is employed.
Leo A. Paquette et al. discloses in Organic Letters, 2 (9) (2000), 1259-1261
the
addition of lead tetraacetate to ring-closing metathesis product mixtures
followed by
filtration over silica gel to remove the colored ruthenium catalysts and
impurities. The
method teaches reduction of ruthenium residues by a factor of about 56.
Disadvantageously,
this method requires the use of lead tetraacetate under anaerobic conditions
and thereafter a
separate filtration step.
Yu Mi Ahn et al. discloses in Organic Letters, 3(9) (2001), 1411-1413, a
method of
similar efficiency that involves treating the crude olefin metathesis product
mixtures with
triphenylphosphine oxide or dimethyl snlfoxide, followed by column
chromatography on
silica gel. Disadvantageously, this method employs a large quantity of
triphenylphosphine
oxide or dimethyl sulfoxide, both of which increase costs and add recovery
steps to any
commercial plan.
An earlier reference, US 6,156,692 (filed 1997), drawn to a ring-opening
polymerization of a cyclic olefin, discloses work-up of a crude polyolefin
product over
DarcoTM brand charcoal. The reference teaches decolorizing the polymer, but
does not
address the problem of stabilizing an olefin metathesis product mixture
against double bond
isomerization and decomposition. Moreover, the final concentration of
ruthenium in the
polymer product (86 parts per million to 0.047 weight percent) is not
sufficiently low to
provide stabilization against double bond migration and decomposition.
In view of the prior art, it would be desirable to discover an improved method
of
stabilizing an olefin metathesis product mixture. It would also be desirable
to discover an
improved method of removing metals from olefin metathesis product mixtures. It
would be
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more desirable if the improved method did not employ expensive reagents that
require recovery. It would be even more desirable if the improved method did
not
employ large quantities of solvents or fluids that also increase costs and
require
recovery and recycle. It would be most desirable if the improved method could
reduce the concentration of metal(s) in metathesis product mixtures more
efficiently than prior art methods. At a high efficiency of metal removal,
olefin
metathesis product mixtures are more likely to be stabilized against double
bond
isomerization and chemical and thermal decomposition.
Summary of the Invention
In a first aspect this invention provides for a novel method of
stabilizing an olefin metathesis product mixture. The method comprises (a)
contacting an olefin metathesis product mixture, comprising one or more
olefins
obtained in a metathesis process, a metathesis-catalyst comprising a catalytic
metal, optionally, one or more metathesis catalyst degradation products, and
optionally, one or more metals derived from sources other than the catalyst
and
catalyst degradation products, with an absorbent; or (b) subjecting the olefin
metathesis product mixture to a first distillation to remove substantially
volatiles
and lights, and thereafter, subjecting bottoms from the first distillation to
a second
distillation; the (a) adsorbent or (b) distillation method being conducted
under
conditions sufficient to remove the metal(s) to a concentration sufficient to
stabilize
the product mixture.
Optionally, the olefin metathesis product mixture may additionally
comprise one or more metathesis reaction by-products, one or more unconverted
reactant olefins, one or more solvents, or a combination thereof. The olefin
metathesis catalyst shall comprise, in addition to the catalytic metal, a
catalytically-active combination of one or more ligands. The metathesis
catalyst
degradation products shall include ligand degradation products, complexes of
the
catalytic metal with one or more ligand degradation products, or complexes of
catalytic metal with a catalytically-inactive combination of ligands.
Additionally,
metals may be derived from sources other than the metathesis catalyst, such
as,
added promoter elements and metals leached out of catalyst supports, other
heterogeneous catalysts, reactors, pipes, and conduits.
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In an embodiment, the invention relates to a method of stabilizing an
olefin metathesis product mixture comprising subjecting the olefin metathesis
product mixture to a first distillation to remove substantially volatiles and
lights,
and thereafter, subjecting bottoms from the first distillation to a second
distillation
in a wiped film evaporator; the distillation method being conducted under
conditions sufficient to remove metal(s) to a concentration less than about
100 parts per billion by weight.
The novel process of this invention beneficially stabilizes a
metathesis product mixture, preferably, against double bond isomerization and
undesirable chemical and thermal decomposition. For the purposes of this
invention, the term "stabilize" shall be taken to mean that the product
mixture is
rendered more resistant to isomerization and chemical and
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thermal decomposition, as compared with the metathesis product mixture prior
to treatment
with adsorbent or distillation as disclosed herein. For the purposes of this
invention, the term
"isomerization" shall be defined as the migration of a carbon-carbon double
bond, either in a
product olefin or a reactant olefin, from one carbon-carbon pair to another
carbon-carbon
pair. The term "thermal decomposition" shall be defined as the heat-induced
break-down of
compound, herein the product olefin(s) and optionally the reactant olefin(s),
into one or
more molecular fragments or residues. The term "chemical decomposition" shall
include any
undesirable chemical transformation of a compound, herein the product
olefin(s) and
optionally the reactant olefm(s), to form a by-product. Accordingly, the novel
stabilization
method of this invention beneficially reduces the chances of such detrimental
processes and
allows for storage of product mixtures at higher temperatures and for longer
periods of time.
Moreover, the novel stabilization method also allows for the subsequent
separation of
products, for example, by distillation, at higher temperatures. Losses in
target product
olefins and raw material olefins are reduced. In contrast to prior art
methods, the adsorbent
method of this invention advantageously involves one process step and uses
inexpensive and
readily accessible materials. Additionally, the process of this invention is
easily integrated
into the work-up of a metathesis product mixture. The selection of adsorbent
method or
distillation method offers flexibility depending, for example, upon the
particular plant design
and economics. Moreover, the stabilization method of this invention typically
does not
introduce additional metals or compounds into the olefin. metathesis product
mixture that
might be difficult to separate or might induce adverse effects.
In a second aspect, this invention pertains to a novel, stabilized olefm
metathesis
product composition comprising one or more olefins produced in a metathesis
process, the
composition having a total concentration of metal(s) of less than about 30
parts per million
(ppm) by weight, based on the weight of the olefin metathesis product mixture.
Optionally,
the olefin metathesis product composition may additionally comprise one or
more
unconverted reactant olefins, one or more olefin metathesis by-products, one
or more
ligands, one or more solvents, or a combination thereof.
Olefins prepared by metathesis find utility as starting materials for the
production of
polyolefins, polyester polyols, polyester polyamines, and polyester
polyepoxides, all of which
find further utility in the manufacture of polymeric thermoset resins.
Stabilized olefin
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metathesis products are more likely to have greater stability and a longer
shelf life without
undesirable isomerization and by-product formation.
In a third aspect this invention provides for two novel methods of removing
catalytic
and non-catalytic metals from an olefin metathesis product mixture. In one
aspect, the
invention comprises contacting an olefm metathesis product mixture comprising
one or more
olefins produced in a metathesis process and one or more metals, with an
adsorbent under
conditions sufficient to reduce the metals to a total concentration of less
than about 30 parts
per million (ppm) by weight, based on the weight of the olefin metathesis
product mixture.
In another aspect, the invention comprises subjecting an olefin metathesis
product mixture to
a first distillation to remove substantially volatiles and lights, and
thereafter, subjecting
bottoms from the first distillation to a second distillation so as to separate
the olefin
metathesis products from the metal(s); the distillations being conducted under
conditions
sufficient to reduce the metal(s) to a concentration of less than about 30 ppm
by weight,
based on the weight of the olefin metathesis product mixture.
In this third aspect, the invention provides for a process of removing the
metals
present in an olefin metathesis product mixture to a low concentration,
namely, a total
concentration of less than about 30 ppm by weight. The process is effected in
one simple
step with inexpensive, readily obtainable adsorbents, or alternatively, with
distillation.
Beneficially, a high efficiency of metal removal is achieved, as compared with
prior art
methods. In preferred embodiments employing specific carbon adsorbents, metal
removal is
highly efficient resulting in a total metal concentration in the parts per
billion range. The
removal of metals from the olefin metathesis product mixture beneficially
enhances product
stability against double bond isomerization and thermal and chemical
decomposition, as well
as providing a product of higher purity. Moreover, the metals removed by the
novel process
can be recovered and reprocessed.
Detailed Description of the Invention
Generally, olefin metathesis product mixtures are obtained by contacting a
first
reactant olefin with a second reactant olefin or a reactant alkyne in the
presence of a
metathesis catalyst under reaction conditions sufficient to prepare one or
more unsaturated
products that are different from the reactant olefins. The metathesis catalyst
generally
comprises one or more catalytic metals and a catalytically active combination
of one or more
ligands. During metathesis, the catalyst may degrade in part, for example,
when the ligand
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reacts to form ligand degradation products or when the catalytic metal binds
to ligand
degradation products. The metathesis catalyst and metathesis catalyst
degradation products
provide a source of metals that can destabilize the olefm metathesis product
mixture.
Destabilization can take the form of double bond isomerization to yield
isomers different
from the target or reactant isomer(s), and/or chemical and thermal
decomposition to yield
undesirable by-products of lower commercial value. Additionally, the olefm
metathesis
product mixture may contain destabilizing metals derived from extraneous
sources, including
metallic promoters added to facilitate the metathesis process itself or metals
leached into the
metathesis reaction from a heterogeneous catalyst, catalyst support, or a
reactor, pipes, and
conduits.
In the novel process of this invention an olefm metathesis product mixture is
beneficially stabilized, preferably, against double bond isomerization and
thermal and
chemical decomposition. The novel process comprises (a) contacting an olefm
metathesis
product mixture, comprising one or more olefins obtained in a metathesis
process, a
metathesis catalyst comprising one or more catalytic metals, optionally, one
or more catalyst
degradation products, and optionally, one or more metals derived from sources
other than
the catalyst and catalyst degradation products, with an adsorbent, or (b)
subjecting the olefm
metathesis product mixture to a first distillation to remove substantially
volatiles and lights,
and thereafter, subjecting bottoms from the first distillation to a second
distillation; the (a)
adsorbent or (b) distillation method being conducted under conditions
sufficient to remove
the metal(s) to a concentration sufficient to stabilize the metathesis product
mixture, as
compared with the untreated product mixture. This invention is not limited to
any particular
form or valence of the metal(s). Elemental metal(s) or metallic ions are all
suitably removed
in the process of this invention.
In another aspect, this invention provides for a novel, stabilized olefin
metathesis
product composition comprising one or more olefms produced in an olefm
metathesis
process, the composition having a total concentration of metal(s) of less than
about 30 parts
per million (ppm) by weight, based on the weight of the olefm metathesis
product mixture.
In yet another aspect, this invention provides for novel methods of reducing
the
concentration of metals in an olefm metathesis product mixture. In one aspect,
the process
comprises contacting an olefm metathesis product mixture comprising one or
more olefms
produced in a metathesis process and one or more metals, with an adsorbent
under
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conditions sufficient to reduce the concentration of metal(s) to less than
about 30 ppra by
weight, based on the weight of the olefin metathesis product mixture. In
another aspect, the
process comprises subjecting the olefin metathesis product mixture comprising
one or more
olefins produced in a metathesis process and one or more metals to a first
distillation to
remove substantially volatiles and lights, and thereafter, subjecting bottoms
from the first
distillation to a second distillation; the distillation method being conducted
under conditions
sufficient to reduce the metal(s) to a concentration less than about 30 ppm by
weight, based
on the weight of the product mixture.
In one preferred embodiment of the aforementioned inventions, the metal
comprises
ruthenium, molybdenum, tungsten, rhenium, or a combination thereof.
In another preferred embodiment of the aforementioned invention, the adsorbent
comprises carbon, more preferably, a wood carbon. In this preferred
embodiment, the
removal of metathesis catalyst and metathesis catalyst degradation products is
highly
efficient, as compared with prior art methods; for example, on treatment with
the preferred
wood carbon, metals are reduced to a total concentration in the parts per
billion range.
In another preferred embodiment of this invention, the distillation method
comprises
subjecting an olefin metathesis product mixture to a first distillation under
conditions
sufficient to remove substantially volatiles and lights; and thereafter
subjecting bottoms from
the first distillation to a short path wiped-film evaporation under conditions
sufficient to
reduce metal(s) in the metathesis product mixture to a concentration of less
than about 100
parts per billion (ppb) by weight.
In the inventions described herein, the starting metathesis product
composition can be
obtained from any metathesis process, including for example, homo-metathesis
processes
between two reactant olefins of identical chemical composition; cross-
metathesis processes
between two reactant olefins of different chemical composition; metathesis
processes
between similar or different acyclic olefins to product acyclic metathesized
olefin products;
ring-opening polymerization metathesis processes to form linear, unsaturated
polymers; ring-
closing metathesis processes to form unsaturated ring compounds; and cross-
metathesis
processes of an alkene and an alkyne to form a conjugated 1,3-diene. A
preferred metathesis
process involves the metathesis of a long chain unsaturated olefin, such as
methyl oleate or
oleic acid, with a short chain olefin, preferably, a C2_8 olefm, more
preferably, ethylene or
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propylene, to form one or more intermediate-chain olefins, such as 1-decene or
methyl 9-
decenoate.
The generation of olefin metathesis product mixtures via olefin metathesis
processes
is well-documented in the art, as noted for example, by K. J. Ivin and J. C.
Mol, Olefin
Metathesis and Metathesis Polymerization, Academic Press, San Diego, 1997, as
well as by
M. R. Buchmeiser, Chemical Reviews, 2000, 100, 1565-1604. Reactant olefins can
include
any hydrocarbon or substituted hydrocarbon having at least one olefinic carbon-
carbon
double bond. Preferred olefins contain from 2 to about 50 carbon atoms, more
preferably,
from 2 to about 30 carbon atoms. The reactant olefins can be the same or
different, and they
can be each independently acyclic or cyclic. The reactant olefins can each
have two or more
double bonds. The substituents on the reactant olefins may include any
substituent that does
not inhibit the desired 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, C746
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
ether, acyl, hydroxy,
halo (preferably, chloro and bromo), nitro, carboxylic acid, ester, and amide
moieties.
Non-limiting examples of suitable reactant olefms include ethylene, propylene,
butylene,
pentene, hexene, heptene, octene, nonene, decene, dodecene, cyclopentene,
cyclohexene,
cyclooctene, butadiene, octadiene, norbornene, dicyclopentadiene,
cyclooctadiene,
acrylamide, methyl acrylate; unsaturated fatty acids, such as 3-hexenoic
(hydrosorbic),
trans-2-heptenoic, 2-octenoic, 2-nonenoic, cis- and trans-4-decenoic, 9-
decenoic (caproleic),
10-undecenoic (undecylenic), cis-4-dodecenoic (linderic), tridecenoic, cis-9-
tetradecenoic
(myristoleic), pentadecenoic, cis-9-hexadecenoic (cis-9-palmitoleic), trans-9-
hexadecenoic
(trans-9-palmitoleic), 9-heptadecenoic, cis-6-octadecenoic (petroselinic),
trans-6-
octadecenoic (petroselaidic), cis-9-octadecenoic (oleic), trans-9-octadecenoic
(elaidic), cis-
11-octadecenoic, trans-11-octadecenoic (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-
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octadecadienoic (linoleic), cis-9-cis-12-cis-15-octadecatrienoic (linolethc),
eleostearic,
12-hydroxy-cis-9-octadecenoic (ricinoleic), cis-5-docosenoic, cis-5,13-
docosadienoic, and
like acids.
Unsaturated fatty acid esters are also suitable metathesis reactants. The
alcohol
segment of the fatty acid ester can be any monohydric, dihydric, or polyhydric
alcohol
capable of condensation with an unsaturated fatty acid to form the ester. In
seed oils the
alcohol segment is glycerol, a trihydric alcohol. If desired, the glycerides
can be converted
via transesterification to fatty acid esters of lower alkanols, which may be
more readily
separated or suitable for downstream chemical processing. Typically, the
alcohol used in
transesterification contains at least one carbon atom. Typically, the alcohol
contains less
than about 15 carbon atoms, preferably, less than about 12 carbon atoms, more
preferably,
less than about 10 carbon atoms, and even more preferably, less than about 8
carbon atoms.
The carbon atoms in the alcohol segment 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 reactant olefin, including the
aforementioned
alkyl, cycloalkyl, monocyclic aromatic, arylalkyl, alkylaryl, hydroxyl, halo,
nitro, carboxylic
acid, ether, ester, acyl, and amide substituents. Preferably, the alcohol
segment of the
unsaturated fatty acid ester is glycerol or a straight-chain or branched C1_8
alkanol. Most
preferably, the alcohol is a C1-4 alkanol, suitable examples of which include
methanol,
ethanol, and propanol.
In a more preferred embodiment, one reactant olefm is a C630 unsaturatedfatty
acid
or unsaturated fatty acid ester, most preferably, oleic acid or an ester of
oleic acid. The
second reactant olefin is more preferably a "lower olefin," that is, a C2_5
olefin, such as,
ethylene, propylene, 1-butene, 2-butene, butadiene, pentenes, or mixtures
thereof. Even
more preferably, the second reactant olefin is ethylene or propylene, most
preferably,
ethylene.
Metathesis process conditions are also well documented in the art. (See
references
cited hereinabove.) The reactant olefins may be fed to the metathesis process
in any operable
quantities. Depending upon the particular reactants and desired products, it
may be
beneficial to minimize the homo-metathesis of the reactant olefms. One skilled
in the art will
know how to choose the relative amounts of reactant olefins, and if desired,
how to minimize
homo-metathesis reactions. Typically, the ratio of a first reactant olefin to
a second reactant
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olefin is at least about 0.8/1. The following molar ratios may be used as a
guideline for the
metathesis of preferred long-chain unsaturated fatty acids or fatty acid
esters with preferred
lower olefins. Typically, the molar ratio of lower olefin to total unsaturated
fatty acids or
fatty acid esters is greater than about 0.8/1.0, preferably, greater than
about 0.9/1Ø
Typically, the molar ratio of lower olefin to total unsaturated fatty acids or
fatty acid esters is
less than about 5/1, and preferably, less than about 3/1. When the lower
olefin is ethylene,
homo-metathesis is not problematical, and the molar ratio of ethylene to
unsaturated fatty
acid or fatty acid ester can range up to about 20/1Ø More preferably, when
ethylene is
employed, the molar ratio is less than about 10/1Ø
The reactant olefin is typically provided to the metathesis process in a neat
liquid
phase without a solvent, because the use of a solvent may increase recycle
requirements and
costs. Optionally, however, a solvent may be employed. When a solvent is used,
the
metathesis olefin product composition further contains the solvent, which may
be
subsequently recovered and recycled to the metathesis process. Non-limiting
examples of
suitable solvents include aromatic hydrocarbons, such as benzene, toluene, and
xylenes;
chlorinated aromatic hydrocarbons, preferably chlorinated benzenes, such as
chlorobenzene
and dichlorobenzene; alkalies, such as pentane, hexane, and cyclohexane;
ethers, such as
diethyl ether and tetrahydrofuran; and chlorinated alkalies, such as methylene
chloride and
chloroform. Any operable amount of solvent is acceptable. Generally, the
concentration of
each reactant olefin in the solvent is greater than about 0.05 M, preferably,
greater than
about 0.5 M, but typically, less than about the saturation concentration, and
preferably, less
than about 5.0 M.
Lower olefins, such as ethylene, propylene, and butenes, can be fed to the
metathesis
as an essentially pure gas or, optionally, diluted with a gaseous diluent. As
the gaseous
diluent, any substantially inert gas may be used, suitable examples of which
include, without
limitation, helium, neon, argon, nitrogen, and mixtures thereof. If a gaseous
diluent is used,
then the concentration of lower olefin in the diluent may suitably range from
greater than
about 5 mole percent, and preferably, greater than about 10 mole percent, to
typically less
than about 90 mole percent lower olefin, based on the total moles of lower
olefm and
gaseous diluent. Typically, oxygen is excluded from the metathesis process, so
as to avoid
undesirable side-reactions with the metathesis catalyst and its component
parts (metal and
ligands) as well as with reactant and product olefins.
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As a further option, a stabilizing ligand may be added to the
metathesis process. The stabilizing ligand can comprise any molecule or ion
that
promotes catalyst stability in the metathesis process, as measured, for
example,
by increased activity or extended catalyst lifetime. Non-limiting examples of
stabilizing ligands include tri(alkyl) phosphines, such as
tricyclohexylphosphine,
tricyclopentylphosphine, and tributylphosphine; tri(aryl) phosphines, such as
tri(phenyl) phosphine and tri(methylphenyl) phosphine; alkyldiarylphosphines,
such as cyclohexyldiphenylphosphine; dialkylarylphosphines, such as
dicyclohexylphenylphosphine; ethers, such as anisole; phosphine oxides, such
as
triphenylphosphine oxide; as well as phosphinites, phosphonites,
phosphoramidites, pyridines, and any combination of the aforementioned
compounds. Preferably, the stabilizing ligand is selected from the
aforementioned
phosphines, and more preferably, is tri(cyclohexyl) phosphine or tri(phenyl)
phosphine. The quantity of stabilizing ligand can vary depending upon the
specific
catalyst employed and its specific ligand components. Typically, the molar
ratio of
stabilizing ligand to catalyst is greater than about 0.05/1, and preferably,
greater
than about 0.5/1. Typically, the molar ratio of stabilizing ligand to catalyst
is less
than about 2.0/1, and preferably, less than about 1.5/1.
The metathesis catalyst can comprise any catalyst that is capable of
facilitating a metathesis process. Many metathesis catalysts are known in the
art,
representative examples of which are disclosed in WO 93/20111, US 5,312,940,
WO 96/04289; and by J. Kingsbury et al. in Journal of the American Chemical
Society, 121 (1999), 791-799; as well as WO 02/076920. The preferred
metathesis catalyst comprises a catalytic metal selected from ruthenium,
molybdenum, tungsten, rhenium or a mixture thereof; more preferably,
ruthenium,
molybdenum, rhenium, or a mixture thereof; and most preferably, ruthenium.
Non-limiting examples of suitable ruthenium catalysts include
dichloro-3,3-diphenylvinylcarbene-bis(tricyclohexylphosphine)ruthenium (II),
bis(tricyclohexylphosphine)benzylidene ruthenium dichloride,
bis(tricyclohexylphosphine)benzylidene ruthenium dibromide,
tricyclohexylphosphine [1,3-bis(2,4,6-trimethylpheny1)-4,5-dihydroimidazol-2-
ylidene][benzylidene]ruthenium dichloride, tricyclohexylphosphine[1,3-
bis(2,4,6-
-12-
=
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trimethylpheny1)-4,5-dihydroimidazol-2-ylidene][benzylidene]ruthenium
dibromide, and
tricyclohexylphosphine[1,3-bis(2,4,6-trimethylpheny1)-4,5-dihydroimidazol-2-
ylidene][benzylidene]ruthenium diiodide. Non-limiting examples of suitable
molybdenum,
rhenium, and tungsten catalysts include Mo03/silica, 2,6- diisopropylphenyl-
imidoneophylidenemolybdenum (VI) bis(hexafluoro-t-butwdde),
Re207lalumina/R4Sn,
Re207/silica-alumina/R4Sn, Re207/B203-alumina/R4Sn, WC16/R4Sn, wherein in the
aforementioned formulas each R is independently selected from alkyl and aryl
moieties and
substituted derivatives thereof, preferably, C1-20 alkyl and C6-20 aryl
moieties.
Most preferably, the ruthenium metathesis catalyst is selected from the group
consisting of dichloro-3,3-diphenylvinylcarbene-
bis(tricyclohexylphosphine)ruthenium (II),
bis(tricyclohexylphosphine)benzylidene ruthenium dichloride,
tricyclohexylphosphine[1,3-
bis(2,4,6-trimethylpheny1)-4,5-dihydroimidazol-2-
ylidene][benzylidene]ruthenium (IV)
dichloride, tricyclohexylphosphine[1,3-bis(2,4,6-trimethylpheny1)-4,5-
dihydroimidazol-2-
ylidene][benzylidene]ruthenium (IV) dibromide, tricyclohexylphosphine[1,3-
bis(2,4,6-
trimethylpheny1)-4,5-dihydroimidazol-2-ylidenel[benzylidene]ruthenium (IV)
diiodide, and
the chelated ruthenium complexes represented by the following formula I:
(R2)bY
(Pa M ______________________________
In formula I, M is Ru; each L is independently selected from neutral and
anionic ligands in
any combination that balances the bonding and charge requirements of M; a is
an integer,
preferably from 1 to about 4, which represents the total number of ligands L;
le is selected
from hydrogen, straight-chain or branched alkyl, cycloalkyl, aryl, and
substituted aryl
radicals; Y is an electron donor group of an element from Group 15 or 16 of
the Periodic
Table, (as referenced by the IUPAC in Nomenclature of Inorganic Chemistry:
Recommendations 1990, G. J. Leigh, Editor, Blackwell Scientific Publications,
1990);
Y being more preferably 0, S, N, or P; each R2 is independently selected from
hydrogen,
alkyl, cycloalkyl, aryl, and substituted aryl radicals sufficient to satisfy
the valency of Y,
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preferably such that Y is formally neutral; b is an integer, preferably 0 to
about 2,
representing the total number of R2 radicals; and Z is an organic diradical
that is bonded to
both Y and the carbene carbon (C) so as to form a bidentate ligand, which
ligand in
connection with the M atom forms a ring of from about 4 to about 8 atoms. More
preferably, each L in formula I is independently selected from the group
consisting of halides,
most preferably, fluoride, chloride, bromide, and iodide; cyanide,
thiocyanate, phosphines of
the formula PR33, amines of the formula NR33, water and ethers of the formula
OR32,
thio ethers of the formula SR32, and ligands having the formulas 11 and 111
hereinafter:
R3 R3
NI
NI
D.0 and :c']
I 3
(1--) (III)
wherein each R3 in any of the aforementioned formulas is independently
selected from the
group consisting of hydrogen, alkyl, preferably, C1-15 alkyl; cycloalkyl,
preferably, C3-8
cycloalkyl; aryl, preferably, C6-15 aryl, and substituted aryl, preferably C6-
15 substituted aryl,
radicals. Mixtures of any of the aforementioned ligands L may be employed in
any given
species of formula I. More preferably, R' in Formula I is selected from the
group consisting
of hydrogen, C1_15 alkyl, C3_8 cycloalkyl, and C6_15 aryl radicals. More
preferably, each R2 is
independently selected from the group consisting of C1-15 alkyl, C3-8
cycloalkyl, and C6_15 aryl
radicals. Preferably, Z is selected from the following diradicals: ethylene
(IV), vinylene (V),
phenylene (VI), substituted vinylenes (VII), substituted phenylenes (VIII),
naphthylene (IX),
substituted naphthylenes (X), piperazindiyl (XI), piperidiyl (XII)
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C R3
1
CH2 110
H2
)(R3
(IV) (V) (VI) (VII)
SO 00
Rn R3n R3n
(VIII) (a) (X)
(IX) (XII)
wherein each R3 may be, as noted above, selected from hydrogen, alkyl,
preferably, C1-15
alkyl; cycloalkyl, preferably, C3_8 cycloalkyl; and aryl, preferably, C6_15
aryl radicals; and
wherein each n is an integer from 1 to about 4. The most preferred embodiment
of formula I
is represented by formula XIII:
CH3
CH3
C= Ru <
H/ t T
PCy3
(XIII)
wherein each T is independently selected from Cl and Br, and PCy3 is
tricyclohexylphosphine.
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Although the metathesis catalyst is preferably a homogeneous catalyst
dissolved in
the metathesis reaction fluid, the catalyst may be provided in a heterogeneous
form bound to
or deposited on any conventional catalyst support. Such supports are known to
the skilled
artisan, and include, for example, silica, alumina, silica-aluminas,
aluminosilicates, titania,
titano silicates, carbon, and reticulated cross-linked polymeric resins, such
as reticulated
cross-linked polystyrenes. If a catalyst support is used, the metathesis
catalyst may be loaded
onto the catalyst support in any amount, provided that the metathesis process
proceeds to
the targeted metathesis products. Generally, the catalyst loading on the
support is greater
than about 0.01 weight percent catalytic metal, and preferably, greater than
about
0.05 weight percent catalytic metal, based on the total weight of catalyst
plus support.
Generally, the loading is less than about 20 weight percent catalytic metal,
and preferably,
less than about 10 weight percent catalytic metal, based on the total weight
of the catalyst
and support.
Metathesis process conditions are well documented in the art, as noted in the
above-
cited references. Typical process conditions are summarized hereinbelow; but
the inventions
disclosed herein should not be bound or limited in any manner by the following
statements.
Other metathesis process conditions may be suitable, depending upon the
particular reactants
and catalyst employed and upon the products targeted. Generally, the process
is conducted
at a temperature greater than about 0 C, preferably, greater than about 15 C,
and more
preferably, greater than about 25 C. Generally, the metathesis process is
conducted at a
temperature less than about 80 C, preferably, less than about 50 C, and more
preferably, less
than about 35 C. The total pressure, including reactant olefins and gaseous
diluent, is
typically 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).
Typically, the total
pressure is less than about 500 psig (2,758 kPa), preferably, less than about
250 psig
(1,723 kPa), and more preferably, less than about 100 psig (690 kPa). If the
metathesis
process is conducted in a batch reactor, the ratio of moles of olefin
feedstock to moles of
metathesis catalyst will typically be greater than about 10:1, preferably,
greater than about
50:1, and more preferably, greater than about 100:1. The molar ratio of olefin
feedstock to
metathesis catalyst will be 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. If the process is
conducted in
a continuous flow reactor, then the weight hourly space velocity, given in
units of grams
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metathesis feedstock per gram catalyst per hour (WI) determines the relative
quantity of
reactant olefins to catalyst employed, as well as the residence time of the
olefin feedstock in
the reactor. Accordingly, the weight hourly space velocity of the reactant
olefin feedstock is
typically greater than about 0.04 g per g catalyst per hour (h4), and
preferably, greater than
about 0.1 111. The weight hourly space velocity of the olefin reactant
feedstock is typically
less than about 100 Ill, and preferably, less than about 20 h-1. The flows of
olefin reactants
are typically adjusted to produce the desired ratio of first reactant olefin
to second reactant
olefin.
When the metathesis process is conducted as described hereinabove, then a
metathesis product mixture is obtained that contains one or more product
olefms, a
metathesis catalyst comprising catalytic metal and one or more ligands;
optionally, one or
more catalyst degradation products; optionally, one or more unconverted olefin
reactants;
and optionally one or more metals obtained from sources other than the
catalyst and catalyst
degradation products including, for example, iron, nickel, copper, zinc,
cobalt, chromium,
lithium, sodium, potassium, magnesium, calcium, and mixtures thereof. Other
optional
components of the metathesis product mixture include one or more metathesis by-
products,
one or more solvents, and one or more stabilizing ligands. The metathesis
product olefins
may include, for example, unsubstituted and substituted acyclic olefins,
unsubstituted and
substituted cyclic olefins, polyolefin polymers, and conjugated 1,3-dienes,
providing at least
one product olefin is different from the reactant olefins. The product olefins
may include
monoolefins, diolefins, and polyolefins, and substituted derivatives thereof.
Suitable
substituents have been. named already in connection with the substituted
reactant olefins.
Preferably, the acyclic olefin is a C2_20 acyclic olefin. Preferably, the
cyclic olefin is a C4_s
cyclic olefin. In a preferred embodiment of the invention, the metathesis
product olefin is a
C2-20 a-olefin, such as 1-decene, or a C2-20 ap-unsaturated ester or acid,
such as methyl
9-decenoate.
It is to be noted that typically metathesis product mixtures contain the
catalytic
metal(s) in a concentration greater than about 1 part per million (ppm), more
typically,
greater than about 30 ppm by weight, based on the weight of the product
mixture. Typically,
the concentration of catalytic metal in the metathesis product mixture is less
than about
500 ppm, preferably, less than about 100 ppm, by weight.
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The metathesis product mixture may be separated by conventional methods known
to
those skilled in the art, for example, distillation, extraction,
precipitation, crystallization,
membrane separation, and the like. Since metals present in the product mixture
can
detrimentally induce double-bond isomerization and thermal and chemical
decomposition, the
process of this invention addresses the need to remove catalytic metals and
other metals
present from extraneous sources. While the metals can be removed any time
after the
metathesis reaction is complete, it is preferable to remove the metals early
on, that is, soon
after the metathesis reaction is finished, and preferably, prior to effecting
separation at
elevated temperature or storage for long periods of time.
In accordance with the process of this invention, the metathesis product
mixture may
be (a) contacted with an adsorbent, or (b) subjected to distillation under
process conditions
sufficient to remove metals to a concentration sufficient to stabili7e the
mixture, relative to
the starting metathesis product mixture that has not been stabilized by the
method described
herein (crude mixture). Typically, after treatment by method (a) or (b), the
total
concentration of metal(s) is less than about 30 parts per million by weight,
based on the
weight of the olefin metathesis product mixture. Preferably, the total
concentration of
metal(s) is reduced to less than about 15 parts per million, more preferably,
to less than
about 5 parts per million, even more preferably, to less than about 1 part per
million. In most
preferred embodiments of the invention, the total concentration of metal(s) is
reduced to less
than about 0.3 parts per million (300 parts per billion), based on the weight
of metathesis
product mixture. The reduced concentration of metal(s), however, is typically,
greater than
about 0 parts per trillion, and more typically, greater than about 1 part per
billion, based on
the weight of metathesis product mixture.
Any adsorbent that is capable of stabili7ing the metathesis product mixture
may be
employed in the process of this invention. Non-limiting examples of suitable
adsorbents
include without limitation carbons, silica gels, diatomaceous earths, clays,
reticular cross-
linked ion-exchange resins, aluminas, silica-aluminas, and mixtures thereof.
Suitable clays
include, without limitation, montmorillonite, bentonite, and kaolin clays.
Suitable carbons
include, without limitation, wood, and coconut carbons. Suitable reticular
cross-linked ion-
exchange resins include, without limitation, reticular cross-linked ionically-
ftmctionali7ed
polystyrene resins. If silica such as silica gel is used, then preferably, the
silica or silica gel is
used exclusive of other treatments, preferably, exclusive of treatments with
lead tetraacetate,
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tris(hydroxymethyl)phosphine, triphenylphosphine oxide, dimethyl sulfrodde, or
mixtures
thereof. Preferably, the adsorbent is selected from carbons, clays, reticular
cross-linked ion-
exchange resins, aluminas, silica-aluminas, and mixtures thereof. More
preferably, the
adsorbent is carbon, even more preferably, a wood carbon. Most preferably, the
carbon
adsorbent is a Westvaco NucharTM brand wood carbon.
Any weight ratio of adsorbent to metathesis product mixture can be employed,
provided that the mixture is stabilind. Generally, the adsorbent is used in a
quantity greater
than about 0.1 weight percent, preferably, greater than about 1 weight
percent, based on the
weight of the metathesis product mixture. Generally, the adsorbent is used in
a quantity less
than about 20 weight percent, preferably, less than about 10 weight percent,
based on the
weight of the metathesis product mixture.
The contacting of the metathesis product mixture with the adsorbent can be
effected
in any conventional mariner, for example, by slurrying the product mixture
with the
adsorbent followed by filtration, or by passing the product mixture through a
fixed column of
the adsorbent. If the metathesis product mixture is not sufficiently fluid at
the contacting
temperature, the product mixture may be dissolved in a suitable solvent for
ease of
contacting with the adsorbent. Any thermally and chemically stable solvent
having
acceptable solubility may be used. Non-limiting examples of suitable solvents
include
aromatic hydrocarbons, such as benzene, toluene, and xylenes; chlorinated
aromatic
hydrocarbons, preferably chlorinated benzenes, such as chlorobenzene and
dichlorobenzene;
alkanes, such as pentane, hexane, and cyclohexane; ethers, such as diethyl
ether and
tetrahydrofuran; and chlorinated alkanes, such as methylene chloride and
chloroform. The
contacting temperature and pressure may vary depending upon the specific
operational
design, product mixture, and adsorbent selected. Usually, the contacting
temperature is
greater than about -10 C, preferably, greater than about 5 C. Usually, the
contacting
temperature is less than about 70 C, preferably, less than about 50 C. The
pressure may
range from subatmospheric to superatmo spheric, with a preferred range from
about
atmospheric to about 100 psig (689.5 kPa). The contacting time can also vary
depending
upon the specifics of the product mixture and adsorbent selected. Typically,
in a slurry or
batch process the contacting time is greater than about 15 minutes.
Preferably, the
contacting time is less than about 24 hours, more preferably, less than about
12 hours, even
more preferably, less than about 6 hours, and most preferably, less than about
4 hours.
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Typically, in a continuous flow, fixed bed process, the weight hourly space
velocity, given in
units of grams metathesis product mixture per gram adsorbent per hour (hr4),
is typically
greater than about 0.01 hr4, preferably, greater than about 0.1 hr-1.
Typically, the weight
hourly space velocity is less than about 10 hfl, and preferably, less than
about 5 Id'.
Otherwise, no special procedures are required for the process of this
invention. The process
may be conducted under air, provided that air/oxygen does not react with the
olefmic
products or reactants.
In an alternative embodiment of this invention, metal(s) can be removed from
an
olefm metathesis product mixture by distillation to yield stabilind metathesis
product
mixtures having the low concentrations of metal(s) described hereinbefore. In
the distillation
method of this invention, the metathesis product mixture is subjected to a
first distillation to
remove substantially lights or volatiles; and thereafter, the bottoms from the
first distillation
are subjected to a second distillation in a short-path wiped film evaporator
to reduce the
metal(s) concentration to less than about 30 ppm, and preferably, less than
about 100 ppb.
Lights removal, as a first stage, appears to be important to the success of
reducing metal(s)
to a final concentration of less than about 100 ppb. If substantial amounts of
lights are
present in the second distillation, then entrainment of the metals into the
olefin distillate may
be unavoidable. After lights and volatiles removal the concentration of
metal(s) achieved in
the distillate at the second stage is generally less than about 100 ppb, and
preferably, less
than about 75 ppb by weight. The phrase "to remove substantially lights and
volatiles"
means that greater than about 75 percent by weight, preferably, greater than
about
85 percent by weight, and more preferably, greater than about 90 percent by
weight, of the
lights and volatiles are removed, based on the weight of the olefin metathesis
product
mixture fed to the first distillation. Lights and volatiles primarily include
metathesis solvent
and may also include lower olefin and volatile metathesis by-products.
The first distillation step may be conducted in any suitable equipment, so
long as the
volatiles and lights are substantially removed without unacceptable loss of
target olefin
products. Equipment suitably employed includes, without limitation, a
distillation tower,
stripper, falling film evaporator, wiped film evaporator, or short-path wiped
film evaporator,
all known to those of skill in the art. The actual equipment chosen will
depend upon the
operating temperature and operating pressure required to remove the volatiles
and lights, as
well cost considerations, equipment availability, and consideration of the
properties (stability,
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volatility, etc.) of the specific components of the olefin product mixture.
Typically, the first
distillation process conditions (for example, T, P) depend upon the specific
volatiles and
lights to be removed. Typically, the temperature of the first distillation is
greater than about
40 C, while the pressure is typically greater than about 15 mm Hg (20 kPa).
Typically, the
temperature of the first distillation is less than about 150 C, while the
pressure is less than
about 100 mm Hg (132 kPa). Other process conditions may be suitable, as
determined by
one skilled in the art.
After removal of lights and volatiles, the metathesis product mixture is fed
to a
second distillation equipment, preferably, a short-path wiped film evaporator,
under
conditions sufficient to reduce metal(s) to a concentration of less than about
30 ppm by
weight. Short path wiped-film evaporators, known to those of skill in the art,
contain
internal condensers and a relatively short path from heated surface to
condenser surface that
renders the pressure drop between the two surfaces negligible. The actual path
distance will
vary depending upon the scale of the evaporator, for example, from about 1 to
about
4 centimeters in a laboratory scale evaporator to about 50 centimeters in a
commercial unit.
A short path evaporation can be effected at low pressures (typically, from
greater than about
0.001 mm Hg (1.3 Pa) to less than about 5 mm Hg (6.6 kPa)), which in turn
allow for lower
boiling temperatures. Lower boiling temperatures are advantageous, because as
noted
throughout this description, olefin metathesis product mixtures are more
unstable at
increasing temperatures due to the presence of metal(s). Additionally, the
wiped film
evaporator also functions to reduce the thickness of a film and distribute it
evenly on the
heated surface, which in turn reduces hot spots that could adversely affect
thermally unstable
compounds.
The temperature and pressure of the short path wiped-film evaporation will
also
depend upon the specific metathesis products to be distilled. One skilled in
the art will know
how to vary temperature and pressure of the second distillation to recover the
desired
products. In a preferred embodiment involving the distillation of 1-decene,
methyl
decenoate, and methyl oleate, typically, the short path wiped-film evaporation
is conducted
at a temperature greater than about 150 C and a pressure greater than about
0.001 mm Hg
(1.3 Pa). Typically, in the preferred embodiment the short-path wiped-film
evaporation is
conducted at a temperature less than about 200 C and a pressure less than
about 5 mm Hg
(6.6 kPa). The actual pressure used depends upon the requirement to stay below
the
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temperature at which thermal decomposition occurs. Residence time of the
metathesis
product in the short path wiped-film evaporator is typically in the range of
about 15 seconds
to about 20 seconds, thereby reducing the heat history on the metathesis
product and further
minimizing the possibility of thermal degradation. When the distillation is
conducted as
described hereinabove first to remove volatile and lights and then via a short
path wiped-film
evaporator, then typically the total concentration of metal(s) in the
metathesis product
mixture is reduced to less than about 100 ppb, and preferably, less than about
75 ppb by
weight.
The following examples are provided as illustrative embodiments of the process
and
composition of this invention. The examples should not be construed to limit
the inventions
in any manner. In light of the disclosure herein, those of skill in the art
will recognize
modifications of the following illustrative embodiments that fall within the
scope of the
invention.
Preparation of Olefm Metathesis Product Mixture
In a dry box, a solution was prepared of a catalytic ruthenium complex (0.01
M) in
toluene, the ruthenium complex being bis(tricyclohexylphosphine)benzylidene
ruthenium
dichloride (Grubb's catalyst). Methyloleate (Aldrich Company) was degassed
with nitrogen
and passed through a column of activated alumina prior to use. In a dry box, a
reactor was
charged with the following reagents: methyloleate (3.50 g, purified as
described above),
tetradecane (0.50 g, used as an internal standard for gas chromatography
analysis), and the
catalyst solution (265 microliters, 0.01 M solution). The molar ratio of
methyloleate to
ruthenium was 4452/1. The reactor was sealed, removed from the dry box, and
attached to
an ethylene manifold (ethylene, 99.8 percent purity, polymer grade). An olefm
metathesis
reaction was effected at 60 psig ethylene (413.7 kPa) and 30 C for 4 hours.
Aliquot samples
were removed from the reactor and analyzed by gas chromatography. An olefin
metathesis
product mixture was obtained comprising 1-decene (19.9 area percent) and
methyl 9-
decenoate (18 area percent), and other components including solvent, methyl
oleate and
homo-metathesis by-products (62.1 area percent).
Examples 1-14.
The general procedure for stabili7ing an olefin metathesis product mixture and
removing catalytic metals from said mixture is described as follows. The crude
metathesis
product mixture obtained hereinabove (10 ml aliquot) containing 65 parts per
million
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ruthenium was slurried with an adsorbent (700 mg) under air for 3 hours at
room
temperature (22 C) and ambient pressure. At the end of the contact period, the
mixture was
filtered through a TefionTm brand tetrafluoroethylene fluorocarbon polymer
filter
(0.45 micron diameter) to yield the stabilized olefin metathesis product
mixture. The
ruthenium content of the stabilized mixture was analyzed by inductively-
coupled plasma mass
spectrometry (ICP-MS).
The above general procedure was carried out with each of the following
adsorbents:
Westvaco NucharTM SA brand wood carbon (Exp. 1), Westvaco NucharTM SA brand
carbon
that was once used (Exp. 2), Westvaco NucharTM SN brand wood carbon (Exp. 3),
Westvaco NucharTM brand wood carbon modified with copper (Exp. 4), Cabot
MonarchTM
brand carbon (Exp. 5), Calgon PCBTM coconut carbon (Exp. 6), Westvaco NucharTM
SA
brand wood carbon modified with potassium carbonate and copper (Exp. 7), Black
Pearl
2000 brand carbon (Exp. 8), diatomaceous earth (Exp. 9), silica gel (Exp. 10),
bentonite clay
(Exp. 11), kaolin clay (Exp. 12), AmberlystTM A21 brand reticulated
polystyrene ion-
exchange resin (Exp. 13), and montmorillonite clay (Exp. 14). Results are set
forth in
Table 1.
Table 1. Stabilization of Olefin Metathesis Product Mixturesa'b
Experiment Adsorbent [Ru] after stabilization
(ppb by weight)
1 Wood carbon (Westvaco) 220
2 Wood carbon (Westvaco, used) 2,000
3 Wood carbon (Westvaco) 170
4 Wood carbon (Westvaco, modified) 850
5 Carbon (Cabot) 14,000
6 Coconut carbon (Calgon) 13,300
7 Wood carbon (Westvaco, modified) 1,140
8 Carbon (Black Pearl) 10,300
9 Diatomaceous earth 13,500
10 Silica gel 3,790
11 Clay (Bentonite) 6,090
12 Clay (Kaolin) 15,100
13 Ion-exchange resin (AmberlystTM) 1,870
14 Clay (Montmorillonite) 9,520
a. Crude Olefin Metathesis Product Mixture: 1-decene (19.9 area percent),
methyl 9-decenoate
(18 area percent), balance containing solvent, methyl oleate, and homo-
metathesis by-products
(62.1 area percent), and 65,000 parts per billion (ppb) ruthenium (65 ppm Ru).
b. Contacting conditions: 3 h at ambient pressure and temperature (-12 C);
0.07 g adsorbent per g
metathesis product mixture.
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From Table 1 it is seen that the adsorbents tested are capable of removing
ruthenium
to a concentration of less than 30,000 parts per billion (ppb) (30 ppm), by
weight, based on
the weight of the olefin metathesis product mixture. Unused wood carbon gave
the best
results, with residual ruthenium concentrations ranging from only 170 ppb to
only 1,140 ppb.
To determine the stability of an olefin metathesis product mixture to olefin
isomerization, two such product mixtures containing methyl 9-decenoate and a
ruthenium
concentration of 100 ppb (Ex. 15) and 423 ppb (Ex. 16), respectively, were
heated to
between 200-220 C and monitored for olefin isomerization by gas phase
chromatography
Table 2. Impact of [Ru] on Olefin Metathesis Product Mixture Stability
Example [Ru] (ppb) Heating Heating Time (h) % Isomerized
Temperature Methyl 9-
( C) Decenoate
15a 100 210-220 2.7 0.2
16b 423 200 1.0 26.3
CE-1 66,500 175 1.0 27.5
175 4.0 48.1
a. Crude Olefin Metathesis Product Mixture: 1-decene (19.8 area percent),
methyl 9-decenoate
15 (19.9 area percent), balance including solvent, methyl oleate, and homo-
metathesis by-products
(60.3 area percent), and [Ru] as shown.
b. Crude Olefin Metathesis Product Mixture: 1-decene (19.9 area percent),
methyl 9-decenoate
(18 area percent), balance including solvent, methyl oleate, and homo-
metathesis by-products
(62.1 area percent), and [Ru] as shown.
20 c. Crude Olefin. Metathesis Product Mixture: 1-decene (10.7 area
percent), methyl 9-decenoate
(14.4 area percent), balance including solvent, methyl oleate, and homo-
metathesis by-products
(74.9 area percent), and [Ru] as shown.
From Table 2 it is seen that when the ruthenium concentration is lowered from
25 423 ppb to 100 ppb, a significant increase in stability to isomerization
is observed.
Specifically, only 0.2 % isomerization occurs at 100 ppb ruthenium (Ex. 15),
as compared
with 26.3 % isomerization occurring at 423 ppb ruthenium (Ex. 16), under
process
conditions wherein the sample of lower ruthenium concentration (Ex. 15) was
heated at a
slightly higher temperature and for a significantly longer time than the
sample of higher
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CA 02501627 2005-04-05
WO 2004/037754 PCT/US2003/030632
ruthenium concentration(Ex. 16). Achieving low ruthenium concentrations is
critical in
order to prevent olefin isomerization during reaction mixture work-up,
purification, and/or
isolation.
Comparative Experiment 1 (CE-1)
For comparative purposes, an olefin metathesis product mixture was heated at
200-220 C and monitored for olefin isomerization by gas chromatography
analysis in a
manner closely similar to that used in Examples 15 and 16, with the exception
that the
ruthenium concentration in this comparative experiment was 66.5 ppm (66,500
ppb). As
shown in Table 2, the comparative product mixture exhibited 27.5 percent
isomerization of
methyl 9-decenoate at 175 C over 1 hour and 48.1 percent isomerization of
methyl
9-decenoate at 175 C over 4 hours. The results shown in Table 2 indicate that
the
comparative olefm metathesis product mixture containing greater than 30 ppm
ruthenium
exhibited a higher instability to isomerization at lower temperature, as
compared with the
olefin metathesis product mixtures of Examples 15 and 16 having a ruthenium
concentration
lower than 30 ppm.
Example 17
An olefin metathesis product mixture similar to that used in Example 1
hereinabove,
comprising 1-decene, methyl decenoate, homo-metathesis by-products, toluene
solvent, and
ruthenium metathesis catalyst (65 ppm Ru) was subjected to a first short-path
wiped-film
evaporation to remove volatiles and lights, including toluene. The evaporator
comprised a
wiped-film evaporator with internal condenser having a distance from heated
surface to
cooled surface of 2 centimeters. The evaporator was operated at 115 C and 30
mm Hg
(39 kPa). Bottoms from the first evaporator were fed into a second short-path
wiped-film
evaporator similar in design to the first evaporator. The second evaporator
was operated at
higher temperature and lower pressure than the first, namely, 185 C and 5 mm
Hg (6.6 kPa).
Residence time of the feed in the second evaporator was estimated to be about
15 to
20 seconds. 1-Decene, methyl deceno ate, and roughly one-half of the methyl
oleate in the
bottoms feed were distilled from the heavies and catalyst. The ruthenium
concentration in
the overheads from the second distillation stage was reduced to between non-
detectable
(<50 ppb) and 75 ppb.
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