Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
21~21 1
The present invention relates to a process for the so-
called ethenolytic metathesis (ethenolysis) of non-
functionalized and functionalized olefins using organic
derivatives of rhenium oxides and to the use of such
derivatives as catalyst~ for this ethenolysis.
The term ethenolysis describes the cleavage of olefinic
compounds in the presence of the olefin parent substance
ethylene, in such a way that the double bonds in the
olefin concerned and in the ethylene are broken apart and
the resulting fragments combine in a random fashion to
give new olefinic compounds. Thus a single product is
produced when a symmetric monoolefin is used. Two
different products are obtained from an asymmetric
monoolefin. The use of di- and oligoolefins increases the
nllmher of products accordingly. Included in the
ethenolysis of olefins in a wider sense is also the ring-
opening of cycloolefins, an ~,~'-diolefin with n+2 chain
members being obtained from a cycloolefin with n ring
members.
For some time, ethenolytic olefin cleavages have been of
industrial interest for the preparation of fine and
large-scale chemicals. Thus the Phillips process for the
preparation of neohexene (3,3-dimethyl-1-butene) and the
Shell process for the preparation of ~,~'-diolefins,
which are industrially important as cross-linking agents
in olefin polymerization or for the preparation of
bifunctional compounds, are examples from industry of
catalytic olefin ethenolysis.
Whereas in conventional olefin metathesis, generally
called "self-metathesis , the objective is to convert an
asymmetric olefin into two other olefins with shorter or
longer C-atom chains or to dimerize or polymerize a
cyclic olefin by opening the ring, ethenolysis is
differentiated from that to the extent that, basically,
terminal olefins (~-olefins) are produced, the fragments
CA 02079211 1998-0~-14
which are produced on cleaving the starting olefin at the
double bond each being lengthened by a CH2 group. Ethenolysis
of non-terminal olefins is therefore the counterpart of self-
metathesis of ~-olefins.
Ethenolysis is virtually always a reaction which is
carried out under pressure and also differs from conventional
olefin metathesis with regard to process engineering. As a
rule, different catalysts are also used for the two processes.
Surprisingly, it has now been found that compounds
of general formula R1aRebOc (I), in which a is 1 to 6, b is 1
to 4 and c is 1 to 12 and the sum of a, b and c is such that
it satisfies rhenium in its 5- or 7-valency states, with the
proviso that c is not greater than 3b, and in which R1 is an
alkyl radical with 1 to 9 carbon atoms, a cycloalkyl radical
with 5 to 10 carbon atoms or an aralkyl radical with 7 to 9
carbon atoms, where R1 may be at least partially fluorinated,
the compounds do not contain more than three groups with more
than 6 carbon atoms per rhenium atom and at least one hydrogen
atom is bonded to the carbon atom in the ~-position, which are
applied to oxidic support materials, are suitable as catalysts
(heterogeneous catalysts) for the ethenolysis (ethenolytic
metathesis) of chain-like and cyclic, non-functionalized and
functionalized olefins. When using these catalysts, the use
of additional activators ("co-catalysts"), which is
disadvantageous for many reasons, may in fact be dispensed
with, this being required in older processes.
29369-15
CA 02079211 1998-0~-14
- 2a -
The invention also relates to a process for the
ethenolysis of olefinic compounds, which is characterized in
that non-funtionalized or funtionalized olefins of the type
YCZ=CZ-(CX2)nR2 (II), in which n is an integer from 1 to 28, X
is H or F, Y is H or alkyl with 1 to 10 carbon atoms and Z is
H or a non-aromatic hydrocarbon
29369-15
_ 3 20~9211
radical with 1 to 6 carbon atoms, Y and Z however not
being hydrogen simultaneously, and the substituent RZ is
H, alkyl, halogen, CoOR3 or oR4, in which R3 and R4 are
alkyl with 1 to 15, preferably 1 to 6, carbon atoms or
phenyl, which may also contain 1 to 3 substituents on the
ring, or in which R4 is trialkylsilyl R53Si, in which R5 is
alkyl with 1 to 5, preferably 1 to 3, carbon atoms,
are reacted with ethylene on catalysts which comprise
oxidic support materials onto which compounds of the
aforementioned type are applied. When Z is different from
H, it is preferably an open-chain alkyl with 1 to 4
carbon atoms. Z as alkyl is, for example, cyclohexyl, but
is preferably an open-chain alkyl with 1 to 4 C-atoms.
When Z is phenyl, the substituents may be halogen, for
example fluorine, chlorine or bromine, NO2, NR6R7, oR8
and/or alkyl. The radicals R6, R7 and R8 are the same or
different and may be hydrogen or alkyl with 1 to 4 carbon
atoms. R2 as halogen may be fluorine, chlorine, bromine or
iodine. The two Zs may be the same or different. When Z
is hydrogen and R2 is halogen, this is preferably bromine.
Compounds in which at least one X = F are, for example,
1,6-di-(perfluoro-n-hexyl)-hex-3-ene of formula
(n-C6F13)-CH2-CH2-CH=CH-CH2CH2-(n-C6F13) and perfluoropropene
C3F6. The number n preferably varies within the range from
1 to 12 and in particular up to 8.
The catalysts are thus not only effective for olefins
where Z = H but also for the ethenolysis of partially
fluorinated olefins. They are also suitable for the
ethenolysis of internal, functionalized olefins of
formula R9CH=CH-(CH2)nR1~ (III), in which R9 is a branched
or expediently non-branched alkyl radical with 1 to 12
carbon atoms, R10 is a carboxyalkyl radical, in which the
alkyl radical expediently has 1 to 4 carbon atoms, and n
is an integer from 1 to 10. Methyl oleate (R9 = n-octyl,
R10 = CO2CH3, n = 7) may be mentioned as an example.
- 20792:11
-- 4 --
The catalysts used according to the invention, however,
not only catalyze the ethenolysis of open-chain
compounds, but also the ring-opening ethenolysis of
cycloolefins and cyclic hydrocarbons having several
olefinic structural elements. Examples are cyclooctene,
1,5-cyclooctadiene and cycloolefins with up to 20 chain
members, as well as cyclic di- and oligoolefins, which
also carry functions contA; n ing hetero atoms.
In formula I, R1 represents an organic group which is
bonded to the metal rhenium via a carbon atom to which at
least one hydrogen atom is also bonded, to be precise
alkyl radicals with 1 to 9 carbon atoms, cycloalkyl with
5 to 10 carbon atoms, such as cyclopentyl, cyclohexyl or
l-norbornyl, or aralkyl with 7 to 9 carbon atoms, such as
benzyl, but preferably methyl. The terms alkyl and
cycloalkyl naturally mean that these groups contain no
multiple bonds. For steric reasons, the presence of more
than three groups with more than 6 carbon atoms per
rhenium atom in the compounds is not possible; the
compounds expediently contain at most only one such
group. In this context, the term metathesis includes the
ring-opening of cycloolefins.
Among compounds of formula I, CH3ReO3, (CH3)6Re2O3,
(CH3)4Re2O4andpentamethylcyclopentadienylrheniumtrioxide
are already known, but the catalytic effectiveness of
these compounds in ethenolysis, i.e. in the reàction of
ethylene under pressure, was not known and was as little
to be expected as that of the whole class of compound~.
The catalytic effect is all the more surprising, as
(trimethylstannoxy)rhenium trioxide t(CH3)3SnO]ReO3, which
has an analogous structure, is just as catalytically
ineffective as all other rhenium compounds containing
oxygen, like dirhenium heptox;~P Re2O7, various
perrhenates with the ~ReO4]~ anion, rhenium trioxide ReO3
and the other rhenium oxides Re2O5 and ReO2. (CH3)3SiOReO3
is also ineffective. In the compounds of formulae I and
207~211
II, alkyl is, for example, methyl, ethyl, propyl,
isopropyl, the various butyl radicals such as n-, sec-,
tert. and isobutyl, and the various pentyl, hexyl and
octyl radicals, such as the 2-ethylhexyl radical.
The catalysts of the formula I used according to the
present invention may be prepared in a very simple way
from Re2O7 using the usual alkylating agents. Such
alkylating agents are, for example, boron, aluminum,
cadmium, mercury and in particular zinc and tin
compounds. For example, dirhenium heptoxide is reacted in
an anhydrous solvent which is inert towards rhenium
compounds (e.g. tetrahydrofuran) at a temperature of -80
to +60aC, preferably -30 to +40~C, with a solution of
Rl2Zn or of another alkylating agent, R1 having the above-
mentioned meaning, the suspension produced in this way
is filtered through an immersed frit and the volatile
fractions are removed from the filtrate. When especially
active zinc alkyls are reacted, it is recommended that
the lower temperatures in the stated ranges are used in
order to obtain selective reaction to give the desired
rhenium compounds and thus to reduce or inhibit the
formation of undesired by-products. In other cases, the
prodcedure is advantageously carried out at from 0 to
60~C, preferably 10 to 40~C. The compounds of formula I
may be solids or liquids. Although they are as such
insensitive to air and moisture, they should, however, be
well dried before use. This also applies above all to the
support materials.
Particularly suitable catalysts are those which contain
methylrhenium trioxide CH3ReO3, which is readily available
and is solid at room temperature, as the rhenium
compound. Suitable support materials are in particular
aluminum oxide and combinations thereof with silicon
dioxide (e.g. SiO2/Al2O3 in a ratio by weight of 87:13),
but also other oxides such as titanium, zirconium,
niobium, tantalum and chromium oxides either on their own
20792ii
- 6 -
or in combination with aluminum oxide and/or silicon
dioxide. The aluminum oxide may be acidic, neutral or
basic, depending on pretreatment. The activity of these
catalysts may be raised considerably if the rhenium
compounds are applied to a support, such as
silica/aluminum oxide, from which water has been
eliminated as far as possible by heating. If the support
material does contain significant amounts of moisture,
the activity is reduced because then the alkyl group
bonded to the rhenium is sometimes abstracted by water as
an alkane, e.g. according to the equation CH3ReO3 + H2O
CH4 + HReO4
Time- and energy-consuming operating steps may be
dispensed with in the process according to the invention
and yet very reproducible catalysts are obtained.
In the present process the catalytically active rhenium
compound is applied to the catalyst support,
advantageously silica gel/aluminum oxide, advantageously
at room temperature, from a solvent, preferably a
dichloromethane solution, the catalyst support simply
being freed from moisture in a stream of nitrogen at 550
to 800~C for 2 hours before use, so that the catalyst
system thereafter exhibits its full activity.
Care should be taken to exclude air and moisture during
ethenolysis with the catalysts used according to the
invention. Also, the olefins should expediently be
thoroughly dried before use in order to avoid the
formation of alkanes as by-products. The ethenolysis is
in general performed at 3 to 30, preferably 5 to 20, bar
pressure of ethylene and a temperature of -25 to +70~C,
expediently +20 to 65~C.
The possibility of working under such relatively mild
conditions is a particular advantage of the process
according to the invention. However, it is also possible
2~792~
to use higher temperatures, for example up to 100~C, or
to work at lower pressures, for example atmospheric
pressure. However, there are usually no advantages
associated with this.
Examples 1 to 13 - Ethenolysis using (CH3)ReO3
A solution of 13 mg (0.052 mmol) of methylrhenium
trioxide, CH3ReO3, in 0.5 ml of dichloromethane was
introduced into a suspension of 2000 mg of SiO2/AlzO3
catalyst support (ratio by weight 87:13, particle size
less than 15~m, maintained at 550~C for 2 h) in 50 ml of
dichloromethane (dried over calcium hydride and stored
under an atmosphere of nitrogen) with stirring, in a
250 ml laboratory autoclave made from safety glass (BUCHI
glass reactor), at the temperature indicated in Table 1.
After 5 minutes' stirring, 2.5 mmol of olefin were
injected (t = 0) and ethylene was injected to the
pressure given in Table 1. After a reaction time of 5 h
the products indicated in Table 1 were detected by gas
chromatography in the liquid phase.
Examples 14 to 17 - Ethenolysis using (CH3)4RezO4
When this compound is used as catalyst for olefin
metathesis, the same procedure was used as is described
in Examples 1 to 13 for methylrhenium trioxide, CH3ReO3,
except that instead of the solution of 13 mg of
methylrhenium trioxide, a solution of 25.4 mg (0.052
mmol) of tetramethyltetraoxodirhenium, (CH3)4RezO4, in
0.5 ml of dichloromethane was introduced into a
suspension of 2000 mg of the catalyst support. After a
reaction time of 5 h, the products indicated in Tab. 2
were detected by gas chromatography in the li~uid phase.
207~
-- 8 --
Table 1
Ethenolysis of non-functionalized and functionalized
open-chain and cyclic olefins using (CH3)ReO3
Example/Starting Reaction Products Yields
material conditions i!
(%)
1) cis/trans-3-heptene 10 bar/40~C l-butene 39
l-pentene 39
2) ~-di-iso-butene* 15 bar/40~C 3,3-dimethyl-
l-butene 46
isobutene 45
3) 1,3-cyclohexadiene 8 bar/28~C 1,5-hexadiene 42
1,3-butadiene 40
1,4,7-octatriene 7
4) cyclododecene 8 bar/30~C 1,13-tetradeca-
diene 98
5) cyclooctene 8 bar/30~C l,9-decadiene 91
6) 1,5-cyclooctadiene 15 bar/35~C 1,5-hexadiene 72
1,5,9-decatriene 12
7) cyclopentene 10 bar/28~C 1,6-heptadiene 80
8) l,9-cyclohexa- 15 bar/40~C 1,9,17-octadeca-
decadiene triene 12
l,9-decadiene 66
9) ~,~'-diphenyl- 18 bar/65~C l,l-diphenyl-
stilbene ethylene 53
10) 2-norbornene 13 bar/30~C 1,4-divinyl-
cyclopentane 67
11) methyl oleate 15 bar/30~C l-decene 44
methyl
9-decenoate 46
12) ethyl linoleate 15 bar/40~C l-heptene 33
1,4-pentadiene 31
ethyl
9-decenoate 21
13) geranylacetone** 14 bar/-5~C isobutylene 33
2-methyl-1,5-
hexadiene 28
4-(1-butenyl)-
methyl ketone 29
~V7g211L
* 2,4,4-trimethyl-2-pentene
** (cH3)2c-cH(cH2)2c(cH3)-cH(cH2)2c( o)cH3
a) Sum of the respective olefins corresponds to the conversion
Table 2
Ethenolysis of olefins using (CH3)4Re204 on Al203/SiO2
Example/Starting Reaction ProductsYields
material conditions (%)
14) cis/trans-3-heptene 10 bar/40~C l-butene 35
l-pentene 35
15) 1,3-cyclohexadiene 10 bar/30~C1,5-hexadiene 34
1,3-butadiene30
1,3,7-octatriene 10
16) cyclopentene 20 bar/30~C 1,6-heptadiene75
17) methyl oleate 15 bar/30~C l-decene 46
methyl
9-decenoate 44
a) Sum of the respective olefins corresponds to the conversion.
