Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
13 3 ~ ~ 6 6
HOECHST AKTlENGESELLSCHAFT HOE 88/F 356K Dr.KLR/AP
Description
Organic derivatives of rhenium oxides and their prepara-
tion and use for the metathesis of olefins
The present invention relates to organic derivatives of
rhenium oxides and to their preparation and use for the
metathesis of olefins as such and also derivatives of
olefins. ~-
The term metathesis designates, as is known, the cleav-
age of olefinic compounds in such a way that the double
bond is broken apart and the two fragments combine to
form new compounds. In the wider sense, metathesis
also includes the ring-opening polymerization of cyclo-
olefins. As a result of the invention, an organorhenium
compound of definite structure, which can be isolated
in an undiluted form, becomes a catalyst for the f;rst
time.
It is kno~n that compounds of the element rhenium exhi-
bit catalytic activity in the metathesis of olefins,
specifically only in the metathesis of olefins as such.
Only if so-called co-catalysts, in particular tetra-
alkyltin compounds are added to such rhenium catalystsis the metathesis of derivatives of olefins, ie. ole-
fins containing heterofunctions, possible (K.J. Ivin~
Olefin Metathesis, Academic Press, London 1983, 32 -
34). Thus the metathesis of olefinically unsaturated
carboxylic acid esters and of allyl halides and the like
on mu~ti-component catalysts, such as ~Cl6/Sn(CH3)4 or ~-
Re207/Sn(CH3)4/Al203 has been described. The
last-named system (R.A. Fridman et al., Dokl. Akad.
Nauk. SSSR 2 , (1977), 1354 - 57; R.H.A. Bosma et al.,
J. Organometal. Chem. 225 (1983) 159 - 171; X. Xiaoding
et al., J. Chem. Soc. Chem. Commun. 1985, 631 - 633;
G.C.N. van den Aardweg, loc. cit. 1983, 262 - 263) is the
only one containing rhenium which is capable of meta-
thesizing olefinically unsaturated organic halides, ~ ,
' ~-
133~56
-- 2
esters and the like. Hitherto there has been no know-
ledge of the effective catalyst species. The following
are practical disadvantages of the rhenium-containing
catalyst systems hitherto used:
S a) the necessity of using at the same t;me highly toxic
tetraalkyltin compounds as activators in the meta-
thesis of derivatives of olefins (J.E. Cremer,
~iochem. J. 68 (1958) 685 - 688; ~.N. Aldridge et
al., The Lancet, Sept. 26, 1981, page 692/3),
b) low catalyst activity, inacceptable for industrial
use, and
c) a breadth of application with relatively narrow
limits, ie. the catalytic action is only found in
the case of simple derivatives of olefins or olefins
as such.
It was therefore required to find a non-toxic and
effective catalyst system which is as readily acces-
sible, simple to handle and stable on storage as
possible and which is also adequate without any activa-
tor in the metathesis of olefin derivatives.
Considerable interest attaches to the industrial fur-
ther processing of the products.
Although some so-called "organorhenium oxides", for
example CH3ReO3, (n5-Cs(CH3)s)ReO3 (= penta-
methylcyclopentadienylrhenium trioxide), are known as
catalyst components for the metathesis of olefins by
homogeneous catalysis (W.A. Herrmann et al., Angew.
30 Chem. 100 (1988) 420 - 422, translation in Angew. Chem.
Int. Ed. Engl. 27 (1988) 394 - 396), the concomitant
use, as activator, of a Lewis acid which is at least
partially soluble in organic solvents was, however,
always necessary, preferably aluminum(III) chloride
and, in most cases, also the concomitant use of toxic
tin tetraalkyls (for example Sn(CH3)4) as further activa-
tors. Even then the catalyst systems thus obtainable
are completely inactive in respect of the metathesis of
derivatives of olefins.
, .. , . , .. . . ... .. --.,,. -- . .. . . . .
~ 13305~6 -
- - 3 - 23221-4607
It has now been found, surprisingly, that methylrhenium
trioxide CH3ReO3 and related compounds of the formula I indicated
below are suitable for use as a metathesis catalyst when supported
on oxide supporting materials, in particular aluminum oxide
supports. The use of additional activator substances ("Co~
catalysts"), which is disadvantageous for many reasons, thus
becomes superfluous for the first time.
Thus, according to one aspect, the invention provides a
compound of the general formula R aRebOc, wherein a is an integer
from 1 to 6, b is an integer from 1 to 4 and c is an integer from ~ -
1 to 14 and the sum of a, b and c conforms to the 5- to 7-valency
of rhenium with the proviso that c does not exceed 3.b, and
wherein R represents alkyl having from 1 to 9 carbon atoms, ;~
cycloalkyl having from 5 to 10 carbon atoms or aralkyl having from
7 to 9 carbon atoms and wherein R1 is unsubstituted or at least ~;;
partially fluorinated, said compounds containing not more than
three groups of more than 6 carbon atoms per rhenium atom and
containing a hydrogen atom bound to the carbon atom in a-position
to the rhenium atom, the methylrhenium oxides CH3ReO3, (CH3)4ReO,
(CH ) ReO , [(CH3)3ccH2]3ReO2~ [(CH3)3c CH2]4 2 4' 3 6 2 3
and the pentamethylcyclopentadienyl-rheniumtrioxide
(~ -C5(CH3)5)ReO3 being excluded.
According to another aspect, the invention provides a
catalytic composition for the metathesis of olefinic compounds .
~ .
~, ,
-4- 23221-4607
13305~6
comprising an oxidic carrier charged with a rhenium compound of
the general formula R1aRebOc, wherein a is an integer from 1 to 6,
b is an integer from 1 to 4 and c is an integer from 1 to 14 and
the sum of a, b and c conforms to the 5- to 7-valency of rhenium
with the proviso that c does not exceed 3.b, and wherein
represents alkyl having from 1 to 9 carbon atoms, cycloalkyl
having from 5 to 10 carbon atoms or aralkyl having from 7 to 9
carbon atoms and wherein R1 is unsubstituted or at least partially
fluorinated, said compounds containing not more than three groups
of more than 6 carbon atoms per rhenium atom and containing a :
hydrogen atom bound to the carbon atom in a-position to the
rhenium atom. ~:~
According to still another aspect, the invention
provides a process for the metathesis of olefins which comprises
reacting an olefin of the formula YCZ=CZ-(CX2)nR2 (II) wherein n .';.-~
is an integer from 1 to 28,
X represents H or F, . ~.
Y represents H or alkyl having from 1 to 10 carbon
atoms and
Z represents H or a non-aromatic hydrocarbon group
having from 1 to 6 carbon atoms and
R2 represents H, alkyl, halogen, CoOR3 or oR4,
wherein R3 and R4 represent alkyl having from 1 to 15
carbon atoms or phenyl which is unsubstituted or
contains from 1 to 3 substituents or wherein R4 is
1~ .. ,.:
- ~a~ 23221-4607
1330~66
trialkylsilyl R53Si, wherein R5 represents alkyl
having from 1 to 5 carbon atoms, ln the pre~ence of a catalytic
composition as defined above.
The invention thus relates to the use of compounds of
rhenium which have the general formula RlaRebOc tI) ln whlch a is -~
1 to 6, b i~ 1 to 4 and c ls 1 to 14 and the total of a, b and c
ls such that lt accords wlth the pentavalency to heptavalency of
rhenlum, subject to the provlso that c ls not greater than 3 x b,
and whlch are supported on oxlde supportlng materlals, as
heterogeneous catalysts for metathesis. In this connection
denotes an organlc group attached to the metal rhenlum via a
carbon atom to whlch at least one hydrogen atom is stlll attached,
speclflcally alkyl radlcals havlng 1 to 9 carbon atoms, cycloalkyl
having 5 to 10 carbon atoms, such as cyclohexyl or l-norbornyl, or
aralkyl having 7 to 9 carbon atoms, such as benzyl, but preferably
methyl. The term~ alkyl and cycloalkyl naturally imply that these
groups contaln no multiple bonds. Rl can be at least partially
fluorinated. For steric reason3, however, the presence of more
than three groups containing more than 6 carbon atoms per rhenium
atom is not possible in the compounds; the compound~ preferably
contain only one such group at the most. The term metathesis in
this context includes the ring-opening polymerization of
cycloolefins.
~'' , .
133Q~66
-4b-
23221-4607
Of the compounds of the formula mentioned above,
CH3ReO3, (CH3)4ReO, (CH3)3ReO2, l(CH3)3CCH2]3ReO2,
3 3 2]4Re204, (CH3)6Re203 and the
pentamethylcyclopentadlenyl-rhenlumtrloxlde (~5-C5(CH3)5)ReO3 are
admlttedly known, but the catalytlc activlty of these compound~
wlthout the concomltant use of activators, that is to say their
sultability as the sole catalyst, was not known and was as
unexpected a~ that of the whole class of compound6. Thls -
catalytlc actlon ls all the more surprising because
(trlmethylstannoxy)-rhenium trioxlde l(CH3)3SnO]ReO3, which ls
lsostructural, 1~ catalytlcally lnactive. This show~ the
lmportance of the alkyl groups attached to rhenium for the
catalytlc actlvity of the compounds according to the inventlon.
In terms of synthesls, the compounds according to the
lnventlon can be syntheslzed ln a very slmple manner from Re207 by
means of cu~tomary alkylatlng agents. For example, dlrhenlum
heptoxlde ls reacted ln an anhydrous solvent whlch is inert
towards the rhenlum compounds, at a temperature from O to 60,
preferably 10 to 40C, wlth a solutlon of R12Zn ln whlch Rl has
the meanlng lndlcated above, and the volatlle constituents are
removed. The compounds accordlng to the inventlon are entlrely
lnsensltive to alr and molsture. When supported on oxldic
supportlng materlals, the rhenium compounds are hlghly active
catalysts for the metathesls of oleflns as such and also
derlvatlves of oleflns of the type YCZ-CZ-(CX2)nR2 (II) in whlch n ;;
18 an lnteger from 1 to 28, X 18 H or F, Y ls H or alkyl havlng 1 ~-
to 10 carbon atoms and Z represents H or a non-aromatlc -~
~D ::
.. -. . ~- . . ~ .
`-
13~66 ~ ~
-4c - 23221-4607
hydrocarbon radical having l to 6 carbon atoms, for example ~:
cyclohexyl, but preferably open-chain alkyl having l to 4 carbon
a~oms, and the subætituent R2 is H, alkyl, halogen, CoOR3 or oR4
in which R3 is alkyl or aryl and R4 i6 alkyl, aryl or tri~
alkylsilyl R53Si. The alkyl groups in R5 contain l to 5,
preferably l to 3 carbon atoms. In R3 and R4 alkyl represents l
to 15, preferably l to 6, carbon atoms and aryl represents phenyl
~hlch can also contain one to three substituents on the ring, such
as halogen, for example ~ -
1 0
,. : ~ , . , --
., . ~. . .. . . .
~33~6~
-- 5
fluor;ne, chlorine or bromine, N0z, NR6R7, oR8 and/or
alkyl. The radicals R6, R7 and R8 are identical or
different and can be hydrogen or alkyl having 1 to 4
carbon atoms. However, the groups YCZ and CZ-(CH2)nR2
S must be different. As halogen, R2 can be fluorine,
chlorine, bromine or iodine. If Z is hydrogen and R2 is ~
halogen, the latter is preferably bromine. Examples of -
compounds in which at least one X is F are 4-(perfluoro-
n-hexyl~but-1-ene, formula (n-C6F13)-CH2-CH2-CH=CH2~
and perfluoropropene C3F6. The number n of units varies,
preferably within the range from 1 to 12 and especially
up to 8.
The novel catalysts are thus not only active in the
case of olefins in which Z = H, but also, for the first
time, in the metathesis of partly or completely fluori-
nated olefins. They are also suitable for the
metathesis of non-terminal olefin derivatives of the
formula R9CH=CH-(CH2)nR10 (IV) in which R9 is a
branched~ or preferably unbranched, alkyl radical
having 1 to 12 carbon atoms, R10 is a carboxyalkyl radi-
cal in which the alkyl radical preferably has 1 to 4
carbon atoms, and n represents an integer from 1 to 10.
Methyl oleate (R9 = n-octyl, R10 = C02CH3 and n = 7) may
ZS be mentioned as an example.
SiO2/Al203 (for examPle in a ratio by weight of 87:13)
and Al203, each of which can be acid, neutral or
basic according to its pretreatment, are particularly ~ -
suitable as supporting materials. The activity of
these catalysts can be increased considerably if the
rhenium,compounds are supported on a thoroughly cal- -~-
' ~ ; cined, ~ as far as possible anhydrous, support, such
as silica/aluminum oxide. This is because if the sup-
porting material contains major amounts of moisture,the activity decreases, because the alkyl group
attached to rhenium is then partly split off as alkane
by means of the water.
1 3 3 ~
The catalytic activity of the catalysts according to
the invention for the metathesis of oLefins is higher
than that of the rhenium-containing catalyst systems
described hitherto. An exemplary proof is afforded by -
the systems A1 and V1 (cf. graphs). The system CH3ReO3/
SiO2/Al203 (A1) metathesizes allyl bromide in only 20
minutes to a Q of over 20,
peak area of ethylene
the ratio Q =
peak area of propane
being obtained using propane as predetermined standard
and being plotted against time. The shape of the curve
provides information on the activity of the particular
catalyst system. The standard catalyst NH4tReO4]/SiO2/
Al2/03 (V1) known from the literature is, in contrast,
only active in the presence of Sn(CH3)4, and even then
only to a comparable extent in 180 minutes. The symbol
"r^ 2" is a measure of the agreement between the shape
of the curve determined by calculation and the experi-
mental values.
The rhenium-containing catalysts hitherto used indus-
trially in olefin metathesis are, as a rule, prepared
(see ~arwel et al., Chem.-Ztg 1û7 (1983), 115-120)
by treating commercially available ammonium perrhenate
NH4tReO4] as a solution in dioxane/water with the sup-
porting material (as a rule aluminum oxide). The
resulting suspension is then evaporated to complete
dryness in a water pump vacuum; the dry material is
then heated at 550C, first for about 2 hours in a stream
of oxygen and then for about 2 hours in a stream of
nitrogen. Only the material obtained in this way and
cooled to room temperature is employed for catalytic
purposes.
For the process according to the invention, on the
other hand, it is possible to dispense with these time-
consuming and energy-consuming process stages, as a
result of ~hich catalysts of better reproducibility are
- _ 7 _ 1 3 3 ~
also obtained. For the present process, the
catalytically active rhenium compound is applied, pre-
ferably at room temperature, from a solvent, preferably
a solution of methylene dichloride, to the catalyst
5 support, preferably silica gel/aluminum oxide, and only ~*~
the catalyst support is freed from moisture, before
use, for 2 hours at 800C in a stream of nitrogen, in
order that the catalyst system may subsequently develop
its full activity.
In metathesis using the catalysts according to the
invention care must be taken that air and moisture are
excluded. The olefins employed must also preferably be
dried thoroughly before use. In general, the metathe-
sis is carried out at atmospheric pressure and atemperature from 0 to 40C, preferably 10 to 35C. The
fact that it is possible to work under such mild reac-
tion conditions is a particular advantage of the
process according to the invention. It is also pos-
sible, however, to use higher temperatures, for exampleup to 100C, or to work under a pressure above or below
atmospheric. Usually, however, no advantages are
associated there~ith. `~
In the characterization of individual compounds in the
following examples "sst" means very strong, "st" means
strong, "br" means broad and "EI-MS" means electron -~
impact mass spectrum.
Exa-ples 1-5 - ~etathesis using CH3ReO
In the following tests the olefins employed were dried ~ -
over CaH2 and distilled before being used. The catalyst
used in these tests was methylrhenium trioxide CH3ReO3
which had been prepared by a simple process in terms of
preparation, avoiding toxic tetramethyltin, Sn(CH3)4,
as follows:
20 ml of a 0.5-molar solution of dimethylzinc Zn(CH3)2 ~-
in tetrahydrofuran were added dropwise at room
... . . . . . ., . ~ .. . . - , . -
, ~
- 8 - 1 33 ~
temperature and in the course of 10 minutes to a solution
of 4.84 9 (10 mmol) of dirhenium heptoxide Re207 (made by
Degussa, 76.9% of Re) in 100 ml of an anhydrous sol-
vent, such as tetrahydrofuran, and the mixture was then -
stirred for a further 60 minutes at room temperature.
The volatile constituents were then stripped off under
an oil pump vacuum into a cold trap. The residue was
sublimed in a high vacuum at 40-55C onto a water-cooled
sublimation finger. This gave 3.89 9 (78X of theory)
of colorless, mostly needle-shaped~ crystals of the
catalyst CH3ReO3. The synthesis is also possible using
unsublimed Re207, but the yields are then lower. The
substance has the following characteristics: Melting
point 106. - IR (cm 1, K~r): 1002 sst, 950 sst,br
tv(Re=0)].-1H-NMR (CDCl3, 28C): ~tCH3) = 2.61 tsing-
let]. - 13C-NMR (CDCl3, 28C): ~(CH3) = 19.03 Cquar-
tet, 1J(C,H) = 138 Hz]. - 170-NMR (CDCl3, 28C: (0)=
829 ppm. - EI-MS : m/z = 250 (molecule-ion, with the cor-
rect pattern of isotopes 185Re/187Re). - The substance
can be stored at room temperature without decomposition.-
Elementary analysis: Calculated for CH303Re (249~21):
C 4.82, H 1.20, 0 19.26, Re 74.72; found: C 4.84, H 1.19,
0 19.30, Re 74.78.
In a 30 ml reaction vessel equipped with a septum, a
reflux condenser and a mercury pressure relief valve, a
solution of 13 mg (0.052 mmol) of methylrhenium tri-
oxide CH3ReO3 in 0.5 ml of methylene dichloride was
introduced with stirring into a suspension of 1,000 mg
of catalyst support tSiO2/Al203, (87:13), particle size
below 15 ~m (preparation No. 14-7150 of Strem Chemicals,
Newburyport/Mass. 01950 (USA), heated at 800C for 2
hours] in 10 ml of methylene dichloride (dried over
calcium hydride and stored under an atmosphere of
nitrogen]. The contents of the flask were heated to
the boil. After thermal equilibrium had been set up,
5.2 mmol of olefin were injected by means of a syringe
through the septum. In order to isolate the product, the
mixture was boiled for several hours under reflux
.,-.- ~
.,.~
..... .., ~ . , , .. ;
~ 3 3 ~ ~ 6 6 b~ ` '
_ 9
(Table 1), the contact catalyst was filtered off with
suction on a frit and was extracted by washing with
twice 10 ml of methylene dichloride. The solvent was
stripped off under an oil pump vacuum, the product was
weighed and its purity was checked by means of a gas
chromatograph with coupled mass spectrometer.
TabLe 1: Metathesis of ~-olefin derivatives of the type
II with the elimination of ethylene
Example/oLefin (*) Time Amount Weight Purity rield
(hrs) (mg) (mg) (%) (%_
1) Allyl bromide4 620100 100 14
2) Ethyl undecenoate 201120 1120 64 64
3) AlLyl isopropyl
ether 4 520220 70 30
4) Allyl ethyl ether 5 448 260 50 39
5) Allyl trimethyl-
silyl ether 24 680530 88 69
' ~'~''
(*) Metathesis products~
1) 1,4-Dibromobut-2-ene.
2) Diethyl eicos-10-ene-~,~'-dicarboxylate.
3) 1,4-Bis-(isopropoxy)-but-2-ene.
4) 1,4-Bis-(ethoxy)-but-2-ene.
5) 1,4-Bis-(trimethylsiloxy)-but-2-ene.
Co-parisons
In a 30 ml reaction vessel closed with a septum, a
solution of 13 mg (0.052 mmol) of methylrhenium tri-
oxide CH3ReO3 in 0.5 ml of methylene dichloride was ~ -
introduced with stirring into a suspension of 1,000 mg
of catalyst support (SiO2/Al203 (weight ratio 87:13,
particle size below 15 ~m; kept at 800C for 2 hours)) in
10 ml of methylene dichloride (dried over calcium hyd-
ride and stored under an atmoçphere of nitrogen). 0.5 ml
of propane was injected as the internal standard.
- ~ 330~66
- 10 -
After stirring for 5 minutes 5 mmol of ole~in were
injected (t = 0) and the ethylene content of the gas
phase was determined by gas chromatography at the
intervals of time evident from graphs A1, A2, V1 and V2
5 (attachments). V1 shows a comparison with A1, A2 shows -
the effect of a greater dilution of the catalyst com-
pared with A1 and V2 shows a comparison with the
rhenium-containing catalyst system hitherto used and
known from the literature, as specified by ~arwel et
al, l.c. For this purpose 900 mg of neutral aluminum
oxide were first impregnated with a solution of 100 mg
of ammonium perrhenate NH4CReO4] in 10 ml of dioxane/
water (9+1 parts by volume). The catalyst system was
then activated at 550C for 2 hours in a stream of
oxygen and then for 2 hours in a stream of nitrogen.
The reaction kinetics tests proceeded analogously to
those with methylrhenium trioxide CH3ReO3, but it was
necessary for activation to inject 0.005 ml of tetra-
methyltin Sn~CH3)4 5 minutes before the addition of
olefin, in order to obtain any catalytic effect at all.
A direct comparison was afforded by comparison test V1, j~
in which 14 mg of ammonium perrhenate NH4[ReO4] were
absorbed onto 1 9 of SiO2/Al203 and activated in a~ ;~
stream of 2 and N2 as indicated above.
In the metathesis of olefins as such CH3ReO3 on the one
hand and NH4CReO4] on the other hand achieved a com- ;~
parable activity on SiO2/Al203. The equilibrium
product distribution in the metathesis of a mixture of
50 mol % of 2-pentene + 25 mol % of 2-butene + 25 mol %
of 3-hexene was set up after approx. 5 minutes in both
systems, but in the case of NH4CReO4] only after
additional activation with tetramethyltin, as can be
seen from a comparison of graphs A3 and V3.
Effects arising from the cataLyst support
As shown in particular by systems A1 and A2 for the
. ,,... . , . . .. ~ ~ . - .. -"~.. , . -
3 ~
r~
, ,. j ~ . . . .. -
13~0~6~
- 11 -
metathesis of allyl bromide, the activity of the cata-
lyst CH3ReO3 increases greatly with dilution (relative
to the amount of oxide supporting material): For a
reaction time of 300 minutes, 13 mg of CH3ReO3 + 1000 mg
of SiO2/Al203 give a value of 30 for Q, while 13 mg of
CH3ReO3 + 2000 mg of SiO2/Al203 give a value of 40
for Q.
Exaoples 6-9 - ~etathesis using (CH3)6Re2O3
10 6) In a 30 ml reaction vessel closed with a septum, a ~-
solution of 25.5 mg (0.052 mmol) of hexamethyltrioxodi- -
rhenium (CH3)6Re203 in 0.5 ml of methylene dichloride
was introduced with stirring into a suspension of 1000 mg
of catalyst support (SiO2/Al203; weight rat;o 87:13,
15 particle size below 15 ~m; kept at 800C for 2 hours) in - ~ ~;
10 ml of methylene dichloride (dried over calcium hyd-
ride and stored under an atmosphere of nitrogen). 0.5
ml of propane were injected as the internal standard. -~
After stirring for 5 minutes 5 mmol of allyl bromide
were injected ( t = 0) and the ethylene content of the
gas phase was determined by gas chromatography at the
intervals of time evident from graph A4 (attachment).
7 - 9) In a 30 ml reaction vessel equipped with a sep-
tum, a reflux condenser and a mercury pressure relief
valve, a solution of 25.5 mg (0.052 mmol) of hexamethyl- -
trioxodirhenium (CH3)6Re203 in 0.5 ml of methylene
dichloride was introduced with stirring into a suspen-
sion of 1000 mg of catalyst support ~SiO2/Al203 (87:13),
30 particle size below 15 ~m (preparation No. 14-7150 of
Strem Chemicals, Newburyport/Mass. 01950 (USA), heated
at 800C for 2 hours] in 10 ml of methylene dichloride
(dried over calcium hydride and kept under an atmos-
phere of nitrogen). The contents of the flask were
heated to the boil. After thermal equilibrium had been
set up, 5.2 mmol of olefin were injected through the
septum by means of a syringe. In order to isolate the
product, the mixture was boiled under reflux for sever-
al hours (Table 2), the contact catalyst was filtered
.,;.: ,
133~
- 12 -
off with suction on a frit and was washed with twice 10 mL
of methylene dichLoride. The solvent was stripped
off in an oil pump vacuum, the product was weighed and
its purity was checked by means of a gas chromatograph
with coupled mass spectrometer.
Table 2
Example/olefin (*) Time Amount Weight Purity Yield
(hrs) (mg) (mg) (%) (%)
7) Allyl bromide 20 680 72 98 12
8) Ethyl undecenoate 20 1410 840 57 34
9) Allyl trimethyl~
silyl ether 15 705 550 48 41
(*) Metathesis products: ~ 9
7) 1,4-Dibromobut-2-ene.
8) Diethyl eicos-10-ene-1,1'-dicarboxylate.
9) 1,4-~is-(trimethylsiloxy)-but-2-ene.
~.
Example 10 - Metathesîs using (CH3)4Re2O4
In a 30 ml reaction vessel closed by means of a septum,
a solution of 25.8 mg (0.052 mmol) of tetramethyltetra-
oxodirhenium (CH3)4Re204 in 0.5 ml of methylene
dichloride was introduced with stirring into a suspen-
sion of 1000 mg of catalyst support (SiO2/Al203; weight
ratio 87:13, particle size below 15 ~m; kept at 800C for
2 hours) in 10 ml of methylene dichloride (dried over
calcium hydride and kept under an atmosphere of nitro-
gen). 0.5 ml of propane were injected as the internal
standard. After stirring for 5 minutes 5 mmol of allyl
bromide were injected (t = 0) and the ethylene content
of the gas phase was determined by gas chromatography
at the intervals of time evident from graph A5
(attachment).
Exaoples 11-15 - Co-pounds of the for-ula R1aReb0c
11. Tri-ethYl(oxo)rhenium, (CH3)3ReO :-
1 33 0 ?~
a) 2.62 g (10 mmol) of triphenylphosphine P(C6Hs)3 and
10.85 9 (0.1 mol) of trimethylchlorosilane (CH3)3SiCl
were added rapidly, successively and at room tempera-
ture and with vigorous magnetic stirring to a solution
of 4.14 9 (10 mmol) of the compound [(CH3)3SnO]ReO3 in
100 ml of anhydrous tetrahydrofuran. After 3 hours
stirring at room temperature a green deposit had formed, l~
consisting of the compound Reocl3[op(c6H5)](oc4H8)
(OC4H8 = tetrahydrofuran). Filtering off this preci-
10 pitate from the supPrnatant solution, washing it with ~
tetrahydrofuran and drying it ;n an oil pump vacuum -
gave 6.19 9 (94% of theory) of this compound in a pure ~-
form.
: :: '
15 b) 3.29 9 (5 mmol) of the compound prepared under a)
were suspended in 20 ml of tetrahydrofuran. A 0.2-
molar solution of lithiummethyl LiCH3 (altogether
16 mmol) were added dropwise at 0C to this suspension,
and the resulting reaction mixture was stirred for a
further 3 hours at room temperature. The volatile
constituents were then removed in an oil pump vacuum.
The dark brown residue, in most cases somewhat oily,
was extracted with approx. 10 ml of toluene. The
extract was evaporated to dryness in an oil pump vacuum.
The residue was chromatographed at -60C on a column
(40 cm long and 2 cm in diameter) of silanized, cal-
cined silica geL (by Merck), the yellow zone of the
compound (CH3)3ReO being developed with toluene. The
eluate was concentrated under an oil pump vacuum. The
residue was then dissolved in 20 ml of n-pentane, and
the solution was left to crystallize at -80 to -40C.
This gave 198 mg (16% of theory) of yellow needles of
(CH3)3ReO.- :
Characterization: Soluble in the customary anhydrous
organic solvents, in particular methylene chloride,
tetrahydrofuran and toluene. The substance is solid
and, in solution, admittedly only stable undecomposed
for some time when stored within the temperature range
from -80 to -40C. - IR (cm 1, K~r): 978 sst [v(Re=0)].
133~
- 14 -
- 1H-NMR (270 MHz; 28C, CD2Cl2): ~CH3 = 5.41 (sin- -
glet). - FD-mass spectrum: Molecule ion m/z = 248
(187Re), with correct pattern of isotopes 185Re/187Re.
12. Tris(neopentyL)oxorhenium, ReCCH2C(CH3)3~30 ;~
This compound was synthesized analogously to the ins-
tructions for Example 11, employing lithiumneopentyl
LitCH2C(CH3)3~ instead of lithiummethyl. The product ;~
was worked up analogously. Yield 249 mg (12% of
theory).-
Characterizat;on: Yellow crystals; stable without de-
composition over a prolonged period (approx. 8 days)
only at temperatures below -20C. - IR (cm 1, K~r):
975 cm 1 sst [v(Re=0)~ H-NMR (400 MHz, 28C,
CDCl3): ~CH3 = 1.12 (singlet, 9H), ~CH2 = 2.21 Csome-
what broadened singlet, 2H]. - FD mass spectrum:
Molecule ion m/z = 416 (187Re), with correct pattern of
isotopes 185Re/187Re~
13. 2,2,2-TrifLuoroethyLtrioxorhenium, (CF3CH2)ReO3
20 mmol of a 0.5-molar solution of bis-(2,2,2-trifluoro-
ethyl)zinc Zn(CH2CF3)2 in tetrahydrofuran was added
dropwise at room temperature and in the course of 10
minutes to a solution of 4.84 g (10 mmol) of dirhenium
heptoxide Re207 (by Degussa, 76.9% of Re) in 100 ml of an
anhydrous solvent such as tetrahydrofuran, and the mix-
ture was then stirred for a further 80 minutes at room
temperature. The volatile constituents were then
stripped off in an oil pump vacuum into a cold trap,
cooled with liquid nitrogen. The residue was sublimed
in a high vacuum at 40 - 85C onto a water-cooled sub-
limation finger. This gave 2.41 9 (38X of theory) of
slightly yellowish needle-shaped crystals of the com-
pound (CF3CH2)ReO3. The synthesis is also possible
using unsublimed Re207, but the yields are then lower
(in the range of 10 - 18X).
The substance has the following characteristics:
Soluble in most anhydrous organic solvents, especially
133~5~6
- 15 -
in tetrahydrofuran, methylene chLoride and toluene,
forming virtually colorless, light-sensitive solutions.
- IR (cm 1, KBr: 1048 st, 960 sst Cv(Re=0)]. - 1H-NMR
(CDCl3, 28C: ~(CH2) = 2.3û Cquartet~. 170-NMR
(CDCl3, 28C): ~(0) = 590 ppm. - EI-MS: m/z = 318 (mole-
cule ion with correct pattern of isotopes 185Re/187Re).
The substance can be kept without decomposition at ice
temperature (0C), if care is taken to exclude light.
Elementary analysis: Calculated for C2H2F303Re
(317.21): C 7.57, H 0.63, F 17.97, Re 58.70; found:
C 7.60, H 0.70, F 18.00, Re 58.59.
The same compound was obtained in a yield of 40 - 48%
when dirhenium heptoxide Re207 was reacted with an equi-
15 molar amount of tetrakis-(2,2,2-trifluoroethyl)-tin
Sn(CH2CF3)4 under the conditions mentioned in the pre-
ceding instructions, the only difference being that the
components were reacted with one another not at room
temperature, but in boiling tetrahydrofuran for 1 to 2
20 hours. The product was worked up analogously. ``~
The use of (CH3CH2)ReO3
~hen this compound is used as a catalyst for olefin
metathesis, the procedure is just the same as that des-
25 cribed in Examples 1 to 5 for methylrhenium trioxide
CH3ReO3.
14. (2,3,4,5,6-pentafluorophenylmethyl)-trioxorheniu-,
C6FsCH2ReO3
30 The corresponding Grignard compound C6FsCH2MgI was f;rst
prepared from a solution of 6.16 g (20 mmol) of u
(2,3,4,5,6-pentafluorophenyl)-methyl iodide C6FsCH2I by a
known process by reacting the latter with magnesium
turnings in diethyl ether as solvent. 12.3 g (9 mmol) of
35 anhydrous zinc chloride were then added to the resulting
solution. The resulting reaction mixture was then
boilded under reflux for 5 hours. The compound bis-
(2,3,4,5,6-pentafluorophenylmethyl)-zinc Zn(CH2C6Fs)2 thus
obtainable could be obtained by filtration from th~
1330~
- - 16 -
solution and by recrystaLLization at Low temperatures
(-80 to -40C).
- 2.14 9 (5 mmoL) of bis-(2,3,4,5,6-pentafLuorophenyl-
methyl)-zinc Zn(CH2C6Fs)z were added at room tempera- ~-
ture to a soLution of 4.84 9 (10 mmoL) of dirhen;um
heptoxide Re207 (by Degussa, 76.9% of Re) in 100 mL of an
anhydrous soLvent such as tetrahydrofuran. The resuLt-
ing soLution was stirred for a further 60 m;nutes at
room temperature. The voLatiLe constituents were then
stripped off in an oiL pump vacuum into a cold trap
cooled with liquid air. The residue was extracted with ;~
three times 20 ml of anhydrous toluene, the extract was
filtered and the filtrate was then evaporated to dry-
ness at 0C under an oil pump vacuum. The residue was
recrystallized at -40 to -8C from a solvent mixture
composed of equal volumes of n-hexane and toluene. ~ -
This gave 581 mg (28% of theory, relative to the zinc
compound employed) of slightly yellow octahedral crys-
tals of the catalyst (C6FsCH2)ReO3.
The substance has the following characteristics:
Soluble in most of the customary anhydrous organic sol-
vents, especially toluene, methylene chloride and
tetrahydrofuran. - IR (cm 1, K3r): 1058 st, 958 sst
~v(Re=0)]. - 1H-NMR (CDCl3, 28C): ~(CH2) = 2.39 ppm
Csomewhat broadened singlet~. -170-NMR (CDCl3, 28C):
~(0) = 604 ppm. - EI-MS: m/z = 416 (molecule ion with -
correct pattern of isotopes 185Re/187Re). - Elementary
analysis: Calculated for C6F5CH2ReO3 (415.26):
C 20.25, H 0.48, F 22.87, Re 44.84; found: C 20.20,
H 0.50, F 22.60, Re 45.00.
15. ~is-C~-oxo(oxo)dimethylrheniu~(VI)], (CH3)4Re204
2.40 9 of dirhenium heptoxide Re207 (6.60 mmol) were
dissolved in 150 ml of anhydrous tetrahydrofuran and
cooled to -78C. 0.48 ml of freshly distilled dimethyl-
zinc Zn(CH3)2 (6.60 mmol) were added dropwise, with
continuous st;rring, to this solution. This must be
carried out with exclusion of air and moisture, since
~.. -............ :
1 3 ~
, . .
- 17 -
dimethylzinc burns in the air and is decomposed by
water. The soLution was stirred at this temperature
for 4 hours and turned a strong yellow color. The
reaction temperature was not allowed to exceed -30C.
The solvent was then stripped off at -40C under an oil
pump vacuum. The product could be sublimed in a high
vacuum in thin yellow needles from the residue which
remained. Yield: 1.64 9 (50% of theory). Melting
point 120C (without decomposition).
C4H12Re24: Calc.: C 9.64 H 2.41 0 12.85
(476.5) Found: C 9.60 H 2.48 0 12.79
EI mass spectrum: m/e = 498 (molecule ion CM ]), m/e 249
(base peak C1/2 M+]).
Infrared spectrum: (cm 1, K3r): 1017/1007 sst C~ (Re=0)].
H-NMR (CDCl3, 28C); ~(CH3) 2.81 ppm,
13C-NMR (CDCl3, 28C); ~(CH3) 30.36 ppm.
The compound is stable in air and readily soluble in
all customary organic solvents.
'~':''' ' '
~,"
