FR2521872A1 - Catalyst for metathesis of substd. olefin(s) - esp. unsatd. ester(s), comprises reaction prod. of lead tetra:alkyl and rhenium aluminate - Google Patents

Abstract

Novel catalyst (A) is made by interaction of a tetra(hydro-carbyl) lead (I) with a rhenium aluminate (II) supported on alumina or silica-alumina. Esp. (I) is 0.1-10 wt.% on supported (II) and (II) contains 0.01-20 wt.% Re. Component (II) is made by reacting a Re cpd. with a mineral contg. alumina (esp. 70-90 wt.% alumina-silica) at 80-200 deg. C, then heated at 400-1000 (800-1000) deg. C. Pref. Re cpds. are the heptoxide, NH4 perrhenate and perrhenic acid and are used as aq. or organic solns. (A) are useful in metathesis of olefins of formula R1CH=CH. Cn-H2nX (III) (R1 is H or hydrocarbyl; X is a functional gp., esp. OCOR2 or COOR3; R2 and R3 are hydrocarbyl; n is at least 1), or co-reaction of (III) with R4CH=CH2 (R4 is H or hydrocarbyl).

Description

The metathesis of olefins or group redistribution reaction
aikylidenes between them, is of great practical interest, for
especially in the case where the olefins are group carriers
functional elements since it allows, from a mono compound
unsaturated functional to obtain an unsaturated difunctional compound.

We know different types of catalysts capable of
catalyze this reaction, these catalysts being either of homogeneous type,
when their constituent elements are all soluble in the middle of
reaction, either of heterogeneous type when at least one of the elements is
insoluble in the said medium. These are particularly interesting.
strong when the active metal is expensive and necessary
consider re-use without loss; this is the case of cataly
sors 9 rhenium base whose use in heterogeneous form has been
recommended (US 3,676,520) to catalyze the metathesis of olefins
simple but which require the addition of tetramethyltin for cat
lyse the metathesis of functional olefins [E. VERKUIJLEN, F.

 KAPTEIJN, J.C. MDL, C. BOELHOUVER J.C.S. Chem. Comm. (1977), 198].

The Applicant has discovered that active catalysts in the meta-
thesis of functional olefins could be obtained by utila
simultaneous tion of a rhenium aluminate on an aluminous support and
an organometallic derivative of lead.

By supported rhenium aluminate is meant the product obtained by reacting alumina, silica-alumina, or a reactive aluminum compound with rhenium oxide or another reactive rhenium compound, this reaction advantageously being carried out by heating in two stages: first at a temperature between about 80 and 2500C then at a temperature of about 400 to 10000C. During the first heating step, the rhenium oxide is converted into a relatively stable catalytic species and which can be subjected to the second heating step without annoying loss of rhenium (rhenium oxide not stabilized by alumina volatilizes when heated above 2500C).

The preparation of a supported rhenium aluminate as can be used according to the invention preferably comprises the following steps
- impregnation of a mineral support containing aluminum with a rhenium compound. The preferred support is alumina, and more particularly 2 gamma-alumina with a surface greater than 50 m per gram and also silica-alumina with variable alumina content, the best results being obtained with minerals with a high alumina content. , that is to say greater than 50% by weight; and in the case of silica-aluminas containing between 30% and 10% by weight of silica, the results are superior to those obtained in the case of alumina alone.

The preferred rhenium compounds are rhenium heptoxide, ammonium perrhenate and perrhenic acid. The rhenium compound is dissolved in water or in an organic solvent. This solvent can be chosen, for example, from alcohols such as methanol. The impregnation is carried out by known techniques for bringing the mineral support into contact with the solution. The quantity of rhenium on the support is regulated by the choice of the concentration and / or the quantity of solution containing the rhenium. This makes it possible to obtain a solid containing from 0.01 to 20% by dry weight of rhenium.

 - stabilization Qu rhenium by heating the previous solid at a temperature sufficient to form the catalytic species, but not excessive to avoid losses of rhenium by volatilization. Heating to a temperature of, for example, 80 to 200 OC, preferably 100 to 180 OC, for 30 minutes to 5 hours gives satisfactory results. It is preferably carried out in a neutral atmosphere, for example under nitrogen, or oxidizing, for example in air. Too short a heating time or too low a temperature is to be avoided because it leads to an incomplete reaction and to a loss of rhenium during the subsequent activation treatment; conversely too high a temperature leads to losses of rhenium during the present stage.

 - Activation of the catalyst by heating between 400 and 1,000 OC, preferably between 800 and 1000 OC.

This heating takes place under an atmosphere of non-reducing gas, for example, oxygen, nitrogen or argon, and preferably in air, under static or dynamic conditions, but it is found that a slight gas stream facilitates the removal of water from the support. This treatment is continued between 10 minutes and 3 hours, after which the catalyst thus obtained is cooled under a preferably anhydrous atmosphere.

The catalyst thus obtained shows a high catalytic activity for the metathesis reaction of simple single monomers such as propylene, pentene-2, or octene-1, but is inactive for the metathesis of olefins carrying functional groups such as ester, nitrile, alcohol, aldehyde group and in particular with the carboxylic acid ester group, as found for example with methyl undecene-lo-oate or methyl oleate.

This latter reaction is however catalyzed by the interaction product of the supported rhenium aluminate, prepared as described above, with an organometallic lead compound.

The organometallic lead compounds which can be used according to the invention have the general formula Pb R4, in which R is a hydrocarbyl group, for example alkyl, cycloalkyl or aryl: among these compounds, tetramethyl lead, tetraethyl lead, lead will be used more particularly tetraphenyl or tetraallyl lead.

The interaction of the supported rhenium aluminate with the organometallic lead derivative can take place, for example, by suspending the rhenium compound in an organic medium containing the lead derivative in solution, or by contact with a gas. containing vapors of the lead derivative, or else without actual contact of the solid with the organometallic compound, according to a technique derived from that described by PANETH and HOFEDITZ (Berichte 62, 1335, 1929) which consists in thermally decomposing the organometallic compound and in react the free radicals which result from it on rhenium aluminate.

According to the first technique, the solid consisting of rhenium aluminate supported in a hydrocarbon or a halogenated, aliphatic, cyclanic or aromatic hydrocarbon, such as pentane, hexane, heptane, benzene, is suspended. toluene, carbon tetrachloride, dichloroethane, methylene chloride, chlorobenzene or their mixtures. Then the lead organometallic compound is introduced while stirring.

According to the second technique, a stream of inert gas such as nitrogen or argon containing in the vapor state, the lead derivative, is passed over the solid.

The third technique is analogous to the second except that when it comes into contact with the solid, the gas containing the lead derivative is brought to a temperature sufficient to decompose the lead derivative.

This temperature is usually between 150 and 350 OC.

This heating causes the formation of a lead mirror, and only the free radicals resulting from the decomposition of the lead compound come into contact with the solid.

The amounts of organometallic compounds used are for example between 0.1% and 10% by weight relative to the mineral.

Rhenium aluminate activated by one of the three previous techniques, catalyzes the metathesis of functional unsaturated compounds.

The olefins liable to react have the general formula
R1 CH = CH - Cn H2n - X in which
R1 represents a radical chosen from the group comprising hydrogen and hydrocarbyl radicals, for example methyl, ethyl, propyl and butyl; X represents a group

R2 and R3 being chosen from hydrocarbyl radicals, for example alkyl or aryl and n is an integer greater than or equal to 1.

It is also possible, with the same catalyst, to catalyze the co-reaction of functional olefins as defined above with the simple olefins of the type R1 CH = CH - R2 or with R1 and R2 as defined above.

Thus, methyl undecene-10-oate leads, with this catalyst, to ethylene and to dimethyl eicosene-10-dioate; methyl oleate leads to octadecene-9 and octadecene-9-dimethyl dioate; hexene-3-yl acetate with hexene-3 and diacetoxy 1, 6-hexene-3.

This is how methyl oleate and ethylene lead, as thesis, with this catalyst to decene-1 and decene-9-methylate.

The metathesis reaction is preferably carried out in the presence of solvent
This solvent may be a hydrocarbon or an aliphatic, cyclanic or aromatic halogenated hydrocarbon. It can be carried out in a stirred reactor or by passing the reagent (s) through a fixed bed of catalyst.

It is most often carried out at a temperature between - 10 OC and 200 OC, preferably between 20 and 120 OC.

The pressure is not critical; this is how it is most easily operated at a pressure close to atmospheric pressure, but when one of the products of the reaction is volatile, it is advantageous to let it escape from the medium to allow a higher advancement of the reaction.

All the operations are preferably carried out in the absence of oxygen and moisture and the reagents and solvents are previously usefully treated in this sense.

The following examples illustrate the invention without limiting its scope
Example 1
Preparation of rhenium aluminate
2 10 g of a gamma-alumina with a surface area of 180 m per gram, in the form of beads of 3 mm in diameter, are treated with a solution of 0.577 g of ammonium perrhinate in 4.2 cm3 of water . The solid thus obtained is heated for 2 hours between 140 and 150 OC in air, then at'900 OC for 5 hours under a weak stream of nitrogen. No vaporization of rhenium heptoxide is observed. The solid is then cooled under a dry gas atmosphere.

The rhenium fixed on the alumina is assayed by X-ray fluorescence. Rhenium losses are very low and between 0 and 5% by weight of the rhenium deposited.

 Metathesis of methyl undecene-10-oate in a nitrogen atmosphere 1 g of the catalyst thus obtained is brought into contact with 1 cm3 of heptane containing 10 moles of tetramethyl lead and then 2 cm3 (10 moles) of undecenoate are added of methyl at room temperature. After 6 hours, the transformation of 15% of the reagent is observed selectively into eicosene-10 dimethyl dioate.

Comparative example
We operated as above, but omitting to introduce the lead tetramethyl. No conversion was observed.

Example 2
. Metathesis of methyl undecene-10oate
Under the same conditions as those of Example 1, we replaced
tetramethyl lead by tetraethyl lead. We observed
transformation of 17% of methyl undeceneate selectively into
dimethyl eicosene-10-dioate.

Example 3
Under the same conditions as those of Example 2 but operating
at 80 OC, 20% conversion of undeceneate was obtained in 2 hours
methyl selectively to dimethyl eicosene-10-dioate.

Example 4
The catalyst used in Example 3 is reused, after
washing with heptane, under the same conditions as those of
Example 2. 10% conversion was obtained; this example shows the
possibility of partially regenerating the catalyst by washing with
a hydrocarbon.

Example 5
The catalyst used in Example 4 is treated at 900 OC of the
same way as in example 1 and then used for metathesis in
the conditions of Example 3. 20% conversion is obtained in
3 hours.

This example therefore describes a preferred method of regenerating the cataly
sister.

Example 6
Under the same conditions as those of Example 2, the alumina was replaced by a silica-alumina containing 15% of silica. The was observed.

transformation of 34% of methyl undeceneate selectively into dimethyl eicosene-10-dioate.

Example 7
Under the same conditions as those of Example 1, the methyl oleate and ethylene were cometathetized, the nitrogen atmosphere being replaced by an ethylene atmosphere. After 12 hours, the medium has the following composition
- decene-l: 17%
- methyl decenoate: 40%
- octadecene-9: 29.5%
- methyl octodecene-9-dioate: 6.5%
- unprocessed methyl oleate: 6.5%
Example 8 1 g of supported rhenium aluminate as obtained in Example 1 is placed in a glass tube 3 mm in diameter through which a stream of dry argon is passed. The part of the tube situated 5 cm upstream of the catalyst balls is heated to 250 ° C. and 25.10 5 liters of tetramethyl lead are introduced dropwise into the gas stream, upstream of the heated part. There is a deposit of a lead mirror on the heated part of the tube. The catalyst thus obtained, which does not contain lead, is transferred to a flask and used under the conditions of Example 2, except that no tetramethyl lead is added. This gives 4% yield of eicosene -10-dimethyl dioate.

Comparative example
By operating under the same conditions as those of Example 7, but using tetramethyl tin in place of tetramethyl lead, the following results were obtained - decene-1: 22% - methyl decenoate: 20% - octodecene-9 : 14.5% - methyl octodecene-9-dioate: 14% - unprocessed methyl oleate: 28.5%

Claims (10)

 R E V E N D I C A T I O N S 1.- Catalyst characterized in that it results from the interaction of a tetrahydrocarbyl lead with a rhenium aluminate supported by an alumina or a silica-alumina. 2. Catalyst according to claim 1, characterized in that the tetrahydrocarbyl lead is present in proportion from 0.1 to 10% of the weight of the supported rhenium aluminate and in that the supported rhenium aluminate has a content of 0 , 01 to 20% by weight of rhenium. 3.- A process for the preparation of supported rhenium aluminate of claim I or 2, characterized by the interaction of a rhenium compound with a mineral material containing aluminum oxide, at a temperature of 80 to 200 "C followed by heating at a temperature of 400 to 1000" C. 4.- Method according to claim 3, characterized in that said heating is carried out at 800 - 1000 C. 5.- Method according to claim 3, characterized in that the mineral material is an alumina silica containing between 70 and 90% by weight of alumina. 6.- Method according to claim 3, 4 or 5, characterized in that the rhenium compound belongs to the group consisting of rhenium heptoxide, ammonium perrhenate and perrhenic acid. 7.- Method according to any one of claims 3 to 6, characterized in that the rhenium compound is used in aqueous solution or in solution in an organic liquid. 8.- Use of the catalyst of claim I or 2 or obtained  according to any one of claims 3 to 7, in the reaction  of metathesis of functional olefins of general formula  R-CH = CH - C H - X  1 n 2n  or R1 represents hydrogen or a hydrocarbyl radical, X is  a functional group and n is an integer equal to or greater than 1. 9. Use according to claim 8, in which X is a  group - 0 - CO - R2 or - CO - OR3 where R2 and R3 are  hydrocarbyl radicals. 10. Use according to claim 8 or 9 in the co-reaction  of metathesis of functional olefins of general formula:  R1 - CH = CH - C n H2 X  as defined in claim 8, with an olefin  non-functional general formula  R2 - CH = CH2  where R2 represents hydrogen or a hydrocarbyl radical.