FR2499558A1 - Metathesis of unsatd. organic cpds. with terminal functional Gps. - using molybdenum or tungsten catalyst and silane co-catalyst - Google Patents

Abstract

Metathesis of unsatd. organic cpds. with a terminal functional gp. is effected using a Mo or W cpd. as catalyst and a silane as co-catalyst, the reaction taking place at at least 50 deg.C. The process is specifically claimed for the metathesis of olefinic cpds. of formula (I) RCH=CH(CH2)X (I) where R is 1-12C alkyl or H, X is a functional gp. and n is an integar and is at least 1, pref. 2-28. Also claimed is an alpha-omega olefin dinitrile comprising 10-eicosene 1,20-diniticle. Use of the co-catalyst results in rapid establishment of equilibrium of the disproportionation reaction 2R'-CH=CH-R2 giving R'-CH=CH-R' + R2-CH=CH-R2. The catalyst system is non-toxic and the catalyst does not become blocked in the presence of e.g. nitrile gps. The process is also applicable to other disproportionation reactions e.g. 'crossed' metathesis with linear or cyclic, opt. functional olefins.

Description

 The present invention relates to the metathesis, that is to say the disproportionation, of olefinic compounds carrying functional groups. It also includes a new dinitrile which the process of the invention makes it possible to obtain more advantageously than the known methods allow.

 The metathesis of unsaturated compounds, which gives - from two molecules of such compounds - two other molecules, with a different distribution of the alkylidene or alkylidyne residues, is a technique known for less than two decades; it is of great industrial interest and has given rise to numerous works.

les deux molécules de départ pouvant d'ailleurs être différentes. Des produits difficiles à synthétiser par d'autres voies, ou tout-à-fait nouveaux, ont pu ainsi être formés gracie à des catalyseurs qui rendent possible cette réaction de métathèse.The principle of this equilibrium reaction can be illustrated as follows s

the two starting molecules can also be different. Products which are difficult to synthesize by other, or entirely new, means have thus been able to be formed thanks to catalysts which make this metathesis reaction possible.

Since its discovery by BANKS and BAILY (Ind.

Eng. Chem. Prod. Res. Develop. - 1964 - 3170), various catalytic systems have been proposed, but the main catalyst is always a compound of W, Mo or Re; associations of such compounds with different co-catalysts, in particular halides or oxides of Al, Li or Sn, have been proposed. The catalytic systems, which seem to have been the most appreciated, are the associations of tungsten hexachloride or molybdenum with tetraalkyl tin. Thus, for example, the French patent publication 2 003 236 indicates good results in the transformation of 2 moles of pentene-2 into 1 mole of butene-2 and 1 mole of hexene-3, in the presence of WC16 + Sn (C4H9 ) 4.

 However, the toxicity and the high cost of organotin derivatives constitute a drawback, all the more since their recovery from the reaction medium is very difficult. On the other hand, if - instead of non-functional olefins - we want to disproportionate unsaturated compounds, carrying functional groups at the end of the chain, the catalytic system containing an organostannic gives less good results. For certain functional groups, in particular nitriles, there is even a risk of blocking the tungsten catalyst.

 The present invention eliminates these drawbacks: it makes it possible to establish equilibrium fairly quickly according to reaction (1) indicated above, for unsaturated groups with functional groups at the end of the chain, by means of a compound of Mo or of W, with a more economical co-catalyst, having no toxicity and avoiding blocking of the catalyst in the presence of groups such as nitriles.

 The process according to the invention for metathesis of unsaturated compounds carrying functional groups in the presence of a catalyst consisting of a tungsten or / and molybdenum compound combined with a cocatalyst, is characterized in that the latter is a silane and that the operation takes place at a temperature of at least 50 ° C.

 More particularly, the catalytic system according to the invention comprises a tungsten uwkslogenide, in particular Wu16, and a disubstituted silane R2SiH2 where R is an aliphatic, cycloaliphatic, aryl or alkaryl hydrocarbon radical, preferably in C1 to C12 and especially in C1 to C8. R can be, for example, linear or branched C1-C12 alkyl, cyclopentyl or cyclohexyl, phenyl, tolyl, xylyl, etc., benzyl or the like.

 The proportion of silane, in its association with the tungsten compound, can vary between 0.25 and 10 moles of silane per mole of tungsten compound; preferably, this ratio is in the margin of 1 to 4 Si for 1 W, or better still between 2 and 4 Si per W.

 The amounts of catalyst, that is to say of compound of Mo or W, to be used for metathesis, are of the order of 0.5 to 10 mole% of the unsaturated substance, with functional groups, which it's about dismuter; the preferred proportions are from 1 to 5, and better still from 1 to 3 mol%. The corresponding amounts of silane are deduced from the si / w ratio chosen within the limits indicated above.

 Temperature plays an important role. While non-functional olefins can be disproportionated at room temperature, at least 500C is required for the metathesis of unsaturated compounds carrying functional groups. Thus, the invention is carried out between 500 and 1300C, preferably between 650 and 1200C, and best within the limits of 700 to 850C.

 Another necessary condition is the absence of any free acidity and moisture.

 The reaction time generally varies between 6 and 60 hours, and most often between 10 and 20 hours.

 As in the known methods, the reaction takes place in an inert atmosphere, that is to say in the absence of oxygen, in particular in dry nitrogen or argon.

The reaction medium is kept away from the outside atmosphere.

 When the unsaturated compounds to be disproportionated are liquid, it is advantageous to operate without a solvent, the catalytic system being dissolved or dispersed in the liquid to be treated itself. It is however possible to use a solvent, preferably chosen from those in which the catalytic system is soluble. In particular suitable aliphatic or aromatic hydrocarbons, optionally halogenated, for example benzene or chlorobenzene.

The most important unsaturated compounds with functional groups which can be subjected to the process of the invention can be represented by the general formula t
RCH = CH (CH2) nX (2) in which R denotes an alkyl, in particular in
C1 to C12, or a hydrogen atom, while X is a functional group; n, an integer at least equal to 1, is preferably greater than 2 and can reach values of the order of 28, but most often does not exceed 10. The alkyl R may carry an aryl substituent.

 Among the functional groups X, practically the most important, are those which contain a carbonyl, carboxyl or nitrile. X is therefore mainly a group -COR ', -COOR', -OOCCH2R "or -6 = N, R 'denoting a hydrocarbon radical, in particular C1 to C6 alkyl, benzyl or phenyl, R" a hydrogen atom or a hydrocarbon group, in particular C1 to C6. In other words, the compounds treated according to the invention are mainly ketones, esters and nitriles, but other unsaturated, functional products can undergo this metathesis, for example amides, amines, halides, ethers, sulfonates, sulfides, etc.

The nature of group X often influences the minimum length of the chain = CH- (CH2) n- in the compound according to formula (2) given above. So when
X is an ester -COOR'-, it suffices that n is at least 1.

On the other hand, if X is an acid residue, -OOCjCH2R, of which the compound treated is 11 ester, it is preferable that n is 2 or more; the same is true if X is a halogen, for example Cl. But, in the case of nitriles, where X is -CfN, good results are obtained only with a sufficiently long chain, ie n greater than 3.

 The formula (2) relates to olefinic compounds, it is however understood that the process of the invention also applies to acetylenic bodies.

 An important application of the invention consists in producing diesters and dinitriles a-W), intermediates for the synthesis of diacids, dialcohols and diamines useful in the manufacture of polyesters and polyamides. It is known in fact to pass economically from a diester to the diacid or to the corresponding dialcohol, and - by conventional hydrogenation - from a dinitrile to the diamine.

The examples given in the remainder of this description illustrate these very useful industrial applications, based on the reaction (1) of metathesis which then corresponds to the scheme s

conduisant à des diènes porteurs d'une fonction X en bout de channe.Ainsi peut-on obtenir par exemple de l'acétate de décadiène-2,7-yle, lorsque R' est CH3, n=2 et X est -OOC-CH3. However, the invention can also be applied to other forms of disproportionation, for example to "cross" metathesis with a linear or cyclic olefin, functional or not. The first of these cases amounts to reacting two different molecules in the left side of the reaction (1). The second case can be illustrated by the example of cyclopentene t

leading to dienes carrying a function X at the end of the chain. Thus one can obtain for example decadiene acetate-2,7-yl, when R 'is CH3, n = 2 and X is -OOC- CH3.

 The invention is illustrated without limitation by the following examples. The operations described are carried out in a reactor heated by a double jacket, magnetically stirred, provided with a thermometer and an introduction closed by a Teflon tap and a septum. This reactor and its accessories are dried in an oven and reassembled hot; they are purged, by placing them successively under vacuum and by filling them with argon U which contains only 5 ppm of oxygen and as much water; the purge is repeated several times.

EXAMPLE 1
792 mg of WC16, or 2 millimoles, previously sublimed, are introduced into the reactor. The latter being still hot, the purges are redone, after which 22.2 ml of a decene-10 methyl oate C = CH- (CH2) 8-COoeH3 are injected into the reactor, using a syringe, through the septum.

This volume of olefinic ester represents 19.8 g or 0.10 mole. The ester was previously rectified under vacuum; its free acidity is only 0.1 mole% and only traces of moisture are present.

The mixture is heated to 500-700C for 30 minutes with stirring, after which 0.735 ml, or 728 mg or 4 millimoles, of diphenyl-silane (C6H5) 2SiH2 are introduced into the reactor.

The reaction mixture then constitutes a very dark red-violet solution, which is heated to 750C. Gas evolution occurs, while the temperature is maintained at 750C for 16 hours, with stirring.

A total of 750 ml of gas consisting of ethylene is collected, in a graduated glass gasometer, out of the theoretical 1140 ml which the reaction would give:

 (dimethyl-10-dioate-1, 20-eicosene) if it was total.

After cooling to approximately 300-350C, 50 ml of petroleum ether are added to the reaction medium, then 5 ml of a concentrated aqueous ammonia solution with a density of 0.92. The mixture is stirred vigorously for a few minutes and filtered through a sintered glass lined with Celite 545; washed on filter until the filtrate is neutral. The latter is dried over anhydrous sodium sulfate, after which its solvent is evaporated, and a yellow oil remains, which crystallizes; 22.5 g of product are thus obtained.

Chromatographic examination in the vapor phase indicates that 61.8% of the initial methyl undecene-10-oate has been transformed, of which 86.5% into dimethyl eicosene-10-dioate-1.20 following the written reaction more high. The selectivity for this dioate is therefore 86.5% and the yield on the starting ester 53.5%.

By rectification under a vacuum of 2 mmHg of the dioate, thus obtained, the remaining methyl undecene-10 is separated, which boils at 980C / 2mmHg of dimethyl eicosene-10-dioate-1.20. This last tip at 2180-2200C / 2mmHg and bottom b 45-46 C.

EXAMPLE 2
The operations are the same as in Example 1, but the reaction is allowed to continue for 60 hours instead of 16 hours, at 750C. The initial lester conversion rate is then 70.8% compared to 61.8% in Example 1, but the selectivity for eicosene-dioate decreased to 81.3%. The yield of dioate on the starting ester thus stands at 57.6%.

It therefore does not seem very advantageous industrially to allow the reaction to continue for 60 hours.

EXAMPLE 3
The procedure of Example 1 is applied to the metathesis of 21.2 g of acetoxy-1 undecene-10, that is to say undecene-10-yl-1 acetate.

CH2 = CH (CH2) 9-OOC-CH3
By the CPV examination, it can be seen that the rate of transformation of this acetate is 61.3%, and that diacetoxy-1.20 eicosene-10 (cis and trans) is obtained, ie eicosene diacetate. Di-yl-1,200 CH3COO- (CH2) gCH = CH (CH2) 9-OOC-CH3 with a selectivity of 52.6% relative to the transformed acetate. The yield of this diacetate on the initial acetate, used, thus stands at 32.8%.

However, isomerization and subsequent metathesis occur at the same time, which give C18 and C19 diacetoxyalkenes. If we then take into consideration the sum of all the diacetoxy derivatives thus formed, we arrive at a selectivity of 58.9% and a yield of 36.1% on the starting acetate.

Diacetoxy-1,20 eicosene-1O trans can be separated by crystallization from the reaction product; this isomer melts at 280-300C.

EXAMPLE 4
By operating in the same manner as in Examples 1 and 3, the metathesis of 19.5 ml, ie 16.5 g = 0.1 mole, of decene-10 nitrile t cH2 = cH (CH2) is carried out. C3N
The tungsten hexachloride dissolves more slowly and more difficultly than in the compounds treated in the preceding examples, but its dissolution is practically complete around 500C, during the injection of the diphenylsilane.

As before, the reaction medium is strongly colored, and gas evolution is observed.

After 16 hours of reaction and separation as above, there is a conversion rate of the nitrile used of 74.6%.

A new chemical, lteicosene-10 dinitrile-1.20, NBC (CH2) 8CH H (CH2) 8C-N, is formed with a selectivity of 56% with respect to neither sorting the transformed, ie a yield of 41.8 % on total nitrile, used at the start.

 Undecene-10 nitrile, which has not undergone metathesis, being separated by vacuum distillation, the eicosene-dinitrile is collected and this new compound has a melting point of 270-280C, after its purification by chromatography on silica and recrystallization from an ether-petroleum ether mixture.

EXAMPLE 5
The procedure is as in Example 4, but instead of 0.735 ml of diphenylsilane, 0.3 ml of
Sn (CH3) 4 to 500. After 16 hours of reaction, the amount of undecene-10 nitrile transformed is 15.8%, and eicosine-10 dinitrile (1.20) is obtained with a selectivity of 54% compared to the starting nitrile.

EXAMPLE 6
The operations of Example 1 are repeated, but without heating. The temperature of the mixture is 200C during the 16 hours of the reaction. The formation of the diester is not observed in appreciable quantities by the usual methods of analysis.

EXAMPLE 7
The procedure is as in Example 4, but it does not heat up. The temperature of the mixture is 20 ° C. during the 16 hours of the reaction. The formation of dinitrile is not observed by usual methods.

 The comparison between Examples 4 and 5 shows that the replacement of the conventional tin-based cocatalyst with a silane according to the invention considerably increases the conversion rate of the starting dinitrile.

Claims (9)

 1. Process for the metathesis of organic compounds, unsaturated, carrying a functional group at the end of the chain, by means of a catalyst, consisting of a compound of Mo- or W associated with a co-catalyst, characterized in that that the latter is a silane, the operation taking place at a temperature of at least 500C.  2. Method according to claim 1, in which the catalyst is a halide of Mo or / and of W, in particular tungsten xhexloride, characterized in that the cocatalyst is a disubstituted silane R2Si d where R denotes a hydrocarbon, aliphatic, cycloaliphatic radical , aryl or alkaryl, preferably C1 to C12 and especially C1 to C8.  3. Method according to claim 1 or 2, characterized in that the co-catalyst is diphenyl-silane (C6H5) 2S N-  4. Method according to one of claims 1 to 3, characterized in that the temperature, during metathesis, is between 50. and 1300C, the preferred range extending from 650 to 1200C or better still from 700 to 850C.  5. Method according to one of claims 1 to 4, characterized in that the reaction time is from 6 to 60 hours, and mainly from 10 to 20 hours.  60 Method according to one of the preceding claims, wherein the amount of catalyst, in particular of tungsten halide, is of the order of 0.5 to 10 mol% or - preferably - from 1 to 3 mol% relative to the unsaturated substance, with functional groups, which is to be transformed, characterized in that the proportion of silane is such that there is, in the reaction medium, 0.25 to 10 moles of silane per mole of compound forming the catalyst or, better still, 1 to 4 moles of silane per mole of catalyst.  7. Application of the method according to one of the preceding claims to the metathesis of olefinic compounds of the type RCH = CH (CH2) nX where R denotes an alkyl, in particular C1 to C12, or else a hydrogen atom, while X is a functional group, n being an integer of at least 1 and preferably greater than 2 but less than 28.  8. Application according to claim 7, characterized in that the functional group X is based on a carboynyl, a carboxyl or a nitrile, the resulting product being an a-4-diketone, diester or olefinic dinitrile.  9. Application according to claim 7 or 8, characterized in that n is from 2 to 10, R possibly carrying an aryl substituent.  10. New a- J-olefinic dinitrile, characterized in that it is constituted by ltéicosene-10 dinitrile-1,20.