FR2910004A1 - Preparation of oligomers/polymers from monomers, comprises oligomerization or polymerization - Google Patents

Abstract

Preparation of oligomers/polymers from monomers (I), comprises oligomerization or polymerization. Preparation of oligomers/polymers from monomers of formula R2R3C=C(R1)CN (I), comprises oligomerization or polymerization. R1H or 1-6C (cyclo)aliphatic hydrocarbon or optionally substituted aromatic; and R2, R3H, 1-6C aliphatic chain, or cycloaliphatic or aromatic.

Description

2910004 Process for oligomerization and / or polymerization of compounds

  unsaturated. The present invention relates to a process for oligomerization and / or polymerization of organic compounds comprising conjugated unsaturation with an electron acceptor group, in particular a nitrile group.

It relates more particularly to an oligomerization and / or polymerization process comprising a particular non-organometallic catalyst consisting of a compound comprising at least one carbon of carbene type, more particularly a derivative of the compounds belonging to the family of carbenes. Among the polymers or oligomers obtained by polymerization of a compound comprising an electroacceptor-activated unsaturation, polyacrylonitriles and polymethacrylonitriles are the best known.

Among the oligomers, the dimer of acrylonitrile is a particular compound which makes it possible to manufacture adiponitrile by hydrogenation of dicyanobutene. Adiponitrile is a major chemical intermediate manufactured at several million tons per year because it is one of the major chemical intermediates used in the manufacture of hexamethylenediamine or caprolactam, which are important monomers for the manufacture of polyamides and isocyanates. and polyurethanes. The acrylonitrile polymers or the acrylonitrile dimer are generally obtained using as basic catalysts such as amines, phosphines or transition metals. These catalytic compounds may exhibit intrinsic toxicity or generate toxic compounds as an example by oxidation of the amine or phosphorus compounds.

In addition, some of these catalysts are found in the polymer and are dangerous for the environment or considered dangerous to humans. Thus, many transition metals are prohibited from use because they may have a carcinogenic character, for example. Consequently, there is a need to find new catalysts which do not have these disadvantages, but which retain a catalytic activity at least similar or similar to those of known catalysts.

One of the aims of the present invention is to propose a process for the polymerization and / or oligomerization of compounds comprising an electroacceptor-activated unsaturation with a catalytic system which does not have disadvantages, in particular from a toxicity point of view and for 'environment.

For this purpose, the invention provides a process for the manufacture of oligomers and / or polymers of compounds of the general formula I ## STR1 ## wherein: R 1 represents hydrogen or an aliphatic hydrocarbon radical or linear or branched cycloaliphatic comprising from 1 to 6 carbon atoms or a substituted or unsubstituted aromatic radical, R2, R3, which may be identical or different, represent hydrogen or a linear or branched aliphatic hydrocarbon radical containing from 1 to 6 carbon atoms or substituted or unsubstituted aromatic or cycloaliphatic radical, comprising performing the oligomerization or polymerization of the compound of formula I in the presence of a catalyst comprising a compound comprising at least one carbene-type carbon and corresponding to the general formula II below. ## STR5 ## wherein: X and Y, which may be identical or different, are atoms selected from the group consisting of C, N, S, P, Si and O; nx and ny are two integers, respectively equal to the valence of the atom X and the valence of the atom Y (ie 2 when the atom is S or O; 3 when the atom is N or P; and 4 when the atom is Si or C); each of the groups Rx and RY bonded to the atoms X and Y represents, independently of the other groups, a hydrocarbon, aliphatic or aromatic, linear or branched chain, optionally cyclized in whole or in part, and optionally substituted, this chain being preferably: a linear or branched, optionally substituted alkyl, alkenyl or alkynyl group, for example by at least one perfluoroalkyl group; a perfluoroalkyl group, linear or branched; a cycloalkyl group, optionally substituted, for example with at least one alkyl or alkoxy group; an aryl group optionally substituted, for example with at least one alkyl or alkoxy group; an alkylaryl or arylalkyl group, where the aryl part is optionally substituted, for example by at least one alkyl or alkoxy group, it being understood that one of the Rx groups carried by the X atom and one of the RY groups carried by the Y atom; may possibly be linked together to form a ring with the X and Y atoms and the formally divalent carbon of the carbene. The cycle thus formed preferably comprises, for example, from 5 to 7 members. By carbene is meant an organic chemical species, electrically neutral, non-radical, comprising a formally divalent carbon which is carrying an electron pair. By derivative or carbene compound is meant a compound comprising a carbene type carbon. In the case of a singlet carbene derivative, the two unpaired 2910004 electrons 4 are paired in the same orbital. As used herein, the concept of carbene also encompasses compounds of the aforementioned type where the divalent carbon carries an additional electron pair or is engaged in a delocalized bond. By family of carbenes is meant all compounds, derivatives comprising a carbene-type carbon or can generate, for example under the action of a base or heat, a compound or derivative of carbene type. Carbenes are well known and may be mentioned as general literature concerning carbenes, especially stable singular carbenes, the following references: F.E. Halm F.E.HALN Angew. Chem. Int. Ed., 45 (2006) 1348; W. Kirmse Angew. Chem. Int.

Ed., 43 (2004) 1767, R. Walder et al. Angew Chem Int Ed., 43 (2004) 5896; Y. Canac et al. J. Organometal. Chem. 689 (2004) 3857. D. Bourissou et al. Chem. Rev., 100 (2000) 39. The carbene derivative of the invention advantageously comprises, in ci of its divalent carbon, an atom selected from C, N, S, P, Si and O. In formula III below the Rx and RY groups are generally sterically hindered electron donor groups.

Preferably, at least one of the X or Y atoms is a heteroatom selected from the group consisting of N, S, P, Si and O. According to a particular embodiment of the invention, X denotes a nitrogen atom. More preferably, X and Y denote a nitrogen atom.

Particularly preferred are NHC (nitrogen heterocycle carbene) carbene derivatives wherein X and Y represent a nitrogen atom and Rx and RY form a ring. The heterocycles envisaged are, for example, pyrrole, pyrroline, pyrrolidine, pyrimidine, triazine, tetrazine, imidazole, and triazole. Particularly preferred are the NHC carbene derivatives of the following formulas: R4 and R5, independently of one another, represent a linear or branched hydrocarbon chain, optionally cyclized in whole or in part, and optionally substituted, such as for example: an optionally substituted linear or branched alkyl, alkenyl or alkynyl group, such as in particular tert-butyl, isopropyl, propyl, n-propyl, butyl, n-butyl and methyl; to - a cycloalkyl group, optionally substituted, for example by at least one alkyl group; an aryl group optionally substituted, for example with at least one alkyl group; an alkylaryl or arylalkyl group, where the aryl part is optionally substituted, in particular by at least one alkyl group. The following NHC carbenic derivatives are particularly mentioned: Other types of carbenic derivatives, such as CAAC (cyclic (alkyl) (amino) carbenes), which are carbenes carrying on both sides of the the carbon atom divalent a nitrogen atom and a carbon atom, said carbon atom being integrated in an aliphatic ring; Examples of these are, for example, those of the following formulas: Another type of carbene derivatives that may be mentioned are thiazoles, which are carbenes carrying, on both sides of the carbon atom, a nitrogen atom and a nitrogen atom. Sulfur atom, such as in particular the alkyl units, benzothiazoles or phenyls for triazoles, for example those of the following formulas: According to one characteristic of the invention, the above carbene derivatives are preferably introduced and present in the reaction medium. . However, they can also be formed in situ by reaction between a strong basic compound and the corresponding iminium salts such as thiazolium imidazolium salts, for example.

These iminium salts are precursors of carbene derivatives and correspond to a carbene derivative in which one of the atoms located at a of the carbene (the X or Y atoms) is positively charged and is in association with an anion, generally selected from the group consisting of Cr, Br, OTf-, BF4-, BPh4-. In this case the formally divalent carbon becomes a formally tetravalent carbon bonded to a hydrogen atom. These salts can release the carbene derivative under the action of a strong base such as for example t-BuONa, Me3SiNLiSiMe3, NaH, nBuLi or else NaH and t-BuOK. The strong base may be added to the solution of the invention before or during process step a) of the process. In particular, it is possible to use iminium, imidazolium or thialozium salts, with as possible anions those especially chosen from Cr, Br, OTf-, BF4, BPh4-. These salts are generally obtained by condensation chemistry from an aromatic or aliphatic primary amine and glyoxal. If it is desired to avoid the use of salts, it is possible to use neutral precursors of carbenes, which at a defined temperature or under the effect of a photonic radiation can release a free carbene derivative. For this purpose, it is possible to use in particular a thermal precursor of a carbene derivative, such as, for example, those whose tetravalent carbon carries a function - Z may be a -CF 3 or OR 4 with R 4 being a methyl, ethyl or isopropyl radical. tert-butyl, a diol, a triol, or a perfluorinated aryl radical. It is also possible to use stable derivatives of carbenes, such as the compounds obtained with tertiary alcohols, aromatic derivatives or with CO 2, for example: ## STR1 ## where: alkyl is Me, iPr,. = H, alkyl: Me, iPr, ... Z = F The release of the carbene is generally done by thermal effect with heating of the compound or derivative at a temperature between 30 C and 150 C. Such compounds or derivatives are described in the following articles: J.HEDRICK et al., Chem.Eur.J., 10 (2004) 4073; J. CASTELLS et al., Tet.Lett., 26 (1985) 5457; J.Louie et al., Chme, Comm., (2004) 112 and R. Rogers et al., Chem.Comm ;, (2003) 28. The unsaturated compounds of formula I suitable for the invention are selected from the group consisting of acrylonitrile, methacrylonitrile, 2-pentenitrile, 2-methyl-2- butenenitrile or the like. Acrylonitrile is the preferred compound of the invention. The polymerization is carried out in the presence or absence of solvent. Thus, apolar non-protic solvents such as toluene, xylenes, cyclohexane, methylcyclohexane, heptane, polar aprotic solvents such as tetrahydrofuran, dioxane, methyl tetrahydrofuran or the like can be used. It is also possible to use protic polar solvents which do not react with the monomer. By way of example of these solvents, mention may be made of secondary or tertiary alcohols of the terbutyl alcohol, teramyl alcohol or isopropyl alcohol type.

In general, the process consists in introducing the monomer to be polymerized, for example acrylonitrile in a medium containing a carbene compound and optionally, but preferably a solvent. The oligomerized product is recovered generally as a precipitate. In a preferred embodiment of the invention, a proton source compound is added to the reaction medium to limit the reaction to very low levels of oligomerization. Suitable proton source compounds for the invention are, for example, secondary and tertiary alcohols such as terbutyl alcohol, teramyl alcohol or isopropyl alcohol. According to another characteristic of the process of the invention, a stable carbene compound or derivative is used, that is to say not sensitive to moisture, especially to the humidity of the air. This compound is added to the reaction medium, the active carbene compound is formed in situ either by thermal action or by addition of a strong base. Advantageously, the process makes it possible to prepare the dimer of acrylonitrile, namely dicyanobutene. This compound is preferably used as a raw material for the manufacture of adiponitrile by hydrogenation as described in numerous patents and articles such as the article entitled Catalytic Dimerization of Acrylonitrile by JR Jennings and RJ Cozens published in Applied Catlysis Vol. 124 (1995) pp297-315. Other advantages, details of the invention will emerge more clearly from the examples given above solely by way of example. EXAMPLE 1 To a glass reactor of 50 ml, 242 mg (1.34 mmol, 0.04 molar equiv., Relative to acrylonitrile) of 1,3-di-tert-butylimidazol-2-ylidene and 20 ml of anhydrous toluene ( clear colorless solution) Cooled to -10 ° C. and poured, over 2 min, at -10 ° C., under argon, 2 ml of acrylonitrile (30.1 mmol, 1 molar equi). There is immediately formation of a yellow precipitate. After natural warming to 25 C the reaction medium is filtered on sintered glass. The cake is washed with 3 times 10ml of dry toluene. 2.52g of wet yellow solid are obtained.

The exclusion-diffusion chromatography (CED) analysis indicates that a polymer with a number-average molecular weight (Mn) of 11000 (polystyrene equivalents) is obtained, ie a degree of polymerization of 207 nitrile units.

EXAMPLE N 2 A 1.3-di-tert-butylimidazol-2-ylidene, 80 mg (0.44 mmol, 0.01 equiv., Molar relative to acrylonitrile), is charged into a 50 ml glass reactor and then 10 ml of anhydrous toluene ( clear colorless solution) 3 ml of acrylonitrile (45.1 mmol, 1 equi molar) are poured at room temperature over 3 min under argon. There is immediately formation of a yellow precipitate. Allowed to react for 20 minutes at room temperature, then the reaction medium is filtered on sintered glass. The cake is washed with 2 times 5ml of dry toluene. 1.18g of yellow solid are recovered. Exclusion diffusion chromatography (EDC) analysis indicates that a number-average molecular weight polymer (Mn) of 12000 (polystyrene equivalent) is obtained, ie a degree of polymerization of 220 nitrile units.

Claims (19)

  1. Process for the Preparation of Oligomers and / or Polymers from Monomers of the Formula I. ## STR1 ## in which: R 1 represents hydrogen or a linear or branched aliphatic or cycloaliphatic hydrocarbon radical comprising of 1 to 6 carbon atoms or a substituted or unsubstituted aromatic radical, R2, R3, which may be identical or different, represent hydrogen or a linear or branched aliphatic hydrocarbon radical comprising from 1 to 6 carbon atoms or a substituted or unsubstituted aromatic or cycloaliphatic radical , characterized in that it consists in performing the oligomerization or polymerization of the monomer of formula (I) in the presence of a compound comprising a carbene-type carbon.   2. Process according to claim 1, characterized in that the carbene derivative corresponds to the general formula (II) below: (RX) nx-1 ù X ù C ù Y ù (RY) ny-1 (II) in which: X and Y, identical or different, are atoms selected from the group consisting of C, N, S, P, Si and O; -nx and ny are two integers, respectively equal to the valency of the atom X and the valency of the atom Y (ie 2 when the atom is S or O; 3 when the atom is N or P; and 4 when the atom is Si or C); each of the groups RX and RY bonded to the X and Y atoms represents, independently of the other groups, a linear or branched hydrocarbon, aliphatic or aromatic hydrocarbon chain, optionally cyclized in whole or in part, and optionally substituted; it being understood that one of the groups Rx carried by the X atom and one of the RY groups carried by the Y atom may optionally be bonded together to form a ring with the X and Y atoms and the formally divalent carbon of the carbene .   3. Process according to claim 2, characterized in that each of the groups Rx and RY 5 bonded to the X and Y atoms represents, independently of the other groups, a hydrocarbon-based chain chosen from the group comprising: a linear alkyl, alkenyl or alkynyl group or branched optionally substituted, a perfluoroalkyl group, linear or branched; an optionally substituted cycloalkyl group, an optionally substituted aryl group, an alkylaryl or arylalkyl group, wherein the aryl part is optionally substituted.   4. Process according to any one of claims 1 to 3, characterized in that the carbenic derivatives are carbenic derivatives NHC (nitrogen heterocycle carbene) in which X and Y represent a nitrogen atom and Rx and RY form a ring .   5. Process according to claim 4, characterized in that the carbenic derivatives NHC carry a heterocycle selected from the group comprising pyrrole, pyrroline, pyrrolidine, pyrimidine, triazine, tetrazine, imidazole, and triazole. .   6. Process according to any one of claims 1 to 5, characterized in that the carbenic derivatives NHC are of the following formulas: R4 NCN R5 (IV) 25 NCN \ R5 2910004 13 in which: R4 and R5 independently represent one of the other a hydrocarbon chain, linear or branched, optionally cyclized in whole or in part, and optionally substituted.   7. Process according to claim 6, characterized in that R4 and R5 represent, independently of each other, a hydrocarbon chain selected from the group consisting of: an optionally substituted linear or branched alkyl, alkenyl or alkynyl group; cycloalkyl group, optionally substituted, an optionally substituted aryl group, and an alkylaryl or arylalkyl group, wherein the aryl portion is optionally substituted. 15   8. Process according to claim 7, characterized in that R4 and R5 represent, independently of one another, a hydrocarbon-based chain chosen from the group comprising tert-butyl, isopropyl, propyl, n-propyl, butyl, n-butyl and methyl groups. 20   9. Process according to claims 6 to 8, characterized in that the carbene derivatives correspond to the following formulas; 25   10. Process according to any one of claims 1 to 3, characterized in that the carbene derivatives are compounds of CAAC type (cyclic (alkyl) (amino) carbenes). v N`, N --- ä (2910004   11. Process according to any one of claims 1 to 3, characterized in that carbene derivatives are derivatives of thiazole type. 5   12. Process according to claim 11, characterized in that the thiazole carbene derivatives have the following formulas:   13. Process according to any one of claims 1 to 12, characterized in that the precursor of a singlet carbene derivative, capable of delivering in situ a free singular carbene derivative, is a salt in which one of the atoms located in carbene is positively charged in association with an anion.   14. The method of claim 11, characterized in that the anion is selected from the group consisting of Cl-, Br, OTf-, BF4, BPh4.   15. The method of claim 10 or 11, characterized in that the precursor is a salt of iminium, imidazolium, or thialozium.   16. Process according to any one of claims 1 to 10, characterized in that the precursor of a singlet carbene derivative, capable of delivering in situ a free singlet carbene derivative, is a neutral and thermal precursor of a carbene derivative whose Tetravalent carbon has a function - Z may be -CF3 or OR6 with R6 being methyl, ethyl, isopropyl, tert-butyl, diol, triol, or perfluorinated aryl. 20 2910004 15   17. Method according to one of claims 1 to 12, characterized in that the precursor of a carbene derivative capable of delivering in situ, by thermal effect, a free singlet carbene derivative is a neutral precursor comprising the compounds obtained by reaction. of a carbene with a tertian alcohol, aromatic compounds or carbon dioxide.   18. Process according to claim 17, characterized in that the carbenic derivative precursor corresponds to one of the following formulas: ## STR5 ## R = H, alkyl: Me, iPr, ... F3C CF3 Z = 15   19. Process according to any one of claims 1 to 18, characterized in that the oligomerization or polymerization reaction is carried out in the presence of a solvent. 2C). Process according to Claim 19, characterized in that the solvent is chosen from the group of apolar protic solvents, aprotic polar solvents and polar protic solvents which do not react with the monomer to be polymerized. 21. The process according to claim 20, wherein the solvent is selected from the group consisting of toluene, xylenes, cyclohexane, methylcyclohexane, heptane, tetrahydrofuran, dioxane, methyl tetrahydrofuran terbutyl alcohol, teramyl alcohol, isopropyl alcohol. 22. Method according to one of the preceding claims, characterized in that the oligomer obtained is the dimer of acrylonitrile. 23. Method according to one of the preceding claims, characterized in that the compound of formula I is selected from the group consisting of acrylonitrile, methacrylonitrile, 2-pentenenitrile, 2-methyl-2-butenenitrile. 24. Process according to one of the preceding claims, characterized in that the compound of formula 1 is acrylonitrile and in that the oligomer obtained is dicyanobutene.