Method for ring-opening or polycondensation polymerization

Abstract

The invention relates to a method for producing linear organopoly siloxanes OL by means of a polymerization reaction from organopoly siloxanes O (cyclic and / or linear), and using a catalytic system AI. More precisely, the method of the present invention makes it possible to obtain linear organopoly siloxanes OL having a controlled molar mass with a very low residual rate of residual cyclic organopoly siloxanes. The present application also relates to the linear organopoly siloxane OL obtained according to the various embodiments of the method of the present invention described above.

Description

[0001] Title of the invention: Cycle-opening or polycondensation polymerization process

[0002] Technical field:

[0003] The invention relates to a process for preparing linear organopoly siloxanes OL by a polymerization reaction from organopoly siloxanes O (cyclic and / or linear), and using an AI catalytic system. More specifically, the process of the present invention makes it possible to obtain linear organopoly siloxanes OL of controlled molar mass with a very low level of residual cyclic organopoly siloxanes.

[0004] The invention also relates to the catalysts used in the AI ​​catalytic system which will be detailed in detail below.

[0005] Technological background:

[0006] A major challenge for the silicone industry in the coming years is to industrially synthesize organopolysiloxanes with very low or even zero residual cyclic content.

[0007] To date, the industrial synthesis of organopolysiloxanes by polycondensation or ring-opening polymerization results in the formation of cyclic organopolysiloxanes such as octamethyltetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) or other unwanted cyclic organopolysiloxanes. In conventional industrial processes, ring-opening polymerization is preferred because it uses monomers that are easily synthesized, purifiable and therefore inexpensive. However, this method is also confronted with the presence of unwanted cyclic products that can amount to a content of between 6 and 15% relative to the total mass of linear organopolysiloxane obtained during the synthesis, which corresponds to thermodynamic equilibrium.Conventionally, this high cyclic product content requires energy-intensive process steps such as a high-temperature and / or reduced-pressure devolatilization step to separate these by-products from the resulting linear organopolysiloxane. Eliminating these steps improves production efficiency and reduces carbon dioxide emissions, thereby producing a more environmentally friendly silicone product.

[0008] Thus, in the interests of economic and energy profitability, there is a need to develop new solutions to eliminate or at least limit these long and costly separation steps. Furthermore, cyclic silicones or organopolysiloxanes such as octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) are and will be subject to restrictions for their use. In addition to the fact that these cyclic compounds present environmental risks due to their non-biodegradability, they are also suspected of being endocrine disruptors and potentially carcinogenic.

[0009] In this sense, in 2018 European regulations limited the content of D4 and D5 to 0.1% by mass in rinse-off cosmetic products. This regulation will soon be adopted for other cosmetic products but also in other areas of silicone application, such as the electronics industry, for example.

[0010] Therefore, there is a need to develop processes for providing linear organopolysiloxanes free of, or at least with a low content of, cyclic silicones. In particular, there is an interest in providing a new catalytic system for implementing such a process. There is also an interest in being able to reliably control the molar mass of the products formed. This possibility increases the prospects for use and applications of such polymers obtained.

[0011] In the prior art, the use of carbene derivatives for the preparation of organopolysiloxane by ring-opening polymerization reaction or by polycondensation has been described in patent application WO2005073279. However, the satisfactory results obtained with the catalytic system disclosed in this patent application do not allow the aforementioned specifications to be met.

[0012] In view of this state of the art, one of the essential objectives of the invention is therefore to improve the preparation of organopolysiloxane by ring-opening polymerization reaction or by polycondensation, by means of a catalytic system which is more efficient than those used previously and which makes it possible to obtain higher yields of linear organopolysiloxane while limiting the formation of cyclic organopolysiloxanes by retroscission reaction.

[0013] The development of this alternative technology allows the manufacture of more environmentally friendly silicone.

[0014] Summary of the invention:

[0015] Surprisingly, the Applicant has developed a catalytic system which meets these expectations. Thus, the present invention relates to a process for preparing linear organopolysiloxanes OL by a polymerization reaction of at least one organopoly siloxane O, in the presence of a catalytic system AI comprising:

[0016] -at least one catalyst A of formula (I):

[0017] / R S laughed, in which:

[0018] Identical or different Ri represent:

[0019] -a hydrogen atom,

[0020] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide

[0021] - an alkenyl group of 2 to 6 carbon atoms,

[0022] - a hydroxyl group,

[0023] - an alkoxyl group having 1 to 6 carbon atoms,

[0024] - a thiol or thioether group having 1 to 6 carbon atoms,

[0025] - an amino or aminoalkyl group having 1 to 6 carbon atoms,

[0026] R2 identical or different represent:

[0027] - a hydrogen atom,

[0028] - an alkyl chain of 1 to 12 carbon atoms,

[0029] -a cycloalkyl group of 5 to 8 carbon atoms,

[0030] -an alkenyl group of 2 to 12 carbon atoms,

[0031] -a benzyl or phenyl group, and optionally at least one initiator I.

[0032] An objective of the present application is therefore to propose a process for preparing linear organopoly siloxanes OL by a polymerization reaction of organopoly siloxanes making it possible to control the molar mass of the final product with a yield of linear organopoly siloxanes OL greater than 90%, preferably greater than 95% and preferentially greater than 98%. Another objective of the present application is to provide a catalytic system AI for implementing this process.

[0033] Another objective of the present application is to propose a simple and non-dangerous catalytic system compatible with the implementation of the process.

[0034] Still other objectives will appear upon reading the description of the invention which follows.

[0035] Detailed description of the invention:

[0036] Silicones, otherwise known as organopolysiloxanes, are polymeric materials comprising alternating silicon and oxygen atoms with various organic radicals bonded to the silicon.

[0037] In the context of the present invention, silicone, silicone product, silicone polymer or organopolysiloxane O means polymers comprising a siloxane backbone (Si-O-Si) having alternating silicon and oxygen atoms with various organic radicals bonded to silicon. These silicone polymers can be liquid or solid, depending on the molecular weight and the degree of polymerization.

[0038] For the purposes of the present invention, the term "reaction mixture" means all of the reactive chemical species present. By way of example, mention may be made of the catalyst(s) A, the initiator(s) I, the organopolysiloxane(s) O, and / or the chain blocker(s) C.

[0039] For the purposes of the present invention, the term AI catalytic system means a system consisting of:

[0040] - catalyst A alone or,

[0041] -the association of catalyst A and at least one initiator I which forms an active species capable of catalyzing the process of the present invention.

[0042] All the viscosities discussed in this presentation correspond to a dynamic viscosity quantity at 25°C called “Newtonian”, i.e. the dynamic viscosity which is measured, in a manner known per se, with a Brookfield viscometer at a shear rate gradient sufficiently low so that the measured viscosity is independent of the rate gradient.

[0043] In the context of the present invention, the organopolysiloxane O present in the reaction mixture is chosen from: a linear organopolysiloxane alone or in mixtures, a cyclic organopolysiloxane alone or in mixtures, or a mixture of one or more linear and cyclic organopolysiloxanes.

[0044] For the purposes of the present invention, the linear organopolysiloxane is represented by the following formula (II):

[0045] Foœiuls II in which,

[0046] R 1 , identical or different, represents:

[0047] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms,

[0048] -an alkenyl group comprising from 2 to 6 carbon atoms,

[0049] -an aryl group comprising from 6 to 18 carbon atoms,

[0050] -a hydroxyl group, or

[0051] R 2identical or different, represents:

[0052] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0053] -a hydroxyl group (OH),

[0054] -a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 5 carbon atoms, q is an integer between 1 and 2000, preferably between 1 and 500, preferably between 1 and 200, more preferably between 1 and 50, and with the condition that at least one radical R 2 is a hydroxyl group (OH).

[0055] For the purposes of the present invention, the linear organopolysiloxane is represented by the formula (II) in which,

[0056] R 1 , identical or different, represents:

[0057] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms,

[0058] -an alkenyl group comprising from 2 to 6 carbon atoms, -an aryl group comprising from 6 to 18 carbon atoms, -a hydroxyl group, or

[0059] R 2 represent:

[0060] - a hydroxyl group (OH), q is an integer between 1 and 500, preferably between 1 and 200, more preferably between 1 and 50.

[0061] According to one embodiment of the invention, the process of the present invention uses at least two organopolysiloxanes O chosen from the linear organopolysiloxanes mentioned above.

[0062] According to one embodiment of the invention, the cyclic organopolysiloxane is represented by the following formula (III): in which, R, identical or different, is a radical representing an alkyl group of 1 to 6 carbon atoms, an alkenyl group of 2 to 6 carbon atoms, or an aryl group of 6 to 18 carbon atoms; and n represents a natural number between 1 and 2.

[0063] On peut notamment citer les organopolysiloxanes cycliques disponibles commercialement comme l’hexamethylcyclotrisiloxane (CAS 541-05-9), le 2-ethenyl- 2’,4,4’,6,6’-pentamethylcyclotrisiloxane (CAS 18395-32-9), le 2,4,6-triethenyl-2,4,6- trimethylcyclotrisiloxane (CAS 3901-77-7), l’hexaphenylcyclotrisiloxane (CAS 512-63-0), le l,3,5-Trimethyl-l,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane (CAS 2374-14-3), le 2,2,4- Trimethyl-4,6,6-triphenyl-l,3,5,2,4,6-trioxatrisilinane, le 1,3,5-Trimethyl-1,3,5- triphenylcyclotrisiloxane (CAS 546-45-2); le 2 4 6-trimethylcyclotrisiloxane (CAS 13269-39- 1), le 3,5-trivinyl-l,3,5-trimethylcyclotrisiloxane (CAS 3901-77-7), le 2-Ethenyl-2,4,4,6,6- pentamethylcyclotrisiloxane (CAS 18395-32-9), le 2,4,6, 8-Tetramethylcyclotetrasiloxane (CAS 2370-88-9), le 2,4,6,8-Tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (CAS 2554-06- 5), le 2,4,6,8-Tetramethyl-2,4,6,8-tetraphenylcyclotetrasiloxane (CAS 77-63-4), l’octaphenylcy cl otetrasil oxane (CAS 546-56-5).

[0064] Advantageously, the cyclic organopolysiloxane is hexamethylcyclotrisiloxane (CAS 541-05-9) or octamethylcyclotetrasiloxane (CAS 556-67-2)

[0065] According to one embodiment of the invention, the method of the present invention uses at least two cyclic organopolysiloxanes chosen from the following compounds: octamethylcyclotetrasiloxane (CAS 556-67-2); hexamethylcyclotrisiloxane (CAS 541-05-9) and 2,4,6-triethenyl-2,4,6-trimethylcyclotrisiloxane (CAS 3901-77-7).

[0066] As mentioned above, according to one embodiment of the invention, the method of the present invention uses a mixture of linear and cyclic organopolysiloxanes. These different organopolysiloxanes have been more fully defined above.

[0067] For the purposes of this application, catalyst A is represented by the formula

[0068] (IV): in which:

[0069] Identical or different Ri represent:

[0070] -a hydrogen atom,

[0071] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide

[0072] - an alkenyl group of 2 to 6 carbon atoms,

[0073] - a hydroxyl group,

[0074] - an alkoxyl group having 1 to 6 carbon atoms,

[0075] - a thiol or thioether group having 1 to 6 carbon atoms,

[0076] - an amino or aminoalkyl group having 1 to 6 carbon atoms,

[0077] R2 identical or different represent:

[0078] - a hydrogen atom,

[0079] - an alkyl chain of 1 to 12 carbon atoms,

[0080] -a cycloalkyl group of 5 to 8 carbon atoms,

[0081] -an alkenyl group of 2 to 12 carbon atoms,

[0082] -a benzyl or phenyl group.

[0083] According to one embodiment of the invention, catalyst A is represented by the following formula (V): in which:

[0084] Identical or different Ri represent:

[0085] -a hydrogen atom,

[0086] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide

[0087] - an alkenyl group of 2 to 6 carbon atoms,

[0088] - a hydroxyl group,

[0089] - an alkoxyl group having 1 to 6 carbon atoms,

[0090] - a thiol or thioether group having 1 to 6 carbon atoms,

[0091] - an amino or aminoalkyl group having 1 to 6 carbon atoms,

[0092] R2 identical or different represent:

[0093] - a hydrogen atom,

[0094] - an alkyl chain of 1 to 12 carbon atoms,

[0095] -a cycloalkyl group of 5 to 8 carbon atoms,

[0096] -an alkenyl group of 2 to 12 carbon atoms,

[0097] -a benzyl or phenyl group.

[0098] According to one embodiment of the invention, catalyst A is represented by the following formula (VI): in which:

[0099] Identical or different Ri represent:

[0100] -a hydrogen atom,

[0101] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide

[0102] - an alkenyl group of 2 to 6 carbon atoms,

[0103] - a hydroxyl group,

[0104] - an alkoxyl group having 1 to 6 carbon atoms,

[0105] - a thiol or thioether group having 1 to 6 carbon atoms,

[0106] - an amino or aminoalkyl group having 1 to 6 carbon atoms,

[0107] R2 identical or different represent:

[0108] - a hydrogen atom,

[0109] - an alkyl chain of 1 to 12 carbon atoms,

[0110] -a cycloalkyl group of 5 to 8 carbon atoms,

[0111] -an alkenyl group of 2 to 12 carbon atoms,

[0112] -a benzyl or phenyl group.

[0113] According to one embodiment of the invention, catalyst A represented by formula (VI) above in which:

[0114] Identical or different Ri represent:

[0115] -a hydrogen atom,

[0116] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide

[0117] - an alkenyl group of 2 to 6 carbon atoms,

[0118] - a hydroxyl group,

[0119] R2 identical or different represent:

[0120] - a hydrogen atom,

[0121] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms,

[0122] -a cycloalkyl group of 5 to 8 carbon atoms,

[0123] -an alkenyl group of 2 to 12 carbon atoms,

[0124] -a benzyl or phenyl group.

[0125] According to one embodiment of the invention, catalyst A is represented by the following formula (VII): in which:

[0126] Identical or different Ri represent:

[0127] -a hydrogen atom,

[0128] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide

[0129] - an alkenyl group of 2 to 6 carbon atoms,

[0130] - a hydroxyl group,

[0131] R2 identical or different represent:

[0132] - a hydrogen atom,

[0133] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms,

[0134] -a cycloalkyl group of 5 to 8 carbon atoms,

[0135] -an alkenyl group of 2 to 12 carbon atoms,

[0136] -a benzyl or phenyl group.

[0137] According to one embodiment, the process of the invention is characterized in that the molar quantity of catalyst A relative to the organopolysiloxane O is from 0.005% to 2%, preferably from 0.01 to 2%, preferentially from 0.05 to 1%, and even more preferentially from 0.1 to 0.5%.

[0138] For the purposes of the present invention, the initiator I is chosen from water, alcohols and their derivatives or their mixtures.

[0139] According to one embodiment of the present invention, the initiator I is chosen from alcohols having a pKa of 10 to 16, preferably a pKa of 12 to 16, preferentially a pKa of 14 to 16.

[0140] According to one embodiment of the invention, the initiator I is chosen from water or the compounds of formula (VIII): Formula VIII in which:

[0141] Y represents a carbon or silicon atom,

[0142] R is the same or different and represents:

[0143] -a hydrogen atom -an alkyl group of 1 to 12 carbon atoms,

[0144] -a cycloalkyl group of 5 to 8 carbon atoms,

[0145] -an alkenyl group of 2 to 12 carbon atoms,

[0146] - a benzyl group or a phenyl, when said radical R may be substituted or not by an alkyl chain of 1 to 12 carbon atoms, alkenyl of 2 to 6 carbon atoms, a cycloalkyl group of 5 to 8 carbon atoms, an aryl group of 6 to 18 carbon atoms or a heteroatom such as oxygen, sulfur or nitrogen.

[0147] According to a preferred embodiment of the invention, the initiator I is represented by the compounds of formula (VIII) above in which:

[0148] Y represents a carbon atom,

[0149] R is the same or different and represents:

[0150] -a hydrogen atom

[0151] -an alkyl group of 1 to 12 carbon atoms,

[0152] -a cycloalkyl group of 5 to 8 carbon atoms,

[0153] -an alkenyl group of 2 to 12 carbon atoms,

[0154] - a benzyl group or a phenyl, when said radical R may be substituted or not by an alkyl chain of 1 to 12 carbon atoms, alkenyl of 2 to 6 carbon atoms, a cycloalkyl group of 5 to 8 carbon atoms, an aryl group of 6 to 18 carbon atoms or a heteroatom such as oxygen, sulfur or nitrogen.

[0155] According to one embodiment, the initiator I is an alcohol chosen from primary alcohols or secondary alcohols. Preferably, the initiator I is an alcohol chosen from primary alcohols.

[0156] According to one embodiment, the initiator I is an alcohol chosen from saturated or unsaturated polyols having 2 to 6 hydroxyl groups. By way of example, the following polyols may be mentioned such as glycerol, pentaerythritol, sorbitol or 1,4 butanediol.

[0157] According to one embodiment, the initiator I is an alcohol having a pKa of 10 to 16, preferably a pKa of 12 to 16, preferentially a pKa of 14 to 16.

[0158] According to one embodiment, the initiator I is an alcohol chosen from: methanol (CAS 67-56-1), ethanol (CAS 64-17-5), propanol (CAS 71-23-8), isopropanol (CAS 67-63-0), butanol (CAS 71-36-3), 2-methylpropan-2-ol (CAS 75-65-0), allyl alcohol (CAS 107-18-6), benzyl alcohol (CAS 100-51-6), 3-buten-1-ol (627-27-0), long chain alkyl alcohols such as undecanol (CAS 112-42-5) or dodecanol (CAS 27342-88-7).

[0159] Preferably, the initiator I is benzyl alcohol (CAS 100-51-6).

[0160] According to another embodiment of the invention, the initiator I is water.

[0161] In one embodiment, the process of the invention is characterized in that the molar ratio of initiator I relative to catalyst A is from 0 to 20, preferably from 0 to 10, preferably from 0 to 5, preferentially from 0 to 2.

[0162] In one embodiment, the method of the invention is characterized in that the molar quantity of initiator I relative to the organopolysiloxane O introduced is from 0.005% to 10%, preferably from 0.01% to 5%, preferentially from 0.05% to 2.5%, and even more preferentially from 0.1% to 1%.

[0163] According to one embodiment, the method of the invention uses an initiator I represented by the formula (IX): Formula IX in which:

[0164] R is the same or different and represents:

[0165] -an alkyl group of 1 to 12 carbon atoms,

[0166] -a cycloalkyl group of 5 to 8 carbon atoms,

[0167] -an alkenyl group of 2 to 12 carbon atoms,

[0168] - a benzyl group or a phenyl, said radical R may be substituted or not by an alkyl chain of 1 to 12 carbon atoms, alkenyl of 2 to 6 carbon atoms, a cycloalkyl group of 5 to 8 carbon atoms, an aryl group of 6 to 18 carbon atoms or a heteroatom such as oxygen, sulfur or nitrogen.

[0169] Preferably, the process of the present invention uses an initiator I chosen from trimethylsilanol (CAS 1066-40-6) or triethyl silanol (CAS 597-52-4).

[0170] In one embodiment of the invention, the polymerization reaction of at least one organopolysiloxane O further comprises at least one chain blocker C. According to one embodiment of the invention, the chain blocker C is represented by the formula (X): in which,

[0171] R 1 , identical or different, represents CH3 or phenyl, preferably CH3;

[0172] R 2 identical or different, represents:

[0173] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0174] -a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 5 carbon atoms, optionally substituted by at least one heteroatom O, N, S or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, for example (Ci-C5)alkyl-CF3, the alkyl being linear or branched,

[0175] - a C5-C10 cycloalkyl group, optionally substituted,

[0176] -a C6-C7 aryl group, optionally substituted, or

[0177] -a hydrogen; and q is an integer between 1 and 50, preferably between 1 and 20, more preferably between 1 and 10.

[0178] Particularly preferably, the C-chain blocker of the invention is represented by formula (X), in which:

[0179] R 1 , identical, represents CH3,

[0180] R 2 identical or different, represents:

[0181] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0182] - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms,

[0183] -a C6-C7 aryl group, optionally substituted, or

[0184] -a hydrogen. and q is an integer between 1 and 20, preferably between 1 and 10, more preferably between 1 and 5.

[0185] Other blockers having a siloxane function according to the invention are described in the book Chemistry and Technology of Silicones, published in 1968 by Académie Press, on page 264. The chain blocker C can be in a solvent. This is particularly advantageous in order to solubilize it in the reaction mixture. The solvent can in particular be an apolar solvent such as an organic solvent of the alkane or aromatic hydrocarbon type. Preferably, the solvent is chosen from n-hexane, n-heptane, n-decane, n-dodecane, isododecane, EXXSOL D60, xylene, toluene and mixtures thereof.

[0186] In one embodiment, the process of the invention is characterized in that the molar ratio of chain blocker C relative to catalyst A is from 0 to 30, preferably from 0 to 20, and preferentially from 0 to 10.

[0187] According to one embodiment of the invention, the linear organopolysiloxane OL may be a compound of formula (XI):

[0188] Formula XI in which,

[0189] R, identical or different, represents:

[0190] -an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably methyl,

[0191] -an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl,

[0192] R 1 , identical or different, represents:

[0193] -an alkyl group comprising from 1 to 5 carbon atoms

[0194] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0195] -a hydroxyl group (OH),

[0196] -a hydrogen;

[0197] -a C6-C7 aryl group, preferably phenyl,

[0198] R 2 identical or different, represents:

[0199] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0200] -a hydroxyl group (OH),

[0201] -a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 5 carbon atoms, optionally substituted by at least one heteroatom O, N, S or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, for example (Ci-C5)alkyl-CF3, the alkyl being linear or branched, -a C5-C10 cycloalkyl group, optionally substituted,

[0202] -an optionally substituted C6-C10 aryl group,

[0203] -a hydrogen or

[0204] -a group (OR 3 ) with R 3 representing: an alkyl group comprising from 1 to 15 carbon atoms, preferably from 1 to 12 carbon atoms, preferably from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, preferably OCH3 or OC2H5, an alkenyl group comprising from 2 to 15 carbon atoms, preferably from 2 to 10 carbon atoms, a C6-C10 aryl group or alkylaryl such as a benzyl group q is an integer between 0 and 50, preferably between 0 and 20, more preferably between 0 and 10; preferably q = 0 ni represents an integer between 10 and 10,000, preferably between 10 and 5,000, preferably between 10 and 1,000, more preferably between 10 and 500; m2 represents an integer between 0 and 5000, preferably between 0 and 1000, more preferably between 0 and 100.

[0205] According to a preferred embodiment of the invention, the linear organopolysiloxane OL is a compound of formula (XI): in which,

[0206] R, identical or different, represents CH3 or phenyl, preferably CH3;

[0207] R 1 identical or different, represents:

[0208] -an alkyl group comprising from 1 to 5 carbon atoms

[0209] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0210] -a C6-C7 aryl group, preferably phenyl,

[0211] -a hydrogen;

[0212] R 2 identical or different, represents:

[0213] -an alkyl group comprising from 1 to 6 carbon atoms

[0214] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0215] -a hydroxyl group (OH),

[0216] -a CÔ-CIS aryl group,

[0217] -a hydrogen;

[0218] -a group (OR 3 ) with R 3 representing: an alkyl group comprising from 1 to 10 carbon atoms, an alkenyl group comprising from 2 to 10 carbon atoms, or a benzyl group q is an integer between 0 and 50, preferably between 0 and 20, more preferably between 0 and 10; preferably q = 0 ni represents an integer between 10 and 10,000, preferably between 10 and 5,000, preferably between 10 and 1,000, more preferably between 10 and 500; m2 represents an integer between 0 and 5,000, preferably between 0 and 1,000, more preferably between 0 and 100.

[0219] According to a particularly preferred embodiment of the invention, the linear organopolysiloxane OL of the invention is a compound of formula (XI) in which,

[0220] R, identical or different, represents CH3 or phenyl, preferably CH3, R 1, identical or different, represents CH3, phenyl or vinyl;

[0221] R 2 identical or different, represents:

[0222] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0223] -a hydroxyl group (OH),

[0224] - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms,

[0225] -a C6-C7 aryl group, optionally substituted, or

[0226] -a hydrogen;

[0227] -a group (OR 3 ) with R 3representing: an alkyl group comprising from 1 to 10 carbon atoms, an alkenyl group comprising from 2 to 10 carbon atoms, or a benzyl group q is equal to 0; n2 represents an integer between 10 and 10,000, preferably between 10 and 5,000, preferably between 10 and 1,000, more preferably between 10 and 500; m2 represents an integer between 0 and 5,000, preferably between 0 and 1,000, more preferably between 0 and 100.

[0228] According to a particularly preferred embodiment of the invention, the linear organopolysiloxane OL of the invention is a compound of formula (XII) in which:

[0229] R, identical or different, represents CH3 or phenyl, preferably CH3, R 1 , identical or different, represents CH3, phenyl or vinyl;

[0230] R 2 identical, represent:

[0231] - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms,

[0232] -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl,

[0233] -a hydroxyl group (OH),

[0234] -a group (OR 3 ) with R 3 representing: an alkyl group comprising from 1 to 10 carbon atoms, an alkenyl group comprising from 2 to 10 carbon atoms, or a benzyl group q is equal to 0; ni represents an integer between 10 and 5,000, preferably between 10 and 1,000, more preferably between 10 and 500; m2 represents an integer between 0 and 1,000, preferably between 0 and 500, more preferably between 0 and 100.

[0235] The linear organopolysiloxane OL of the invention is characterized in that its degree of polymerization is strictly greater than that of the organopolysiloxane O introduced into the reaction mixture.

[0236] According to one embodiment of the process of the invention, the linear organopolysiloxane OL of the invention is characterized in that its degree of polymerization is at least twice as high, at least three times as high or at least five times as high as that of the organopolysiloxane O introduced into the reaction mixture.

[0237] For the purposes of the present invention, the mass-average molar mass and the number-average molar mass denoted respectively Mw and M n of different linear organopolysiloxanes OL can be determined by size exclusion chromatography (SEC) in the presence of polystyrene standards in a solvent such as toluene at 35 °C.

[0238] According to one embodiment of the process of the invention, the linear organopolysiloxane OL of the invention is characterized in that its number-average molar mass M nis between 500 and 1,000,000 g / mol, preferably between 500 and 500,000 g / mol, preferentially between 500 and 100,000 g / mol and even more preferentially between 500 and 50,000 g / mol.

[0239] According to one embodiment of the process of the invention, the linear organopolysiloxane OL of the invention is characterized in that its dynamic viscosity is between 100 and 1,000,000 mPa.s at 25°C, preferably between 100 and 500,000 mPa.s at 25°C, even more preferably between 100 and 100,000 mPa.s at 25°C. In the context of the present application, the mass percentage or the percentage by weight of cyclic organopolysiloxanes (such as D4) of the products obtained according to the process of the present invention can be measured via the quantitative NMR spectra. 29Yes. Alternatively, the mass percentage or weight percentage of D4 of the products obtained according to the process of the present invention could be measured via the chromatograms resulting from a size exclusion chromatography (SEC) analysis.

[0240] Hereinafter, the product resulting from the reaction is the sum of the linear organopolysiloxane OL and the organopolysiloxane OC resulting from the process of the present invention.

[0241] In one embodiment, the process according to the invention is characterized in that the content of cyclic organopolysiloxanes OC is less than 2%, preferably less than or equal to 1%, preferably less than or equal to 0.5% relative to the total mass of product resulting from the reaction.

[0242] In one embodiment, the process according to the invention is characterized in that the content of octamethylcyclotetrasiloxane (D4) is less than 2%, preferably less than or equal to 1%, preferably less than or equal to 0.5% relative to the total mass of product resulting from the reaction.

[0243] In one embodiment, the method according to the invention is carried out in a non-polar solvent. The solvent may in particular be an organic solvent of the alkane, aromatic hydrocarbon or alcohol type such as ethanol.

[0244] Preferably, the solvent is chosen from n-hexane, n-heptane, n-decane, n-dodecane, cyclohexane, isododecane, EXXSOL D60, xylene, toluene and mixtures thereof.

[0245] According to one embodiment of the invention, the quantity of solvent used in the process of the invention is the minimum quantity necessary to solubilize catalyst A in the reaction mixture. The catalyst can thus be solubilized in ethanol or toluene.

[0246] Advantageously, and preferably, the reaction is carried out at a temperature between 50°C and 170°C, preferably between 80 and 150°C, more preferably between 80 and 110°C. According to the process of the invention, the duration of the reaction is between 1h and 72h, preferably between 8h and 72h, more preferably between 18h and 72h. Those skilled in the art will know how to adapt these parameters according to the nature of the reactors and the species used.

[0247] The present application also relates to the linear organopolysiloxane OL obtained according to the different embodiments of the process of the present invention described above. It also relates to a silicone composition comprising the organopolysiloxane OL obtained according to the different embodiments of the process of the present invention described above.

[0248] The present application also relates to a composition for implementing the method of the present invention comprising:

[0249] - at least one cyclic organopolysiloxane O as defined above,

[0250] - an AI catalytic system as defined previously, and optionally a C chain blocker as defined previously.

[0251] The present application also relates to the use of the organopolysiloxanes OL obtained according to the process of the present invention as an ingredient which can be directly used in various silicone formulations useful in fields such as cosmetics, household cleaning products, automobiles, energy.

[0252] The present application also relates to catalysts A represented by the following formula (XII): in which:

[0253] Identical or different Ri represent:

[0254] -a hydrogen atom,

[0255] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide

[0256] - an alkenyl group of 2 to 6 carbon atoms, - a hydroxyl group,

[0257] - an alkoxyl group having 1 to 6 carbon atoms,

[0258] - a thiol or thioether group having 1 to 6 carbon atoms,

[0259] - an amino or aminoalkyl group having 1 to 6 carbon atoms,

[0260] R2 identical or different represent:

[0261] - a hydrogen atom,

[0262] - an alkyl chain of 1 to 12 carbon atoms,

[0263] -a cycloalkyl group of 5 to 8 carbon atoms,

[0264] -an alkenyl group of 2 to 12 carbon atoms, -a benzyl group or a phenyl.

[0265] According to one embodiment, the catalysts A are represented by the following formula (XIII): in which:

[0266] Identical or different Ri represent:

[0267] -a hydrogen atom,

[0268] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide

[0269] - an alkenyl group of 2 to 6 carbon atoms,

[0270] - a hydroxyl group,

[0271] - an alkoxyl group having 1 to 6 carbon atoms,

[0272] - a thiol or thioether group having 1 to 6 carbon atoms,

[0273] - an amino or aminoalkyl group having 1 to 6 carbon atoms,

[0274] R2 identical or different represent:

[0275] - a hydrogen atom,

[0276] - an alkyl chain of 1 to 12 carbon atoms,

[0277] -a cycloalkyl group of 5 to 8 carbon atoms, -an alkenyl group of 2 to 12 carbon atoms, -a benzyl group or a phenyl.

[0278] More specifically, the present invention relates to catalysts A represented by the following formula (XIV): in which:

[0279] Identical or different Ri represent:

[0280] -a hydrogen atom,

[0281] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide

[0282] - an alkenyl group of 2 to 6 carbon atoms,

[0283] - a hydroxyl group,

[0284] R2 identical or different represent:

[0285] - a hydrogen atom,

[0286] - a linear or branched alkyl group comprising from 1 to 12 carbon atoms,

[0287] -a cycloalkyl group of 5 to 8 carbon atoms,

[0288] -an alkenyl group of 2 to 12 carbon atoms,

[0289] -a benzyl or phenyl group.

[0290] The present application also relates to the use of the catalysts defined according to the formulae (XII, XIII and XIV) as catalysts for ring-opening polymerization or polycondensation.

[0291] Examples:

[0292] Organopolysiloxanes used in the examples:

[0293] Cyclic organopolysiloxane Oi: hexamethylcyclotrisiloxane (CAS 541-05-9)

[0294] Cyclic organopolysiloxane O2: octamethylcyclotetrasiloxane (CAS 556-67-2) Linear organopoly siloxane O3:

[0295] Catalysts A used in the examples:

[0296] Catalyst Ai:

[0297] Acompi Catalyst:

[0298] Initiators implemented in the examples:

[0299] Initiator Ii: benzyl alcohol (CAS 100-51-6)

[0300] Initiator I2: ethanol (CAS 64-17-5)

[0301] Initiator I3: H2O

[0302] Chain blockers used in the examples: Chain blocker Ci: divinyltetramethyldisiloxane (CAS 2627-95-4).

[0303] In the context of the examples described below, the residual mass percentages of cyclic organopolysiloxanes OC and the mass percentages of linear organopolysiloxane OL obtained according to the process of the present invention are measured by size exclusion chromatography (SEC) in the presence of polystyrene standards in a solvent such as toluene at 35°C. Similarly, the number-average molar mass denoted M n of the different linear organopolysiloxanes according to the present invention OL is determined by the same size exclusion chromatography (SEC) method.

[0304] In the context of the examples described below, the mass percentage of residual cyclic organopolysiloxanes is referred to as the mass percentage of cyclic organopolysiloxane at the end of the process implemented according to the present invention.

[0305] Example 1: Synthesis of the catalysts of the present invention A1, A2 and A3:

[0306] Initially, the precursors xas mentioned in the reaction scheme below are obtained by the reaction of diiodine (1.4 eq.) and imidazole (1.5 eq.) which are added to a PI13P solution (1.3 eq.) in dichloromethane (50 mL) at room temperature with stirring for 5 minutes. Then, a solution of the precursor alcohol (ix) (1.0 eq.) in dichloromethane (10 mL) is added to the reaction mixture by syringe and then said mixture is stirred at room temperature overnight. The reaction mixture is then washed with an aqueous NaiSCh solution (2 x 100 mL), then this aqueous phase is rinsed twice with dichloromethane (2 x 100 mL). The organic phases are combined and then dried (NaSCU). Once the filtration is carried out, the organic phases obtained are evaporated under a rotary evaporator. The crude product obtained is purified by flash chromatography (EtOAc / petroleum ether: 1 / 9) and results in a yellow oil.The yields obtained for each iodized intermediate are mentioned below:.

[0307] In a second step, the product synthesized in the previous step (1.2 eq.) was added to a solution of l-(tert-butyl)- 1 / 7- imidazole (leq.) in toluene (20 mL). ; The reaction medium placed under argon flow is thus mixed at 80°C overnight. After removal of the solvent, the crude reaction product is washed with a distilled ether solution (3x10 mL) then dried under vacuum in order to obtain the imidazole salt in the form of a white solid noted bx in the reaction scheme below.

[0308] The yields obtained for each of these intermediaries are mentioned below:

[0309] In a final step, the product bx formed in the previous step is placed in 20 mL of THF and then KHMDS (leq.) was added to the reaction mixture. The reaction mixture is stirred at room temperature for 1 h. Then, the solvent was removed and the product was extracted with pentane and then filtered. After drying under vacuum, catalysts Ai, A2, or A3 are obtained in the form of a white solid. The synthesis yields of these catalysts are shown below.

[0310] Example 2: General protocol for implementing the method of the present invention:

[0311] The AI ​​catalytic system is formed by the association of catalyst A (Ai, A20U A3 for example) (leq, 0.025mmol) and from 0 to n equivalents of initiator I, (such as Ii, I2 or I3 for example). The different tables below indicate the different I / A molar ratios.

[0312] This freshly formed catalyst system AI is mixed in a solution containing an organopolysiloxane Oi, O2 OR O3 (5.07 mmol). The content of catalyst A is 0.5 mol% relative to the organopolysiloxane O. Optionally, a chain blocker such as Ci is added to the reaction mixture. The reaction mixture is then heated to a temperature and for a time indicated in each of the examples of the present invention.

[0313] Example 3a: Implementation of the process of the present invention in the presence of organopolysiloxane O2

[0314] In this example, the general protocol of Example 2 was implemented. In this example, organopolysiloxane O2 (CAS 556-67-2) was used. The initiator is Ii and the molar ratio I / A is equal to 1. The reaction mixture was heated to 80°C for a period of 16 h.

[0315] The table below describes the different catalysts used as well as the characteristics of the product obtained OL according to the process of the invention.

[0316] It can be noted that in the presence of the catalysts described according to the process of the invention as A2, an OL product is obtained having a cyclic organopoly siloxane content of less than 1% under these operating conditions.

[0317] In the table below, the process of the present invention was repeated with the catalysts of the present invention Ai and A3 at 110°C for 2 days. The initiator is Ii and the molar ratio I / A is equal to 1.

[0318] Each of these tests led to the production of a linear organopolysiloxane OL having a mass percentage greater than 99% compared to the products resulting from the reaction.

[0319] Example 3b: Implementation of the process of the present invention in the presence of the organopolysiloxane Oi:

[0320] For this example, the general protocol of Example 2 was implemented. In this example, organopolysiloxane Oi (CAS 541-05-9) was used. The initiator is Ii. In Test 1 in the table below, the reaction mixture was heated to 110°C for a period of 24 hours for Test 1.

[0321] Concerning test 2 in the table below, the reaction mixture was heated at 80°C for a period of 16 hours. The table below describes the different catalysts used, the I / A molar ratios used, as well as the characteristics of the OL product obtained according to the process of the invention.

[0322] It can be noted that in the presence of the catalysts described according to the process of the invention Ai and A2, more than 99% of linear organopolysiloxane OL is obtained.

[0323] Example 4: Implementation of the process of the present invention with different initiators I:

[0324] For the purpose of this example, the general protocol of Example 2 was implemented.

[0325] In this example, organopolysiloxane O2 (CAS 556-67-2) and catalyst A2 were used. The molar ratio I / A is equal to 1.

[0326] The various tests listed in the example below were carried out at a temperature of 80°C for a period of 16 hours. The table below indicates the various initiators I used as well as the characteristics of the product OL obtained according to the process of the invention.

[0327] It can be observed that the method of the present invention is versatile and allows satisfactory results to be obtained with different initiators as set out in the table above.

[0328] Example 5: Influence of different C / A molar ratios on the process of the present invention: In the context of this example, the general protocol of example 2 was implemented.

[0329] In this example, organopoly siloxane O2 (CAS 556-67-2), catalyst Ai, initiator Ii and chain blocker Ci were used.

[0330] In these tests, the reaction mixture was heated to a temperature of 80°C for a period of 48 hours.

[0331] The table below shows the molar ratio of chain blocker C to the molar quantity of catalyst A used, as well as the characteristics of the product OL obtained according to the process of the invention. In this example, the molar ratio I / A is 5.

[0332] These different tests demonstrate the control of the number-average molar mass (M n ) of the linear organopolysiloxane OL obtained according to the process of the invention.

[0333] Varying the amount of chain blocker material C influences the molar mass of the product obtained according to the process of the present invention.

[0334] Furthermore, it can be noted that the OL product obtained according to the process of the invention has a very low mass percentage of residual cyclic organopolysiloxane OC (less than 1% by mass relative to the total mass of the product resulting from the reaction).

[0335] Example 6: Implementation of the process of the present invention without initiator:

[0336] In this example, the general protocol of Example 2 was implemented. In this example, organopolysiloxane O2 (CAS 556-67-2), catalyst Ai and chain blocker Ci were used. In these tests, the reaction mixture was heated to a temperature of 110°C for a period of 48 h.

[0337] The table below mentions the molar ratio of the chain blocker used in relation to the molar quantity of catalyst A used as well as the characteristics of the OL product obtained according to the process of the invention.

[0338] Even without initiator, the process of the present invention makes it possible to obtain a linear organopolysiloxane OL without or with a very low mass percentage of residual cyclic organopolysiloxane OC.

[0339] Example 7: Polycondensation reaction: process of the present invention carried out in the presence of organopolysilxoane O3 without initiator:

[0340] In this example, catalyst Ai (0.5mol%, 0.0137mmol) is mixed into a solution containing organopolysiloxane O3 (2.73mmol).

[0341] Optionally, a chain blocker such as Ci is added to the reaction mixture as shown in the table below.

[0342] The reaction mixture was heated to a temperature of 110°C for a period of 48 hours. The table below shows the molar ratio of chain blocker Ci used to the molar quantity of catalyst A used, as well as the characteristics of the product OL obtained according to the process of the invention.

[0343] As indicated in the table above, this example demonstrates that the process of the present invention leads to the obtaining of very satisfactory results for polycondensation reactions.

[0344] Example 8: Process of the present invention carried out in the presence of O3:

[0345] In this example, catalyst Ai (0.5mol%, 0.0136mmol) is mixed in a solution containing a mixture of organopolysiloxane O2 (1.36mmol) and O3 (1.36mmol). The reaction mixture was heated to a temperature of 110°C for a period of 48h.

[0346] Thus, 99.9% of the linear organopolysiloxane OL was obtained (and only 0.1% of residual cyclic organopolysiloxane OC). The molar mass of the obtained OL product is 75,000 g / mol.

Claims

CLAIMS

1. Process for the preparation of linear organopolysiloxanes OL by a polymerization reaction of at least one organopolysiloxane O, in the presence of a catalytic system AI comprising: -at least one catalyst A of formula (I): R; / RFI Rj in which: Identical or different Ri represent: -a hydrogen atom, - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide, - an alkenyl group of 2 to 6 carbon atoms, - a hydroxyl group, - an alkoxyl group having 1 to 6 carbon atoms, - a thiol or thioether group having 1 to 6 carbon atoms, - an amino or aminoalkyl group having 1 to 6 carbon atoms, R2 identical or different represent: - a hydrogen atom, - an alkyl chain of 1 to 12 carbon atoms, -a cycloalkyl group of 5 to 8 carbon atoms, -an alkenyl group of 2 to 12 carbon atoms, -a benzyl or phenyl group, and optionally at least one initiator I.

2. Method according to claim 1 in which the organopolysiloxane O is chosen from: a linear organopolysiloxane alone or in mixtures, an organopolysiloxane cyclic alone or in mixtures, or a mixture of one or more linear and cyclic organopolysiloxanes.

3. A method according to claim 1 or 2, wherein the catalyst A is represented by the following formula (VI): in which: Identical or different Ri represent: -a hydrogen atom, - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide - an alkenyl group of 2 to 6 carbon atoms, - a hydroxyl group, - an alkoxyl group having 1 to 6 carbon atoms, - a thiol or thioether group having 1 to 6 carbon atoms, - an amino or aminoalkyl group having 1 to 6 carbon atoms, R2 identical or different represent: - a hydrogen atom, - an alkyl chain of 1 to 12 carbon atoms, -a cycloalkyl group of 5 to 8 carbon atoms, -an alkenyl group of 2 to 12 carbon atoms, -a benzyl group or a phenyl.

4. Process according to any one of the preceding claims, in which the molar quantity of catalyst A relative to the organopolysiloxane O is from 0.005% to 2%, preferably from 0.01 to 2%, preferentially from 0.05 to 1%, and even more preferentially from 0.1 to 0.5%.

5. A process according to any one of the preceding claims, wherein the initiator I is selected from water or compounds of formula (VIII): Formula VIII in which: Y represents a carbon or silicon atom, R is the same or different and represents: -a hydrogen atom -an alkyl group of 1 to 12 carbon atoms, -a cycloalkyl group of 5 to 8 carbon atoms, -an alkenyl group of 2 to 12 carbon atoms, - a benzyl group or a phenyl, when said radical R may be substituted or not by an alkyl chain of 1 to 12 carbon atoms, alkenyl of 2 to 6 carbon atoms, a cycloalkyl group of 5 to 8 carbon atoms, an aryl group of 6 to 18 carbon atoms or a heteroatom such as oxygen, sulfur or nitrogen.

6. Process according to any one of the preceding claims, in which during the polymerization reaction of at least one organopolysiloxane O at least one chain blocker C represented by the formula (X) is added: in which, R 1 , identical or different, represents CH3 or phenyl, preferably CH3; R 2 identical or different, represents: -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, -a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 5 carbon atoms, optionally substituted by at least one heteroatom O, N, S or a halide such as a fluorine atom, for example 1 to 10 fluorine atoms, for example (Ci-Csjalkyl-CFs, the alkyl being linear or branched, - a C5-C10 cycloalkyl group, optionally substituted, -a C6-C7 aryl group, optionally substituted, or -a hydrogen; and q is an integer between 1 and 50, preferably between 1 and 20, more preferably between 1 and 10.

7. Silicone composition comprising the linear organopolysiloxane OL obtained according to one of the preceding claims 1 to 6.

8. Composition for implementing the method defined according to claims 1 to 7 comprising: - at least one cyclic organopolysiloxane O as defined in claim 1 or 2, - a catalytic system AI as defined in claim 1, 3, 4 or 5 and optionally a chain blocker C as defined in claim 6.

9. Catalysts A represented by the following formula (XIII): in which: Identical or different Ri represent: -a hydrogen atom, - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide - an alkenyl group of 2 to 6 carbon atoms, - a hydroxyl group, - an alkoxyl group having 1 to 6 carbon atoms, - a thiol or thioether group having 1 to 6 carbon atoms, - an amino or aminoalkyl group having 1 to 6 carbon atoms, R2 identical or different represent: - a hydrogen atom, - an alkyl chain of 1 to 12 carbon atoms, -a cycloalkyl group of 5 to 8 carbon atoms, -an alkenyl group of 2 to 12 carbon atoms, -a benzyl or phenyl group.

10. Catalysts A represented by the following formula (XIV): Formula XIV in which: Identical or different Ri represent: -a hydrogen atom, - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, optionally substituted by a heteroatom O, N, S or a halide - an alkenyl group of 2 to 6 carbon atoms, - a hydroxyl group, R2 identical or different represent: - a hydrogen atom, - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, -a cycloalkyl group of 5 to 8 carbon atoms, -an alkenyl group of 2 to 12 carbon atoms, -a benzyl or phenyl group.

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