Ring-opening or polycondensation polymerization process

Abstract

The invention relates to a process for preparing linear organopolysiloxanes OL by a polymerization reaction from organopolysiloxanes 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 organopolysiloxanes OL of controlled molar mass with a very low residual level of residual cyclic organopolysiloxanes. 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.

Description

Title of the invention: Cycle-opening or polycondensation polymerization process Technical field

[0001] The invention relates to a process for preparing linear organopolysiloxanes OL by a polymerization reaction from organopolysiloxanes O (cyclic and / or linear), and using a catalytic system AI. More precisely, the process of the present invention makes it possible to obtain linear organopolysiloxanes OL of controlled molar mass with a very low level of residual cyclic organopolysiloxanes.

[0002] The invention also relates to the catalysts used in the AI catalytic system which will be detailed in detail below. Technological background:

[0003] A major challenge for the silicone industry in the coming years is to industrially synthesize organopolysiloxanes with a very low or even zero residual cyclic content.

[0004] To date, the industrial synthesis of organopolysiloxanes by polycondensation or by ring-opening polymerization sees 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 which 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.Typically, 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.

[0005] Thus, in the interests of economic and energy profitability, there is a need to develop new solutions to avoid or at least limit these long and costly separation stages.

[0006] 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 can- cerigenic.

[0007] In this sense, in 2018 European regulations limited the content of D4 and D5 to a content of 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 application of silicones such as the electronics industry for example.

[0008] Therefore, there is a need to develop processes for providing linear organopolysiloxanes free from or at least having a low content of cyclic silicones. There is in particular 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 makes it possible to increase the prospects for use and applications of such polymers obtained.

[0009] 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 make it possible to meet the aforementioned specifications.

[0010] 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. Summary of the invention

[0011] 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 organopolysiloxane O, in the presence of a catalytic system AI comprising: -at least one catalyst A of formula (I): [Chem 1] )y x J ,î Formula î / H,? 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 possibly at least one initiator I.

[0012] An objective of the present application is therefore to propose a process for preparing linear organopolysiloxanes OL by an organopolysiloxane polymerization reaction making it possible to control the molar mass of the final product with a yield of linear organopolysiloxanes OL greater than 90%, preferably greater than 95% and preferentially greater than 98%.

[0013] Another objective of the present application is to provide an AI catalytic system for implementing this process.

[0014] Another objective of the present application is to propose a simple and non-dangerous catalytic system compatible with the implementation of the process.

[0015] Still other objectives will appear on reading the description of the invention which follows. Description of the embodiments

[0016] Silicones, otherwise known as organopolysiloxanes, are polymeric materials comprising alternating silicon and oxygen atoms with various organic radicals bonded to the silicon.

[0017] 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.

[0018] 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.

[0019] For the purposes of the present invention, the term AI catalytic system means a system consisting of: - catalyst A alone or, -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.

[0020] All the viscosities referred to in the present disclosure correspond to a dynamic viscosity quantity at 25°C known as “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.

[0021] 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 even a mixture of one or more linear and cyclic organopolysiloxanes.

[0022] For the purposes of the present invention, the linear organopolysiloxane is represented by the following formula (II): [Chem 2], in which, R1, identical or different, represents: - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, -an alkenyl group comprising from 2 to 6 carbon atoms, -an aryl group comprising from 6 to 18 carbon atoms, -a hydroxyl group, or R2, identical or different, represents: -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), - 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 R2 is a hydroxyl group (OH).

[0023] For the purposes of the present invention, the linear organopolysiloxane is represented by the formula (II) in which, R1, identical or different, represents: - a linear or branched alkyl group comprising from 1 to 12 carbon atoms, preferably from 1 to 8 carbon atoms, -an alkenyl group comprising from 2 to 6 carbon atoms, -an aryl group comprising from 6 to 18 carbon atoms, -a hydroxyl group, or R2 represent: -a hydroxyl group (OH), q is an integer between 1 and 500, preferably between 1 and 200, more preferably between 1 and 50.

[0024] 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.

[0025] According to one embodiment of the invention, the cyclic organopolysiloxane is represented by the following formula (III): [Chem 3] R .. R „ R ...........gj ........... 0 . g j........0 gj ........... Q LR TO | 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 between 1 and 2.

[0026] 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 l,3,5-Trimethyl-l,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’octaphenylcyclotetrasiloxane (CAS 546-56-5).

[0027] Advantageously, the cyclic organopolysiloxane is hexamethylcyclotrisiloxane (CAS 541-05-9) or octamethylcyclotetrasiloxane (CAS 556-67-2)

[0028] 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).

[0029] 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.

[0030] In the context of the present application, catalyst A is represented by the formula (IV): [Chem 4]

[0031] 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. According to one embodiment of the invention, catalyst A is represented by the following formula (V): [Chem 5] R, .A 'h 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.

[0032] According to one embodiment of the invention, catalyst A is represented by the following formula (VI): [Chem 6] s; February 1st, 2016 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.

[0033] According to one embodiment of the invention, catalyst A represented by the formula (VI) above 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.

[0034] According to one embodiment of the invention, catalyst A is represented by the following formula (VII): [Chem 7] ..■■z ' m Formula VII 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.

[0035] 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%.

[0036] For the purposes of the present invention, the initiator I is chosen from water, alcohols and their derivatives or their mixtures.

[0037] According to an 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.

[0038] According to one embodiment of the invention, the initiator I is chosen from water or the compounds of formula (VIII): [Chem 8] R HQ---Y---R | 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 or phenyl group, 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.

[0039] According to a preferred embodiment of the invention, the initiator I is represented by the compounds of formula (VIII) above in which: Y represents a carbon 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 or phenyl group, 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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).

[0044] Preferably, the initiator I is benzyl alcohol (CAS 100-51-6).

[0045] According to another embodiment of the invention, the initiator I is water.

[0046] 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.

[0047] In one embodiment, the process 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%.

[0048] According to one embodiment, the method of the invention uses an initiator I represented by the formula (IX): [Chem 9] HO---------Si-------------R | Formula IX R in which: R is the same or different and represents: -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 or phenyl group, 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.

[0049] Preferably, the process of the present invention uses an initiator I chosen from trimethylsilanol (CAS 1066-40-6) or triethylsilanol (CAS 597-52-4).

[0050] In one embodiment of the invention, the polymerization reaction of at least one organopolysiloxane O further comprises at least one chain blocker C.

[0051] According to one embodiment of the invention, the chain blocker C is represented by the formula (X): [Chem 10] in which, R1, identical or different, represents CH3 or phenyl, preferably CH3; R2, 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-C5)alkyl-CF3, the alkyl being linear or branched, - a C5-C10 cycloalkyl group, optionally substituted, - a C6-C18 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.

[0052] Particularly preferably, the chain blocker C of the invention is represented by the formula (X), in which: R1, identical, represents CH3 R2, 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 10 carbon atoms, preferably from 1 to 5 carbon atoms, - a C6-C18 aryl group, optionally substituted, or -a hydrogen. and q is an integer between 1 and 20, preferably between 1 and 10, more preferably between 1 and 5.

[0053] Other blockers having a siloxane function according to the invention are described in the book Chemistry and Technology of Silicones, published in 1968 by Academy 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 a non-polar 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.

[0054] 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.

[0055] According to one embodiment of the invention, the linear organopolysiloxane OL may be a compound of formula (XI): [Chem 11] in which, R, identical or different, represents: -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, - an aryl group comprising from 6 to 10 carbon atoms, preferably phenyl, R1, identical or different, represents: -an alkyl group comprising from 1 to 5 carbon atoms -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), -a hydrogen; - a C6-C18 aryl group, preferably phenyl, R2, identical or different, represents: -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), -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, - an optionally substituted C6-C aryl group, -a hydrogen or -a group (O-R3) with R3 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-C18 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 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 5000, preferably between 0 and 1000, more preferably between 0 and 100.

[0056] According to a preferred embodiment of the invention, the linear organopolysiloxane OL is a compound of formula (XI): in which, R, identical or different, represents CH3 or phenyl, preferably CH3; R1, identical or different, represents: -an alkyl group comprising from 1 to 5 carbon atoms -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, - a C6-C18 aryl group, preferably phenyl, -a hydrogen; R2, identical or different, represents: -an alkyl group comprising from 1 to 6 carbon atoms -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), -a C6-C18 aryl group, -a hydrogen; -a group (O-R3) with R3 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 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 5000, preferably between 0 and 1000, plus preferably between 0 and 100.

[0057] According to a particularly preferred embodiment of the invention, the linear organopolysiloxane OL of the invention is a compound of formula (XI) in which, R, identical or different, represents CH3 or phenyl, preferably CH3, R1, identical or different, represents CH3, phenyl or vinyl; R2, identical or different, represents: -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, - a C6-C18 aryl group, optionally substituted, or -a hydrogen; -a group (O-R3) with R3 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; 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 5000, preferably between 0 and 1000, more preferably between 0 and 100.

[0058] According to a particularly preferred embodiment of the invention, the linear organopolysiloxane OL of the invention is a compound of formula (XII) in which: R, identical or different, represents CH3 or phenyl, preferably CH3, R1, identical or different, represents CH3, phenyl or vinyl; R2 identical, represent: - a linear or branched alkyl group comprising from 1 to 10 carbon atoms, preferably from 1 to 5 carbon atoms, -an alkenyl group comprising from 2 to 6 carbon atoms, preferably vinyl, -a hydroxyl group (OH), -a group (O-R3) with R3 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; n2 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 1000, preferably between 0 and 500, plus preferably between 0 and 100.

[0059] 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.

[0060] 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 even at least five times as high as that of the organopolysiloxane O introduced into the reaction mixture.

[0061] For the purposes of the present invention, the mass-average molar mass and the number-average molar mass, denoted respectively Mw and Mn, of the various 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.

[0062] 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 Mn is 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.

[0063] 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.

[0064] In the context of the present application, the mass percentage or the weight percentage of cyclic organopolysiloxanes (such as D4) of the products obtained according to the process of the present invention can be measured via the quantitative 29Si NMR spectra. Alternatively, the mass percentage or the 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.

[0065] Hereinafter, the product resulting from the reaction is called the sum of the linear organopolysiloxane OL and the organopolysiloxane OC resulting from the process of the present invention.

[0066] 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.

[0067] In one embodiment, the method according to the invention is characterized in that the content of octamethylcyclotetrasiloxane (D4) is less than 2%, preferably in 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.

[0068] In one embodiment, the method according to the invention is implemented in an apolar solvent. The solvent may in particular be an organic solvent of the alkane, aromatic hydrocarbon or alcohol type such as ethanol.

[0069] Preferably, the solvent is chosen from n-hexane, n-heptane, n-decane, n-dodecane, cyclohexane, isododecane, EXXSOL D60, xylene, toluene and mixtures thereof.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] The present application also relates to a composition for implementing the method of the present invention comprising: - at least one cyclic organopolysiloxane O as defined previously, - a catalytic system AI as defined previously, and optionally a chain blocker C as defined previously.

[0075] 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.

[0076] The present application also relates to catalysts A represented by the following formula (XII): [Chem 12]

[0077] Ri / W 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. According to one embodiment, the catalysts A are represented by the following formula (XIII): [Chem 13] R, 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.

[0078] More specifically, the present invention relates to catalysts A represented by the following formula (XIV): [Chem 14] 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.

[0079] The present application also relates to the use of the catalysts defined according to formulas (XII, XIII and XIV) as catalysts for opening polymerization cycle or polycondensation. Examples

[0080] Organopolysiloxanes used in the examples:

[0081] Cyclic organopolysiloxane Oi: hexamethylcyclotrisiloxane (CAS 541-05-9)

[0082] Cyclic organopolysiloxane O2: octamethylcyclotetrasiloxane (CAS 556-67-2)

[0083] Linear organopolysiloxane O3: [Chem 15] with n=8 Catalysts A implemented in the examples:

[0084] Catalyst Ai: [Chem 16] Catalyst A2: [Chem 17] Catalyst A3: [Chem 18] Acompl Catalyst [Chem 19]

[0085] Initiators implemented in the examples: Initiator Ii: benzyl alcohol (CAS 100-51-6) Initiator I2: ethanol (CAS 64-17-5) Initiator I3: H2O

[0086] Chain blockers implemented in the examples:

[0087] Chain blocker Ci: divinyltetramethyldisiloxane (CAS 2627-95-4).

[0088] 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 Mn of the different linear organopolysiloxanes according to the present invention OL is determined by the same size exclusion chromatography (SEC) method.

[0089] In the context of the examples described below, the mass percentage of residual cyclic organopolysiloxanes is called the mass percentage of cyclic organopolysiloxane at the end of the process implemented according to the present invention.

[0090] Example 1: Synthesis of the catalysts of the present invention A^ A? and A3:

[0091] Firstly, the precursors ax as 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 Ph3P solution (1.3 eq.) in dichloromethane (50 mL) at room temperature with stirring for 5 minutes. Then, a solution of the alcohol precursor (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 Na2SO3 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 (NaSO4). 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: .

[0092] [Chem. 20]

[0093]

[0094] In a second step, the product synthesized in the previous step (1.2 eq.) was added to a solution of l-(tert-butyl)-177-imidazole (leq.) in toluene (20 mL). ; The reaction medium placed under a flow of argon 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. The yields obtained for each of these intermediaries are mentioned below: [Chem 21]

[0095] b. R» Sfe In a final step, the product bx formed in the previous step is placed in 20mL of THF and then KHMDS (leq.) was added to the reaction mixture. The reaction mixture is stirred at room temperature for 1h. 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.

[0096] [Chem.22] VR » H (39*4 / 4j R.»Xfe^

[0097] Example 2: General protocol for implementing the method of the present invention:

[0098] The catalytic system AI is formed by the association of catalyst A (Ai, A2 or A3 for example) (leq, 0.025 mmol) and from 0 to n equivalents of initiator I, (such as Ii, I2 or I3 for example). The different tables below indicate the different molar ratios I / A

[0099] This freshly formed catalytic 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.

[0100] Example 3a: Implementation of the process of the present invention in the presence of organopolysiloxane O2

[0101] 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. 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. [Tables 1] Test number Catalyst A Mn of OL product (g / mol) Mass percentage of OL product (%) Mass percentage of residual OC (%) 1 Acompl 66,094 90.7 9.3 2 A2 (nhc-h) 60,700 99.3 0.7

[0102] It can be noted that in the presence of the catalysts described according to the process of the invention as A2, a product OL is obtained having a cyclic organopolysiloxane content less than 1% under these operating conditions.

[0103] In the table below, the process of the present invention was repeated with the catalysts of the present invention A1 and A3 at 110°C for 2 days. The initiator is I1 and the molar ratio I / A is equal to 1. [Tables 2] Test number Catalyst A Mn of OL product (g / mol) Mass percentage of OL product (%) Mass percentage of residual OC (%) 1 Al (NHC-Me) 69,560 99.2 0.8 2 A3(NHCMes) 137,839 99.7 0.3

[0104] Each of these tests led to the production of a linear organopolysiloxane OL having a mass percentage greater than 99% relative to the products resulting from the reaction.

[0105] Example 3b: Implementation of the process of the present invention in the presence of the organopolysiloxane OL;

[0106] In this example, the general protocol of Example 2 was implemented. In this example, organopolysiloxane Oi (CAS 541-05-9) was used. The initiator is Ip

[0107] In test 1 of the table below, the reaction mixture was heated to 110°C for a period of 24 hours for test 1.

[0108] Concerning test 2 in the table below, the reaction mixture was heated to 80°C for a period of 16 hours. The table below describes the different catalysts used, the molar ratios I / A used, as well as the characteristics of the OL product obtained according to the process of the invention.

[0109] [Tables3] Test number Catalyst A Molar ratio 1 / A Mn of the OL product (g / mol) Mass percentage of OL product (%) Mass percentage of residual OC (%) 1 Al (NHC-Me) 1 35,090 99.7 0.3 2 A2 (NHC-H) 5 26,670 99.1 0.9

[0110] 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. [YES] Example 4: Implementation of the method of the present invention with different initiators I:

[0112] In this example, the general protocol of Example 2 was implemented. In this example, organopolysiloxane O2 (CAS 556-67-2) and catalyst A2 were used. The molar ratio I / A is equal to 1. 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.

[0113] [T ables 4] Test number Initiator I Mn of OL product (g / mol) Mass percentage of OL product (%) Mass percentage of residual OC (%) 1 Ii 60 700 99.3 0.7 2 I2 152 950 97.1 2.9 3 I3 176 760 96.5 3.5

[0114] 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.

[0115] Example 5: Influence of the different C / A molar ratios on the process of the present invention:

[0116] In this example, the general protocol of Example 2 was implemented. In this example, organopolysiloxane O2 (CAS 556-67-2), catalyst Ai, initiator Ii and chain blocker Ci were used.

[0117] In the context of these tests, the reaction mixture was heated to a temperature of 80°C for a period of 48 hours.

[0118] The table below mentions the molar ratio of chain blocker C relative 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 the context of this example, the molar ratio I / A is 5. [Tables 5] Test number Molar ratio C / A Mn of the OL product (g / mol) Mass percentage of OL product (%) Mass percentage of residual OC (%) 1 0 60 700 99.3 0.7 2 1 30 100 99.8 0.2 3 2 26 500 99.8 0.2 4 5 11 200 99.7 0.3 5 10 6 340 99.8 0.2

[0119] These different tests demonstrate the control of the number-average molar mass (Mn) of the linear organopolysiloxane OL obtained according to the process of the invention.

[0120] The variation in the amount of material of the chain blocker C influences the molar mass of the product obtained according to the process of the present invention.

[0121] 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).

[0122] Example 6: Implementation of the method of the present invention without initiator:

[0123] In the context of this example, the general protocol of example 2 was implemented work. 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 hours.

[0124] 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 product OL obtained according to the process of the invention. [Tables] Test number Initiator I Molar ratio C / A Mn of the OL product (g / mol) Mass percentage of OL product (%) Mass percentage of residual OC (%) 1 - 0 203 300 100 - 2 1 43 100 99.9 0.1 3 5 11 500 99.8 0.2

[0125] 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.

[0126] Example 7: Polycondensation reaction: process of the present invention carried out in the presence of organopolysilxoane O^without initiator:

[0127] In this example, catalyst Ai (0.5mol%, 0.0137mmol) is mixed in a solution containing an organopolysiloxane O3 (2.73mmol).

[0128] Optionally, a chain blocker such as Ci is added to the reaction mixture as set forth in the table below.

[0129] 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 the chain blocker Ci used relative 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. [Paintings?] Test number Initiator I Molar ratio C / A Mn of the OL product (g / mol) Mass percentage of OL product (%) Mass percentage of residual OC (%) 1 0 125 890 99.9 0.1 2 1 70 610 99.6 0.4 3 2 66 250 99.5 0.5 4 5 31 230 99.6 0.4 5 10 20 660 99.7 0.3

[0130] 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.

[0131] Example 8: Process of the present invention carried out in the presence of O2 and O±:

[0132] In the context of this example, the 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 48 hours.

[0133] Thus, the linear organopolysiloxane OL was obtained at 99.9% (and only 0.1% of residual cyclic organopolysiloxane OC). The molar mass of the product OL obtained is 75,000 g / mol.

Claims

1. Claims 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): [Chem 23]

2.

3. 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. Process according to claim 1 in which the organopolysiloxane O 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. Process according to claim 1 or 2, in which the catalyst A is represented by the following formula (VI): [Chem 24] R:-s ..A . / "a" ''A " A—-h ; in which: Ri, identical or different, 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 0, 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.^Claim 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%. ^Claim 5] Process according to any one of the preceding claims, in which the initiator I is chosen from water or the compounds of formula (VIII): [Chem 25] R IA--y.--- R | Formula VIS R. 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 or phenyl group, 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: [Chem 26] R' R1 1 v 1, -, r aroma A R' R1 in which, R1, identical or different, represents CH3 or phenyl, preferably CH 3 ; R2 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 -C5)alkyl-CF3, the alkyl being linear or branched, - a C5-C10 cycloalkyl group, optionally substituted, - a C6-C18 aryl group, optionally substituted, or -a hydrogen; and q is an integer between 1 and 50, preferably between 1 and 20, plus 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): [Chem 27] r, "Y" ''H- X ' 1 Formula XIII R. in which: Ri, identical or different, 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.

10. Catalysts A represented by the following formula (XIV): [Chem 28] 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.