Polythiol compositions and method for the preparation thereof

Abstract

The present invention relates to a method for preparing a polythiol from a polyene, and to polythiol compositions obtained from cycloaliphatic or isocyanurate polyenes. The method for preparing a polythiol comprises the following steps: a) reacting a polyene with a thiocarboxylic acid in the presence of oxygen (O2) and at least one organic solvent so as to obtain a reaction medium comprising a polythioester and the at least one solvent; b) carrying out a step of deprotecting the polythioester obtained in step a) so as to obtain a polythiol; wherein step a) and step b) are carried out as a one-pot synthesis.

Description

[0001] DESCRIPTION

[0002] TITLE: POLYTHIOL COMPOSITIONS AND PROCESS FOR THEIR PREPARATION

[0003] The present invention relates to a process for preparing polythiol compositions, as well as to the polythiol compositions obtainable by this process.

[0004] Polythiols are molecules of great industrial interest. For example, they are used as crosslinking agents, particularly at low temperatures.

[0005] There are currently several synthetic routes for obtaining polythiols. Among the most widely used methods, we can cite the reaction between polyols and mercaptoacids (described for example in application US 2005153231). While this reaction is easy and allows access to varied polythiol structures, the products obtained generally have low resistance to hydrolysis due to the significant presence of ester functions. Alternatively, the direct addition of hydrogen sulfide to polyenes by acid or photochemical catalysis allows the production of molecules without hydrolyzable functions. This addition is notably described in application WO 12018757. However, with this method, large quantities of sulfide-type compounds can be co-produced and, depending on the reagents used, conversion problems can arise.Thus, the molecules obtained may contain numerous unconverted double bonds, which generates stability problems and lowers the overall rate of -SH functions. In the case of a triene-type starting reagent, for example, this results in particular in the presence of mono- and / or dithiols in significant quantities in the composition obtained.

[0006] However, controlling and / or reducing the formation of these by-products such as mono- and / or di-thiols is important depending on the application areas targeted. Indeed, their content has an influence on the degree of crosslinking of the materials subsequently prepared, in particular thermosetting materials produced from a resin and a polythiol-type hardener. It has thus been demonstrated that the degree of crosslinking influences the physical and viscoelastic properties of polymers such as their density, their modulus, their limits of the elastic domain or their glass transition temperature (Tg). The Tg is conventionally determined by the DSC method for Differential Scanning Calorimetry in English or by dynamic mechanical analysis (DM(T)A). These parameters are directly linked to the behavior of materials such as hardness, elasticity, flexibility or even tear resistance.

[0007] In particular, polymers with a high glass transition temperature are sought in order to obtain materials with greater thermal resistance (i.e., which retain their characteristics over a wider temperature range). There is therefore a need for an industrial process for the preparation of polythiols that allows the conversion of C=C double bonds into -SH functions to be controlled, or even maximized. There is also a need for a process for the preparation of polythiols that allows the formation of by-products (for example, mono- and / or dithiols in the case of the preparation of trithiols, or sulfides) to be controlled, or even reduced.

[0008] One technical solution is to use polythioester intermediates: the C=C double bonds are converted into -R'-C(O)-SR” type functions, which are then deprotected to obtain the desired polythiols. However, these polythioester intermediates represent a great technical difficulty for industrial implementation. They are generally very viscous or even solid compounds. They are therefore difficult to handle for use in the deprotection step. They therefore generate many practical problems at the industrial level and are in reality little used.

[0009] Furthermore, these polythioesters are conventionally obtained by reacting a polyene with a thiocarboxylic acid, in particular thioacetic acid. However, this reaction involves the use of a large excess of thiocarboxylic acid, which must be removed before the deprotection step. Thus, additional steps of evaporation of this excess thiocarboxylic acid and / or purification of the polythioesters are necessary to carry out the next deprotection step.

[0010] There is therefore a need for an improved process for the preparation of polythiols via polythioesters.

[0011] There is a need for polythiol compositions whose -SH function content is controlled, or even maximized. By "-SH function content" we mean the ratio of the mass of all the -SH functions / total mass of the composition.

[0012] The present invention aims to provide an improved process for preparing polythiol compositions, the industrial implementation of which is simplified.

[0013] The present invention aims to provide an improved process for preparing polythiol compositions by which the level of -SH functions is controlled or even maximized.

[0014] The present invention also aims to provide improved polythiol compositions, in particular with a controlled, or even maximized, level of -SH functions.

[0015] In particular, the present invention aims to provide trithiol compositions with a controlled, or even reduced, quantity of dithiols.

[0016] The present invention aims to provide polythiol compositions useful for the preparation of polymers, preferably thermosetting polymers. The present invention meets all or part of the above objectives.

[0017] The present inventors have surprisingly discovered that it is possible to implement a "one pot" (also called monotope) process for the synthesis of polythiols. By "one pot process" is meant in particular a process in which the synthesis intermediates (i.e. the polythioesters such as according to the invention) are not isolated from the reaction medium to carry out the following deprotection step. In the context of the industrial synthesis of polythiols, such a one pot process has numerous advantages.

[0018] In particular, the step of forming the polythioester intermediates according to the invention (hereinafter step a)) makes it possible to obtain a very good conversion (in particular between 90% and 100% conversion of the polyene) while avoiding using too much excess of thiocarboxylic acid. Indeed, a significant excess of thiocarboxylic acid is conventionally used in the processes of the prior art, which represents a loss for the process and generates a large quantity of waste to be isolated and treated. In addition, such an excess is not compatible with a “one pot” process because it must be eliminated before the deprotection step. The present invention makes it possible to avoid these drawbacks, which represents an economic but also an environmental advantage.

[0019] Another advantage of the present invention is that the reaction medium comprising the polythioester intermediates obtained at the end of step a) can be stirred and handled easily. It can in particular be in the form of a liquid or a suspension, slightly viscous or viscous. This avoids operability difficulties at the industrial level.

[0020] The reaction medium comprising the polythioester intermediates is also compatible with the deprotection step (hereinafter step b)), which represents a simplification of the process.

[0021] Thus, steps a) and b) as according to the invention are carried out in "one pot". The process is therefore significantly improved because the intermediate steps of removing excess thiocarboxylic acid and / or purifying the polythioester intermediates, such as extraction, recrystallization and / or distillation, are thus avoided.

[0022] The polythiol compositions that can be obtained by the process according to the invention are new and have a controlled, or even maximized, -SH rate. They are characterized in particular by a high mass ratio as defined below. For example, in the case of a dep triene

[0023] 1 art, said mass ratio is the ratio of t i r th it i h o l ° l(s l )

[0024] These compositions are particularly suitable for the preparation of materials such as thermosetting plastics, from resins. Thus, the present invention makes it possible to obtain materials with superior properties. For example, polymers having a higher Tg, therefore a higher thermal resistance, and / or higher compressive strength properties and / or a larger modulus and elastic range can be obtained.

[0025] Thus, the present invention relates to a process for preparing a polythiol comprising the following steps: a) a polyene is reacted with a thiocarboxylic acid in the presence of oxygen (O2) and at least one organic solvent, so as to obtain a reaction medium comprising a polythioester and said at least one organic solvent; and b) a step of deprotection of the polythioester obtained in step a) is carried out, so as to obtain a polythiol; in which step a) and step b) are carried out in one-pot (or monotope) synthesis.

[0026] The present invention also relates to a polythiol composition A obtained from a cycloaliphatic polyene containing x C=C double bonds, said composition comprising: the polythiol corresponding to said cycloaliphatic polyene comprising x -SH functions; and the thiol(s) corresponding to said cycloaliphatic polyene comprising (x-1) -SH functions; and in which the mass ratio (Aiy °(s) is between 10.1:1 and 50,000:1, preferably between 10.1:1 and 20,000:1; and x being an integer greater than or equal to 3.

[0027] The present invention relates to a polythiol composition B obtained from an isocyanurate of the following general formula (I):

[0028] [Chem 1]

[0029] (in which R is a linear or branched hydrocarbon chain comprising at least one C=C double bond, which may optionally comprise one or more heteroatoms, such as oxygen, nitrogen, sulfur and / or phosphorus, and which may optionally comprise one or more chemical group(s); said composition comprising: the polythiol corresponding to said isocyanurate comprising x -SH functions; and the thiol(s) corresponding to said isocyanurate comprising (x-1) -SH functions; in which the mass ratio is between 2:1 and 50,000:1, preferably between 2:1 and 20,000:1; and x being an integer greater than or equal to 3.

[0030] By “alkyl” is meant in particular a saturated, linear, branched or cyclic hydrocarbon radical, comprising from 1 to 10, preferably from 1 to 4, carbon atoms.

[0031] By “aryl” is meant in particular a cyclic (monocyclic, bicyclic or tricyclic) aromatic hydrocarbon radical comprising from 6 to 10 carbon atoms, preferably a phenyl or a naphthyl, more preferably a phenyl.

[0032] By "aralkyl" is meant in particular an alkyl substituted by an aryl, for example benzyl.

[0033] Polyenes

[0034] The term “polyene” means any organic compound comprising at least 3 C=C double bonds. Hereinafter, “x” refers to the number of C=C double bonds contained in said polyene, x being an integer greater than or equal to 3. Preferably, x is between 3 and 10, more preferably between 3 and 6, more preferably between 3 and 5.

[0035] Said polyene may be functionalized (i.e. comprise one or more chemical functions). Said polyene represents in particular a linear, branched, cyclic or branched cyclic hydrocarbon chain, which may optionally comprise one or more heteroatom(s), such as halogens, silicon, oxygen, nitrogen, sulfur and / or phosphorus, and which may optionally comprise one or more chemical group(s), for example chosen from halogens, -OH, -C(O)-, amine, amide, ester, ether, urea, thioether, sulfoxide, sulfone, carbamate or thiocarbamate, preferably -OH or ether.

[0036] Such chemical groups are for example chosen from: -OH, -O(O)-, -NH2, -NHR8, - NR8R9, -C(O)NH2, -C(O)NHR8, -C(O)NR8R9, -C(O)OH, -C(O)OR8, -NH-C(O)-NH2, -NH-C(O)- NHR8, -NH-C(O)-NR8R9, -NR7-C(O)-NH2, -NR7-C(O)-NHR8, -NR7-C(O)-NR8R9, -NH-C(O)- OR8, -NR7-C(O)-OR8, -OC(=S)-NH2, -OC(=S)-NHR8, -OC(=S)-NR8R9, -SC(=O)-NH2, -S- C(=O)-NHR8, -SC(=O)-NR8R9, -S(=O)R8OR -S(=O)2R8, and in which R7, R8 and R9 are independently of each other chosen from alkyls as defined above.

[0037] Said polyene may contain between 4 and 40, for example between 4 and 30, preferably between 4 and 20, more preferably between 10 and 15, carbon atoms. It is in particular aliphatic (i.e. non-aromatic).

[0038] Preferably, said polyene is chosen from: cycloaliphatic polyenes and polyenes of general formula (I) as defined below. ■ Cycloaliphatic polyenes

[0039] Cycloaliphatic polyene refers to non-aromatic cyclic polyenes. They can be cyclic and branched, as in the case of trivinylcyclohexane.

[0040] Preferably, they are not branched and their C=C double bonds are therefore intracyclic. In particular, they are formed from a hydrocarbon chain preferably comprising between 7 and 15 carbon atoms.

[0041] Preferably, said cycloaliphatic polyene is 1,5,9-cyclododecatriene (1,5,9-CDT or CDT hereinafter).

[0042] We can cite in particular its isomers, with the following formulas:

[0043] Particularly preferred is cis, trans, trans-,5,9-cyclododecatriene, of the following formula: e isocvan urate of the following general formula (I): in which R is a linear or branched hydrocarbon chain comprising at least one C=C double bond, which may optionally comprise one or more heteroatom(s), such as oxygen, nitrogen, sulfur and / or phosphorus, and which may optionally comprise one or more chemical group(s) (in particular such as those mentioned above).

[0044] Preferably, R comprises a single C=C double bond and may optionally comprise one or more heteroatom(s) and in particular oxygen. Preferably, R comprises between 2 and 15 carbon atoms, for example between 2 and 5 carbon atoms.

[0045] The following two compounds are particularly preferred:

[0046] [Chem 2]

[0047] , triallyl isocyanurate (hereinafter TAIC), and

[0048] [Chem 3] , trimethallyl isocyanurate.

[0049] In particular, said polyene is chosen from CDT and TAIC.

[0050] ■ Trienes

[0051] Preferably, said polyene is a triene. By triene is meant a polyene as defined above and comprising only 3 C=C double bonds (i.e. x=3).

[0052] It is notably chosen from:

[0053] - linear, branched or cycloaliphatic hydrocarbon trienes; and

[0054] - trienes of general formula (I) as defined above and in which R comprises a single C=C double bond.

[0055] Trienes include, specifically, trivinylcyclohexane, trivinylbenzene, cycloheptatriene, dimethylheptatriene, octatriene, cyclooctatriene, cyclododecatriene (CDT), triallyl isocyanurate (TAIC), triallyl cyanurate, trimethallyl isocyanurate, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, trimethylolpropane triallyl ether, and triallylamine.

[0056] The preferred trienes according to the invention are cyclododecatriene (CDT) and triallyl isocyanurate (TAIC).

[0057] Polythiols

[0058] According to the invention, the term "polythiol" refers to the polythiol corresponding to the starting polyene as defined above. By "corresponding to the starting polyene" is meant that the structure of the starting polyene and the polythiol obtained are identical, with the exception of the C=C double bonds which have been converted into -SH functions (i.e. -CH-C(SH)-): for x C=C double bonds of the starting polyene, x -SH functions are obtained, with x as defined above. Also included by the term "polythiol" are polythiols which are position isomers of the double bonds of the starting polyene. The polythiols according to the invention can also be called (x)thiols.

[0059] Polythioester intermediates

[0060] By "polythioester intermediate" or "polythioester" is meant the polythioester corresponding to the starting polyene. By "corresponding to the starting polyene" is meant that the structure of the starting polyene and the resulting polythioester are identical, except for the C=C double bonds which have been converted into -CH-C(O)-S-Ri functions (Ri depends on the thiocarboxylic acid used, preferably Ri is a methyl): for x 0=0 double bonds, x thioester functions are obtained, with x as defined above. Also included by the term "polythioesters" are polythioesters which are position isomers of the double bonds of the starting polyene.

[0061] METHOD ACCORDING TO THE INVENTION

[0062] Step a)

[0063] In step a), a polyene as defined above is reacted with a thiocarboxylic acid in the presence of oxygen (O2) and at least one organic solvent, so as to obtain a reaction medium comprising a polythioester as defined above and said at least one organic solvent.

[0064] The reaction is as follows: R-CH=CH-R + Ri-C(O)-SH -> R-CH2-CH(SC(O)-RI)-R

[0065] Step a) is carried out in the presence of oxygen (O2), acting here as a reaction initiator. Step a) can thus be carried out in the presence of air, depleted air (mixture of oxygen and nitrogen N2) or a mixture of oxygen and another inert gas. Oxygen can be introduced into the reaction medium by any technique. Oxygen can also be added throughout step a) or not.

[0066] In particular, oxygen is bubbled into the reaction medium, preferably in the form of depleted air. For example, the depleted air is passed through a frit or diffuser which is immersed in the reaction medium. Alternatively, oxygen can be bubbled into the reaction medium and nitrogen can be introduced into the gas phase of the reactor (i.e. the reactor headspace). The oxygen flow rate can be between 0.01 and 100 nL / h, preferably between 0.05 and 10 nL / h, more preferably between 0.05 and 5 nL / h, in particular between 0.05 and 2 nL / h (normo liters / h).

[0067] Step a) is notably carried out in the absence of any other reaction initiator, and more preferably in the absence of AIBN (azobisisobutyronitrile) and / or in the absence of UV radiation.

[0068] Step a) is also carried out in the presence of an organic solvent or a mixture of organic solvents. A polar solvent or a mixture of polar solvents is particularly chosen. The solvent(s) may be polar protic or polar aprotic. Among the solvents that may be used, mention may be made of: alcohols, ethers (preferably cyclic ethers and glycol ethers such as, for example, glycol dialkyl ethers), organochlorine solvents, carboxylic acids or mixtures thereof.

[0069] Alcohols are preferred, in particular of the following general formula (IV):

[0070] FL-OH (IV) in which R4 represents an alkyl as defined above. Preferably, the alcohol is chosen from the group consisting of: methanol, ethanol, isopropanol, n-propanol, n-butanol, butan-2-ol, isobutanol, tert-butanol, more preferably ethanol.

[0071] Preferably, the solvent is chosen from the group consisting of: tetrahydrofuran (THF), 2-methyl-tetrahydrofuran (Me-THF), dioxane, chloroform, acetic acid, methanol, ethanol, isopropanol, n-propanol, n-butanol, butan-2-ol, isobutanol, tert-butanol, dimethoxyethane (also called glyme), diethoxyethane, dibutoxyethane or mixtures thereof, more preferably ethanol.

[0072] The amount of solvent used is generally chosen according to the desired viscosity of the reaction medium. Total or partial solubilization can be carried out by a person skilled in the art, depending on the desired viscosity of the reaction medium. Preferably, between 1 eq. and 50 molar eq., more preferably between 1 eq. and 20 eq. of solvent(s) are used relative to the polyene.

[0073] The solvent can be added at the beginning of step a) in whole or in part. It can be added punctually in one go, in several times (semi-continuously) or gradually (continuously), during step a).

[0074] The thiocarboxylic acid is preferably of the following general formula (II):

[0075] Ri-C(O)-SH (II) in which:

[0076] Ri represents an alkyl radical, an aryl radical or an aralkyl radical as defined above.

[0077] Preferably, R 1 is selected from methyl, ethyl and benzyl. Thioacetic acid, in which R 1 is methyl, is particularly preferred according to the invention (hereinafter also referred to as ATA). For example, with thioacetic acid, a polythioacetate is obtained as a polythioester intermediate.

[0078] According to one embodiment, the thiocarboxylic acid can be generated in situ (see document US 3,270,063, THOMPSON CHEMICAL CO, 1963: “Methods of making primary mercaptans”): the thioacetic acid can be produced from acetic anhydride and hydrogen sulfide, in the presence of a catalyst.

[0079] Preferably, to carry out step a), the thiocarboxylic acid and the solvent(s) are first introduced into the reactor, then the oxygen is introduced, for example by bubbling air. The polyene can then be added to the reaction medium.

[0080] The temperature of step a) can be between 5 and 80 0 C, preferably between 5 and 50 0 C, more particularly between 5 and 25 °C, for example between 5 and 10 °C. Step a) is generally carried out at atmospheric pressure.

[0081] The molar ratio of thiocarboxylic acid to double bond of the polyene may be between 1 and 20, preferably between 1 and 10, for example between 1 and 5, more preferably between 1 and 3.

[0082] Step a) allows, from a polyene, the formation of a polythioester intermediate as defined above. The reaction medium obtained at the end of step a) can thus comprise:

[0083] - a polythioester intermediate as defined above;

[0084] - the solvent or mixture of solvents as defined above;

[0085] - possibly by-products such as (x-1)polythioesters; and

[0086] - possibly one or more reagents that have not reacted.

[0087] By "(xl)polythioester" is meant in particular a compound comprising x-1 thioester functions, with x being as defined above. This is a compound having retained a C=C double bond (i.e. a C=C double bond which has not reacted).

[0088] The reaction medium can thus comprise between 10% and 85% by weight of polythioester intermediate, relative to the totality of the reaction medium.

[0089] The reaction medium may comprise between 15% and 90% by weight of solvent(s), relative to the totality of the reaction medium.

[0090] Step b)

[0091] Step b) of deprotection of the polythioester intermediate obtained in step a) makes it possible to obtain a polythiol. It can be carried out by any means known to those skilled in the art. Step a) and step b) being carried out in one-pot synthesis according to the invention, it is understood that the reaction medium comprising the polythioester obtained at the end of step a) is retained to carry out the deprotection step b). Thus, steps a) and b) are carried out in the presence of the same solvent (or mixture of solvents). It is possible to add said solvent (or said mixture of solvents) during step b). In particular, the process according to the invention does not comprise a step of separation and / or extraction and / or washing of the (organic) phase which comprises the polythioester between steps a) and b). In particular, no intermediate step of purification of the polythioester is carried out. More particularly, no recrystallization and / or distillation step of the polythioester is carried out.

[0092] Deprotection b) can be carried out by conventional methods: using a base or an acid, a Dy(OTf)3 type catalyst (cf. Liang et al., Asian J. Org. Chem. 10.1002 / ajoc.201700481) or a quaternary ammonium cyanide salt type compound (cf. US 7,173,156).

[0093] Preferably, deprotection b) is a basic deprotection, preferably in the presence of an alcohol as defined above. It is generally carried out by adding an alkali hydroxide, preferably NaOH or KOH. The addition can be carried out dropwise.

[0094] Deprotection step b) may also be an acid deprotection, preferably in the presence of an alcohol as defined above. It may be carried out with hydrochloric acid, methanesulfonic acid or anhydrous methanesulfonic acid. When the deprotection is acidic, it is preferred to use an alcohol as defined above as the solvent.

[0095] Sulfonic acid

[0096] The sulfonic acid is preferably an organosulfonic acid, optionally anhydrous.

[0097] The sulfonic acid can be of the following general formula (III):

[0098] R2-SO3H (III), where R2 represents:

[0099] - an alkyl radical, preferably as defined above, optionally substituted, in whole or in part, by one or more identical or different halogen atoms, or

[0100] - an aryl radical, preferably as defined above, optionally substituted by a saturated, linear or branched hydrocarbon chain, comprising from 1 to 4 carbon atoms. The halogen atom may be chosen from fluorine, chlorine and bromine. In particular, said alkyl may be perhalogenated, more particularly perfluorinated.

[0101] Preferably, the sulfonic acid is an alkanesulfonic acid, optionally anhydrous (in the above formula, R2 is an alkyl).

[0102] Thus, the sulfonic acids (as well as their anhydrous forms) may be chosen from: methanesulfonic acid, ethanesulfonic acid, n-propanesulfonic acid, / so-propanesulfonic acid, n-butanesulfonic acid, / so-butanesulfonic acid, sec-butanesulfonic acid, te / -butanesulfonic acid, trifluoromethanesulfonic acid, para-toluenesulfonic acid, benzenesulfonic acid and mixtures of two or more of them in all proportions. According to a particularly preferred embodiment, the sulfonic acid used in the context of the present invention is methanesulfonic acid (MSA) or anhydrous methanesulfonic acid (AMSA).

[0103] Said sulfonic acid may be supported or unsupported. Preferably, it is unsupported.

[0104] When supported, sulfonated resins of the styrene-divinylbenzene copolymer type can be used, for example Amberlyst® 15 resin, or Nation®.

[0105] For example, between 0.1 and 10 eq. of acid are used for a polythioester.

[0106] For example, between 3 and 60 eq., preferably between 3 and 20 eq. (molar equivalent) of alcohol are used for a polythioester.

[0107] Deprotection step b) can be carried out at a temperature between 10 and 100°C, preferably between 25 and 80°C, more preferably between 40 and 80°C. It is generally carried out at atmospheric pressure.

[0108] Steps a) and b) can be carried out in the same reactor. For example, a batch reactor can be used.

[0109] Subsequent steps of conventional recovery and / or purification of the polythiol obtained at the end of step b) can be carried out, depending on the desired degree of purity. For example, when deprotection is carried out by the addition of a base, the reaction medium can then be acidified and vice versa: when deprotection is carried out by the addition of an acid, the reaction medium can be basified. The resulting organic phase, comprising the different thiols (in particular the polythiol and the (xl)thiols), can then be extracted and optionally concentrated.

[0110] Thus and in particular, the polythiol obtained may be in the form of a polythiol composition as mentioned below.

[0111] COMPOSITIONS ACCORDING TO THE INVENTION

[0112] When preparing a polythiol from a polyene having x C=C double bonds, the conversion of these double bonds into -SH functions is generally not complete and by-products can be formed at each of the different stages, regardless of the process used.

[0113] According to the invention, the term "polythiol" is therefore used to refer to the polythiol corresponding to the starting polyene and comprising x -SH functions. For example, trimercaptocyclododecane corresponds to cyclododecatriene. In this case, the conversion of the x starting C=C double bonds into -SH functions is complete.

[0114] According to the invention, the term "(xl)thiol" refers to a thiol corresponding to the starting polyene and comprising (x-1) -SH functions. By "corresponding to the starting polyene" is meant that the structures of the starting polyene and the (xl)thiol obtained are identical, with the exception of the x C=C double bonds which have been converted into (x-1) -SH functions. In this case, the conversion of the C=C double bonds into -SH functions has not been complete: an -SH function is missing. The C=C double bond not converted into an -SH function may in particular be:

[0115] - always in the form of a C=C double bond; or

[0116] - in the form of a thioester function which has not been deprotected.

[0117] There may therefore be different structures of (x-1)thiols, but they are grouped here under this general name characterizing their number of -SH functions (unless otherwise specifically mentioned). Also included are the (x-1)thiols that are position isomers of the double bonds of the starting polyene.

[0118] It is thus possible to obtain a polythiol composition derived from a polyene having x C=C double bonds and comprising:

[0119] - the polythiol corresponding to said polyene comprising x -SH functions; and

[0120] - The thiol(s) corresponding to said polyene comprising (x-1) -SH functions.

[0121] Such a composition may optionally include other by-products or impurities (e.g. monothiols). It can be characterized by the mass ratio H this is the mass ratio: [polythiol corresponding to said polyene comprising x -SH functions] / [thiol(s) corresponding to said polyene comprising (x-1) -SH functions],

[0122] In particular, a trithiol composition can be obtained from a triene, said composition comprising:

[0123] - the corresponding trithiol; and

[0124] - The corresponding dithiol(s).

[0125] For example, in the case of a polythiol formed from cis, trans, trans-1,5,9-cyclododecatriene as the starting polyene, the following dithioester can be obtained as a by-product from step a):

[0126] [Chem 4]

[0127] In step b), it is also possible that the deprotection is not complete.

[0128] Thus, it is possible to form according to the method according to the invention:

[0129] - (x-1)thiols from the (xl)thioesters formed in step a); and / or

[0130] - (x-1)thiols from polythioesters that are not completely deprotected. In the case of CDT, the following dithiols can therefore be obtained at the end of step b): [Chem 5]

[0131] Composition A obtained from a cycloaliphatic polyvinyl alcohol

[0132] The present invention relates to a polythiol composition A obtained from a cycloaliphatic polyene containing x C=C double bonds and as defined above, said composition comprising: the polythiol corresponding to said cycloaliphatic polyene comprising x -SH functions; and the thiol(s) corresponding to said cycloaliphatic polyene comprising (x-1) -SH functions (also called (xl)thiols as explained above), with x as defined above.

[0133] In particular, said composition A comprises at least 85% by weight, preferably at least 90% by weight, more preferably at least 95% by weight of said polythiol, relative to the total weight of composition A.

[0134] In particular, said composition A comprises less than 9% by weight, preferably less than 5% by weight, more preferably less than 1% by weight of said (xl)thiol(s), relative to the total weight of said composition A.

[0135] Preferably, the mass ratio of composition A is between 10.1:1 and 20,000:1, preferably between 10.5:1 and 20,000:1, more preferably between 15:1 and 20,000:1, for example between 15:1 and 20,000:1.

[0136] Particularly preferably, the mass ratio of composition A is between 10.1:1 and 10,000:1, preferably between 10.5:1 and 10,000:1, more preferably between 15:1 and 1,000:1, for example between 15:1 and 500:1. Even more preferably, the mass ratio of composition A is between 10.5:1 and 1,000:1.

[0137] The preferred starting cycloaliphatic polyene is cyclododecatriene, preferably 1,5,9-cyclododecatriene, and more preferably still its cis, trans, trans-1,5,9-cyclododecatriene isomer. In particular, the present invention relates to a polythiol composition A obtained from cyclododecatriene as defined above, said composition comprising: trimercaptocyclododecane;

[0138] - dimercaptocyclododecene; and

[0139] - S-[bis(sulfanyl)cyclododecyl]ethanethioate.

[0140] Thus, the mass ratio [trimercaptocyclododecane / (dimercaptocyclododecene + S- [bis(sulfanyl)cyclododecyl]ethanethioate)] is in particular as defined above.

[0141] Composition B obtained from an isocvanurate type polyvinyl alcohol

[0142] The present invention also relates to a polythiol composition B obtained from an isocyanurate of the following general formula (I) and as defined above:

[0143] [Chem 1] in which R is a linear or branched hydrocarbon chain comprising at least one C=C double bond, which may optionally comprise one or more heteroatoms, such as oxygen, nitrogen, sulfur and / or phosphorus, and which may optionally comprise one or more chemical group(s); said composition comprising: the polythiol corresponding to said isocyanurate comprising x -SH functions; and the (x-1)thiol(s) corresponding to said isocyanurate comprising (x-1) -SH functions, with x as defined above.

[0144] In particular, said composition B comprises at least 70% by weight, preferably at least 80% by weight, more preferably at least 90% by weight of said polythiol, for example at least 95% by weight of said polythiol, relative to the total weight of composition B.

[0145] In particular, said composition B comprises less than 30% by weight, preferably less than 20% by weight, more preferably less than 10% by weight, for example less than 5%, or even less than 1% by weight of said (x-1)thiol(s), relative to the total weight of said composition B. Preferably, the mass ratio of composition B is between 2:1 and

[0146] 20,000:1, for example between 2.3:1 and 20,000:1, preferably between 4:1 and 20,000:1, more preferably between 9:1 and 20,000:1, for example between 19:1 and 20,000:1.

[0147] Preferably, the mass ratio of composition B is between 2:1 and

[0148] 10,000:1, for example between 2.3:1 and 10,000:1, preferably between 4:1 and 10,000:1, more preferably between 9:1 and 1,000:1, for example between 100:1 and 1,000:1.

[0149] Even more preferably, the mass ratio of composition B is comprised between 10:1 and 1000:1.

[0150] The preferred starting isocyanurate is triallyl isocyanurate.

[0151] In particular, a polythiol composition B is obtained from triallyl isocyanurate as defined above, said composition comprising:

[0152] - 1,3,5-tris(3-mercaptopropyl)-1,3,5-triazinane-2,4,6-trione, as well as its isomers; and

[0153] - the corresponding dithiols (B1) and (B2) with the following formulae, as well as their isomers:

[0154] [Chem 6]

[0155] [Chem 7]

[0156] Thus, the mass ratio [(1,3,5-tris(3-mercaptopropyl)-1,3,5-triazinane-2,4,6-trione) / (B1 +B2)] is in particular as defined above.

[0157] The above compositions are novel and therefore form part of the present invention.

[0158] The present invention also relates to said polythiol compositions obtainable, obtained or directly obtained by the process according to the invention. The present invention also relates to the polythiols obtained or directly obtained by the process according to the invention.

[0159] It is understood that, unless a specific isomer is mentioned, the name of a compound includes all of its possible positional isomers.

[0160] It is understood that ranges given such as "between X and X" include the upper and lower limits.

[0161] The following examples are given for illustrative purposes and are not limiting of the present invention.

[0162] EXAMPLES:

[0163] EXAMPLE 1: One-pot synthesis of a polythiol composition from the CDT according to the invention, with basic deprotection

[0164] 155g (2.04 moles) of ATA (thioacetic acid) are introduced into a 1 L jacketed reactor. The medium is stirred at 5°C and then 28.4g (0.62 moles) of ethanol are quickly added. Air is bubbled into the reaction medium via a frit at a flow rate of approximately 0.4NI / h and nitrogen is passed into the reactor headspace at a flow rate of approximately 4NI / h.

[0165] 100g (0.62 mol) of 1,5,9-cyclododecatriene (CDT) are then added dropwise via a peristaltic pump over approximately 1 h. Once the addition is complete, 113.6g (2.47 mol) of EtOH are added to the reaction medium.

[0166] The reaction medium is kept stirring at approximately 5°C overnight. A GC / FID analysis shows complete conversion of 1,5,9-cyclododecatriene. The air supply is cut off.

[0167] 171 g of EtOH are then added to the reaction medium. The reaction medium is then degassed with nitrogen for 1 h and then brought to approximately 40 °C and 177 g of a previously degassed 46% aqueous sodium hydroxide solution are added via a dropping funnel. The reaction medium is left stirring under nitrogen at 40 °C for 2 to 3 h.

[0168] Recovery stage:

[0169] The reaction medium is then cooled to 20°C and 200 g (2.03 moles) of 37% HCl are then added dropwise via a peristaltic pump into the medium. The organic phase comprising the thiols is withdrawn. The aqueous phase is extracted with 105 g (1.24 moles) of dichloromethane.

[0170] The organic phases are then combined and washed 4 times with 14.8g (0.82 moles) of water then concentrated on a rotary evaporator.

[0171] A GC / FID analysis shows complete conversion of trithioacetate.

[0172] The resulting composition includes:

[0173] - 0.36% of dithiol corresponding to CDT with 1 residual double bond,

[0174] - 0.47% of dithiol-monothioacetate corresponding to CDT,

[0175] - 95.87% of trimercaptocyclododecane, and - the remainder in impurities (100%).

[0176] The mass ratio pol y thl ° l es td e 95 87:0.83, or 116:1.

[0177] EXAMPLE 2: One-pot synthesis of a polythiol composition from the CDT according to the invention, with acid deprotection (AMSA and ethanol)

[0178] 155g (2.04 moles) of ATA are introduced into a 1 L jacketed reactor. The medium is stirred at 5°C and then 29g (0.63 moles) of ethanol are quickly added. Air is bubbled into the reaction medium via a frit at a flow rate of approximately 0.4NI / h and nitrogen is passed into the reactor headspace at a flow rate of approximately 4NI / h.

[0179] 100g (0.62 mol) of 1,5,9-cyclododecatriene are then added dropwise via a peristaltic pump over approximately 1 h. Once the addition is complete, 113.6g (2.47 mol) of EtOH are added to the reaction medium.

[0180] The reaction medium is kept stirring at approximately 5°C overnight.

[0181] GC / FID analysis shows complete conversion of 1,5,9-cyclododecatriene.

[0182] The air supply is cut off.

[0183] Step b) acid deprotection:

[0184] The temperature of the reaction medium is raised to 20°C, 85g (1.85 moles) of EtOH are added to the reaction medium. 74g of anhydrous methanesulfonic acid (0.77 moles) are added dropwise via a dropping funnel. The medium is stirred at reflux under nitrogen for 10 hours.

[0185] The reaction medium is then cooled to 20°C, and 154 g (0.77 moles) of a previously degassed 20% NaOH solution are then added dropwise via a peristaltic pump into the medium. The organic phase comprising the thiols is withdrawn. The aqueous phase is extracted with 105 g (1.24 moles) of dichloromethane.

[0186] The organic phases are combined, then washed 4 times with 14.8g (0.82 moles) of water and then concentrated using a rotary evaporator.

[0187] A GC / FID analysis shows complete conversion of trithioacetate.

[0188] The resulting composition includes:

[0189] - 5.26% of the dithiol corresponding to the CDT with 1 residual double bond, - 0.58% of the dithiol-monothioacetate corresponding to the CDT,

[0190] - 90.60% of trimercaptocyclododecane, and

[0191] - the remainder in impurities (100%).

[0192] The mass ratio pol y thl ° les td e 90.60:5.84 or 16:1.

[0193] EXAMPLE 3: One-pot synthesis of a polythiol composition from TAIC according to the invention, with basic deprotection

[0194] 101 g (1.33 moles) of ATA are introduced into a 1 L jacketed reactor. The medium is stirred at 5°C and then 92 g (2.00 moles) of EtOH are quickly added. Air is bubbled into the reaction medium via a frit at a flow rate of approximately 0.4 NI / h and nitrogen is passed into the reactor headspace at a flow rate of approximately 4 NI / h.

[0195] 100g (0.40 mol) of triallyl isocyanurate (TAIC) dissolved in 19g (0.41 mol) of EtOH are then added dropwise via a peristaltic pump over approximately 40 min. Once the addition is complete, 148g (3.21 mol) of EtOH are gradually added to the reaction medium.

[0196] The reaction medium is kept stirring at 5°C for approximately 6 hours.

[0197] A GC / FID or HPLC / UV analysis shows complete conversion of triallyl isocyanurate. The air supply is turned off.

[0198] The reaction medium is then degassed with nitrogen for 1 hour and then 15.1 g of a previously degassed 46% aqueous sodium hydroxide solution are added dropwise via a dropping funnel. The reaction medium is left stirring under nitrogen at 25°C for 5 hours and then cooled to 10°C for approximately 17 hours.

[0199] Recovery stage:

[0200] The reaction medium is then cooled to 20°C, and 483 g (1.32 moles) of a 10% HCl solution are then added dropwise via a peristaltic pump into the medium. The organic phase comprising the thiols is withdrawn. The aqueous phase is extracted with three times 68 g (0.80 moles) of dichloromethane.

[0201] The organic phases are combined, then washed twice with 14.4 g (0.80 mol) of water and then concentrated using a rotary evaporator. GC / FID analysis shows complete conversion of trithioacetate.

[0202] A polythiol composition comprising 95% by weight of trithiol corresponding to TAIC and approximately 0.2% by weight of dithiol corresponding to TAIC, relative to the total weight of the composition, is obtained.

[0203] The mass ratio is 475:1.

[0204] EXAMPLE 4: One-pot synthesis of a polythiol composition from the CDT according to the invention, with acid deprotection (HCl and methanol)

[0205] 155g (2.04 moles) of ATA are introduced into a 3L jacketed reactor. The medium is stirred at 5°C and then 19.8g (0.62 moles) of MeOH are quickly added. Air is bubbled into the reaction medium via a frit at a flow rate of approximately 0.4NI / h and nitrogen is passed into the reactor headspace at a flow rate of approximately 4NI / h.

[0206] 100g (0.62 mol) of 1,5,9-cyclododecatriene are then added dropwise via a peristaltic pump over approximately 1 h. Once the addition is complete, 78.9g (2.46 mol) of MeOH are added to the reaction medium.

[0207] The reaction medium is kept stirring at approximately 5°C overnight.

[0208] GC / FID analysis shows complete conversion of 1,5,9-cyclododecatriene.

[0209] The air supply is cut off.

[0210] Step b) acid deprotection:

[0211] The reaction medium is brought back to 20°C, 1119g (34.93 moles) of MeOH are added to the reaction medium. The medium is heated to 40°C, and 576.9g (5.85 moles) of 37% HCl are added dropwise via a peristaltic pump and then the medium is refluxed under nitrogen for 48 hours.

[0212] Recovery stage:

[0213] The reaction medium is then cooled to 20 °C, the organic phase comprising the thiols is withdrawn, and 105 g (1.24 moles) of dichloromethane is then added to the aqueous phase. The organic phases are combined and then washed four times with 74 g (4.11 moles) of water and then concentrated on a rotary evaporator. A GC / FID analysis shows complete conversion of the trithioacetate. A polythiol composition comprising 96.28% trimercaptocyclododecane and 0.25% dithiol(s) corresponding to the CDT is obtained.

[0214] The mass ratio pol y thl ° l es td e96.28:0.25 or 385:1.

[0215] EXAMPLE 5: One-pot synthesis of a polythiol composition from the CDT according to the invention, with acid deprotection (HCl and ethanol)

[0216] 774.0g (10.17 moles) of ATA are introduced into a 3L jacketed reactor. The medium is stirred at 5°C and then 142.0g (3.08 moles) of ethanol are quickly added. Air is bubbled into the reaction medium via a frit at a flow rate of approximately 0.4NI / h and nitrogen is passed into the reactor headspace at a flow rate of approximately 4NI / h.

[0217] 500g (3.08 moles) of 1,5,9-cyclododecatriene are then added dropwise via a peristaltic pump over approximately 4.5 hours. Once the addition is complete, 851.7g (18.49 moles) of ethanol are added to the reaction medium.

[0218] The reaction medium is kept stirring at 5°C for approximately one night.

[0219] GC / FID analysis shows complete conversion of 1,5,9-cyclododecatriene.

[0220] The air supply is cut off.

[0221] Step b) acid deprotection:

[0222] The temperature of the reaction medium is raised to 20 °C and 1478.6 g (30.81 moles) of 96% EtOH are added to the reaction medium. The medium is heated to 40 °C, and 910.9 g (9.24 moles) of 37% HCl are added dropwise via a peristaltic pump. Then, the medium is refluxed under nitrogen for 22 hours.

[0223] Recovery stage:

[0224] The reaction medium is then cooled to 30°C, the organic phase comprising the thiols is withdrawn and 261.7 g (3.08 moles) of dichloromethane are then added to it.

[0225] The organic phase thus obtained is washed four times with 110.9 g (6.16 moles) of water and then concentrated on a rotary evaporator. A GC / FID analysis shows a total conversion of trithioacetate. A polythiol composition comprising 94.84% trimercaptocyclododecane and 5.17% dithiol(s) corresponding to the CDT is obtained.

[0226] The mass ratio pol y thl ° l es td e 94.84:5.17 or 18.34:1

[0227] EXAMPLE 6: One-pot synthesis of a polythiol composition from TAIC according to the invention, with acid deprotection (HCl and ethanol)

[0228] 302.3g (3.97 mol) of ATA are introduced into a 3L jacketed reactor. The medium is stirred at 5°C and then 166.3g (3.61 mol) of EtOH are quickly added. Air is bubbled into the reaction medium via a frit at a flow rate of approximately 0.4NI / h and nitrogen is passed into the reactor headspace at a flow rate of approximately 4NI / h.

[0229] 300g (1.20 moles) of triallyl isocyanurate (TAIC) dissolved in 27.7g (0.60 moles) of EtOH are then added dropwise via a peristaltic pump over approximately 1 h 15 min. Once the addition is complete, 221.8g (4.81 moles) of EtOH are gradually added to the reaction medium.

[0230] The reaction medium is kept stirring at 5°C for approximately 6 hours.

[0231] A GC / FID or HPLC / UV analysis shows complete conversion of triallyl isocyanurate. The air supply is turned off.

[0232] Step b) acid deprotection:

[0233] The temperature of the reaction medium is raised to 20 °C and 462.1 g (9.63 moles) of 96% EtOH are added to the reaction medium. The medium is heated to 40 °C, and 355.8 g (3.61 moles) of 37% HCl are added dropwise via a peristaltic pump. Then, the medium is refluxed under nitrogen for 28 h.

[0234] Recovery stage:

[0235] The reaction medium is then cooled to 30°C, the organic phase comprising the thiols is withdrawn, and 102.2g (1.20 moles) of dichloromethane are then added to it.

[0236] The organic phase thus obtained is washed four times with 43g (2.41 moles) of water then concentrated on a rotary evaporator.

[0237] HPLC / UV analysis shows complete conversion of trithioacetate. A polythiol composition comprising 95.16% by weight of trithiol corresponding to TAIC and approximately 0.2% by weight of dithiol corresponding to TAIC, relative to the total weight of the composition, is obtained.

[0238] The mass ratio pol y ttll ° l es td e 95.16:0.2 or 476:1.

[0239] Example 7: Application Testing

[0240] Two compositions of polythiols from triallyl isocyanurate (TAIC) were prepared to carry out an application test.

[0241] The trithiol / dithiol mass ratios as well as the -SH percentages of these compositions are given in the table below:

[0242] The polythiol composition P1 is that obtained according to example 6.

[0243] Polythiol composition P2 was prepared using the same protocol as described in Example 6 but using AIBN (azobisisobutyronitrile) as initiator instead of oxygen and heating in step a) to 65°C

[0244] Polythiol compositions P1 and P2 were used as hardeners for an epoxy resin (Araldite® LY 556 from Huntsman), with a tertiary amine (DABCO® 33-LV from Sigma-Aldrich) as catalyst. Curing was carried out at room temperature (i.e. 25°C) using a stoichiometric ratio of thiol functions to epoxy functions.

[0245] The quantities used are summarized in the table below:

[0246] The mixtures were prepared in aluminum cups: the quantities of Araldite® LY 556, polythiol and then amine were weighed respectively. The mixture was quickly mixed with a spatula. The compositions began to harden within a few minutes and were left at room temperature for 7 days.

[0247] A bar of each cured composition was taken and placed on the rectangular torsion equipment fixed on an ARES rheometer (Rheometer Scientific) in order to carry out a Dynamic Mechanical Analysis (DMA in French and DMA in English for Dynamic Mechanical Analysis). The samples underwent a sinusoidal deformation at the frequency of 1 Hz over a temperature range varying from -50 to 110 °C.

[0248] The glass transition temperature (Tg) was determined at the maximum of the mechanical loss factor (tan delta). This value as well as the value of the elastic modulus at the plateau were recorded and are summarized in the table below: The use of a polythiol composition P1 according to the invention in an epoxy resin therefore makes it possible to obtain a more crosslinked and denser network. The resin thus obtained is notably characterized by a higher Tg and plateau modulus.

Claims

CLAIMS 1. Process for preparing a polythiol comprising the following steps: a) a polyene is reacted with a thiocarboxylic acid in the presence of oxygen (O2) and at least one organic solvent, so as to obtain a reaction medium comprising a polythioester and said at least one solvent; and b) a step of deprotecting the polythioester obtained in step a) is carried out, so as to obtain a polythiol; in which step a) and step b) are carried out in one-pot synthesis.

2. Preparation process according to claim 1, in which step b) of deprotection is a basic deprotection, preferably carried out by adding an alkali hydroxide.

3. Preparation process according to claim 1, in which step b) of deprotection is an acid deprotection, preferably in the presence of an alcohol.

4. Preparation process according to any one of the preceding claims, in which said reaction medium comprises between 15% and 90% by weight of solvent(s) at the end of step a), relative to the totality of said reaction medium.

5. Preparation process according to any one of the preceding claims, wherein said organic solvent is chosen from the group consisting of; alcohols, ethers, organochlorine solvents, carboxylic acids or mixtures thereof.

6. Preparation process according to any one of the preceding claims, in which the organic solvent is chosen from alcohols of the following general formula (IV): FU-OH (IV) in which R4 represents a saturated, linear, branched or cyclic hydrocarbon radical, comprising from 1 to 10, preferably from 1 to 4, carbon atoms.

7. Preparation process according to any one of the preceding claims, in which the thiocarboxylic acid is thioacetic acid.

8. Preparation process according to any one of the preceding claims, wherein said polyene is a triene.

9. Preparation process according to any one of the preceding claims, in which the polyene is chosen from cycloaliphatic polyenes and polyenes isocyanurates of the following general formula (I): in which R is a linear or branched hydrocarbon chain comprising at least one C=C double bond, which may optionally comprise one or more heteroatom(s), such as oxygen, nitrogen, sulfur and / or phosphorus, and which may optionally comprise one or more chemical group(s).

10. Composition A of polythiol obtained from a cycloaliphatic polyene containing x C=C double bonds, said composition comprising: - the polythiol corresponding to said cycloaliphatic polyene comprising x -SH functions; and - The thiol(s) corresponding to said cycloaliphatic polyene comprising (x-1) -SH functions; and in which the mass ratio est between 10.1:1 and 50,000:1; x being an integer greater than or equal to 3.

11. Polythiol composition A according to claim 10, wherein said cycloaliphatic polyene is cyclododecatriene, preferably its cis, trans, trans-1,5,9-cyclododecatriene isomer.

12. Composition B of polythiol obtained from an isocyanurate of the following general formula (I): in which R is a linear or branched hydrocarbon chain comprising at least one C=C double bond, which may optionally comprise one or more heteroatom(s), such as oxygen, nitrogen, sulfur and / or phosphorus, and which may optionally comprise one or more chemical group(s); said composition comprising: - the polythiol corresponding to said isocyanurate comprising x -SH functions; and - The thiol(s) corresponding to said isocyanurate comprising (x-1) -SH functions; in which the mass ratio is between 2:1 and 50,000:1; and x being an integer greater than or equal to 3.

13. Polythiol composition B according to claim 12, in which the isocyanurate is triallyl isocyanurate.

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