Compositions of polythiols and their preparation process

Abstract

The present invention relates to a process for preparing a polythiol from a polyene, as well as polythiol compositions obtained from cycloaliphatic or isocyanurate-type polyenes. The process 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 to obtain a reaction medium comprising a polythioester and said at least one solvent; b) deprotection of the polythioester obtained in step a) to obtain a polythiol, wherein steps a) and b) are carried out in a one-pot synthesis. Figure: None

Description

Title of the invention: POLYTHIOL COMPOSITIONS AND THEIR PREPARATION PROCESS

[0001] The present invention relates to a method for preparing polythiol compositions, as well as the polythiol compositions that can be obtained by this method.

[0002] Polythiols are molecules of great industrial interest. They are used, for example, as crosslinking agents, particularly at low temperatures.

[0003] Several synthetic routes exist today for obtaining polythiols. Among the most widely used methods is the reaction between polyols and mercaptoacids (described, for example, in US patent application 2005153231). While this reaction is straightforward and allows access to a variety of polythiol structures, the products obtained generally exhibit low resistance to hydrolysis due to the significant presence of ester groups.

[0004] Alternatively, the direct addition of hydrogen sulfide to polyenes by acid or photochemical catalysis allows the production of molecules without hydrolyzable functional groups. This addition is described in particular 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 may arise. Thus, the molecules obtained may contain numerous unconverted double bonds, which generates stability problems and lowers the overall -SH functional group content. In the case of a triene-type starting reagent, for example, this results in the presence of significant amounts of mono- and / or dithiols in the resulting composition.

[0005] However, controlling and / or reducing the formation of these by-products, such as mono- and / or di-thiols, is important depending on the intended applications. Indeed, their content influences the degree of crosslinking of the materials subsequently prepared, particularly thermosetting materials produced from a polythiol-type resin and hardener. It has been demonstrated that the degree of crosslinking influences the physical and viscoelastic properties of polymers, such as their density, modulus, elastic limits, and glass transition temperature (Tv, or Tg). Tg is conventionally determined by Differential Scanning Calorimetry (DSC) or by dynamic mechanical analysis (DM(T)A). These parameters are directly related to the behavior of the materials, such as hardness, elasticity, flexibility, and tear resistance.

[0006] In particular, we seek to obtain polymers with a high glass transition temperature, in order to obtain materials with greater thermal resistance (i.e., which retain their characteristics over a wider temperature range).

[0007] There is therefore a need for an industrial polythiol preparation process that allows control, or even maximization, of the conversion of C=C double bonds into -SH functions. There is also a need for a polythiol preparation process that allows control, or even reduction, of the formation of by-products (for example, mono- and / or dithiols in the case of trithiol preparation, or sulfides).

[0008] One technical solution involves using 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 present a significant technical challenge for industrial implementation. They are generally very viscous or even solid compounds. This makes them difficult to handle for the deprotection step. Consequently, they generate numerous practical problems at the industrial level and are, in reality, rarely 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 evaporating this excess thiocarboxylic acid and / or purifying the polythioesters are necessary to carry out the subsequent deprotection step.

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

[0011] There is a need for polythiol compositions in which the proportion of -SH functions is controlled, or even maximized. The term "proportion of -SH functions" refers to the ratio of the mass of all -SH functions to the total mass of the composition.

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

[0013] The present invention aims to provide an improved method for preparing polythiol compositions in which the rate 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, -SH function ratio.

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

[0016] The present invention aims to provide polythiol compositions useful for the preparation of polymers, preferably thermosetting polymers.

[0017] The present invention meets all or part of the above objectives.

[0018] The present inventors have discovered, surprisingly, that it is possible to implement a "one-pot" (also called monotope) process for the synthesis of polythiols. A "one-pot process" is understood to mean, in particular, a process in which the synthesis intermediates (i.e., the polythioesters such as those according to the invention) are not isolated from the reaction medium to carry out the subsequent deprotection step. In the context of the industrial synthesis of polythiols, such a one-pot process offers numerous advantages.

[0019] In particular, the polythioester intermediate formation step according to the invention (hereinafter referred to as step a)) makes it possible to obtain a very good conversion (in particular between 90% and 100% polyene conversion) while avoiding the use of an excessive excess of thiocarboxylic acid. Indeed, a significant excess of thiocarboxylic acid is conventionally used in prior art processes, which represents a loss for the process and generates a large quantity of waste to be isolated and treated. Moreover, 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 as well as an environmental advantage.

[0020] Another advantage of the present invention is that the reaction medium comprising the polythioester intermediates obtained at the end of step a) can be easily stirred and handled. In particular, it can be in the form of a liquid or a slightly viscous or viscous suspension. This avoids operational difficulties at an industrial level.

[0021] The reaction medium comprising the polythioester intermediates is also compatible with the deprotection step (hereinafter step b)), which represents a simplification of the process.

[0022] Thus, steps a) and b) according to the invention are carried out in a "one pot" process. The process is therefore significantly improved because the intermediate steps of removing excess thiocarboxylic acid and / or purifying polythioester intermediates, such as extraction, recrystallization and / or distillation, are thus avoided.

[0023] The polythiol compositions that can be obtained by the process according to the invention are novel and have a controlled, or even maximized, -SH content. They are characterized in particular by a high mass ratio pdythwï as defined below. (x-i)thiol(s) For example, in the case of a starting triene, said mass ratio is the dithiol(s) ratio

[0024] These compositions are particularly well-suited to 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, it is possible to obtain polymers with a higher Tg value, and therefore higher thermal resistance, and / or higher compressive strength properties and / or a larger modulus and elastic range.

[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 deprotection step is carried out on the polythioester obtained in step a), so as to obtain a polythiol;

[0026] wherein step a) and step b) are carried out in one pot (or monotope) synthesis.

[0027] The present invention also relates to a polythiol composition A obtained starting from a cycloaliphatic polyene containing x C=C double bonds, said composition comprising: - the polythiol corresponding to the cycloaliphatic polyene comprising x -SH functions; and - the thiol(s) corresponding to the cycloaliphatic polyene comprising (x-1) -SH functions; and

[0028] in which the mass ratio ^yMol is between 10.1:1 and 50,000:1, of (x- μ)thiol(s) preference between 10.1:1 and 20,000:1; and

[0029] x being an integer greater than or equal to 3.

[0030] The present invention relates to a polythiol composition B obtained from an isocyanurate of the following general formula (I):

[0031] [Chem.l] R or A, 4) R" Sç. n

[0032] (in which R is a linear or branched hydrocarbon chain comprising at least one C=C double bond, possibly comprising one or more heteroatom(s), such as oxygen, nitrogen, sulfur and / or phosphorus, and possibly comprising one or more chemical group(s);

[0033] said composition comprising: - the polythiol corresponding to the isocyanurate comprising x -SH functions; and - the corresponding thiol(s) of the isocyanurate comprising (x-1) -SH functions;

[0034] in which the mass ratio potyl M is between 2:1 and 50,000:1, of (x-i)thiol(s) preference between 2:1 and 20,000:1; and

[0035] x being an integer greater than or equal to 3.

[0036] By "alkyl" is understood in particular a saturated hydrocarbon radical, linear, branched or cyclic, comprising from 1 to 10, preferably from 1 to 4, carbon atoms.

[0037] By "aryl" is meant in particular an aromatic cyclic hydrocarbon radical (monocyclic, bicyclic or tricyclic) comprising 6 to 10 carbon atoms, preferably a phenyl or a naphthyl, more preferably a phenyl.

[0038] By "aralkyl", we mean in particular an alkyl substituted by an aryl, for example benzyl. Polyenes#

[0039] The term "polyene" means any organic compound comprising at least 3 C=C double bonds. Hereinafter "x" is 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, and even more preferably between 3 and 5.

[0040] Said polyene can be functionalized (i.e. include one or more chemical functions). Said polyene represents in particular a linear, branched, cyclic or branched cyclic hydrocarbon chain, which may optionally include one or more heteroatom(s), such as halogens, silicon, oxygen, nitrogen, sulfur and / or phosphorus, and which may optionally include one or more chemical group(s), for example selected from halogens, -OH, -C(O)-, amine, amide, ester, ether, urea, thioether, sulfoxide, sulfone, carbamate or thiocarbamate, preferably -OH or ether.

[0041] Such chemical groups are, for example, selected from: -OH, -C(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

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052] , -OC(=S)-NR8R9, -SC(=O)-NH2, -SC(=O)-NHR8, -SC(=O)-NR8R9, -S(=O)R8 or -S(=O)2R8, and in which R7, R8 and R9 are independently chosen from among the alkyls as defined above. The polyene may contain between 4 and 40, for example between 4 and 30, preferably between 4 and 20, and preferably between 10 and 15, carbon atoms. It is notably aliphatic (i.e., non-aromatic). Preferably, said polyene is chosen from: cycloaliphatic polyenes and polyenes of general formula (I) as defined below. • Cycloaliphatic polyenes The term "cycloaliphatic polyene" refers to non-aromatic cyclic polyenes. They can be cyclic and branched, as in the case of trivinylcyclohexane. Preferably, they are unbranched 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. Preferably, said cycloaliphatic polyene is 1,5,9-cyclododecatriene (1,5,9-CDT or CDT hereafter). In particular, we can mention its isomers, with the following formulas: [Chem. 8] We particularly prefer cz5,tran5,tran5-l,5,9-cyclododecatriene, with the following formula: [Chem 9] • Isocyanurate-type polyenes with the following general formula (I): [Chem.l]

[0053] wherein R is a linear or branched hydrocarbon chain comprising at least one C=C double bond, optionally comprising one or more heteroatom(s), such as oxygen, nitrogen, sulfur and / or phosphorus, and optionally comprising one or more chemical group(s) (in particular such as those mentioned above).

[0054] Preferably, R comprises a single C=C double bond and may optionally comprise one or more heteroatom(s), and in particular oxygen.

[0055] Preferably, R comprises between 2 and 15 carbon atoms, for example between 2 and 5 carbon atoms.

[0056] The following two compounds are particularly preferred:

[0057] [Chem.2] O A ^^CH2 NO^N^O , triallyl isocyanurate (hereinafter TAIC), and

[0058] [Chem.3] k Q.A-O ; , trimethallyl isocyanurate.

[0059] In particular, said polyene is chosen from CDT and TAIC. • Triene s

[0060] Preferably, said polyene is a triene. By triene, we mean a polyene as defined above and comprising only 3 C=C double bonds (i.e. x=3).

[0061] It is notably chosen from among:

[0062] - linear, branched or cycloaliphatic hydrocarbon trienes; and

[0063] - the trienes of general formula (I) as defined above and in which R includes a single C=C double bond.

[0064] Among triena, we can specifically mention:

[0065] trivinylcyclohexane, trivinylbenzene, cycloheptatriene, dimethylheptatriene, octatriene, cyclooctatriene, cyclododecatriene (CDT), triallyl isocyanurate (TAIC), triallyl cyanurate, trimethylallyl isocyanurate, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, trimethylolpropane triallyl ether and triallylamine.

[0066] The preferred trienes according to the invention are cyclododecatriene (CDT) and triallyl isocyanurate (TAIC). Polythiols

[0067] According to the invention, the polythiol corresponding to the starting polyene as defined above is called "polythiol".

[0068] By "corresponding to the starting polyene," it is meant that the structure of the starting polyene and the resulting polythiol are identical, except for the C=C double bonds, which have been converted into -SH functions (i.e., -CH-C(SH)-): for x C=C double bonds in the starting polyene, x -SH functions are obtained, with x as defined above. The term "polythiol" also includes polythiols that are positional isomers of the double bonds in the starting polyene. Polythiols according to the invention may also be called (x)thiols. Polythioester intermediates

[0069] The term "intermediate polythioester" or "polythioester" refers to the polythioester corresponding to the starting polyene. "Corresponding to the starting polyene" means that the structure of the starting polyene and the resulting polythioester are identical, except that the C=C double bonds have been converted into -CH-C(O)-S-Ri functional groups (Ri depends on the thiocarboxylic acid used, preferably Ri is a methyl group): for x C=C double bonds, x thioester functional groups are obtained, with x as defined above. The term "polythioesters" also includes polythioesters that are positional isomers of the double bonds of the starting polyene. METHOD ACCORDING TO THE INVENTION Step a)

[0070] 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.

[0071] The reaction is as follows: R-CH=CH-R + RrC(O)-SH -> R-CH2-CH(SC(O)-Ri)-R

[0072] Step a) is carried out in the presence of oxygen (O2), which acts here as a reaction initiator. Step a) can therefore be carried out in the presence of air, depleted air (a 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 during the entire duration of step a) or not.

[0073] In particular, oxygen is bubbled into the reaction medium, preferably in the form of depleted air. For example, depleted air is passed through a sintered diffuser that is immersed in the reaction medium. Alternatively, oxygen can be bubbled into the reaction medium and nitrogen introduced into the gas phase of the reactor (i.e., the reactor headspace).

[0074] The oxygen flow rate can be between 0.01 and 100 nL / h, preferably between 0.05 and 10 nL / h, preferably again between 0.05 and 5 nL / h, in particular between 0.05 and 2 nL / h (normo litres / h).

[0075] Step a) is carried out in particular in the absence of any other initiator of the reaction, and more preferably in the absence of AIBN (azobisisobutyronitrile) and / or in the absence of UV radiation.

[0076] 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 preferred. The solvent(s) may be protic or aprotic. Examples of solvents that may be used include: alcohols, ethers (preferably cyclic ethers and glycol ethers such as dialkyl glycol ethers), organochlorine solvents, carboxylic acids, or mixtures thereof.

[0077] Alcohols are preferred, in particular those of the following general formula (IV):

[0078] R4-OH (IV)

[0079] 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, preferably ethanol.

[0080] Preferably, the solvent is chosen from the group consisting of: tetrahydrofuran (THF), 2-methyltetrahydrofuran (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.

[0081] The amount of solvent used is generally chosen according to the desired viscosity of the reaction medium. Total or partial solubilization can be achieved by those skilled in the art, depending on the target viscosity of the reaction medium. Preferably, between 1 and 50 molar eq., and even more preferably between 1 and 20 eq. of solvent(s) relative to the polyene, is used.

[0082] The solvent can be added from the beginning of step a) in whole or in part. It can be added at one point, in several stages (semi-continuous) or gradually (continuously), during step a).

[0083] The thiocarboxylic acid preferably has the following general formula (II):

[0084] RrC(O)-SH (II)

[0085] in which:

[0086] Ri represents an alkyl radical, an aryl radical or an aralkyl radical as defined above.

[0087] Preferably, Ri is chosen from methyl, ethyl and benzyl.

[0088] Thioacetic acid, for which Ri is a methyl group, is particularly preferred according to the invention. For example, with thioacetic acid, a polythioacetate is obtained as a polythioester intermediate.

[0089] According to one embodiment, thiocarboxylic acid can be generated in situ (cf. US document 3,270,063, THOMPSON CHEMICAL CO, 1963: “Methods of making primary mercaptans”): thioacetic acid can be produced from acetic anhydride and hydrogen sulfide, in the presence of a catalyst.

[0090] Preferably, to carry out step a), the thiocarboxylic acid and the solvent(s) are introduced into the reactor first, then oxygen is introduced, for example by bubbling air. The polyene can then be added to the reaction mixture.

[0091] The temperature of step a) can be between 5 and 80°C, preferably between 5 and 50°C, more particularly between 5 and 25°C, for example between 5 and 10°C. Step a) is generally carried out at atmospheric pressure.

[0092] The thiocarboxylic acid / polyene double bond molar ratio can be between 1 and 20, preferably between 1 and 10, for example between 1 and 5, preferably still between 1 and 3.

[0093] Step a) allows the formation of a polythioester intermediate as defined above, starting from a polyene. The reaction medium obtained at the end of step a) may thus comprise: - a polythioester intermediate as defined above; - the solvent or mixture of solvents as defined above; - possibly by-products such as (xl)polythioesters; and - possibly one or more reagents that did not react.

[0094] By "(xl)polythioester", we mean in particular a compound comprising x-1 thioester functions, with x being as defined above. It is a compound having retained a C=C double bond (i.e., a C=C double bond that has not reacted).

[0095] The reaction medium can thus comprise between 10% and 85% by weight of polythioester intermediate, relative to the total reaction medium.

[0096] The reaction medium may comprise between 15% and 90% by weight of solvent(s), relative to the total reaction medium. Step b)

[0097] Step b) of deprotection of the polythioester intermediate obtained in step a) yields a polythiol. It can be carried out by any means known to those skilled in the art. Since steps a) and b) are performed 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 mixture of solvents) during step b). In particular, the process according to the invention does not include any step of separation and / or extraction and / or washing of the (organic) phase comprising the polythioester between steps a) and b). In particular, no intermediate step of purification of the polythioester is carried out. More specifically, no recrystallization and / or distillation step of the polythioester is carried out.

[0098] 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).

[0099] 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 made dropwise.

[0100] Step b) of deprotection can also be acid deprotection, preferably in the presence of an alcohol as defined above. It can be carried out with hydrochloric acid, methanesulfonic acid, or anhydrous methanesulfonic acid. When the deprotection is acidic, it is preferable to use an alcohol as defined above as the solvent.

[0101] Sulfonic acid

[0102] The sulfonic acid is preferably an organosulfonic acid, possibly anhydrous.

[0103] Sulfonic acid can have the following general formula (III):

[0104] R2-SO3H (III),

[0105] where R2 represents:

[0106] - an alkyl radical, preferably as defined above, optionally substituted, in whole or in part, by one or more identical or different halogen atoms, or

[0107] - an aryl radical, preferably as defined above, optionally substituted by a saturated hydrocarbon chain, linear or branched, comprising 1 to 4 carbon atoms.

[0108] The halogen atom can be chosen from fluorine, chlorine, and bromine. In particular, said alkyl can be perhalogenated, more particularly perfluorinated.

[0109] Preferably, the sulfonic acid is an alkane-sulfonic acid, possibly anhydrous (in the formula above, R2 is an alkyl).

[0110] Thus, sulfonic acids (as well as their anhydrous forms) can be chosen from:

[0111] methanesulfonic acid, ethanesulfonic acid, n-propanesulfonic acid, Ao-propanesulfonic acid, n-butanesulfonic acid, Ao-butanesulfonic acid, sec-butanesulfonic acid, / e / 7-butanc-sulionic acid, trifluoromethanesulfonic acid, para-toluenesulfonic acid, benzenesulfonic acid and mixtures of two or more of them in any proportions.

[0112] 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 (ASA).

[0113] Said sulfonic acid may or may not be tolerated. Preferably, it is not tolerated.

[0114] When supported, sulfonated resins of the type can be used, for example. styrene-divinylbenzene copolymer, for example Amberlyst® 15 resin, or Nafion®.

[0115] For example, between 0.1 and 10 eq. of acid are used for a polythioester.

[0116] For example, between 3 and 60 eq. are used, preferably between 3 and 20 eq. (equivalent molar) of alcohol for a polythioester.

[0117] Step b) of deprotection can be carried out at a temperature between 10 and 100°C, preferably between 25 and 80°C, and even more preferably between 40 and 80°C. It is generally carried out at atmospheric pressure.

[0118] Steps a) and b) can be carried out in the same reactor. For example, a batch reactor can be used.

[0119] Subsequent conventional recovery and / or purification steps 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 achieved by the addition of a base, the reaction medium can then be acidified, and conversely: when deprotection is achieved by the addition of an acid, the reaction medium can be made alkaline. The resulting organic phase, comprising the various thiols (in particular the polythiol and the (xl)thiols), can then be extracted and possibly concentrated.

[0120] Thus and in particular, the polythiol obtained may be in the form of a polythiol composition as mentioned below. COMPOSITIONS ACCORDING TO THE INVENTION

[0121] 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 total and by-products may form at each of the different steps, regardless of the process used.

[0122] According to the invention, the polythiol corresponding to the starting polyene and comprising x -SH functional groups is therefore called a "polythiol". For example, trimercaptocyclododecane corresponds to cyclododecatriene. In this case, the conversion of the x starting C=C double bonds into -SH functional groups is complete.

[0123] According to the invention, a thiol corresponding to the starting polyene and comprising (x-1) -SH functional groups is called "(xl)thiol". By "corresponding to the starting polyene", it is understood that the structures of the starting polyene and the (xl)thiol obtained are identical, except for the x C=C double bonds which have been converted into (x-1) -SH functional groups. In this case, the conversion of the C=C double bonds into -SH functional groups was not complete: one -SH functional group is missing. The C=C double bond not converted into a -SH functional group may, in particular, be: - always in the form of a C=C double bond; or - in the form of a thioester function that has not been deprotected.

[0124] There can therefore be different structures of (xl)thiols, but they are grouped here under this general designation characterizing their number of -SH functions (unless otherwise specifically stated). Also included are (xl)thiols that are positional isomers of the double bonds of the starting polyene.

[0125] A polythiol composition can thus be obtained from a polyene having x C=C double bonds and comprising:

[0126] - the polythiol corresponding to said polyene comprising x -SH functions; and

[0127] - the thiol(s) corresponding to said polyene comprising (x-1) -SH functions.

[0128] Such a composition may optionally include other by-products or impurities (for example, monothiols). It can be characterized by the polythiol mass ratio; 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].

[0129] In particular, a trithiol composition can be obtained from a triene, said composition comprising: - the corresponding trithiol; and - the corresponding dithiol(s).

[0130] 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 at the end of step a):

[0131] [Chem.4]

[0132] During step b), it is also possible that the deprotection is not total.

[0133] Thus, it is possible to form according to the process according to the invention: - (xl)thiols from the (xl)thioesters formed in step a); and / or - (xl)thiols from polythioesters that are not totally unprotected.

[0134] In the case of CDT, the following dithiols can therefore be obtained at the end of step b):

[0135] [Chem.5]

[0136] Composition A obtained from a cycloaliphatic polyene

[0137] 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 the cycloaliphatic polyene comprising x -SH functions; and - the thiol(s) corresponding to the cycloaliphatic polyene comprising (x-1) -SH functions (also called (xl)thiols as explained above),

[0138] with x as defined above.

[0139] In particular, said composition A comprises at least 85% by weight, preferably at least 90% by weight, preferably again at least 95% by weight of said polythiol, relative to the total weight of composition A.

[0140] In particular, said composition A comprises less than 9% by weight, preferably less than 5% by weight, preferably even less than 1% by weight of said (xl)thiol(s), relative to the total weight of said composition A.

[0141]

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[0146]

[0147]

[0148] Preferably, the mass ratio pdyMol of composition A is between (x-i)thiol(s) 10.1:1 and 20,000:1, preferably between 10.5:1 and 20,000:1, preferably still between 15:1 and 20,000:1, for example between 15:1 and 20,000:1. In a particularly preferred way, the mass ratio of the composition A is between 10.1:1 and 10,000:1, preferably between 10.5:1 and 10,000:1, and even 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 (xA)thiol(s) 10.5:1 and 1000:1. The preferred starting cycloaliphatic polyene is cyclododecatriene, preferably 1,5,9-cyclododecatriene, and even more preferably 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; - dimercaptocyclododecene; and - of S-[bis(sulfanyl)cyclododecyl]ethanethioate. Thus, the mass ratio [trimercaptocyclododecane / (dimercaptocyclododecene + S-[bis(sulfanyl)cyclododecyl]ethanethioate) ] is notably as defined above. Composition B obtained from an isocyanurate-type polyene The present invention also relates to a composition B of polythiol obtained from an isocyanurate of the following general formula (I) and as defined above: [Chem.l] R

[0149]

[0150] in which R is a linear or branched hydrocarbon chain comprising at least one C=C double bond, possibly comprising one or more heteroatom(s), such as oxygen, nitrogen, sulfur and / or phosphorus, and possibly comprising one or more chemical group(s); said composition comprising: - the polythiol corresponding to the isocyanurate comprising x -SH functions; And - the (xl)thiol(s) corresponding to the isocyanurate comprising (x-1) -SH functions, with x as defined above.

[0151] In particular, said composition B comprises at least 70% by weight, preferably at least 80% by weight, preferably still 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.

[0152] In particular, said composition B comprises less than 30% by weight, preferably less than 20% by weight, preferably even less than 10% by weight, for example less than 5%, or even less than 1% by weight of said (xl)thiol(s), relative to the total weight of said composition B.

[0153] Preferably, the mass ratio of polythiol to composition B is between 2:1 and 20,000:1, for example between 2.3:1 and 20,000:1, preferably between 4:1 and 20,000:1, preferably again between 9:1 and 20,000:1, for example between 19:1 and 20,000:1.

[0154] Preferably, the mass ratio polythiol i |a composition B is between (x- l)thiol(s) 2:1 and 10,000:1, for example between 2.3:1 and 10,000:1, preferably between 4:1 and 10,000:1, preferably still between 9:1 and 1,000:1, for example between 100:1 and 1,000:1.

[0155] Even more preferably, the mass ratio polythiol i |a composition B is (x-i)thiol(s) between 10:1 and 1000:1.

[0156] The preferred starting isocyanurate is triallyl isocyanurate.

[0157] In particular, a polythiol composition B is obtained from triallyl isocyanurate as defined above, said composition comprising: - of 1,3,5-tris(3-mercaptopropyl)-1,3,5-triazinane-2,4,6-trione, as well as its isomers; and - the corresponding dithiols (B1) and (B2) of the following formulas, as well as their isomers:

[0158] [Chem.6] (81) And

[0159] [Chem.7] <B2)

[0160] Thus, the mass ratio [(l,3,5-tris(3-mercaptopropyl)-l,3,5-triazinane-2,4,6-trione) / (B1+B2)] is in particular as defined above.

[0161] The above compositions are novel and therefore form part of the present invention.

[0162] The present invention also relates to said polythiol compositions which may be obtained, obtained or directly obtained by the process according to the invention.

[0163] The present invention also relates to polythiols obtained or directly obtained by the process according to the invention.

[0164] It is understood that, unless a specific isomer is mentioned, the name of a compound includes all of its possible positional isomers.

[0165] It is understood that given ranges such as "between X and X" include upper and lower limits.

[0166] The following examples are given for illustrative purposes only and are not limiting to the present invention. EXAMPLES#:

[0167] EXAMPLE 1: One-pot synthesis of a polythiol composition from CDT according to the invention, with basic deprotection

[0168] Step a):

[0169] In a double-jacketed IL reactor, 155 g (2.04 moles) of ATA (thioacetic acid) are introduced. The mixture is stirred at 5°C, and then 28.4 g (0.62 moles) of ethanol are rapidly added. Air is bubbled into the reaction mixture via a sintered nozzle at a flow rate of approximately 0.4 Nl / h, and nitrogen is introduced into the reactor head at a flow rate of approximately 4 Nl / h.

[0170] 100g (0.62 moles) of 1,5,9-cyclododecatriene (CDT) are then added dropwise to drop via a peristaltic pump for approximately 1h. Once the addition is complete, 113.6g (2.47 moles) of EtOH are added to the reaction medium.

[0171] The reaction medium is kept under stirring at about 5°C overnight.

[0172] A GC / FID analysis shows complete conversion of 1,5,9-cyclododecatriene.

[0173] The air supply is cut off.

[0174] Basic deprotection step b:

[0175] 171 g of EtOH are then added to the reaction medium. The reaction medium The mixture is then degassed with nitrogen for 1 hour and heated to approximately 40°C. 177 g of a previously degassed 46% aqueous sodium hydroxide solution are added via a dropping funnel. The reaction mixture is stirred under nitrogen at 40°C for 2 to 3 hours.

[0176] Recovery stage:

[0177] The reaction medium is then cooled to 20°C and 200 g (2.03 moles) of 37% HCl are added dropwise via a peristaltic pump. The organic phase, including the thiols, is withdrawn. The aqueous phase is extracted with 105 g (1.24 moles) of dichloromethane.

[0178] The organic phases are then collected and washed with 4 times 14.8g (0.82 moles) of water and then concentrated in the rotary evaporator.

[0179] A GC / FID analysis shows complete conversion of trithioacetate.

[0180] The resulting composition comprises:

[0181] - 0.36% of the dithiol corresponding to CDT with 1 residual double bond,

[0182] - 0.47% of the dithiol-monothioacetate corresponding to CDT,

[0183] - 95.87% of trimercaptocyclododecane, and

[0184] - the remainder in impurities (100%).

[0185] The mass ratio pdythM is 95.87:0.83, or 116:1. (x- )thiol(s)

[0186] EXAMPLE 2: One-pot synthesis of a polythiol composition from CDT according to the invention, with acid deprotection (AMSA)

[0187] Step a):

[0188] In a double-jacketed IL reactor, 155 g (2.04 moles) of ATA are introduced. The mixture is stirred at 5°C, and then 29 g (0.63 moles) of ethanol are rapidly added. Air is bubbled into the reaction mixture via a sintered nozzle at a flow rate of approximately 0.4 Nl / h, and nitrogen is introduced into the reactor head at a flow rate of approximately 4 Nl / h.

[0189] 100g (0.62 moles) of 1,5,9-cyclododecatriene are then added dropwise via a peristaltic pump for about 1h. Once the addition is complete, 113.6g (2.47 moles) of EtOH are added to the reaction medium.

[0190] The reaction medium is kept under stirring at about 5°C overnight.

[0191] A GC / FID analysis shows complete conversion of 1,5,9-cyclododecatriene.

[0192] The air supply is cut off.

[0193] Step b) of acid deprotection:

[0194] The temperature of the reaction medium was raised to 20°C, and 85 g (1.85 moles) of EtOH were added to the reaction medium. 74 g of anhydrous methanesulfonic acid (0.77 moles) are added dropwise via a dropping funnel. The medium is stirred under reflux in nitrogen for 100 minutes.

[0195] Recovery stage:

[0196] The reaction medium is then cooled to 20°C, and 154 g (0.77 moles) of a previously degassed 20% NaOH solution are added dropwise via a peristaltic pump. The organic phase, including the thiols, is withdrawn. The aqueous phase is extracted with 105 g (1.24 moles) of dichloromethane.

[0197] The organic phases are collected, then washed 4 times with 14.8g (0.82 moles) of water and then concentrated in the rotary evaporator.

[0198] A GC / FID analysis shows complete conversion of trithioacetate.

[0199] The resulting composition comprises:

[0200] - 5.26% of the dithiol corresponding to CDT with 1 residual double bond,

[0201] - 0.58% of the dithiol-monothioacetate corresponding to CDT,

[0202] - 90.60% of trimercaptocyclododecane, and

[0203] - the remainder in impurities (100%).

[0204] The polythiol mass ratio is 90.60:5.84 or 16:1. (x-)thiol(s)

[0205] EXAMPLE 3: One-pot synthesis of a polythiol composition from TAIC according to the invention with basic deprotection Step a)#:

[0206] In a double-jacketed IL reactor, 101 g (1.33 moles) of ATA are introduced. The mixture is stirred at 5°C, and then 92 g (2.00 moles) of EtOH are rapidly added. Air is bubbled into the reaction mixture via a sintered nozzle at a flow rate of approximately 0.4 Nl / h, and nitrogen is introduced into the reactor head at a flow rate of approximately 4 Nl / h.

[0207] 100g (0.40 moles) of triallyl isocyanurate (TAIC) in solution in 19g (0.41 moles) of EtOH are then added dropwise via a peristaltic pump for approximately 40 minutes. Once the addition is complete, 148 g (3.21 moles) of EtOH are gradually added to the reaction mixture.

[0208] The reaction medium is kept under stirring at approximately 5°C for about 6 hours.

[0209] A GC / FID or HPLC / UV analysis shows complete conversion of triallyl isocyanurate.

[0210] The air supply is cut off.

[0211] Step b) of basic deprotection:

[0212] The reaction mixture is then degassed with nitrogen for 1 h, and then 115.1 g of a previously degassed 46% aqueous sodium hydroxide solution is added dropwise via a dropping funnel. The reaction mixture is stirred under nitrogen at 25 °C for 5 h and then cooled to 10 °C for approximately 17 h.

[0213] Recovery stage:

[0214] The reaction medium is then cooled to 20°C, and 483 g (1.32 moles) of a 10% HCl solution are added dropwise via a peristaltic pump. The organic phase, including the thiols, is withdrawn. The aqueous phase is extracted with three times 68 g (0.80 moles) of dichloromethane.

[0215] The organic phases are collected, then washed twice with 14.4g (0.80 moles) of water and then concentrated in the rotary evaporator.

[0216] A GC / FID analysis shows complete conversion of trithioacetate.

[0217] A polythiol composition comprising 95% by weight of trithiol corresponding to TAIC and about 0.2% by weight of dithiol corresponding to TAIC, relative to the total weight of the composition, is obtained.

[0218] The mass ratio pdythid. is 95:0.2 or 475:1. (x-ï)thiol{s)

[0219] EXAMPLE 4: One-pot synthesis of a polythiol composition from CDT according to the invention, with acid deprotection (HCl)

[0220] Step a):

[0221] 155 g (2.04 moles) of ATA are introduced into a 3 L double-jacketed reactor. The mixture is stirred at 5°C, and then 19.8 g (0.62 moles) of MeOH are rapidly added. Air is bubbled into the reaction mixture via a sintered sinter at a flow rate of approximately 0.4 Nl / h, and nitrogen is introduced into the reactor head at a flow rate of approximately 4 Nl / h.

[0222] 100g (0.62 moles) of 1,5,9-cyclododecatriene are then added dropwise via a peristaltic pump for approximately 1h. Once the addition is complete, 78.9g (2.46 moles) of MeOH are added to the reaction medium.

[0223] The reaction medium is kept under stirring at approximately 5°C overnight.

[0224] A GC / FID analysis shows complete conversion of 1,5,9-cyclododecatriene.

[0225] The air supply is cut off.

[0226] Step b) of acid deprotection:

[0227] The reaction mixture was brought back to 20°C, 1119 g (34.93 moles) of MeOH were added to the reaction mixture. The mixture was heated to 40°C, and 576.9 g (5.85 moles) of 37% HCl were added dropwise via a peristaltic pump, then the mixture was heated under reflux in nitrogen for 48 h.

[0228] Recovery stage:

[0229] The reaction medium is then cooled to 20°C, the organic phase comprising the thiols is withdrawn, and 105g (1.24 moles) of dichloromethane is then added to the aqueous phase.

[0230] The organic phases are collected and then washed four times with 74g (4.11 moles) of water and then concentrated in the rotary evaporator.

[0231] A GC / FID analysis shows complete conversion of trithioacetate. A polythiol composition comprising 96.28% trimercaptocyclododecane and 0.25% dithiol(s) corresponding to CDT is obtained.

[0232] The mass ratio p <AyMol est de 96,28:0,25 soit 385:1.

Claims

Demands

1. A process for preparing a polythiol comprising 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 said at least one solvent; and b) carrying out a deprotection step of the polythioester obtained in step a), so as to obtain a polythiol; wherein steps a) and b) are carried out in one pot synthesis, the reaction medium comprising the polythioester obtained at the end of step a) being retained to carry out the deprotection step b);and in which the polyene is chosen from among cycloaliphatic polyenes comprising at least three C=C double bonds, and isocyanurate polyenes of the following general formula (I): R cv A ^0 AA 8 (1), in which R is a linear or branched hydrocarbon chain comprising at least one C=C double bond, possibly comprising one or more heteroatom(s), such as oxygen, nitrogen, sulfur and / or phosphorus, and possibly comprising one or more chemical group(s).

2. A preparation method according to claim 1, wherein the deprotection step b) is a basic deprotection, preferably carried out by adding an alkali hydroxide.

3. A method according to claim 1, wherein the deprotection step b) is an acid deprotection, preferably in the presence of an alcohol.

4. A preparation method according to any one of the preceding claims, wherein said organic solvent is selected from the group consisting of: alcohols, ethers, organochlorine solvents, carboxylic acids or mixtures thereof.

5. A preparation method according to any one of the preceding claims, wherein the organic solvent is selected from the alcohols of the following general formula (IV): R4-OH (IV) in which R4 represents a saturated hydrocarbon radical, linear, branched or cyclic, comprising from 1 to 10, preferably from 1 to 4, carbon atoms.

6. A preparation method according to any one of the preceding claims, wherein the thiocarboxylic acid is thioacetic acid.

7. A preparation method according to any one of the preceding claims, wherein said polyene is a triene.

8. 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 wherein the mass ratio is between 10.1:1 and (x-1)thiol(s) 50,000:1; x being an integer greater than or equal to 3.

9. Composition A of polythiol according to claim 8, wherein said cycloaliphatic polyene is cyclododecatriene, preferably its cis,trans,trans-l,5,'9-cyclododecatriene isomer.

10. Composition B of polythiol obtained from an isocyanurate of the following general formula (I): [Chem 1] R (k À AO ■Ç- AAR" R ô (1). wherein R is a linear or branched hydrocarbon chain comprising at least one C=C double bond, optionally comprising one or more heteroatom(s), such that oxygen, nitrogen, sulfur and / or phosphorus, and may possibly include 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; wherein the polythiol mass ratio is between 2:1 and 50 (x-οthiofis) 000:1; and x being an integer greater than or equal to 3.

11. Composition B of polythiol according to claim 10, wherein the isocyanurate is triallyl isocyanurate.