Polythiol compositions and methods of making same from terpenes or terpene derivatives

Abstract

The present invention relates to a process for preparing a polythiol from a terpene or a terpene derivative, as well as a polythiol composition and a novel polythiol. The method comprises the following steps: a)-reacting a terpene or a terpene derivative with a thiocarboxylic acid in the presence of oxygen (O2) and at least one organic solvent, in order to obtain a reaction medium comprising a polythioacid ester and at least one solvent; b) deprotecting the polythioacid ester obtained in stage a) in order to obtain a polythiol; wherein the stage a) and the stage b) are carried out in one-pot synthesis.

Description

Technical Field

[0001] This invention relates to a method for preparing polythiol compositions using terpenes or terpene derivatives as starting reactants, and also to polythiol compositions that can be obtained by this method. Background Technology

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

[0003] Several synthetic routes exist for obtaining polythiols. Among the most widely used methods, the reaction between a polyol and a mercapto acid can be mentioned (described, for example, in application US2005153231). Although this reaction is straightforward and allows for the acquisition of various polythiolastic structures, the resulting products typically exhibit low hydrolytic resistance due to the prominent presence of ester functional groups.

[0004] Alternatively, the direct addition of hydrogen sulfide to polyenes via acid or photocatalysis can yield molecules without hydrolyzable functional groups. This addition is specifically described in application WO 12018757. However, using this method, a large number of sulfide-type compounds can be generated, and conversion problems may arise depending on the reactants used. Consequently, the resulting molecules may contain many unconverted double bonds, which introduces stability issues and reduces the total content of -SH functional groups. This is particularly evident, for example, in the case of triene-type starting reactants, through the presence of a large amount of monothiols and / or dithiols in the resulting compositions.

[0005] In fact, depending on the target application, controlling and / or reducing the formation of these byproducts, such as monothiols and / or dithiols, is important. This is because their content affects the degree of crosslinking of the subsequently prepared materials, particularly thermosetting materials produced from resins and hardeners of the polythiol type. Therefore, the degree of crosslinking has been shown to affect the physical and viscoelastic properties of polymers, such as their density, modulus, limits of their elastic range, or glass transition temperature (Tg). Tg is routinely determined by DSC methods for differential scanning calorimetry or by dynamic mechanical analysis (DM(T)A). These parameters are directly related to the behavior of the material, such as hardness, elasticity, flexibility, or tear strength.

[0006] In particular, there is a search for polymers with high glass transition temperatures in order to obtain materials with high heat resistance (that is, materials that retain their properties over a wide temperature range).

[0007] Therefore, there is a need for an industrial method for the preparation of polythiols that allows for controllability, and in fact, even maximization, of the conversion of C=C double bonds to -SH functional groups. There is also a need for a method for the preparation of polythiols that allows for controllability, and in fact, even reduction, of the formation of byproducts (e.g., monothiols and / or dithiols in the case of the preparation of trithiols or sulfides).

[0008] One technical solution involves converting the C=C double bond in a polythioester intermediate to a functional group of the type -R'-C(O)-S-R'', followed by deprotection to obtain the desired polythiol. However, these polythioester intermediates represent a significant technical challenge for industrial applications. They are typically very viscous, even solid compounds. Consequently, they are difficult to process to participate in the deprotection stage. Therefore, they cause numerous practical problems at the industrial level and are rarely used in practice.

[0009] Furthermore, these polythioesters are typically obtained by reacting polyenes with thiocarboxylic acids, particularly thioacetic acids. However, this reaction involves the use of a large excess of thiocarboxylic acid, which must be removed before the deprotection stage. Therefore, an additional stage is required to evaporate the excess thiocarboxylic acid and / or purify the polythioester in order to carry out the subsequent deprotection stage.

[0010] Finally, the reactants used in these methods are typically oil-derived hydrocarbons. Given current environmental and climate challenges, approaches using bio-based and / or renewable starting materials are desirable.

[0011] Therefore, an improved method is needed for the preparation of polythiols via polythioesters.

[0012] An improved method for preparing polythiols from bio-based and / or renewable starting materials is also needed.

[0013] A polythiol composition is required in which the content of -SH functional groups is controlled, and in fact even maximized. The term "content of -SH functional groups" should be understood as the ratio of the weight of all -SH functional groups to the total weight of the composition.

[0014] Polythiol compositions derived from bio-based and / or renewable materials are also required. Summary of the Invention

[0015] The objective of this invention is to provide an improved method for preparing polythiol compositions from terpenes or terpene derivatives, which simplifies its industrial implementation.

[0016] The object of this invention is to provide an improved method for preparing polythiol compositions from terpenes or terpene derivatives, wherein the content of -SH functional groups is controlled, and in fact even maximized, by means of the method.

[0017] Another object of the present invention is to provide improved polythiol compositions, particularly having a controlled, and in fact even maximized, content of -SH functional groups.

[0018] Another objective of the present invention is to provide polythiol compositions obtained from bio-based and / or renewable starting materials, namely terpenes and terpene derivatives.

[0019] One object of the present invention is to provide polythiol compositions for preparing polymers, preferably thermosetting polymers.

[0020] This invention is wholly or partially in response to the above objectives.

[0021] The inventors have surprisingly discovered that polythiols can be synthesized from terpenes or terpene derivatives using a "one-pot" method. The term "one-pot method" should be understood to specifically refer to a method in which synthetic intermediates (i.e., polythioesters as described in the invention) are not separated from the reaction medium for subsequent deprotection stages. Such a one-pot method exhibits numerous advantages in the context of the industrial synthesis of polythiols.

[0022] In particular, the formation stage of the polythioester intermediate according to the invention (hereinafter referred to as stage a) allows for very good conversion (especially 90% to 100% conversion of terpenes or terpene derivatives) while avoiding the use of excessive amounts of thiocarboxylic acids. In fact, prior art methods typically use large amounts of excess thiocarboxylic acids, which represents a loss to the method and generates a large amount of waste to be separated and treated. Furthermore, this excess is incompatible with the "one-pot" method, as it must be removed before the deprotection stage. The present invention allows these disadvantages to be avoided, representing both economic and environmental advantages.

[0023] Another advantage of this invention is that the reaction medium containing the polythioester intermediate obtained at the end of stage a) can be easily stirred and handled. It can be present, in particular, as a liquid or suspension, which is viscous or slightly viscous. This avoids difficulties in industrial-scale operability.

[0024] The reaction medium containing the polythioester intermediate is also compatible with the deprotection stage (hereinafter referred to as stage b), which represents a simplification of the method.

[0025] Therefore, for example, stages a) and b) according to the invention are carried out as a "one-pot" reaction. Thus, the method is significantly improved because it avoids intermediate stages such as extraction, recrystallization and / or distillation for removing excess thiocarboxylic acids and / or purifying polythioester intermediates.

[0026] Furthermore, terpenes and their derivatives have proven particularly useful as starting polyenes for the production of polythiols. Terpenes and their derivatives respond to many current environmental and climatic issues. They are typically bio-based, meaning they are produced from renewable organic matter (biomass) of plant or animal origin. They also exhibit great structural diversity, which enables their wide versatility in use.

[0027] The polythiol compositions obtainable by the method according to the invention are novel and exhibit controlled, and virtually even maximized, -SH content. They are particularly characterized by high... (as defined below) Weight ratio.

[0028] They are particularly suitable for materials made from resins, such as thermosetting plastics. Therefore, this invention makes it possible to obtain materials with excellent properties. For example, polymers with a high Tg, and thus excellent heat resistance and / or excellent compressive strength and / or a large modulus and a large elastic range, can be obtained.

[0029] Therefore, the present invention relates to a method for preparing polythiols, comprising the following stages:

[0030] a) Reacting a terpene or terpene derivative 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 organic solvent; and

[0031] b) Perform a stage to deprotect the polythioester obtained in stage a) to obtain a polythiol;

[0032] Stages a) and b) are carried out in a one-pot synthesis.

[0033] This invention relates to a polythiol composition A obtained from a terpene or terpene derivative having x C=C double bonds, said composition comprising:

[0034] - A polythiol containing x -SH functional groups corresponding to the terpene or a derivative of the terpene; and

[0035] - A thiol corresponding to the terpene or the terpene derivative containing (x-1) -SH functional groups, where x is an integer greater than or equal to 3; and preferably wherein... The weight ratio is between 1:1 and 50,000:1, preferably between 2:1 and 50,000:1.

[0036] The present invention also relates to a polythiol selected from trithiol derived from dihydrofarnesene, heptathiol derived from isosqualene, and tetrathiol derived from camphene.

[0037] The term "alkyl" should be understood, in particular, to refer to a saturated, straight-chain, branched, or cyclic hydrocarbon group comprising 1 to 10, preferably 1 to 4, carbon atoms.

[0038] The term "aryl" should be understood to specifically refer to a cyclic (monocyclic, bicyclic, or tricyclic) aromatic hydrocarbon group containing 6 to 10 carbon atoms, preferably phenyl or naphthyl, more preferably phenyl.

[0039] The term "aralkyl" should be understood to specifically refer to alkyl groups substituted with aryl groups, such as benzyl.

[0040] Terpenes

[0041] The term "terpene" should be understood specifically to refer to the isoprene repeating unit (C5C8). n The terpene is a straight-chain, branched, or cyclic hydrocarbon compound, where n is an integer between 2 and 8, preferably between 2 and 6. In particular, the terpene contains at least three C=C double bonds. Preferably, the terpene contains 3, 4, 5, or 6 C=C double bonds.

[0042] Terpenes are commercially available in the form of compositions comprising different isomers, the proportions of which can vary (particularly depending on the method of obtaining them). Such compositions are within the scope of this invention and can be used directly as starting reactants.

[0043] According to the table below, terpenes are typically classified based on the value of n (which corresponds to the number of carbon atoms):

[0044] [Table 1]

[0045]

[0046] Specifically, the terpene is selected from monoterpenes, triterpenes, and sesquiterpenes. More specifically, the terpene is selected from straight-chain or branched terpenes.

[0047] Among the preferred terpenes, myrcene and farnesene can be mentioned.

[0048] Myrcene:

[0049] Myrcene is a monoterpene. Various isomers of myrcene exist, including ocimene and alloocimene. In particular, α-myrcene, β-myrcene, cis-α-ocimene, trans-α-ocimene, cis-β-ocimene, trans-β-ocimene, 4-cis-6-cis-alloocimene, 4-cis-6-trans-alloocimene, 4-trans-6-cis-alloocimene, and 4-trans-6-trans-alloocimene (see […]) Figure 1 Preferably, β-myrcene of the following formula is used, in its natural form (CAS No.: 123-35-3):

[0050] [Chemistry 1]

[0051]

[0052] Farnese:

[0053] Farnese is a sesquiterpene. It exists in two isomers: α-farnese (CAS No.: 502-61-4) and β-farnese (CAS No.: 502-60-3).

[0054] [Chemistry 2]

[0055]

[0056] α-farnesene

[0057]

[0058] β-farnesene

[0059] More specifically, cis-α-farnesene, trans-α-farnesene, cis-β-farnesene, and trans-β-farnesene may be mentioned. β-farnesene is preferred, and trans-β-farnesene (CAS No.: 18794-84-8) is more preferred.

[0060] Other terpenes that may be used include humulene (CAS 6753-98-6), elemene, gemmaene, bisabolene, cembrene, casbene, zingiberene, camphene, and their isomers. In particular, the following isomers may be mentioned: α-elemene, β-elemene, γ-elemene, δ-elemene, gemmaene A, gemmaene B, gemmaene C, gemmaene D, gemmaene E, α-bisabolene, β-bisabolene, and γ-bisabolene.

[0061] Terpene derivatives:

[0062] The term "terpene derivative" is understood to specifically refer to compounds whose structure is derived from that of terpenes. They can be produced by chemical transformation of the latter or can exist naturally. In particular, said terpene derivatives contain at least three C=C double bonds, for example, 3 to 10 C=C double bonds.

[0063] The following terpene derivatives may be mentioned.

[0064] Hydrogenated derivatives of terpenes or hydrogenated terpenes:

[0065] The term "hydrogenated derivatives of terpenes" is understood to specifically refer to empirical formulas (C... 5n H 8n+2zThe compound is z, which is an integer at least equal to 1, and n is as defined above. Preferably, z is between 1 and 10, more preferably between 1 and 3.

[0066] Among the hydrogenated derivatives, squalene and dihydrofarnese are particularly preferred.

[0067] Squalene (CAS No.: 111-02-4) has the following formula:

[0068]

[0069] It has empirical C 30 H 50 .

[0070] Dihydrofarnese has the empirical formula C0 15 H 26 It can exist in different isomers, depending on the double bond of the hydrogenated farnese and the selected α or β isomer of the farnese. Dihydro-β-farnese (and all its isomers) is preferred.

[0071] More specifically, the following isomers of dihydrofarnese can be used according to the present invention:

[0072] [Chemistry 3]

[0073]

[0074] [Chemistry 4]

[0075] and

[0076] [Chemistry 5]

[0077]

[0078] When performing farnesene (C 15 H 24 When partially hydrogenated, a composition comprising dihydrofarnese and one or more other partially hydrogenated compounds selected from the following can also be obtained:

[0079] Tetrahydrofarnese (C 15 H 28 ) and hexahydrofarnese (C 15 H 30This composition can be used as a starting reactant in the context of this invention: the dihydrofarnese it contains will provide the corresponding trithiol according to the method of the invention. Preferably, this composition contains at least 70% by weight of dihydrofarnese relative to the total weight of the composition, more preferably at least 80% by weight of dihydrofarnese. More preferably, the composition contains at least 85% by weight of dihydrofarnese relative to the total weight of unreacted farnese, of farnesane present in the composition and all partially hydrogenated compounds generated from farnese. In this type of composition, the β-isomer of farnese is particularly preferred to be used to obtain dihydro-β-farnese.

[0080] Therefore, Myralene 10™ (CAS No.: 1581740-29-5) is preferably mentioned, as the composition obtained by the partial hydrogenation of β-farnesene and its preparation method are disclosed in application WO 2016 / 064853. Myralene 10™ mainly comprises dihydro-β-farnesene. This composition is perfectly suitable as a starting material according to the present invention.

[0081] Terpenes:

[0082] The term "terpene compound" is understood, in particular, to mean a compound whose structure is derived from a terpene and which optionally contains one or more heteroatoms (especially oxygen and / or nitrogen, preferably oxygen) and / or one or more chemical functional groups. For example, terpene compounds may contain at least one functional group selected from alcohols, ketones, ethers, esters or aldehydes.

[0083] They can in particular possess empirical (C) 5n H 8n-2y ), where n is as defined above, and y is an integer between 1 and 4.

[0084] Preferably, the terpenoid compounds are selected from the following:

[0085] p-Menthol-1,8-diene, β-carotene, lycopene, farnesol, retinol, retinaldehyde, vitamin A, nerolidol, isomyrcenol, and isopreneol.

[0086] Terpenes and / or hydrogenated derivatives of terpenes and / or oligomers of terpenoid compounds:

[0087] The term "oligomer" specifically corresponds to an aggregate of 2 to 10 identical or different terpenes and / or hydrogenated derivatives of terpenes and / or terpene compounds as defined above, preferably identical. Preferably, dimers and / or trimers of terpenes and / or terpene compounds are used. More preferably, terpene dimers are used.

[0088] The dimer of β-farnesene, known as isosqualene, deserves special mention. It has the empirical formula C2. 30 H 48 And has the following formula (e.g., as described in document US2011 / 0287988 A1):

[0089] [Chemistry 6]

[0090]

[0091] The following isomeric isomers of squalene can also be used according to the present invention:

[0092] [Chemistry 7]

[0093]

[0094] [Chemistry 8]

[0095] and

[0096] [Chemistry 9]

[0097]

[0098] Therefore, the term "terpenes and terpene derivatives" is preferably understood to mean:

[0099] Terpenes, hydrogenated derivatives of terpenes, terpenoids and oligomers of terpenes and / or hydrogenated derivatives of terpenes and / or terpenoids.

[0100] Therefore, the terpene or terpene derivative may be selected from the following:

[0101] Myrcene, farnesene, humulene, elemene, gemmaene, bisabolene, p-menthen-1,8-diene, cedrene, ricinene, gingerene, β-carotene, lycopene, camphene, squalene, isosqualene, dihydrofarnesene, farnesol, retinol, retinaldehyde, vitamin A, nerolidol, isomarcol, and isopreneol.

[0102] More preferably, the terpene or terpene derivative is selected from the following: myrcene, farnesene, squalene, isosqualene, humulene, and dihydrofarnesene.

[0103] These starting materials are naturally occurring in plants, marine species, or can be produced through fermentation, genetically modified or non-genetically modified organisms, and may utilize renewable carbon sources. They are also commercially available. For example, Amyris sells trans-β-farnesene under the name Biofene®, and DRT sells myrcene.

[0104] polythiols

[0105] According to the present invention, the term "polythiol" refers to a polythiol corresponding to a starting terpene or a derivative of a starting terpene as defined above.

[0106] The term "corresponding to the starting polyene" should be understood to mean that the starting terpene or its derivative and the resulting polythiol have the same structure, except that the C=C double bond has been converted into a -SH functional group (i.e., -CH-C(SH)-): for x C=C double bonds in the starting terpene or its derivative, x -SH functional groups are obtained, where x is as defined above. The term "polythiol" also includes polythiools that are positional isomers of the double bond.

[0107] Therefore, the number of C=C double bonds contained in the terpene or terpene derivative is referred to hereinafter as "x", where x is an integer, preferably greater than or equal to 3. Preferably, x is between 3 and 10, more preferably between 3 and 7. The polythiol according to the invention may also be referred to as (x)thiol, where x is as defined above.

[0108] Polythioester intermediates

[0109] The terms "polythioester intermediate" or "polythioester" should be understood to mean a polythioester corresponding to a starting terpene or a starting terpene derivative. The term "corresponding to a starting terpene or a starting terpene derivative" should be understood to mean that the starting terpene or the starting terpene derivative and the resulting polythioester have the same structure, except that the C=C double bond has been converted to a -CH-C(O)-S-R1- functional group (R1 depends on the thiocarboxylic acid used; preferably, R1 is methyl): for x C=C double bonds, x thioester functional groups are obtained, where x is as defined above. The term "polythioester" also includes polythioesters that are positional isomers of the double bonds of the starting terpene or the starting terpene derivative.

[0110] According to the method of the present invention

[0111] Phase a)

[0112] During stage a), a terpene or terpene derivative as defined above is reacted with a thiocarboxylic acid in the presence of oxygen (O2) and at least one organic solvent to obtain a reaction medium comprising a polythioester as defined above and said at least one organic solvent.

[0113] The reaction is as follows: R-CH=CH-R+R1-C(O)-SH->R-CH2-CH(SC(O)-R1)-R

[0114] Phase a) takes place in the presence of oxygen (O2), which acts as the initiator of the reaction. Therefore, phase a) can proceed 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 may be added or not added throughout the duration of phase a).

[0115] Specifically, oxygen is bubbled into the reaction medium, preferably in the form of depleted air. For example, depleted air can pass through a filter or diffuser 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 headspace of the reactor).

[0116] The oxygen flow rate can be from 0.01 to 100 Sl / h, preferably from 0.05 to 10 Sl / h, more preferably from 0.05 to 5 Sl / h, and especially from 0.05 to 2 Sl / h (standard liters / h).

[0117] Phase a) is carried out, particularly in the absence of any other initiator for the reaction, and more preferably in the absence of AIBN (azobisisobutyronitrile) and / or in the absence of UV radiation.

[0118] Step a) is also carried out in the presence of an organic solvent or a mixture of organic solvents. Polar solvents or mixtures of polar solvents are particularly preferred. The solvent can be a polar protic or a polar aprotic solvent. Among the solvents that can be used, the following may be mentioned: alcohols, ethers (preferably cyclic ethers and glycol ethers, such as dialkyl glycol ethers), organic chlorinated solvents, carboxylic acids, or mixtures thereof.

[0119] Alcohols are preferred, especially those of the following general formula (IV):

[0120] R4-OH(IV)

[0121] Wherein R4 represents an alkyl group as defined above. Preferably, the alcohol is selected from methanol, ethanol, isopropanol, n-propanol, n-butanol, but-2-ol, isobutanol, and tert-butanol, more preferably ethanol.

[0122] Preferably, the solvent is selected from the following: tetrahydrofuran (THF), 2-methyltetrahydrofuran (Me-THF), dioxane, chloroform, acetic acid, methanol, ethanol, isopropanol, n-propanol, n-butanol, but-2-ol, isobutanol, tert-butanol, dimethoxyethane (also known as glycol dimethyl ether), diethoxyethane, dibutoxyethane, and mixtures thereof, more preferably ethanol.

[0123] The amount of solvent used is typically selected based on the desired viscosity of the reaction medium. Complete or partial dissolution can be performed by someone skilled in the art, depending on the target viscosity of the reaction medium. Preferably, a solvent of 1 to 50 molar equivalents, more preferably 1 to 20 molar equivalents, is used relative to the terpene or terpene derivative.

[0124] The solvent may be added completely or partially at the beginning of stage a). It may be added once, several times (semi-continuously), or gradually (continuously) during stage a).

[0125] Thiocarboxylic acids preferably have the following general formula (II):

[0126] R1-C(O)-SH(II)

[0127] in:

[0128] R1 represents alkyl, aryl, or aralkyl as defined above.

[0129] Preferably, R1 is selected from methyl, ethyl and benzyl.

[0130] According to the invention, thioacetic acid is particularly preferred, wherein R1 is methyl (hereinafter referred to as TAA). For example, using thioacetic acid, polythiol acetates are obtained as polythioester intermediates.

[0131] According to one implementation, thiocarboxylic acids can be produced in situ (see reference US 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.

[0132] Preferably, for stage a), a thiocarboxylic acid and one or more solvents are first introduced into the reactor, and then oxygen is introduced, for example, by bubbling with air. Terpenes or derivatives may then be added to the reaction medium.

[0133] The temperature of stage a) can be from 5°C to 80°C, preferably from 5°C to 50°C, and more particularly from 5°C to 25°C, for example from 5°C to 10°C. Stage a) is usually carried out at atmospheric pressure.

[0134] The molar ratio of the double bond of the thiocarboxylic acid / polyene can be between 1 and 20, preferably between 1 and 10, for example between 1 and 5, and more preferably between 1 and 3.

[0135] Stage a) enables the formation of polythioester intermediates as defined above from terpenes or terpene derivatives.

[0136] Therefore, the reaction medium obtained at the end of stage a) may contain:

[0137] - Polythioester intermediates as defined above;

[0138] - Solvents or solvent mixtures as defined above;

[0139] -Possible byproducts, such as (x-1) polythioesters; and

[0140] - One or more possible unreacted reactants.

[0141] The term "(x-1) polythioester" should be understood specifically to refer to compounds containing x-1 thioester functional groups, where x is as defined above. It is a compound that retains the C=C double bond (i.e., the unreacted C=C double bond).

[0142] Therefore, the reaction medium may contain 10% to 85% by weight of polythioester intermediates relative to the entire reaction medium.

[0143] The reaction medium may contain 15% to 90% by weight of one or more solvents relative to the entire reaction medium.

[0144] Phase b)

[0145] Stage b), which deprotects the polythioester intermediate obtained in stage a), allows the production of polythiols. This can be carried out by any means known to those skilled in the art. Since stages a) and b) are conducted in a one-pot synthesis according to the invention, it should be understood that the reaction medium containing the polythioester obtained at the end of stage a) is retained for the deprotection stage b). Therefore, stages a) and b) are carried out in the presence of the same solvent (or solvent mixture). More of the solvent (or solvent mixture) may be added during stage b). Specifically, the method according to the invention does not include a stage for separating and / or extracting and / or washing the (organic) phase containing the polythioester between stages a) and b). Specifically, no intermediate stage for purifying the polythioester is performed. More specifically, no stage for recrystallizing and / or distilling the polythioester is performed.

[0146] Deprotection b) can be carried out by conventional methods: using bases or acids, Dy(OTf)3 type catalysts (see Liang et al., Asian J.Org.Chem., 10.1002 / ajoc.201700481) or quaternary ammonium cyanide salts (see US7173 156).

[0147] Preferably, deprotection b) is a basic deprotection, preferably in the presence of an alcohol as defined above. This is typically carried out by adding a basic hydroxide, preferably NaOH or KOH. The addition can be done dropwise.

[0148] Deprotection stage b) can also be acidic 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 deprotection is acidic, an alcohol as defined above is preferably used as the solvent.

[0149] sulfonic acid

[0150] The sulfonic acid is preferably an organic sulfonic acid, and optionally anhydrous.

[0151] Sulfonic acids can have the following general formula (III):

[0152] R2-SO3H (III),

[0153] Where R2 represents:

[0154] -alkyl groups, preferably as defined above, may optionally be wholly or partially substituted with one or more identical or different halogen atoms, or

[0155] -aryl, preferably as defined above, is optionally substituted with a saturated, straight-chain or branched hydrocarbon chain comprising 1 to 4 carbon atoms.

[0156] The halogen atom can be selected from fluorine, chlorine, and bromine. In particular, the alkyl group can be fully halogenated, and more especially fully fluorinated.

[0157] Preferably, the sulfonic acid is an alkyl sulfonic acid, which is optionally anhydrous (in the above formula, R2 is an alkyl group).

[0158] Therefore, sulfonic acids (and their anhydrous forms) can be selected from:

[0159] Methanesulfonic acid, ethanesulfonic acid, n-propanesulfonic acid, isopropanesulfonic acid, n-butanesulfonic acid, isobutanesulfonic acid, sec-butanesulfonic acid, tert-butanesulfonic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, and mixtures of two or more of them in all proportions.

[0160] According to a very particularly preferred embodiment, the sulfonic acid used in the context of this invention is methanesulfonic acid (MSA) or anhydrous methanesulfonic acid (AMSA).

[0161] The sulfonic acid may be loaded or unloaded. Preferably, it is unloaded.

[0162] When it is loaded, sulfonated resins of the styrene-divinylbenzene copolymer type can be used, such as Amberlyst® 15 resin or Nafion®.

[0163] For example, for polythioesters, use 0.1-10 equivalents of acid.

[0164] For example, for polythioesters, use 3-60 equivalents (molar equivalents), preferably 3-20 equivalents of alcohol.

[0165] The deprotection stage b) can be carried out at a temperature of 10°C to 100°C, preferably 25°C to 80°C, and more preferably 40°C to 80°C. It is usually carried out at atmospheric pressure.

[0166] Stages a) and b) can be carried out in the same reactor. For example, a batch reactor can be used.

[0167] Depending on the desired purity, the polythiols collected at the end of stage b) may be subjected to subsequent stages of routine collection and / or routine purification. For example, when deprotection is performed by adding a base, the reaction medium may subsequently be acidified, and conversely, when deprotection is performed by adding an acid, the reaction medium may be alkalized.

[0168] The organic phase obtained therefrom, which contains various thiols (especially polythiols and (x-1)thiols), can then be extracted and optionally concentrated.

[0169] Therefore, and specifically, the obtained polythiols can be in the form of polythiols compositions mentioned below.

[0170] The composition according to the invention

[0171] When polythiols are prepared from terpenes or terpene derivatives having x C=C double bonds, the conversion of these double bonds to -SH functional groups is usually incomplete and can form byproducts at each stage, regardless of the method used.

[0172] According to the present invention, the term "polythiol" therefore refers to a polythiol corresponding to the starting terpene or a derivative of the starting terpene and containing x -SH functional groups. In this case, the conversion of the initial x C=C double bonds to -SH functional groups is complete.

[0173] According to the present invention, the term "(x-1)thiol" refers to a thiol corresponding to the starting terpene or a starting terpene derivative and containing (x-1) -SH functional groups. The term "corresponding to the starting polyene" should be understood to mean that the starting terpene or starting terpene derivative and the obtained (x-1)thiol have the same structure, except that x C=C double bonds have been converted into (x-1) -SH functional groups. In this case, the conversion of the C=C double bonds to the -SH functional groups is not complete: the -SH functional groups are missing.

[0174] C=C double bonds that have not been converted to the -SH functional group can specifically be:

[0175] - Still in the form of a C=C double bond; or

[0176] - In the form of unprotected thioester functional groups.

[0177] Therefore, different structures of (x-1)thiols can exist, but they are grouped under this common name, which characterizes the number of their -SH functional groups (unless otherwise specifically mentioned). Also included are (x-1)thiols that are positional isomers of the double bond.

[0178] For example, during stage a), (x-1) thioesters can be formed. In this case, for x initial C=C double bonds, only (x-1) C=C double bonds react with thiocarboxylic acids to form (x-1) thioester functional groups.

[0179] Furthermore, during phase b), deprotection may not be complete.

[0180] Therefore, according to the method of the present invention, it is possible to form:

[0181] - (x-1) thiols derived from the (x-1) thioester formed in stage a); and / or

[0182] - (x-1)thiols derived from incompletely deprotected polythioesters.

[0183] Therefore, it is possible to obtain a polythiol composition derived from a terpene or terpene derivative having x C=C double bonds, comprising:

[0184] - Polythiols containing x -SH functional groups corresponding to terpenes or terpene derivatives; and

[0185] -Thiols containing (x-1) -SH functional groups corresponding to terpenes or terpene derivatives;

[0186] Where x is defined as above.

[0187] Such compositions may optionally contain other byproducts or impurities (e.g., monothiols).

[0188] In particular, trithiol compositions can be obtained from terpenes or terpene derivatives having three C=C double bonds, said compositions comprising:

[0189] - trithiols corresponding to the terpenes; and

[0190] - Dithiols corresponding to the terpenes.

[0191] In particular, tetrathiol compositions can be obtained from terpenes or terpene derivatives having four C=C double bonds, said compositions comprising:

[0192] - A tetrathiol corresponding to the terpene or a derivative of the terpene; and

[0193] - Trithiols corresponding to the terpene or the terpene derivative.

[0194] Therefore, the present invention relates to a polythiol composition A obtained from a terpene or terpene derivative having x C=C double bonds, said composition comprising:

[0195] - Polythiols containing x -SH functional groups corresponding to terpenes or derivatives of said terpenes; and

[0196] - A thiol corresponding to a terpene or a derivative of the terpene and containing (x-1) -SH functional groups, where x is as defined above.

[0197] Specifically, relative to the total weight of composition A, composition A contains at least 50% by weight, preferably at least 60% by weight, for example at least 70% by weight, more preferably at least 80% by weight, and even more preferably at least 90% by weight, for example at least 95% by weight of the polythiol.

[0198] Specifically, relative to the total weight of the composition A, the composition A contains less than 40% by weight, preferably less than 30% by weight, more preferably less than 25% by weight of the (x-1)thiol.

[0199] Preferably, composition A The weight ratio is 1:1 to 20,000:1, for example 1:1 to 10,000:1, preferably 1:1 to 1,000:1, more preferably 1:1 to 100:1, and even more preferably 1:1 to 10:1, for example 2:1 to 10:1.

[0200] The weight ratio is as follows: [polythiols containing x -SH functional groups corresponding to the terpene or the terpene derivative] / [thiols containing (x-1) -SH functional groups corresponding to the terpene or the terpene derivative].

[0201] In a very particularly preferred manner, composition A is obtained from a terpene or terpene derivative selected from myrcene, farnesene, squalene, isosqualene, humulene, and dihydrofarnesene.

[0202] The polythiols according to the present invention

[0203] The present invention also relates to trithiols produced from dihydrofarnesene, heptathiols produced from isosqualene, and tetrathiols produced from camphene (i.e., trithiols corresponding to dihydrofarnesene, heptathiols corresponding to isosqualene, and tetrathiols corresponding to camphene).

[0204] Preferably, the trithiol is a trithiol of dihydro-β-farnesene. The trithiol of dihydro-β-farnesene can, in particular, be one of its positional isomers:

[0205] [Chemistry 10]

[0206]

[0207] [Chemistry 11]

[0208]

[0209] [Chemistry 12]

[0210] and

[0211] [Chemistry 13]

[0212]

[0213] The trithiol of dihydrofarnesene can be obtained from a starting composition comprising at least 70% by weight, more preferably at least 80% by weight, of dihydrofarnesene relative to the total weight of the composition. Preferably, the composition comprises at least 85% by weight of dihydrofarnesene, of all partially hydrogenated compounds present in the composition resulting from the hydrogenation of farnesene and of farnesane, relative to the total weight of farnesene.

[0214] More specifically, the composition is derived from Myralene 10 TM The trithiol of dihydro-β-farnesene was obtained.

[0215] The heptathiol of isosqualene can be, in particular, one of its positional isomers:

[0216] [Chemistry 14]

[0217]

[0218] [Chemistry 15]

[0219]

[0220] [Chemistry 16]

[0221] and

[0222] [Chemistry 17]

[0223]

[0224] The present invention also relates to polythiols derived from β-carotene, lycopene, farnesol, retinol, retinaldehyde, vitamin A, nerolidol, isomalteneol and isopreneol.

[0225] These compounds are new and constitute part of this invention.

[0226] The present invention also relates to compositions as defined above and which can be obtained, acquired, or directly obtained by the methods according to the invention. Similarly, polythiols as defined above can be obtained, acquired, or directly obtained by the methods according to the invention. Attached Figure Description

[0227] Figure 1 Isomers of myrcene

[0228] It should be understood that, unless a specific isomer is mentioned, the name of a compound includes all of its possible positional isomers.

[0229] The following examples are given by way of illustration and are not intended to limit the invention. Example

[0230] Example 1 By Myralene 10 TM The trithiol obtained from dihydro-β-farnesene, according to the method of the present invention

[0231] Phase a):

[0232] 48.7 g (0.64 mol) of TAA was introduced into a 250-ml jacketed reactor. The medium was stirred at 5°C. Air was bubbled into the reaction medium through a filter at a flow rate of approximately 0.4 Sl / h, and nitrogen was introduced into the top space of the reactor at a flow rate of approximately 4 Sl / h.

[0233] 40 g (0.19 mol) of Myralene 10™ was then added dropwise over approximately 27 minutes via a peristaltic pump. Once the addition was complete, 35.7 g (0.77 mol) of EtOH was added to the reaction medium.

[0234] Keep the reaction medium stirred overnight at 5°C.

[0235] GC / FID analysis showed that Myralene 10 was completely converted.

[0236] The air supply was cut off.

[0237] Stage b) of alkaline deprotection

[0238] Then, 26.8 g (0.58 mol) of EtOH was added to the reaction medium. The reaction medium was then degassed with nitrogen for 1 hour, cooled to approximately 10°C, and 103 g (0.64 mol) of pre-degassed 25% sodium hydroxide solution was added over 38 minutes via a dropping funnel. The reaction medium was stirred overnight at 10°C under nitrogen, and then stirred at 25°C for 6 hours.

[0239] GC / FID analysis showed complete conversion of trithioacetic acid ester.

[0240] Collection phase:

[0241] The reaction medium was then cooled to 20°C, and 117 g (0.64 mol) of 20% HCl (pre-degassed with nitrogen) was added dropwise to the reaction medium via a peristaltic pump. The trithiol phase was then removed. The aqueous phase was extracted three times with 16.5 g (0.19 mol) of dichloromethane.

[0242] The organic phases were combined, then washed four times with 7 g (0.39 mol) of water, and then concentrated on a rotary evaporator.

[0243] A composition comprising 82.29% by weight of a trithiol of dihydro-β-farnesene and 9.71% by weight of a dithiol of dihydro-β-farnesene was obtained (relative to the total weight of the composition).

[0244] The weight ratio is 82.29:9.71, or 8.5:1.

[0245] Example 2 Myrcene trithiol, according to the method of the present invention

[0246] Phase a):

[0247] 64.5 g (0.85 mol) of TAA was introduced into a 250-ml jacketed reactor. The medium was stirred at 5°C, and then 5.9 g (0.13 mol) of EtOH was rapidly added. Air was bubbled into the reaction medium through a filter at a flow rate of approximately 0.4 Sl / h, and nitrogen was introduced into the top space of the reactor at a flow rate of approximately 4 Sl / h.

[0248] Subsequently, 35 g (0.26 mol) of myrcene was added dropwise over approximately 22 minutes via a peristaltic pump. Once the addition was complete, 23.7 g (0.51 mol) of EtOH was added to the reaction medium.

[0249] Keep the reaction medium stirred overnight at 5°C.

[0250] GC / FID analysis showed complete conversion of myrcene.

[0251] The air supply was cut off.

[0252] Stage b) of alkaline deprotection

[0253] Then, 82.9 g (1.80 mol) of EtOH was added to the reaction medium. The reaction medium was then degassed with nitrogen for 1 hour, then the temperature was raised to approximately 30°C, and 73.7 g (0.85 mol) of 46% sodium hydroxide solution (pre-degassed) was added via a dropping funnel. The reaction medium was stirred at 40°C under nitrogen for 21 hours.

[0254] GC / FID analysis showed complete conversion of trithioacetic acid ester.

[0255] Collection phase:

[0256] The reaction medium was then cooled to 20°C, and 154.6 g (0.85 mol) of 20% HCl (pre-degassed with nitrogen) was added dropwise to the reaction medium via a peristaltic pump. The trithiol phase was removed. The aqueous phase was extracted three times with 21.8 g (0.26 mol) of dichloromethane.

[0257] The organic phases were combined, then washed four times with 9.2 g (0.51 mol) of water, and then concentrated on a rotary evaporator.

[0258] A composition comprising 50.56% by weight of myrcene trithiol and 23.6% by weight of myrcene dithiol (relative to the total weight of the composition) is obtained.

[0259] The weight ratio is 50.56:23.6, or 2.1:1.

[0260] Example 3: Tetrathiol obtained from farnesene, according to the method of the present invention

[0261] Phase a):

[0262] 163.9 g (2.15 mol) of TAA was introduced into a 1-liter jacketed reactor. The medium was stirred at 5°C, and then 23.0 g (0.50 mol) of EtOH was rapidly added. Air was bubbled into the reaction medium through a filter at a flow rate of approximately 0.4 Sl / h, and nitrogen was introduced into the top space of the reactor at a flow rate of approximately 4 Sl / h.

[0263] 100 g (0.49 mol) of farnesene (sold under the trade name Biofene®) was then added dropwise over approximately 47 minutes via a peristaltic pump. Once the addition was complete, 90.1 g (1.96 mol) of EtOH was added to the reaction medium.

[0264] Keep the reaction medium stirred overnight at 5°C.

[0265] GC / FID analysis showed that farnesene and its reaction intermediates were completely transformed.

[0266] The air supply was cut off.

[0267] Stage b) of alkaline deprotection

[0268] The reaction medium was then degassed with nitrogen for 1 hour, cooled to approximately 10°C, and 187.2 g (2.15 mol) of pre-degassed 46% sodium hydroxide solution was added over 35 minutes via a dropping funnel. The reaction medium was then stirred at 25°C under nitrogen for 19 hours.

[0269] GC / FID analysis showed complete conversion of tetrathioacetic acid ester.

[0270] Collection phase:

[0271] The reaction medium was then cooled to 20°C, and 294.4 g (1.61 mol) of 20% HCl (pre-degassed with nitrogen) was added dropwise to the reaction medium via a peristaltic pump. The tetrathiol phase was removed. The aqueous phase was extracted three times with 41.6 g (0.49 mol) of dichloromethane.

[0272] The organic phases were combined, washed four times with 17.6 g (0.98 mol) of water, and then concentrated on a rotary evaporator.

[0273] A composition comprising 61.24% by weight of farnesene tetrathiol and 25.77% by weight of farnesene trithiol (relative to the total weight of the composition) was obtained.

[0274] The weight ratio is 61.24:25.77, or 2.4:1.

Claims

1. A method for preparing polythiols, comprising the following stages: a) Reacting a terpene or terpene derivative 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 organic solvent; and b) Perform a stage to deprotect the polythioester obtained in stage a) in order to obtain a polythiol; Stages a) and b) are carried out in a one-pot synthesis.

2. The preparation method according to claim 1, wherein the deprotection stage b) is alkaline deprotection, preferably carried out by adding an alkaline hydroxide.

3. The preparation method according to claim 1, wherein the deprotection stage b) is acidic deprotection, preferably in the presence of an alcohol.

4. The preparation method according to any one of the preceding claims, wherein the organic solvent is selected from: alcohols, ethers, organic chlorinated solvents, carboxylic acids and mixtures thereof.

5. The preparation method according to any one of the preceding claims, wherein the organic solvent is selected from alcohols of the following general formula (IV): R4-OH(IV) R4 represents a saturated, straight-chain, branched, or cyclic hydrocarbon group containing 1 to 10, preferably 1 to 4, carbon atoms.

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

7. The preparation method according to any one of the preceding claims, wherein the terpene or terpene derivative is selected from myrcene, farnesene, squalene, isosqualene, humulene, and dihydrofarnesene.

8. A polythiol composition A obtained from a terpene or terpene derivative having x C=C double bonds, said composition comprising: - A polythiol containing x -SH functional groups corresponding to the terpene or the terpene derivative; -Thiols containing (x-1) -SH functional groups corresponding to the terpene or the terpene derivative; Where x is an integer greater than or equal to 3.

9. The polythiol composition A according to claim 8, wherein... The weight ratio is between 1:1 and 50,000:1, preferably between 2:1 and 50,000:

1.

10. The polythiol composition A according to claim 8 or 9, wherein the terpene or terpene derivative is selected from myrcene, farnesene, squalene, isosqualene, humulene, and dihydrofarnesene.

11. Polythiols, selected from trithiols derived from dihydrofarnesene, heptathiols derived from isosqualene, and tetrathiols derived from camphene.

12. The polythiol according to claim 11, having one of the following formulas: and .

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