Antioxidant compositions of dianhydrohexitols containing benzophenone or derivatives thereof

Abstract

An object of the present application is a composition comprising a compound having at least one heterocyclic ring and at least one antioxidant selected from the group consisting of antioxidants having at least two aromatic rings. In particular, the compound is selected from the group consisting of dianhydrohexitols, most particularly isosorbide. The compositions exhibit improved oxidation resistance, as well as lower yellowing during storage and after heat treatment. These compositions are useful in the preparation of polymers comprising isosorbide as comonomer.

Description

Technical Field

[0001] This invention relates to the field of using antioxidants on dipeptide hexitol or dipeptide hexitol derivatives to protect said dipeptide hexitol or its derivatives from oxidation-induced degradation reactions. Background Technology

[0002] The main problem with disohydrated hexitols or their derivatives (especially their esters) is their chemical instability, which can occur anywhere and at any time from the start of their synthesis.

[0003] The production of mono- or di-dehydrated hexitols typically requires a polyol as a starting material. This polyol may have been previously obtained through the hydrogenation of sugars.

[0004] The production process of disohydrated hexitol typically involves the following main steps: 1) synthesis of disohydrated hexitol, 2) purification of the disohydrated hexitol, and 3) shaping of the purified disohydrated hexitol. In the case of derivatives of disohydrated hexitol, such as its ethers or esters, additional similar steps are required: 4) synthesis of the disohydrated hexitol derivative from the previously obtained disohydrated hexitol, 5) purification of the disohydrated hexitol derivative, and 6) shaping of the purified disohydrated hexitol. Furthermore, at the end of each process, the product must be stored for weeks to months to years.

[0005] Generally, production methods, and especially purification steps involving high temperatures (e.g., in the range of 100°C–250°C), require special care to avoid thermal degradation of the compounds. Furthermore, prolonged storage in containers at ambient temperatures can also cause slow degradation.

[0006] Several methods have been devised in the prior art, typically relying on the addition of one or a mixture of compounds that can protect disodihydrohexitol or its derivatives from thermal degradation or oxidation. These compounds are referred to as "stabilizers" or "stabilizing agents".

[0007] In the prior art, several compounds with stable properties to disodihydrohexitol or its derivatives have been identified, such as those listed in EP1,446,373:

[0008] - Reducing agents, and especially boron-based or aluminum-based compounds, such as sodium borohydride (NaBH4) or lithium aluminum hydride (LiAIH4).

[0009] - Phosphorus compounds, such as phosphine or phosphites;

[0010] - Antioxidants, and in particular nitrogen-based compounds, especially aromatic or non-aromatic amines, containing or not containing at least one alcohol functional group, such as hydroxylamine, morpholine and their derivatives, or such as monoethanolamine, diethanolamine (DEA), triethanolamine (TEA), which are the objects of the applicant's EP2,991,991, or mixtures thereof, or cyclic amines such as WO2017 / 095016;

[0011] -Aromatic compounds, whether nitrogen-containing or nitrogen-free, containing or not containing at least one alcohol functional group, such as hydroquinone, phenol, tocopherol and their corresponding derivatives;

[0012] - Antioxidant compounds based on phosphorus or sulfur, such as phosphites, phosphonites, sulfites, thiodipropionates, and mixtures thereof;

[0013] -Antioxidant;

[0014] - Metal passivating agents, such as complexing or chelating agents of naturally derived metals;

[0015] - Products approved as food additives, particularly those identified as antioxidants, acid regulators or chelating agents within the meaning of European regulations, such as ascorbic acid (vitamin C), isoascorbic acid, lactic acid, citric acid, gallic acid, tocopherol, derivatives of all these products (especially salts), BHT, butylated hydroxyanisole (BHA) and any mixtures of these products.

[0016] Recently, the applicant continued its research to obtain more stable compositions of disohydrated hexitol, concluding that oxidation is a major phenomenon; in other words, the stability of the compositions is primarily determined by their antioxidant properties. In this way, the applicant successfully identified a special class of compounds that are particularly effective in improving this oxidative stability: gallic esters, also known as gallate salts, as disclosed in the applicant's patent application FR2108221.

[0017] Technical issues

[0018] The latest stabilizers identified by the applicant, namely esters of gallic acid, have a drawback: they are temperature unstable because their ester functional groups hydrolyze in the presence of water at temperatures above 60°C–100°C. This hydrolysis leads to the formation of organic acids, which react to form colored compounds when further exposed to temperatures above 150°C–200°C. This limits the scope of use of such stabilizers. In the production of isosorbide, they cannot be added before any process step (e.g., distillation) involving temperatures above 60°C–100°C in the presence of water.

[0019] In fact, the applicant attempted to stabilize isosorbide solutions with gallic acid esters at high temperatures (such as those typically occurring in the distillation of such solutions, ranging from about 100°C to about 250°C, more typically about 200°C-250°C), and obtained unacceptable levels of yellowing due to the organic acids produced by the thermal degradation of gallic acid esters.

[0020] One easy way to avoid this problem in isosorbide production would be to ensure that the stabilizer is added at the final stage of the isosorbide production process, where no further heat treatment is performed. This would, to some extent, limit the effectiveness of the stabilizer in the final stage of the production process, while it might be helpful to add the stabilizer to earlier production steps to protect isosorbide from oxidation as early as possible during its purification and / or shaping processes.

[0021] Therefore, an antioxidant stabilizer is needed that can withstand (i.e., maintain its chemical structure) exposure to heat treatment. Furthermore, this stabilization should be effective for isosorbide in any possible state (liquid or solid form, such as crystals, granules, or flakes) and should not affect its color, odor, or physicochemical properties. Attached Figure Description

[0022] Other features, details, and advantages will be shown in the following detailed description and accompanying drawings, wherein:

[0023] Figure 1

[0024] [ Figure 1 [ ] is a graph representing the PetroOxy test method used to determine the induction time;

[0025] Implementation Plan Description

[0026] The implementation scheme for the purpose of this application is as follows.

[0027] Implementation Scheme 1: A composition comprising:

[0028] - At least one compound having at least one heterocycle,

[0029] - and at least one antioxidant of formula (I):

[0030] (I)

[0031] in:

[0032] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0033] -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof.

[0034] -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0035] -m, n, and p are integers in the range 0 to 10, and when p=0, then m and / or n are greater than or equal to 1, or when both m and n are equal to 0, then p is greater than or equal to 1.

[0036] Implementation Scheme 2: The composition according to Implementation Scheme 1, wherein the antioxidant has formula (II):

[0037] (II)

[0038] in:

[0039] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0040] -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof.

[0041] -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0042] -n is an integer in the range of 0 to 10.

[0043] Implementation Scheme 3: The composition according to Implementation Scheme 1, wherein the antioxidant has formula (III):

[0044] (III)

[0045] in:

[0046] -R1 is selected from oxygen, CH2, and saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms.

[0047] -R2 to R11 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0048] Implementation Scheme 4: The composition according to Implementation Scheme 3, wherein the antioxidant is a benzophenone compound of formula (IV):

[0049] (IV)

[0050] R1 to R8 are selected from H, OH, CH3, and O-CH3.

[0051] Implementation Scheme 5: The composition according to Implementation Scheme 4, wherein the benzophenone compound of formula (III) is a compound of formulas (V) to (VIII):

[0052] (V) (VI)

[0053] (VII) (VIII)

[0054] Implementation Scheme 6: The composition according to Implementation Scheme 4, wherein the benzophenone compound of formula (III) is 2-hydroxy-4-methoxybenzophenone of formula (VII).

[0055] (VII)

[0056] Implementation Scheme 7: The composition according to Implementation Scheme 1, wherein the antioxidant has the formula (IX):

[0057] (IX)

[0058] in:

[0059] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0060] -R4 to R18 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0061] -m and n are integers in the range of 0 to 10.

[0062] Implementation Scheme 8: The composition according to any one of the preceding embodiments, wherein the content of the antioxidant in the composition is equal to or less than 1000 ppm relative to the weight of the organic compound, particularly equal to or less than 500 ppm, or equal to or less than 400 ppm, or equal to or less than 300 ppm, or equal to or less than 200 ppm, or equal to or less than 100 ppm.

[0063] Implementation Scheme 9: The composition according to any one of the preceding embodiments, wherein the composition further comprises at least one stable compound selected from gallic acid, gallic ester, phosphate compound, amine or cyclic amine.

[0064] Implementation Scheme 10: The composition according to Implementation Scheme 9, wherein the stable compound is selected from ethyl gallate, propyl gallate, disodium phosphate, diethanolamine, triethanolamine, tetramethylpiperidine, tetramethylpiperidone, diazabicyclononene, diazabicycloundecene, or mixtures thereof.

[0065] Implementation Scheme 11: The composition according to any one of the foregoing embodiments, wherein the composition is a liquid composition or a solid composition.

[0066] Implementation Scheme 12: The composition according to Implementation Scheme 11, wherein the content of the compound having at least one heterocyclic ring in the composition is at least 50% by weight, particularly at least 60% by weight, or at least 70% by weight, or at least 80% by weight, or at least 90% by weight, or at least 95% by weight, or at least 98% by weight, or at least 99% by weight.

[0067] Implementation Scheme 13: The composition according to Implementation Scheme 11, wherein the solid composition is a crystalline solid composition, a semi-crystalline solid composition, or an amorphous solid composition.

[0068] Implementation Scheme 14: The composition according to Implementation Scheme 13, wherein the solid composition is in the form of crystals, particles or flakes.

[0069] Implementation Scheme 15: The composition according to Implementation Scheme 11, wherein the composition has a water content of up to 50% by weight, particularly up to 40% by weight, or up to 30% by weight, or up to 20% by weight, or up to 10% by weight, or up to 5% by weight, or up to 1% by weight, or up to 0.5% by weight, or up to 0.1% by weight, or up to 0.01% by weight.

[0070] Implementation Scheme 16: The composition according to any one of the preceding embodiments, wherein the compound having at least one heterocycle is a heterocyclic compound or a derivative thereof.

[0071] Implementation Scheme 17: The composition according to Implementation Scheme 16, wherein the heterocyclic compound is generated by intramolecular dehydration of a hydrogenated sugar, or is a derivative of the intramolecular dehydration product of a hydrogenated sugar.

[0072] Implementation Scheme 18: The composition according to Implementation Scheme 17, wherein the hydrogenated sugar is selected from sorbitol, mannitol or xylitol or mixtures thereof, particularly sorbitol.

[0073] Implementation Scheme 19: The composition according to Implementation Scheme 17, wherein the heterocyclic compound is selected from monohydrohexitol, disohydrohexitol, or mixtures thereof, particularly from isosorbide, iso-idylol, or isomannitol, or mixtures thereof, and more particularly isosorbide.

[0074] Implementation Scheme 20: The composition according to Implementation Scheme 17, wherein the derivative of the intramolecular dehydration product is selected from monoesters, diesters, monoethers, diethers or combinations thereof, particularly from monoesters or diesters, and more particularly from diesters.

[0075] Implementation Scheme 21: The composition according to Implementation Scheme 20, wherein the derivative is selected from monoesters, diesters, monoethers, diethers, or combinations thereof of dipyrohexitol, particularly monoesters or diesters of dipyrohexitol, and more particularly diesters of dipyrohexitol.

[0076] Implementation Scheme 22: The composition according to any one of the preceding embodiments, wherein it exhibits an induction time of greater than or equal to 3.8 hours, particularly greater than or equal to 4.0 hours, more particularly greater than or equal to 4.5 hours, and most particularly greater than or equal to 5.0 hours, as measured according to the "PetroOxy test" at 120°C and 7 bar of oxygen.

[0077] Implementation Scheme 23: The composition according to the aforementioned Implementation Scheme 22, wherein it exhibits a yellowing index equal to or less than 13.0 YID, particularly equal to or less than 5.0 YID, more particularly equal to or less than 3.0 YID, and most particularly equal to or less than 2.5 YID.

[0078] Implementation Scheme 24: The composition according to the aforementioned Implementation Scheme 22 or 23, wherein it exhibits a yellowing index equal to or less than 50.0 YID, particularly equal to or less than 10.0 YID, more particularly equal to or less than 8.0 YID, and most particularly equal to or less than 6.5 YID after a heat treatment test.

[0079] Implementation Scheme 25: A method for preparing the composition according to any one of Implementation Schemes 1 to 24, comprising:

[0080] a) An intramolecular dehydration step of hydrogenated sugars to obtain the dehydrated product in the crude reaction mixture.

[0081] b) Optionally, a derivatization step of the dehydrated product obtained in step a) to obtain a derivative of the dehydrated product in the crude reaction mixture.

[0082] c) Optionally, a distillation step of the crude reaction mixture obtained in step a) and / or step b) to obtain a distillate rich in the dehydrated product or its derivatives.

[0083] d) Optionally, a purification step of the crude reaction mixture obtained in step a) and / or step b) and / or the distillate obtained in step c) to obtain a purified dehydrated product.

[0084] e) Optionally, shaping the crude reaction mixture obtained in step a) and / or step b), and / or shaping the distillate obtained in step c), and / or shaping the purified dehydrated product obtained in step d), to obtain a shaped dehydrated product.

[0085] f) The step of adding at least one antioxidant of formula (I) to the crude reaction mixture obtained in step a) and / or step b), and / or to the distillate obtained in step c), and / or to the purified dehydrated product obtained in step d), and / or to the shaped dehydrated product obtained in step e),

[0086] (I)

[0087] in:

[0088] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0089] -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof.

[0090] -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0091] -m, n, and p are integers in the range 0 to 10, and when p=0, then m and / or n are greater than or equal to 1, or when both m and n are equal to 0, then p is greater than or equal to 1.

[0092] Implementation Scheme 26: The method according to Implementation Scheme 25, wherein the antioxidant has formula (II):

[0093] (II)

[0094] in:

[0095] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0096] -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof.

[0097] -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0098] -n is an integer in the range of 0 to 10.

[0099] Implementation Scheme 27: The method according to Implementation Scheme 25, wherein the antioxidant has formula (III):

[0100] (III)

[0101] in:

[0102] -R1 is selected from oxygen, CH2, and saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms.

[0103] -R2 to R11 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0104] Implementation Scheme 28: The method according to Implementation Scheme 27, wherein the antioxidant is a benzophenone compound of formula (IV):

[0105] (IV)

[0106] R1 to R8 are selected from H, OH, CH3, and O-CH3.

[0107] Implementation Scheme 29: The method according to Implementation Scheme 28, wherein the benzophenone compound of formula (III) is a compound of formulas (V) to (VIII):

[0108] (V) (VI)

[0109] (VII) (VIII).

[0110] Implementation Scheme 30: The method according to Implementation Scheme 28, wherein the benzophenone compound of formula (III) is 2-hydroxy-4-methoxybenzophenone of formula (VII).

[0111] (VII)

[0112] Implementation Scheme 31: The method according to Implementation Scheme 25, wherein the antioxidant has the formula (IX):

[0113] (IX)

[0114] in:

[0115] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0116] -R4 to R18 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0117] -m and n are integers in the range of 0 to 10.

[0118] Implementation Scheme 32: The method according to Implementation Scheme 25, wherein the method includes:

[0119] a) Intramolecular dehydration of hydrogenated sugars to obtain the dehydrated product.

[0120] b) A subsequent distillation step of the crude reaction mixture obtained in step a) to obtain a distillate rich in the dehydrated product.

[0121] c) A purification step of the distillate obtained in step b) that is rich in the dehydrated product, particularly selected from crystallization, activated carbon treatment, or resin demineralization, or combinations thereof, to obtain a purified dehydrated product.

[0122] d) Adding at least one antioxidant according to formula (I) to the purified dehydrated product obtained in step c) to obtain a composition.

[0123] e) The shaping step of the composition obtained after step d), particularly the concentration step, or the crystallization step, or the step of converting it into flakes or granules.

[0124] Implementation Scheme 33: Antioxidant of Formula (I)

[0125] (I)

[0126] Use in compositions comprising at least one compound having at least one heterocyclic ring for preventing or reducing the chemical degradation of the dehydration product or its derivatives.

[0127] in:

[0128] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0129] -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof.

[0130] -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0131] -m, n, and p are integers in the range 0 to 10, and when p=0, then m and / or n are greater than or equal to 1, or when both m and n are equal to 0, then p is greater than or equal to 1.

[0132] Implementation Scheme 34: According to the use described in Implementation Scheme 33, wherein the antioxidant has the formula (II):

[0133] (II)

[0134] in:

[0135] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0136] -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof.

[0137] -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0138] -n is an integer in the range of 0 to 10.

[0139] Implementation Scheme 35: According to the use described in Implementation Scheme 33, wherein the antioxidant has formula (III):

[0140] (III)

[0141] in:

[0142] -R1 is selected from oxygen, CH2, and saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms.

[0143] -R2 to R11 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0144] Implementation Scheme 36: According to the use described in Implementation Scheme 35, wherein the antioxidant is a benzophenone compound of formula (IV):

[0145] (IV)

[0146] R1 to R8 are selected from H, OH, CH3, and O-CH3.

[0147] Implementation Scheme 37: According to the use described in Implementation Scheme 36, wherein the benzophenone compound of formula (III) is a compound of formulas (V) to (VIII):

[0148] (V) (VI)

[0149] (VII) (VIII).

[0150] Implementation Scheme 38: According to the use described in Implementation Scheme 36, wherein the benzophenone compound of formula (III) is 2-hydroxy-4-methoxybenzophenone of formula (VII).

[0151] (VII)

[0152] Implementation Scheme 39: According to the use described in Implementation Scheme 33, the antioxidant has the formula (IX):

[0153] (IX)

[0154] in:

[0155] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0156] -R4 to R18 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0157] -m and n are integers in the range of 0 to 10.

[0158] Implementation Scheme 40: The use according to any one of Implementation Schemes 33 to 39, wherein the content of the antioxidant in the composition is equal to or less than 1000 ppm relative to the weight of the organic compound, particularly equal to or less than 500 ppm, or equal to or less than 400 ppm, or equal to or less than 300 ppm, or equal to or less than 200 ppm, or equal to or less than 100 ppm.

[0159] Embodiment 41: The use according to any one of embodiments 33 to 40, wherein the composition further comprises at least one stable compound selected from gallic acid, gallic ester, phosphate compound, amine or cyclic amine.

[0160] Implementation Scheme 42: The use according to Implementation Scheme 41, wherein the stable compound is selected from ethyl gallate, propyl gallate, disodium phosphate, diethanolamine, triethanolamine, tetramethylpiperidine, tetramethylpiperidone, diazabicyclononene, diazabicycloundecene, or mixtures thereof.

[0161] Implementation Scheme 43: Use according to any one of Implementation Schemes 33 to 42, wherein the composition is a liquid composition or a solid composition.

[0162] Implementation Scheme 44: According to the use described in Implementation Scheme 43, the content of the compound having at least one heterocyclic ring in the composition is at least 50% by weight, particularly at least 60% by weight, or at least 70% by weight, or at least 80% by weight, or at least 90% by weight, or at least 95% by weight, or at least 98% by weight, or at least 99% by weight.

[0163] Implementation Scheme 45: The use according to Implementation Scheme 43, wherein the solid composition is a crystalline solid composition, a semi-crystalline solid composition, or an amorphous solid composition.

[0164] Implementation Scheme 46: According to the use described in Implementation Scheme 45, the solid composition is in the form of crystals, granules or flakes.

[0165] Implementation Scheme 47: The use according to Implementation Scheme 43, wherein the composition has a water content of up to 50% by weight, particularly up to 40% by weight, or up to 30% by weight, or up to 20% by weight, or up to 10% by weight, or up to 5% by weight, or up to 1% by weight, or up to 0.5% by weight, or up to 0.1% by weight, or up to 0.01% by weight.

[0166] Implementation Scheme 48: The use according to any one of Implementation Schemes 33 to 47, wherein the compound having at least one heterocycle is a heterocyclic compound or a derivative thereof.

[0167] Implementation Scheme 49: The use according to Implementation Scheme 48, wherein the heterocyclic compound is generated by intramolecular dehydration of a hydrogenated sugar, or is a derivative of the intramolecular dehydration product of a hydrogenated sugar.

[0168] Implementation Scheme 50: The use according to Implementation Scheme 49, wherein the hydrogenated sugar is selected from sorbitol, mannitol or xylitol or mixtures thereof, particularly sorbitol.

[0169] Implementation Scheme 51: The use according to Implementation Scheme 49, wherein the heterocyclic compound is selected from monohydrohexitol, dihydrohexitol, or mixtures thereof, particularly from isosorbide, iso-idylol, or isomannitol, or mixtures thereof, and more particularly isosorbide.

[0170] Implementation Scheme 52: The use according to Implementation Scheme 49, wherein the derivative of the intramolecular dehydration product is selected from monoesters, diesters, monoethers, diethers or combinations thereof, particularly from monoesters or diesters, and more particularly from diesters.

[0171] Implementation Scheme 53: The use according to Implementation Scheme 52, wherein the derivative is selected from monoesters, diesters, monoethers, diethers, or combinations thereof of dipyrohexitol, particularly monoesters or diesters of dipyrohexitol, and more particularly diesters of dipyrohexitol.

[0172] Implementation Scheme 54: Use according to any one of Implementation Schemes 33 to 53, wherein the composition exhibits an induction time of 3.8 hours or more particularly 4.0 hours, even more particularly 4.5 hours or more particularly 5.0 hours, as measured by the PetroOxy test at 120°C and 7 bar of oxygen.

[0173] Implementation Scheme 55: According to the use described in the preceding implementation scheme 54, the composition exhibits a yellowing index equal to or less than 13.0 YID, particularly equal to or less than 5.0 YID, more particularly equal to or less than 3.0 YID, and most particularly equal to or less than 2.5 YID.

[0174] Implementation Scheme 56: The use according to any one of Implementation Schemes 54 or 55, wherein the composition exhibits a yellowing index equal to or less than 50.0 YID, particularly equal to or less than 10.0 YID, more particularly equal to or less than 8.0 YID, and most particularly equal to or less than 6.5 YID after heat treatment testing.

[0175] Implementation Scheme 57: Use of the composition according to any one of Implementation Schemes 1 to 24 for the preparation of polymeric or nonpolymeric, biodegradable or non-biodegradable products or mixtures for use in the chemical, pharmaceutical, cosmetic or food industries.

[0176] Implementation Scheme 58: The use according to Implementation Scheme 57, wherein the use is to prepare the intramolecular dehydration product containing hydrogenated sugar as a comonomer, particularly a polyester or polycarbonate containing isosorbide as a comonomer. Detailed Implementation

[0177] Compounds containing at least one heterocycle

[0178] A compound having at least one heterocycle is a substance comprising carbon and hydrogen, and at least one different chemical element selected from oxygen, sulfur, and nitrogen, which is part of the heterocycle. The heterocycle of the organic compound is a ring having carbon atoms and hydrogen atoms, and at least one atom selected from oxygen, sulfur, and nitrogen as its constituent members.

[0179] In one embodiment, the compound having at least one heterocycle is an organic compound consisting of carbon atoms and hydrogen atoms, as well as at least one different atom selected from oxygen, sulfur, and nitrogen.

[0180] In one embodiment, the organic compound having at least one heterocycle is composed of carbon atoms, hydrogen atoms and oxygen atoms, and has two heterocycles consisting of four carbon atoms and one oxygen atom.

[0181] In one embodiment, the organic compound is an intramolecular dehydration product of a hydrogenated sugar, or a derivative of said product. Specifically, the sugar is selected from pentoses or hexoses. More specifically, the product is mono-dehydrated hexitol, diso-dehydrated hexitol, or a mixture thereof.

[0182] Heterocyclic compounds

[0183] Heterocyclic compounds are cyclic compounds composed of heterocycles, that is, their entire structure consists of heterocycles that share some atoms as constituent members and do not have any alkyl groups attached to the heterocycles.

[0184] Intramolecular dehydration products of hydrogenated sugars

[0185] Sugars, such as pentoses or hexoses, can be hydrogenated to convert their aldehyde functional groups into alcohol functional groups, thus forming hydrogenated sugars, which belong to the polyol family. Under appropriate chemical conditions, a hydroxyl functional group of a hydrogenated sugar can nucleophilically substitute a carbon atom with a hydroxyl group in the same hydrogenated sugar, thereby forming a heterocycle within the hydrogenated sugar. This intramolecular reaction releases water molecules, which is why it is called an intramolecular dehydration reaction. Depending on the structure of the resulting hydrogenated sugar, a second intramolecular dehydration can occur, yielding a compound with two heterocycles.

[0186] The polyol obtained from the hexose can then be converted into a heterocyclic compound called "disodehydrated hexitol" (also known as "isohexitol"). Disodehydrated hexitol is the product of intramolecular dehydration of the hexose, and therefore has two heterocycles. Hexoses are C6 hydrogenated sugars, also known as hexitols, such as sorbitol, mannitol, and idole. Intramolecular dehydration is typically carried out under acidic conditions at high temperatures of 120°C–200°C using a catalyst. In this application, the term "mono-dehydrated hexitol" includes 1,4-dehydrated sorbitol (1,4-dehydrated-sorbitol), dehydrated idulol (1,4-mono-dehydrated-idulol), and dehydrated mannitol (2,5-dehydrated-mannitol, 1,4-dehydrated-mannitol); the term "didehydrated hexitol" includes isosorbitol (which is 1,4-3,6-didehydrated-sorbitol), isomannitol (which is 1,4-3,6-didehydrated-mannitol), and isoidulol (which is 1,4-3,6-didehydrated-idulol), as well as mixtures of these products.

[0187] The products obtained during or after intramolecular dehydration of hydrogenated sugars can be a mixture of unreacted reactants, intermediates, and final products, which can be varied and numerous depending on the chemoselectivity of the reaction, all in a solvent, such as water in the case of dehydrated hexitol. This mixture of all these compounds and solvents constitutes a “crude reaction mixture” during or at the end of the reaction (when the reaction is complete and stopped).

[0188] Derivatives of intramolecular dehydration products of hydrogenated sugars

[0189] The intramolecular dehydration products of hydrogenated sugars contain hydroxyl groups on the ring formed by intramolecular dehydration or on the remaining linear polyol moiety, which can be esterified or etherified. The derivatives according to this application are esters and ethers obtained through such esterification or etherification. According to one embodiment, derivatization of the intramolecular dehydration product means, in particular, esterification of the dehydration product.

[0190] In one embodiment, the derivative is a monoester, diester, or mixture thereof of dialysylhexyl alcohol. Specifically, the monoester or diester has a saturated or unsaturated alkyl chain comprising 2 to 22 carbon atoms.

[0191] In one embodiment, the derivative is a monoether of dialysylhexyl alcohol, a diether of dialysylhexyl alcohol, or a mixture thereof. Specifically, the monoether or diether has a saturated or unsaturated alkyl chain comprising 2 to 22 carbon atoms.

[0192] antioxidants

[0193] The antioxidants included in the compositions according to this application are organic molecules capable of inhibiting free radicals that may be generated by oxidation reactions within the compositions according to the invention. This inhibition allows degradation to be stopped in two ways: firstly, by stopping the formation of hydrogen peroxide, and secondly, by stopping any chain reaction of free radicals. Both actions prevent and stop the degradation of compounds having heterocyclic structures.

[0194] Hydrogen peroxide can transform into a free radical called a "superoxide," which can react with water to form hydrogen peroxide. Hydrogen peroxide can then oxidize compounds with heterocyclic rings, producing degradation products such as organic acids and alcohols. Antioxidants can react with superoxide radicals, returning to hydrogen peroxide and thus becoming free radicals themselves. The resulting antioxidant with free radicals will dimerize or even trimerize with another free radical carried by another antioxidant, which will eliminate all the free radicals.

[0195] Superoxides can also react with a first compound containing a heterocycle, particularly with the oxygen contained within that heterocycle. This opens the heterocycle and thus generates a free radical on the first compound, which can then react with the oxygen in a second compound containing a heterocycle. This reaction again opens the heterocycle of the second compound, generating yet another free radical on it. This process can repeat itself and is known as a free radical chain reaction until all heterocycles are opened, that is, when all the compounds initially containing heterocycles have been chemically degraded. To prevent this, the free radical chain reaction must be stopped. This is where antioxidants come in: they react with the free radicals formed from compounds containing heterocycles, converting them into non-free radical compounds, while becoming free radicals themselves. The resulting antioxidant with free radicals will dimerize or even trimerize with another free radical carried by another antioxidant, which will eliminate all the free radicals.

[0196] Antioxidants that can be used in the compositions according to the invention are organic molecules comprising at least two aromatic rings linked together by carbon chains. Their general chemical formula is as follows (I):

[0197] (I)

[0198] in:

[0199] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0200] -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof.

[0201] -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0202] -m, n, and p are integers in the range 0 to 10, and when p=0, then m and / or n are greater than or equal to 1, or when both m and n are equal to 0, then p is greater than or equal to 1.

[0203] Antioxidants according to formula (I) can make heterocyclic compounds or their aqueous solutions antioxidant even at temperatures above 100°C, particularly above 150°C, more particularly above 200°C, and most particularly above 250°C. According to one embodiment, antioxidants according to formula (I) can make heterocyclic compounds (particularly heterocyclic compounds generated from the intramolecular dehydration of hydrogenated sugars) antioxidant even at temperatures above 100°C, particularly above 150°C, more particularly above 200°C, and most particularly above 250°C.

[0204] The substituents R4 to R13 attached to the aromatic ring of the antioxidant of formula (I) can be advantageously selected to enhance the antioxidant properties of the antioxidant and thus increase the antioxidant activity of the heterocyclic compound or its aqueous solution. Unbound by theory, the applicant believes that this selection can help stabilize free radicals formed on the antioxidant and increase the dimerization of free radical antioxidants with each other, thereby reducing or eliminating the possibility of free radical antioxidants reacting with heterocyclic compounds. Specifically, the applicant has found that the presence of a hydroxyl group and a methoxy group on the same aromatic ring greatly improves the antioxidant efficiency against aqueous compositions comprising compounds having at least one heterocyclic compound or derivatives thereof.

[0205] Compared to antioxidants of formula (I) where all R4 to R13 are hydrogen, antioxidants of formula (I) where at least one of R4 to R13 is a hydroxyl group or where at least one of R4 to R13 is a hydroxyl group and at least one of R4 to R13 is a methoxy group can increase antioxidant activity from slightly to significantly. Specifically, antioxidants of formula (I) where at least one of R4 to R13 is a hydroxyl group and at least one of R4 to R13 is a methoxy group exhibit significantly increased antioxidant properties, resulting in a significantly increased antioxidant activity of the compositions according to the invention. More specifically, antioxidants of formula (I) where at least one of R4 and / or R13 is a hydroxyl group and at least one of R6 and / or R11 is a methoxy group exhibit significantly increased antioxidant properties, resulting in a significantly increased antioxidant activity of the compositions according to the invention. For example, the antioxidant 2-hydroxy-4-methoxybenzophenone of formula (VII)

[0206] (VII)

[0207] This process enables isosorbide aqueous solutions to exhibit strong antioxidant properties, with an induction time of approximately 4-6 hours, as measured by the PetroOxy test of this application. Another example is 2,2'-dihydroxy-4-methoxy-benzophenone of formula (VIII).

[0208] (VIII)

[0209] The induction time was 5.2 hours.

[0210] Antioxidant properties

[0211] The composition according to this application is antioxidant. According to this application, "antioxidant" means that a compound having at least one heterocycle does not undergo chemical degradation for a duration of at least six months at a temperature of 4°C to 25°C. Such chemical degradation is the opening of the heterocycle, resulting in the formation of organic acids and alcohols, as well as other yellow degradation products. Therefore, such chemical degradation can be characterized by monitoring the pH and yellowing index of the composition over time. Since high levels of antioxidant activity are currently achieved using recently identified antioxidants, the applicant sought and discovered a faster method capable of providing results and demonstrating differences in antioxidant activity within hours rather than months. This is the "PetroOxy" method, commonly used in the petrochemical industry, and first applied by the applicant to isosorbide solutions, as disclosed in the applicant's previous patent application FR2108221.

[0212] The antioxidant properties of the compositions according to the invention can actually be characterized by a measurement known as the “PetroOxy test,” which involves measuring the pressure within a container holding a sample of the composition exposed to hydrogen peroxide at an initial pressure and a constant temperature over time. The protocol for this test is described below.

[0213] In one embodiment, "antioxidant" means an induction time greater than or equal to 3.8 hours according to the PetroOxy test of this application (at 120°C and 7 bar of oxygen). In a preferred embodiment, "antioxidant" means an induction time greater than or equal to 4.0 hours, particularly greater than or equal to 4.5 hours, and even more particularly greater than or equal to 5.0 hours, as measured by the PetroOxy test of this application at 120°C and 7 bar of oxygen.

[0214] Yellowing

[0215] Yellowing indicates two conditions within the compositions of this application: one is the internal color of the antioxidant; the other is the presence of degradation products resulting from oxidation. Antioxidants of formula (I) according to this application are inherently colored due to their aromatic rings, as are their degradation products and the resulting dimers or trimers produced by oxidation.

[0216] On the one hand, for some end uses, yellowing due to antioxidants is acceptable because it will be masked by pigments. On the other hand, for other end uses of the compositions according to the invention, yellowing must be as low as possible on freshly obtained compositions, or on compositions stored for several months, or even on compositions processed to produce end-use products. Yellowing after several months can be simulated by accelerated aging, which involves subjecting samples of the composition to heat treatment, such as the “heat treatment test” described below.

[0217] The compositions of the present invention have moderate to very low yellowing, or even no yellowing. "Moderate yellowing" means a yellowing index of 20.0 YID to 13.1 YID. "Low yellowing" means a yellowing index of 13.0 YID to 5.1 YID. "Very low yellowing" means a yellowing index of 5.0 YID to 3.0 YID. "No yellowing" means a yellowing index equal to or less than 3.0 YID, particularly equal to or less than 2.5 YID.

[0218] In one embodiment, the composition according to the invention exhibits high antioxidant properties and a moderate level of yellowing. Specifically, in this embodiment, high antioxidant properties mean an induction time greater than or equal to 5 hours, and a moderate level of yellowing means a yellowing index of 20.0 YID to 13.1 YID, and a high yellowing index after heat treatment means a yellowing index of 50.0 YID to 20.0 YID after heat treatment testing according to the present application.

[0219] In another embodiment, the composition according to this application exhibits good antioxidant properties and no yellowing, as measured according to the tests and methods described below. Specifically, in this embodiment, good antioxidant properties mean an induction time of 4.0 hours to 4.9 hours, and no yellowing means a yellowing index less than or equal to 3.0 YID before heat treatment and a yellowing index less than or equal to 10.0 YID after heat treatment.

[0220] Additional stabilizing compounds

[0221] According to one embodiment, several additional stabilizing compounds known in the art may be added to the composition according to the invention to provide further protection against chemical degradation or to enhance the antioxidant properties provided by the antioxidant according to the invention. These stabilizing compounds may be antioxidants that stabilize the composition by preventing or reducing oxidation reactions in a manner similar to that of antioxidants of formula (I) according to the invention. They may also function by neutralizing acidic degradation products, thereby preventing these acidic degradation products from further degrading compounds containing at least one heterocycle.

[0222] These optional additional stabilizing compounds are selected from gallic acid, gallate esters, phosphate compounds, amines, cyclic amines, or mixtures thereof. Specifically, they are selected from ethyl gallate, propyl gallate, disodium phosphate, diethanolamine, triethanolamine, tetramethylpiperidine, tetramethylpiperidinone, diazabicyclononene, diazabicycloundecene, or mixtures thereof.

[0223] According to another embodiment, the composition of the present invention does not contain any additional stabilizing compounds.

[0224] Method for preparing the composition according to the invention

[0225] The method according to the invention produces a composition of at least one heterocyclic compound, the composition being antioxidant and also exhibiting moderate to very low yellowing, or even no yellowing. This is due to the addition of an antioxidant of formula (I) after any one of steps a), b), c), d), or e):

[0226] (I)

[0227] in:

[0228] -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof.

[0229] -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof.

[0230] -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

[0231] -m, n, and p are integers in the range 0 to 10, and when p=0, then m and / or n are greater than or equal to 1, or when both m and n are equal to 0, then p is greater than or equal to 1.

[0232] purification

[0233] According to the method of the present invention, purification step d) removes impurities from the crude reaction mixture obtained in step a) and / or step b) or from the distillate obtained in step c).

[0234] According to one embodiment, step d) consists of at least one purification device selected from decolorization devices and ion exchange devices.

[0235] The term "decolorization device" specifically refers to activated carbon and adsorption resin in granular or powdered form. For example, granular activated carbon such as CECA DC 50, powdered activated carbon such as NORIT SX+, and / or resins such as DUOLITEXAD 761, MACRONET MN-600, or MACRONET MN-400 can be used. The term "ion exchange" specifically refers to weak or strong anion exchange resins, as well as weak or strong cation exchange resins. For example, strong anion exchange resins such as AMBERLITE IRA 910 or strong cation exchange resins such as PUROLITE C 150 S can be used alone or in combination. The ion exchange medium can advantageously comprise at least one anion exchange resin and at least one cation exchange resin. Preferably, the device consists of a mixed bed of anion and cation exchange resins, or a continuous bed of cation and then anion exchange resins, or a continuous bed of anion and then cation exchange resins.

[0236] Specifically, in step d) of the method according to the invention, the crude reaction mixture obtained in steps a) and / or b) or the distillate obtained in step c) is treated in any order with at least one activated carbon and at least one ion-exchange resin or non-ion-exchange resin. According to one embodiment, the first purification is performed by passing through activated carbon, followed by at least one resin, and then through activated carbon again.

[0237] Forming

[0238] According to the method of the present invention, the forming step e) alters the physical state of any substance obtained in steps a), b), c), or d) by changing at least one characteristic of the physical state (which is either liquid or solid) while keeping the physical state (which is one of the same category) in the same category, or by changing the physical state to another physical state (e.g., changing a liquid to a solid, or a solid to a liquid).

[0239] Specifically, forming encompasses the following physical states: solutions, especially aqueous solutions; molten liquids; bulk solids, especially granules or flakes; and dispersed solids, especially crystals.

[0240] Specifically, at least one characteristic of the physical state that changes while keeping the physical state within the same category is the dry matter content of the liquid, the water content of the solid, the size distribution of the dispersed solid, or the crystallinity of the solid. Crystallinity refers to one of crystalline, semi-crystalline, or amorphous.

[0241] The shaping method for step e) can be selected from evaporation concentration, membrane filtration concentration, vacuum drying, fluidized bed drying, horizontal cylindrical dryer, solvent evaporation crystallization, cooling crystallization, or molten crystallization.

[0242] "PetroOxy" test: A method for measuring induction time

[0243] The method described below is for isosorbide as a compound having at least one heterocycle, and is also applicable to any compound having at least one heterocycle.

[0244] A solution of 3 g of purified 50 wt% dry isosorbide in distilled water (with or without antioxidant) was precisely weighed into a glass beaker and placed in the sealed housing of a Petrotest (now Anton Paar GmbH) measuring device, model 13-3002. At room temperature, the air in the container was purged three times with pure oxygen from a pressurized cylinder (Alphagas, purity >99.5%). The temperature and working pressure of the pure oxygen were then set to 120 °C and 700 kPa (7 bar). The pressure was continuously monitored during the experiment. The pressure drop in the test chamber was due to oxygen consumption during the oxidation reaction of the sample under study. The change in relative pressure during the experiment allowed determination of the time after the sample began oxidative degradation under the test conditions, referred to as the induction time, also known as the "OIT".

[0245] The induction time for the sample was determined as follows:

[0246] The relative pressure of oxygen consumption is given by the relationship (Pmax - Pt) / Pmax. Pmax is the maximum pressure reached by the system during the measurement period, corresponding to the maximum pressure at the beginning of the time interval, while Pt is the pressure that changes over time during oxygen consumption. The induction time of the sample is given by the inflection point of the oxygen consumption curve, i.e., as shown below. Figure 1 The intersection of the two linear domains shown.

[0247] The longer the induction time, the better the antioxidant properties of the sample. To accurately calculate this parameter, a linear regression calculation was performed between two line segments before and after the inflection point.

[0248] Methods for measuring yellowing index

[0249] The yellowing index (expressed in YID units) was measured using a Colorflex EZ spectrophotometer from Hunterlab, according to ASTM E313. The spectrophotometer is a hermetically sealed optical device with a 256-element diode array, a spectral range of 400 nm–700 nm, and a high-resolution concave holographic grating. 55 g of the composition was placed in a 64 mm diameter cylindrical container, including a ring and a white disc lid, at 65 °C. The color of the composition was measured in liquid form at 65 °C.

[0250] "Heat Treatment" Test: A method for determining the thermal stability of a composition to temperature.

[0251] The method described below is for isosorbide as a compound having at least one heterocycle, and is also applicable to any compound having at least one heterocycle.

[0252] The thermal stability of isosorbide compositions was studied according to the following protocol: 70 g of an 80% by weight solution of isosorbide in water was placed in a three-necked round-bottom flask and inertized over 10 minutes with high-purity nitrogen (purity >99.9%) at a flow rate of approximately 2000 mL / min. The product was then heated at 245 °C for 40 minutes using an oil bath at a nitrogen flow rate of 500 mL / min. The product was then cooled to 80 °C at the same nitrogen flow rate, and the yellowing index (YID) was immediately measured.

[0253] The color and its difference before and after "heat treatment" are related to the thermal stability of the product, that is, to the product's sensitivity to oxidation.

[0254] Example

[0255] Example 1: Preparation of unstable isosorbide compositions and study of their induction time and yellowing index .

[0256] The unstable isosorbide solution is prepared as follows:

[0257] In a double-jacketed stirred reactor, we introduced 1 kg of a 70% by weight dry matter (MS) sorbitol solution sold by the applicant under the name NEOSORB 70 / 02 and 7 g of concentrated sulfuric acid. The resulting mixture was heated under vacuum (100 mbar) for 5 hours to remove water contained in the reaction medium and from the dehydration reaction of sorbitol.

[0258] The crude reaction product was then cooled to 100°C and neutralized with 11.4 g of 50% sodium solution. The isosorbide composition was then distilled under vacuum (pressure less than 50 mbar).

[0259] The slightly colored (pale yellow) isosorbide distillate was then dissolved in isopropanol at 60°C to obtain a homogeneous solution of 75% by weight dry matter. This solution was then slowly cooled to 10°C over 5 hours. Recrystallized isosorbide primers were added at 40°C.

[0260] The crystals were then wrung dry in a vortex mixer and washed with isopropanol. After vacuum drying, the crystals were redissolved in water to obtain an aqueous solution of 50% by weight of dry matter.

[0261] The solution was then percolated on a granular activated carbon column (GC 12-40, relative velocity 0.5 V / V / h (product volume / resin volume / hour)). The resulting decolorized isosorbide composition was continuously passed through a strong cation exchange resin column (PUROLITE C150 S) at a rate of 2 V / V / h, followed by a strong anion exchange resin AMBERLITE IRA910. The solution was then treated with powdered activated carbon (NORIT SX+) at 20°C for one hour. The amount of coal used was 0.5% by weight relative to the dry weight of the solution.

[0262] After filtering with activated carbon, the isosorbide solution was recovered and stored in a high-density polyethylene container in a dark room at 4°C. It was then analyzed according to the method described above.

[0263] The induction time for the unadulterated isosorbide solution was 3.5 h. This value will be used as a reference for determining the efficacy of the antioxidant.

[0264] Example 2: Preparation of a stable isosorbide solution and study of its induction time and yellowing index.

[0265] Various stable isosorbide solutions were prepared according to the following scheme:

[0266] 1000 g of the unstable isosorbide solution prepared in Example 1 was introduced into a flask under nitrogen atmosphere. 50 mg of antioxidant was added to the isosorbide solution. Mixing was performed with a magnetic stirrer over 180 minutes to ensure homogeneous blending of isosorbide and antioxidant. Therefore, the antioxidant content was equal to 100 ppm of antioxidant dry matter relative to the dry matter of isosorbide. The stable isosorbide solution was then stored at 4°C under nitrogen atmosphere.

[0267] The induction time of each stable isosorbide solution was characterized using the PetroOxy test, and its yellowing index (YID) was characterized before and after the thermal test. The results are shown in Table 1.

[0268] [Table 1]

[0269]

[0270] The results in Table 1 show that the four benzophenone compounds can increase the induction time of isosorbide aqueous solution, which means that they can delay the onset of oxidation in such isosorbide solutions.

[0271] The induction time of 2,2'-dihydroxy-4-methoxy-benzophenone increased the most, which means it has the highest antioxidant activity.

[0272] These results show that the use of benzophenone compounds can delay the oxidation of isosorbide solutions by oxygen. The momentum of the delay is surprisingly dependent on the nature of the substituents on the aromatic ring and varies in unpredictable ways.

[0273] Example 3: Resistance to degradation of stable isosorbide solutions during heat treatment

[0274] According to this application, samples of isosorbide solutions (without antioxidant or with 100 ppm antioxidant) prepared according to the scheme of Example 2, as shown in Table 2, were subjected to heat treatment tests. Yellowing of each isosorbide solution was measured before and after the heat treatment test.

[0275] [Table 2]

[0276]

[0277] In Table 2, the yellowing index values ​​before heat treatment are the result of the internal yellowing defined by the chemical structure of each antioxidant. Therefore, it can be seen that, compared to benzophenone, the substituents of the aromatic rings cause increased yellowing.

[0278] After heat treatment, the yellowing index increased compared to before heat treatment because a pale yellow compound was formed through the thermal degradation of isosorbide and antioxidants.

[0279] Benzophenone advantageously provides the lowest yellowing index before heat treatment and a yellowing index below 10 after heat treatment, corresponding to a yellow tint that is imperceptible to the naked eye. To a certain extent, the induction time of isosorbide solutions containing benzophenone increases by only about 9% compared to isosorbide solutions without antioxidants. Therefore, benzophenone is best suited for increasing the antioxidant stability of isosorbide solutions when the lowest yellowing index is required and in applications where heat treatment of the isosorbide solution is not performed.

[0280] 2,2'-Dihydroxy-4-methoxy-benzophenone exhibited the highest yellowing index both before and after heat treatment testing. Although it showed the highest induction time, i.e., the highest antioxidant protection, according to PetroOxy testing, the high yellowness may be problematic for some end uses of isosorbide. Therefore, this antioxidant should only be used for isosorbide solutions that have not undergone heat treatment (e.g., the "Heat Treatment Test" of this application), or for uses where yellowness is acceptable or can be masked by incorporating appropriate pigments into the final product containing isosorbide.

[0281] Compared to 2,2'-dihydroxy-4-methoxy-benzophenone, 4,4'-dihydroxy-benzophenone exhibited a lower yellowing index both before (three times lower) and after (almost five times lower) the yellowing index, with both values ​​below 10. Considering its 3.9-hour induction time, this antioxidant provides comparable antioxidant protection to benzophenone but with a higher yellowing index. It represents, to some extent, an acceptable alternative to benzophenone.

[0282] Prior to heat treatment testing, 2-hydroxy-4-methoxy-benzophenone surprisingly produced one-sixth the yellowing of 2,2'-dihydroxy-4-methoxy-benzophenone, despite the sole structural difference being the absence of a hydroxyl group in one of the two aromatic rings. It also produced the lowest yellowing after heat treatment among all the benzophenone derivatives tested, equivalent to a surprising quarter of the increase in yellowing after heat treatment compared to 2,2'-dihydroxy-4-methoxy-benzophenone. Surprisingly, this minute difference in chemical structure (i.e., the absence of a hydroxyl group at the 2-position of one aromatic ring) had such a significant impact on the yellowing index. Since 2-hydroxy-4-methoxy-benzophenone ranked second in induction time according to PetroOxy testing, and due to its lowest induced yellowing, this antioxidant was the best among all tests in Tables 1 and 2. It maintained a yellowing index below 7 after heat treatment, corresponding to a yellowing that is imperceptible to the naked eye, while providing very good antioxidant protection. This antioxidant offers the optimal balance between anti-oxidation and low yellowing.

Claims

1. A composition comprising: - At least one compound having at least one heterocycle, - and at least one antioxidant of formula (I): (I) in: -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof. -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof. -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10. -m, n, and p are integers in the range 0 to 10, and when p=0, m and / or n are greater than or equal to 1, or when both m and n are equal to 0, p is greater than or equal to 1.

2. The composition according to claim 1, wherein the antioxidant has formula (II): (II) in: -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof. -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof. -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10. -n is an integer in the range of 0 to 10.

3. The composition according to claim 1, wherein the antioxidant has formula (III): (III) in: -R1 is selected from oxygen, CH2, and saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms. -R2 to R11 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10.

4. The composition according to claim 3, wherein the antioxidant is a benzophenone compound of formula (IV): (IV) R1 to R8 are selected from H, OH, CH3, and O-CH3.

5. The composition according to claim 4, wherein the benzophenone compound of formula (III) is a compound of formulas (V) to (VIII): (V)、 (VI) (VII)、 (VIII)。 6. The composition according to claim 4, wherein the benzophenone compound of formula (III) is 2-hydroxy-4-methoxybenzophenone of formula (VII). (VII)。 7. The composition according to any one of the preceding claims, wherein the content of the antioxidant in the composition is equal to or less than 1000 ppm relative to the weight of the organic compound, particularly equal to or less than 500 ppm, or equal to or less than 400 ppm, or equal to or less than 300 ppm, or equal to or less than 200 ppm, or equal to or less than 100 ppm.

8. The composition according to any one of the preceding claims, wherein the heterocyclic compound is generated by intramolecular dehydration of a hydrogenated sugar, or is a derivative of the intramolecular dehydration product of a hydrogenated sugar.

9. The composition according to claim 8, wherein the hydrogenated sugar is selected from sorbitol, mannitol, or xylitol or mixtures thereof, particularly sorbitol.

10. The composition according to any one of the preceding claims, wherein it exhibits an induction time of 3.8 hours or more, particularly 4.0 hours or more, even more particularly 4.5 hours or more, and most particularly 5.0 hours or more, as measured by the "PetroOxy test" at 120°C and 7 bar of oxygen.

11. The composition according to claim 10, wherein it exhibits a yellowing index equal to or less than 13.0 YID, particularly equal to or less than 5.0 YID, more particularly equal to or less than 3.0 YID, and most particularly equal to or less than 2.5 YID.

12. The composition according to any one of claims 10 or 11, wherein it exhibits a yellowing index equal to or less than 50.0 YID, particularly equal to or less than 10.0 YID, more particularly equal to or less than 8.0 YID, and most particularly equal to or less than 6.5 YID after a heat treatment test.

13. A method for preparing the composition according to any one of claims 1 to 12, comprising: a) An intramolecular dehydration step of hydrogenated sugars to obtain the dehydrated product in the crude reaction mixture. b) Optionally, a derivatization step of the dehydrated product obtained in step a) to obtain a derivative of the dehydrated product in the crude reaction mixture. c) Optionally, a distillation step of the crude reaction mixture obtained in step a) and / or step b) to obtain a distillate rich in the dehydrated product or its derivatives. d) Optionally, a purification step of the crude reaction mixture obtained in step a) and / or step b) and / or the distillate obtained in step c) to obtain a purified dehydrated product. e) Optionally, shaping the crude reaction mixture obtained in step a) and / or step b), and / or shaping the distillate obtained in step c), and / or shaping the purified dehydrated product obtained in step d), to obtain a shaped dehydrated product. f) The step of adding at least one antioxidant of formula (I) to the crude reaction mixture obtained in step a) and / or step b), and / or to the distillate obtained in step c), and / or to the purified dehydrated product obtained in step d), and / or to the shaped dehydrated product obtained in step e), (I) in: -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof. -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof. -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10. -m, n, and p are integers in the range 0 to 10, and when p=0, m and / or n are greater than or equal to 1, or when both m and n are equal to 0, p is greater than or equal to 1.

14. Antioxidants of Formula (I) (I) Use in compositions comprising at least one compound having at least one heterocyclic ring for preventing or reducing the chemical degradation of the dehydration product or its derivatives. in: -R1 and R3 are selected from oxygen, CH2, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, or combinations thereof. -R2 and R2' are selected from hydrogen, CH3, saturated or unsaturated alkyl groups containing 2 to 10 carbon atoms, aromatic rings, or combinations thereof. -R4 to R13 are selected from H, OH, C x H 2x+1 OC y H 2y+1 x and y are integers in the range of 1 to 10. -m, n, and p are integers in the range 0 to 10, and when p=0, m and / or n are greater than or equal to 1, or when both m and n are equal to 0, p is greater than or equal to 1.

15. Use of the composition according to any one of claims 1 to 12 for the preparation of polymeric or non-polymeric, biodegradable or non-biodegradable products or mixtures for use in the chemical, pharmaceutical, cosmetic or food industries.

16. The use according to claim 15, wherein the use is to prepare the intramolecular dehydration product containing hydrogenated sugar as a comonomer, particularly a polyester or polycarbonate containing isosorbide as a comonomer.

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