Alkali metal phenolic compound and application thereof

Abstract

The invention relates to the use of alkali metal phenolic compounds of formula (I) or (II) as catalysts in the ring-opening polymerization of heterocycles, such as cyclic esters, ethers and carbonates, for the industrial production of biodegradable polymers. The invention also relates to a polymerization process using said compounds. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the use of alkali metal phenolate compounds as catalysts in the ring-opening polymerization of heterocycles (such as cyclic esters, ethers, and carbonates), which is used in the industrial production of biodegradable polymers.

[0002] Therefore, the present invention belongs to the field of chemistry, belonging to the sub-fields of organic and inorganic synthetic chemistry and polymers, where the obtained plastic materials have numerous applications in fields such as food packaging, agriculture, the textile industry, etc., as well as in the production of consumer goods such as automobiles, household appliances, and various utensils. Background Art

[0003] Currently, there is great interest in the development of biodegradable polymers, among which aliphatic polyesters and polycarbonates are particularly prominent. Among them, polylactide or polylactic acid, abbreviated as PLA, is an aliphatic polyester produced on an industrial scale and has extensive applications in important fields such as food packaging, agriculture, or consumer goods. For decades, many catalysts and different methods have been described to obtain PLA, and the number of studies in this area has been increasing annually. The most widely used catalyst for its production is tin bis(2-ethylhexanoate) (commonly known as tin octoate), a catalyst containing a toxic metal. Tin octoate is a hazardous substance that can cause allergic skin reactions, severe eye damage, damage to fertility or harm to the fetus, and is highly harmful to aquatic organisms with a long-lasting impact, but there is no better alternative for its industrial use. Therefore, a final purification step is required to remove unreacted reagents from the medium. This process involves high energy costs, which often raises questions about the effectiveness of the method.

[0004] In extensive research, the use of non-metal catalysts has been proposed. However, the obtained polymers exhibit low molecular weights (M n <15 kDa), which often limits many of their possible applications. In addition, they often use longer reaction times, which has a negative impact on the economics of the process.

[0005] In the PLA production processes described in various patent documents (such as, for example, EP2992029B1, WO2017128049A1 and EP2507289B1), the conversion of lactide monomers to PLA polymers is not complete, i.e., at the end of the reaction, not all lactide is converted to PLA. Therefore, a large part of the lactide remains in the final material, which has a negative impact on the properties and processing of the polymer. In addition, in these processes, it is necessary to add an inactivator to deactivate the catalyst used to prevent the reverse depolymerization reaction. This reagent is added to the reaction mixture after the devolatilization process of removing unreacted lactide from the medium when the monomer conversion reaches at least 90%. When the monomer-polymer equilibrium changes, i.e., when the unreacted monomer is removed from the medium, the depolymerization method can occur.

[0006] Many studies on various organometallic compounds have been published in the literature, many of which are based on alkali metals (Group 1), including potassium, and also contain phenolic acid groups (Wu, Inorg. Chem. 2012, 5113380; Wu, Indorg. Chem. 2016, 55136; Wu, ACS Macro Lett. 2015, 4556; Tang, Inorganic Chemistry Communications 2010, 13376), and are used as catalysts for producing polymers with low molecular weights (not exceeding 30 kDa). In addition, the catalysts described in these studies require cocatalysts.

[0007] Several patents are related to the production processes of lactide polymers; however, most patents describe improvements to the industrial processes for obtaining PLA (US5258488A, ES2017562, ES2292338, ES2311024) or synthetic lactide monomers (US5247059A, US20110306749). The catalyst used in most cases is tin octoate (US5770682A, US20110306749). Other patents detail the use of novel catalysts based on rare earth metals such as scandium, yttrium (US5292859), lanthanum, and other patents detail the use of metals such as zirconium or hafnium (EP2992029B1), zinc (EP2507289B1) or metal-organic frameworks (WO2017128049A1). No patented method using the alkali metal catalysts described in the present invention has been found.

[0008] In view of the above-mentioned drawbacks existing in the prior art, the present invention describes a non-toxic alkali metal compound for polymerization reactions to obtain polymers with high molecular weights and on an industrial scale, such as PLA, etc. Summary of the Invention

[0009] The inventors have found that certain alkali metal phenolate compounds catalyze polymerization or copolymerization reactions (collectively referred to as (co)polymerization reactions) in quantitative yields to produce polymers of great interest in a simple manner.

[0010] Thus, in a first aspect, the present invention relates to the use of a compound of general formula (I) or (II) as a catalyst in a heterocyclic ring-opening (co)polymerization process:

[0011]

[0012] Where:

[0013] R1 and R2 are independently selected from hydrogen, C3-C8 alkyl, C3-C8 haloalkyl, C3-C8 alkoxide, C3-C8 haloalkoxide, C3-C8 dialkylamino, C3-C8 halodialkylamino, C3-C8 hydroxyalkyl or cyanide,

[0014] R3 is selected from: H, C3-C8 alkyl, C3-C8 haloalkyl, C3-C8 cyanoalkyl, C3-C8 alkoxy, C3-C8 dialkylamino or cyanide,

[0015] n is an integer between 1 and 3, and

[0016] M is an alkali metal selected from Li, Na and K.

[0017] In the reaction catalyzed by the compound of formula (I) or (II), a single heterocycle (polymerization reaction) or at least two different heterocycles (copolymerization reaction) may be involved.

[0018] In the present invention, the term "heterocycle" refers to a compound formed by a cyclic hydrocarbon chain having 3 to 20 chains, wherein at least one carbon atom of the main chain has been replaced by O, N or S. It can be saturated or unsaturated, although they are preferably saturated. These heterocycles may optionally be substituted at one or more positions by one or more groups such as hydroxyl, amine, amide, oxygen, cyanide, halogen, aryl, etc.

[0019] The synthesis of the compound of formula (I) is shown in Scheme 1. The preparation of the compounds of general formula (1) and (I) has been described by D.J. Mindiola et al. in the patent document US2014 / 0213805A1. The derivatives of type (2) are the corresponding metal precursors and they are commercially available compounds or can be easily prepared by those skilled in the art.

[0020] Scheme 1:

[0021]

[0022] In the MR reagent (2), M is an alkali metal selected from Li, Na, and K, and R represents a hydrogen atom, a halogen atom, or an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an amide group, a haloalkyl group, an alcoholate group, a cycloalkanolate group, a haloalcoholate group, an aryloxy group, a thioalkyl group, a thiocycloalkyl group, a thioaryl group, an amino group, an alkylamino group, a dialkylamino group, a halodialkylamino group, a cycloalkylamino group, a dicycloalkylamino group, an alkyl(cycloalkyl)amino group, an arylamino group, a diarylamino group, an alkylarylamino group, a cyanoalkyl group, or a hydrocarbon alkyl group, and the alkyl group present in the said group is preferably a C3-C8 alkyl group.

[0023] In the compound of general formula (1), R1, R2, and R3 have the same meanings as the groups R1, R2, and R3 of the compound of the aforementioned formula (I).

[0024] The reaction of the compound of general formula (1) with the compound of general formula (2) to obtain the compound of general formula (I) can be carried out as described in the patent document US 2014 / 0213805A1. Briefly, the reaction is carried out in an inert atmosphere, such as an argon or nitrogen atmosphere, in an aprotic solvent, at a temperature between -90 and +50 °C. The compound obtained thereby is purified by standard purification methods, such as recrystallization or washing with a non-coordinating solvent such as n-hexane.

[0025] Aromatic hydrocarbons, such as benzene or toluene; aliphatic hydrocarbons, such as pentane, hexane, heptane, cyclohexane; ethers, such as diethyl ether, dioxane, tetrahydrofuran (THF), or ethyl tert-butyl ether, can be used as aprotic solvents.

[0026] In the presence of a coordinating solvent such as THF or other neutral compounds such as crown ethers, the compound of general formula (I) can incorporate them as ligands into its coordination sphere.

[0027] The compound of formula (II) can be obtained in a manner similar to that for obtaining the compound of formula (I), that is, by reacting the compound of general formula (1) with the compound of general formula (2), as described in the patent document US2014 / 0213805 A1, but adding a crown ether to the reaction medium, and preferably the molar ratio of the compound of formula (1):crown ether is 1:1. In a preferred embodiment, the crown ether used is 18-crown-6 ether.

[0028] The terms "C3-C8 alkyl" and "C3-C8 cycloalkyl" used in the present invention respectively refer to straight-chain or cyclic carbon groups between 3 and 8 carbon atoms, which may or may not be branched. Examples of unbranched and straight-chain alkyl groups are methyl, ethyl, propyl, pentyl, hexyl, heptyl. Examples of branched alkyl groups are 2-propyl, 2-butyl. Cyclic groups include cyclopropyl, cyclobutyl, or cyclohexyl, etc.

[0029] The term "C3-C8 alkenyl" or "C3-C8 alkynyl" refers to groups similar to those defined for alkyl, but having one or more double bonds C=C or triple bonds C≡C, respectively. They may be branched or may not be branched, and they may be straight-chain or cyclic, with between 3 and 8 carbon atoms. They may be substituted or unsubstituted, just like alkyl.

[0030] The term "amide" refers to groups such as (NH2) - or (N(alkyl)2) - where alkyl is as defined previously (C3-C8 alkyl).

[0031] The term "halogen" (or halide) refers to F, Cl, Br or I.

[0032] The term "aryl" refers to single or multiple aromatic rings from which a proton has been removed from the ring. Examples of aryl are phenyl, naphthyl and anthracenyl.

[0033] The term "C3-C8 haloalkyl" refers to a C3-C8 alkyl having one or more halogen substituents.

[0034] The term "C3-C8 alkoxide" (or "C3-C8 alkoxy") refers to a group such as O-C3-C8 alkyl.

[0035] The term "C3-C8 cycloalkoxide" refers to a group such as O-C3-C8 cycloalkyl.

[0036] The term "C3-C8 halo-alkoxide" refers to a group in which the C3-C8 alkyl of the alkoxide has one or more halogen substituents.

[0037] The term "aryloxide" refers to a group such as O-aryl; aryl is as defined previously.

[0038] The term "C3-C8 thioalkyl" refers to a group such as S-C3-C8 alkyl.

[0039] The term "C3-C8 thiocycloalkyl()" refers to a group such as S-C3-C8 cycloalkyl.

[0040] The term "thiocycloalkyl" refers to a group such as S-aryl; aryl is as defined previously.

[0041] The term "amino" refers to a group such as -NH2.

[0042] The term "C3-C8 alkylamino" refers to an amino group in which one hydrogen is replaced by a C3-C8 alkyl group.

[0043] The term "C3-C8 dialkylamino" refers to a group such as -N(alkyl)2; the alkyl group is as defined previously (C3-C8 alkyl).

[0044] The term "C3-C8 halo-dialkylamino" refers to a dialkylamino group in which at least one alkyl group has a halide substituent.

[0045] The term "C3-C8 cycloalkylamino" refers to an amino group in which one hydrogen is replaced by a C3-C8 cycloalkyl group.

[0046] The term "di(cycloalkyl)amino" refers to a group such as -N(cycloalkyl)2; the cycloalkyl group is as defined previously (C3-C8 cycloalkyl).

[0047] The term "alkyl(cycloalkyl)amino" refers to an amino group in which two hydrogens are replaced by an alkyl group and a cycloalkyl group; these terms are as defined previously (C3-C8 alkyl or cycloalkyl).

[0048] The term "arylamino" refers to an amino group in which one hydrogen is replaced by an aryl group, the aryl group being as defined previously.

[0049] The term "diarylamino" refers to groups such as -N(aryl)2; the aryl group is as defined previously.

[0050] The term "C3-C8 alkylarylamino" refers to an amino group in which two hydrogens are each replaced by a C3-C8 alkyl group and an aryl group; the C3-C8 alkyl group and the aryl group are as defined previously.

[0051] The term "(cycloalkyl)arylamino" refers to an amino group in which two hydrogens are each replaced by a C3-C8 cycloalkyl group and an aryl group; the cycloalkyl group and the aryl group are as defined previously.

[0052] The term "C3-C8 cyanoalkyl" refers to an alkyl group that is substituted by one or more cyano (-CN) substituents.

[0053] The term "C3-C8 hydroxyalkyl" refers to an alkyl group that is substituted by one or more hydroxy substituents.

[0054] In a preferred embodiment of using the compound of formula (I) or (II), R1 and R2 are H.

[0055] In another preferred embodiment of using the compound of formula (I) or (II), R3 is a C3-C8 alkyl group, more preferably tert-butyl.

[0056] In another preferred embodiment of using the compound of formula (I) or (II), M is sodium or potassium.

[0057] In another preferred embodiment of using the compound of formula (II), n is 3.

[0058] In a more preferred embodiment, the compound is selected from one of the following:

[0059]

[0060] Potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenol

[0061]

[0062] In the (co)polymerization reaction, the compound of formula (I) or (II) also functions as a reaction initiator and / or regulator.

[0063] The compound of general formula (I) or (II) is particularly useful and active in the ring-opening (co)polymerization reaction of heterocycles selected from cyclic esters (including diesters, i.e., the ring includes two ester groups), ethers, thioethers, amides, and carbonates.

[0064] In a preferred embodiment, the heterocycle is a diester, a cyclic ester of general formula (a), a cyclic amide of general formula (b), and a cyclic carbonate of general formula (c), wherein the rings a), b), and c) can have 3 to 20 linkages:

[0065]

[0066] In a more preferred embodiment, the heterocycle is selected from: cyclic esters (including diesters) and carbonates. Preferably, the heterocycle is selected from: lactide, preferably L-lactide, ε-caprolactone, trimethylene carbonate, and ethylenebrassylate. More preferably, the starting heterocycle is lactide, preferably L-lactide and / or ε-caprolactone. Even more preferably, the starting heterocycle is lactide, preferably L-lactide.

[0067] In another preferred embodiment, the heterocycle is selected from epoxides and thioepoxides.

[0068] Another aspect of the present invention relates to a method for the ring-opening polymerization or copolymerization of heterocycles selected from cyclic esters, ethers, thioethers, and carbonates, which comprises contacting the starting heterocycle(s) with a compound of formula (I) or (II) as defined above.

[0069] In a preferred embodiment, the preferred starting heterocycle is the heterocycle shown in the first aspect of the present invention.

[0070] In particular, using lactide as the starting heterocycle for the ring-opening polymerization reaction, PLA can be obtained at room temperature in just one minute. The obtained PLA has a high molecular weight (greater than 100 kDa), which opens the door for using this method on an industrial scale. In addition, the obtained polymer has a bimodal weight distribution, indicating the presence of two very different sets of polymer chains in the material. This bimodal distribution is due to the majority of the chain groups with a molecular weight exceeding 100 kDa, while the second set of chains consists of PLA oligomers of about 500 Da. PLA oligomers are used as plasticizing additives for bioplastics, especially industrially obtained PLA, which is well-known in the industry for exhibiting rigidity and brittleness problems and is increasingly being produced and incorporated into plastic formulations. The lactide polymerization method described in the present invention allows for the obtaining of a material whose composition already contains a small portion of PLA oligomers acting as plasticizers, which represents a significant industrial breakthrough in material processing without the need for subsequent modification. In addition, all the lactide monomers are completely converted into the PLA polymer, i.e., at the end of the reaction, all the lactide is converted into poly(lactide). This represents an improvement over the industrial process using tin octoate as a catalyst, which does not convert all the monomers into polymers and leaves a large portion of lactide in the material, significantly deteriorating its physical properties and thus requiring a purification process. By the method described in the present invention, the purification of the material at the end of the reaction to remove lactide monomers required in the industrial process is avoided.

[0071] If the starting heterocycle is a liquid, the method can be carried out in the presence or absence of a solvent. If the starting heterocycle is a solid at room temperature, the reaction can be carried out in the molten state.

[0072] If the reaction is carried out in the presence of a solvent, the solvent is preferably an aprotic solvent, whether polar or non-polar, such as aromatic hydrocarbons (toluene), ethers (tetrahydrofuran, THF), or aliphatic halogenated compounds (dichloromethane, DCM) and aromatic halogenated compounds (bromobenzene).

[0073] (Co)polymerization reactions can be carried out within a wide temperature range from 0 °C to 200 °C, preferably between 15 and 30 °C, and more preferably at room temperature (20 - 25 °C), provided that the reaction is carried out in the presence of a solvent or the starting heterocycle is liquid at said temperature. If the reaction is carried out in the molten state, the reaction temperature will be higher than the temperature at which the starting heterocycle melts.

[0074] The duration of the reaction can range from 1 second to 300 hours, but the reaction time is typically between 1 second and 72 hours.

[0075] In a preferred embodiment, the method is carried out in the presence of a catalyst of formula (I) or (II) at 0.1 to 2 mol%, more preferably 2 mol%, relative to the starting heterocycle.

[0076] In a preferred embodiment, the method is carried out without a cocatalyst, so the compound of formula (I) or (II) is the sole catalyst for the reaction.

[0077] In another preferred embodiment, the method is carried out in the presence of a cocatalyst. Some examples of the indicated cocatalysts are benzyl alcohol or isopropyl alcohol.

[0078] In a preferred embodiment, the method starts with L-lactide in dichloromethane or toluene and is carried out at room temperature.

[0079] In another preferred embodiment, the method starts with L-lactide in the molten state at 145 °C without a solvent.

[0080] In another preferred embodiment, the method starts with L-lactide in dichloromethane at room temperature and in the presence of benzyl alcohol as a cocatalyst.

[0081] In a preferred embodiment, the method starts with L-lactide and ε-caprolactone in dichloromethane at room temperature.

[0082] In a preferred embodiment, the method starts with ε-caprolactone at 80 °C without a solvent (molten state).

[0083] In a preferred embodiment, the method starts with trimethylene carbonate or ethylidene barate at 80 °C without a solvent (molten state).

[0084] The method described as such has the following remarkable advantages:

[0085] · The compounds of the present invention contain alkali metals such as lithium, sodium or potassium, which do not have intrinsic toxicity, which represents an advantage over prior art catalysts that include toxic or health - harmful metals;

[0086] · It can be carried out with purified or unpurified monomers in an inert atmosphere and in air;

[0087] · The reaction has a quantitative yield because all initial reagents are converted into products, which reduces the need for purifying the obtained polymer;

[0088] · The obtained polymer does not undergo racemization or depolymerization reactions;

[0089] · In the last step, no catalyst deactivator is required to prevent depolymerization and racemization reactions;

[0090] · It is particularly advantageous for obtaining high - molecular - weight PLA with piezoelectric capacitance potential;

[0091] · The polydispersity (M w / M n ) of the obtained (co) polymer can be modified by leaving the reaction mixture at the reaction temperature after complete conversion of the monomers due to intramolecular or intermolecular chain - transfer processes; the quality of the (co) polymer is hardly affected during these processes (H.R. Kricheldorf, M. Berl and N. Scharnagl, Macromolecules, 1988, 21 286);

[0092] · The applications of the obtained polymer may be similar to those of conventional plastic products such as polypropylene, polystyrene, polyethylene, etc.

[0093] The last aspect of the present invention relates to the use of the previously defined compounds of formula (I) or (II) as catalysts in a depolymerization method to obtain oligomers and derivatives of monomers that form polymers. The method requires an alcohol, such as methanol, ethanol or benzyl alcohol, to be present in an amount in excess relative to the catalyst, preferably more than 50 equivalents. In this reaction, the alcohol serves as a chain - transfer agent to obtain derivatives of the starting heterocycle from polymers that have heteroatoms in their structure. The method will be included in the concept of chemical recycling.

[0094] The alcohol has the formula ROH, where R represents a C3 - C8 alkyl or benzyl group. Thereby, PLA oligomers and products derived from the starting heterocycle of interest, such as methyl lactate or ethyl lactate, are produced, which can be used as solvents and are considered better alternatives to other more polluting solvents.

[0095] Preferred embodiments of using a compound of formula (I) or (II) as a catalyst in the depolymerization method include depolymerizing polylactide in a DCM or ethyl acetate solution by an alcoholysis process at 25 °C in the presence of methanol.

[0096] Throughout the specification and claims, the word "comprise" and its variants are not intended to exclude other technical features, additives, components or steps. For those skilled in the art, other objects, advantages and features of the present invention will become more apparent in part from the description and in part by putting the present invention into practice. The following examples are provided only as examples and are not intended to limit the present invention. Examples

[0097] By way of non-limiting illustration of the present invention, the examples conducted by the inventors are shown below, which clearly demonstrate the effectiveness of the method of the present invention.

[0098] Example 1: Preparation of a compound of general formula II: potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr·crown).

[0099] Under an argon atmosphere, 1000 mg of 2,6-bis(diphenylmethyl)-4-tert-butylphenol (HOAr) of general formula 1 (as described by Keith Searles, Ba L. et al., Inorg. Chem. 2013, 52, 191126 - 11135) was dissolved in 20 mL of diethyl ether in a Schlenk equipped with a magnetic stirrer. The solution was added to a suspension of potassium benzyl (KBn) in a -78 °C cold bath. After addition, the red solution was kept stirring at room temperature for one hour, at which time an insoluble white solid formed. Next, 550 mg of 18-crown-6 ether was dissolved in 10 mL of diethyl ether under an argon atmosphere. The solution was added to the above white suspension. A clear solution was obtained and kept stirring at room temperature for 30 minutes, and finally dried under vacuum. 1480 mg (yield 91%) was obtained.

[0100]

[0101] Example 2: Preparation of a compound of general formula I: potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr).

[0102] Under an argon atmosphere, 1000 mg of 2,6-bis(diphenylmethyl)-4-tert-butylphenol (HOAr) of general formula 1 was dissolved in 20 mL of diethyl ether in a Schlenk equipped with a magnetic stirrer. The solution was added to a suspension of potassium benzyl (KBn) in a -78 °C cold bath. After addition, the red solution was stirred at room temperature for one hour, at which time an insoluble white solid formed.

[0103] Next, the solution was filtered and finally the solid was dried under vacuum. 992 mg (yield 92%) was obtained.

[0104]

[0105] Example 3: Preparation of the compound of general formula I: sodium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (NaOAr).

[0106] Under an argon atmosphere, 1000 mg of 2,6-bis(diphenylmethyl)-4-tert-butylphenol (HOAr) of general formula 1 was dissolved in 20 mL of diethyl ether in a Schlenk equipped with a magnetic stirrer. Sodium bis(trimethylsilyl)amide was added to this solution in a cold bath at -78 °C. After 15 minutes, the solution was kept stirring at room temperature for one hour. All the solvents were evaporated under vacuum and dry hexane was added to remove the amine formed. Next, the solution was filtered and finally the solid was dried under vacuum. 1830 mg (yield 95%) was obtained.

[0107]

[0108] Example 4: Preparation of a lactide polymer in dichloromethane (DCM) solution.

[0109] 50 mg of potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr·crown, prepared as described in Example 1) was dissolved in 10 mL of DCM and 4 g of recrystallized L-lactide was added in a vial in the drying oven. After reacting at 25 °C for 15 minutes, the polymer obtained was dried under vacuum. According to 1 1H-NMR spectroscopic studies, the monomer-to-polymer conversion was 83%. GPC-SEC studies carried out in THF with polystyrene standards and correction factors showed that a macromolecular mixture with a medium molecular weight (M w = 20.7 kDa) (M w / M n = 1.5) was obtained.

[0110] Example 5: Preparation of a lactide polymer in toluene solution.

[0111] 50 mg of potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr·crown, prepared as described in Example 1) was dissolved in 20 mL of toluene and 4 g of recrystallized L-lactide was added in a vial in the drying oven. After reacting at 25 °C for 30 minutes, the polymer obtained was dried under vacuum. According to 1H-NMR spectroscopic study showed that the monomer-to-polymer conversion rate was >99%. GPC-SEC study carried out in THF with polystyrene standards and correction factors indicated that a macromolecular mixture with a medium molecular weight (M w = 30.7 kDa) was obtained (M w / M n = 1.3).

[0112] Example 6: Preparation of lactide polymer at 145 °C in the absence of solvent.

[0113] 50 mg of potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenolate (KOAr·crown, prepared as described in Example 1) was added to 4 g of recrystallized L-lactide melted in a ROTA FLO ampoule. After reacting at 145 °C for 14 hours, the solution acquired a certain viscosity. According to 1 H-NMR spectroscopic study, the monomer-to-polymer conversion rate was 93%. GPC-SEC study carried out in THF with polystyrene standards and correction factors indicated that a macromolecular mixture with a medium molecular weight (M w = 14.4 kDa) was obtained (M w / M n = 2.5).

[0114] Example 7: Preparation of lactide polymer in dichloromethane (DCM) solution.

[0115] 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenolate (KOAr, prepared as described in Example 2) was dissolved in 10 mL of DCM and added to 6 g of recrystallized L-lactide in a vial in the drying oven. After reacting at 25 °C for 1 minute, the solution acquired a high viscosity. The obtained polymer was dried under vacuum. According to 1 H-NMR spectroscopic study, the monomer-to-polymer conversion rate was >99%. GPC-SEC study carried out in THF with polystyrene standards and correction factors indicated that a macromolecular mixture with a high molecular weight (M w = 190.3 kDa) was obtained (M w / M n = 2.4).

[0116] Example 8: Preparation of lactide polymer in dichloromethane (DCM) solution in the presence of benzyl alcohol as a co-catalyst.

[0117] Dissolve 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) and 11 μL of benzyl alcohol (BnOH) in 10 mL of DCM, and add 6 g of recrystallized L-lactide in a vial in the drying oven. After reacting for 4 minutes at 25 °C, the solution obtained high viscosity. The polymer obtained was dried under vacuum. According to 1 1H-NMR spectroscopic studies, the monomer-to-polymer conversion > 99%. GPC-SEC studies carried out with polystyrene standards in THF showed that a macromolecular mixture with a high molecular weight (M w = 43.2 kDa) was obtained (M w / M n = 1.3).

[0118] Example 9: Preparation of a lactide polymer under solvent-free conditions at 145 °C.

[0119] Add 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) to 6 g of recrystallized L-lactide melted in a ROTA-FLO ampoule. After reacting for 14 hours at 145 °C, the solution obtained high viscosity. According to 1 1H-NMR spectroscopic studies, the monomer-to-polymer conversion was 95%. GPC-SEC studies carried out with polystyrene standards in THF showed that a macromolecular mixture with a medium molecular weight (M w = 19.4 kDa) was obtained (M w / M n = 2.4).

[0120] Example 10: Preparation of a polymer from unpurified lactide in dichloromethane solution.

[0121] Under an argon atmosphere, dissolve 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) in 10 mL of DCM in a Schlenk connected to a Schlenk line, and add 6 g of L-lactide taken directly from an open vial. After reacting for 1 minute at 25 °C, the solution obtained high viscosity. The polymer obtained was dried under vacuum. According to 1 1H-NMR spectroscopic studies, the monomer-to-polymer conversion > 99%.

[0122] Example 11: Preparation of a lactide polymer in dichloromethane (DCM) solution.

[0123] Dissolve 50 mg of sodium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (NaOAr, prepared as described in Example 3) in 10 mL of DCM, and add 6 g of recrystallized L-lactide in a vial in the drying oven. After reacting for 1 minute at 25 °C, the solution acquired high viscosity. The obtained polymer was dried under vacuum. According to 1 H-NMR spectroscopic studies, the monomer-to-polymer conversion > 99%. GPC-SEC studies carried out with polystyrene standards in THF showed that a macromolecular mixture with high molecular weight (M w = 275.9 kDa) was obtained (M w / M n = 2.6).

[0124] Example 12: Preparation of a polymer from unpurified lactide in dichloromethane solution.

[0125] Under an argon atmosphere, dissolve 50 mg of sodium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (NaOAr, prepared as described in Example 3) in 10 mL of DCM in a Schlenk connected to a Schlenk line, and add 6 g of L-lactide taken directly from an uncapped vial. After reacting for 1 minute at 25 °C, the solution acquired high viscosity. The obtained polymer was dried under vacuum. According to 1 H-NMR spectroscopic studies, the monomer-to-polymer conversion > 99%.

[0126] Example 13: Preparation of ε-caprolactone polymer without solvent at 80 °C.

[0127] Under an argon atmosphere, dissolve 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) in 4.6 mL of ε-caprolactone in a ROTA-FLO ampoule connected to a Schlenk line, and place it in a bath at 80 °C. After reacting for 2 hours, the medium acquired high viscosity. The obtained polymer was dried under vacuum. According to 1 H-NMR spectroscopic studies, the monomer-to-polymer conversion was 95%. GPC-SEC studies carried out with polystyrene standards in THF showed that a macromolecular mixture with high molecular weight (M w = 105.1 kDa) was obtained (M w / M n = 2.2).

[0128] Example 14: Preparation of a lactide and ε-caprolactone diblock copolymer in dichloromethane solution.

[0129] Under an argon atmosphere, 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) was dissolved in 4.6 mL of ε-caprolactone in a ROTA FLO ampoule connected to a Schlenk line, and the mixture was placed in a bath at 80 °C. After 2 hours, a solution of 6 g of L-lactide in 10 mL of DCM was added at room temperature. The resulting polymer was dried under vacuum. According to 1 1H-NMR spectroscopic studies, the conversion of ε-caprolactone to the polymer was 95%, while the conversion of L-lactide reached 92% within 3 hours. GPC-SEC studies carried out with polystyrene standards in THF showed that a macromolecular mixture with a high molecular weight (M w = 102.1 kDa) was obtained (M w / M n = 2.6).

[0130] Example 15: Preparation of trimethylene carbonate polymer at 80 °C without solvent.

[0131] 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) was added to 4.3 g of molten trimethylene carbonate in a ROTA FLO ampoule. After reacting at 80 °C for 14 hours, the medium obtained a high viscosity. According to 1 1H-NMR spectroscopic studies, the conversion of the monomer to the polymer was 93%. GPC-SEC studies carried out with polystyrene standards in THF showed that a macromolecular mixture with a medium molecular weight (M w = 40.5 kDa) was obtained (M w / M n = 2.2).

[0132] Example 16: Preparation of a polymer from ethylidene malonate at 80 °C without solvent.

[0133] Under an argon atmosphere, 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) was dissolved in 11 mL of ethylidene malonate in a ROTA FLO ampoule connected to a Schlenk line, and the mixture was placed in a bath at 80 °C. After reacting for 14 hours, the medium obtained a high viscosity. According to 1 1H-NMR spectroscopic studies, the conversion of the monomer to the polymer > 99%. GPC-SEC studies carried out with polystyrene standards in THF showed that a macromolecular mixture with a high molecular weight (M w = 83.1 kDa) was obtained (M w / M n = 2.3).

[0134] Example 17: Depolymerization of poly(lactide) in dichloromethane (DCM) and methanol solution at 25 °C.

[0135] Under an argon atmosphere, 200 mg of potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenolate (KOAr·crown, prepared as described in Example 1) was dissolved in a solvent mixture containing 28 mL of DCM and 7 mL of methanol in a Schlenk connected to a Schlenk line, and 4 g of commercially available poly-L-lactide (PLLA) was added. The reaction was carried out at 25 °C for 10 minutes. According to 1 1H-NMR spectroscopic studies, the conversion of the polymer to methyl-L-lactide was 99%, the PLLA was completely degraded, and the by-product was 1% oligomer. It should be noted that the by-product can be separated from the desired product by distillation.

[0136] Example 18: Depolymerization of poly(lactide) in dichloromethane (DCM) and methanol solution at 25 °C.

[0137] Under an argon atmosphere, 200 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenolate (KOAr, prepared as described in Example 2) was dissolved in a solvent mixture containing 40 mL of DCM and 10 mL of methanol in a Schlenk connected to a Schlenk line, and 6 g of commercially available poly-L-lactide (PLLA) was added. The reaction was carried out at 25 °C for 10 minutes. According to 1 1H-NMR spectroscopic studies, the conversion of the polymer to methyl-L-lactide was 99%, the PLLA was completely degraded, and the by-product was 1% oligomer. It should be noted that the by-product can be separated from the desired product by distillation.

[0138] Example 19: Depolymerization of poly(lactide) in ethyl acetate (AcOEt) and methanol solution at 25 °C.

[0139] Under an argon atmosphere, 200 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenolate (KOAr, prepared as described in Example 2) was dissolved in a solvent mixture containing 40 mL of AcOEt and 10 mL of methanol in a Schlenk connected to a Schlenk line, and added to 6 g of commercially available poly-L-lactide (PLLA). The reaction was carried out at 25 °C for 60 minutes. According to 1 1H-NMR spectroscopic studies, the conversion of the polymer to methyl-L-lactide was 97%, the PLLA was completely degraded, and the by-product was 3% oligomer. The proportion of oligomer is variable and related to the proportion of alcohol used, so a higher proportion of oligomer can be achieved by reducing the proportion of alcohol. It should be noted that the by-product can be separated from the desired product by distillation.

Claims

1. Use of compounds of formula (I) or (II) as catalysts in heterocyclic ring-opening (co)polymerization processes: in: R1 and R2 are independently selected from hydrogen, C3-C8 alkyl, C3-C8 haloalkyl, C3-C8 alkoxide, C3-C8 haloalkoxide, C3-C8 dialkylamino, C3-C8 halodialkylamino, C3-C8 hydroxyalkyl or cyanide, R3 is selected from the group consisting of: H, C3-C8 alkyl, C3-C8 haloalkyl, C3-C8 cyanoalkyl, C3-C8 alkoxide, C3-C8 dialkylamino or cyanide, and n is an integer between 1 and 3, and M is an alkali metal selected from Li, Na and K.

2. The method according to claim 1, wherein R1 and R2 are H.

3. The method according to claim 1 or 2, wherein R3 is a C3-C8 alkyl group.

4. The method according to claim 3, wherein the alkyl group is tert-butyl.

5. Use according to any one of the preceding claims, wherein M is Na or K.

6. The use according to any one of the preceding claims, wherein the compounds of formula (I) and (II) are selected from the following:

7. Use according to any one of the preceding claims, wherein the heterocycle is selected from cyclic esters, diesters, ethers, thioethers, amides and carbonates.

8. The use according to claim 1, wherein the heterocycle is selected from the group consisting of lactide, ε-caprolactone, trimethylene carbonate and ethylene glycol benzoate.

9. Use according to claims 1 and 2, wherein the heterocycle is an epoxide or a thioepoxide.

10. A process for the ring-opening polymerization or copolymerization of a heterocycle, which comprises contacting the starting heterocycle(s) with a compound of formula (I) or (II) as defined in any one of claims 1 to 6.

11. The process according to claim 10, wherein the starting heterocycle is as defined in any one of claims 7 to 9.

12. The method according to claim 10 or 11, which is carried out at room temperature.

13. The process according to any one of the preceding claims 10 to 12, carried out in the presence or absence of a solvent, if the starting heterocycle is liquid.

14. The process according to any one of the preceding claims 10 to 12, which is carried out in the presence of a polar or nonpolar aprotic solvent.

15. The process according to any one of the preceding claims 10 or 11, which is carried out in the molten state.

16. The process according to any one of the preceding claims 10 to 15, wherein the content of the compound of formula (I) or (II) is between 0.1 and 2 mol% relative to the starting heterocycle.

17. The process according to any one of the preceding claims 10 to 16, which is carried out in the presence or absence of a promoter.

18. Use of a compound of formula (I) or (II) as claimed in any one of claims 1 to 6 as a catalyst in a process for the depolymerization of polymers having heteroatoms in their structure to obtain oligomers and derivatives of the monomers from which the polymers are formed, wherein the process is carried out in the presence of an R-OH alcohol, wherein R is a C3-C8 alkyl or benzyl group.

19. Compounds of formula (II): wherein R1, R2, R3, n and M are as defined in any one of claims 1 to 6.

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