Alkali metal phenolic compounds and uses thereof

Abstract

The present 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 present invention also relates to polymerization processes using these compounds.

Description

[Technical Field]

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

[0002] The present invention therefore belongs to the subsector of organic and inorganic synthetic chemistry and polymers within the chemical field, and the resulting plastic materials may have a myriad of applications in areas such as food packaging, agriculture, the textile industry, and the production of consumer goods such as automobiles, household appliances, and a wide range of appliances. [Background technology]

[0003] Currently, there is great interest in the development of biodegradable polymers, particularly aliphatic polyesters and polycarbonates. Among these, polylactide or polylactic acid, abbreviated as PLA, is an aliphatic polyester produced on an industrial scale and has numerous applications in important areas such as food packaging, agriculture, and consumer goods. For decades, numerous catalysts and various methods for obtaining PLA have been described, and the amount of research in this field is increasing year by year. The most widely used catalyst for its production is tin bis(2-ethylhexanoate) (commonly known as tin octoate), a catalyst containing toxic metals. Tin octoate is extremely harmful, potentially causing allergic skin reactions, serious eye damage, reduced fertility, or harm to the fetus, and has long-lasting effects on aquatic life. However, there are no better alternatives to its industrial use. Therefore, a final purification step is required to remove unreacted reagents from the medium. This process requires high energy costs, and the effectiveness of this method is often questioned.

[0004] The use of non-metallic catalysts has been proposed in extensive studies, but the resulting polymers tend to be of low molecular weight (M n <15 kDa), which often limits many of the possible applications. Furthermore, reaction times are often long, which adversely affects the economics of the process.

[0005] In the PLA production processes described in various patent documents, such as EP2992029B1, WO2017128049A1, and EP2507289B1, the conversion of lactide monomer to PLA polymer is incomplete; i.e., not all of the lactide is converted to PLA at the end of the reaction. Therefore, a significant proportion of lactide remains in the final material, which adversely affects the polymer's properties and processing. Furthermore, these processes require the addition of a deactivating agent to inactivate the catalyst used to prevent reverse depolymerization. This agent is added to the reaction mixture once the monomer conversion rate reaches at least 90% and after the devolatilization step, which removes unreacted lactide from the medium. Depolymerization can be performed once the monomer-polymer equilibrium has changed, i.e., once the unreacted monomer has been removed from the medium.

[0006] The literature contains numerous studies on a wide range of organometallic compounds, many of which are based on alkali metals (Group 1), including potassium, and also contain phenolate groups (Wu, Inorg. Chem. 2012, 51, 13380; Wu, Inorg. Chem. 2016, 55, 136; Wu, ACS Macro Lett. 2015, 4, 556; Tang, Inorganic Chemistry Communications 2010, 13, 376), which act as catalysts to produce low-molecular-weight polymers not exceeding 30 kDa. Furthermore, the catalysts described in these studies require a cocatalyst.

[0007] There are several patents related to the production process of lactide polymers, but most of them describe improvements to industrial processes for obtaining PLA (US Pat. No. 5,258,488A, ES2017562, ES2292338, ES2311024) or for synthesizing lactide monomer (US Pat. No. 5,247,059A, US Pat. No. 20110306749). The catalyst used is most often stannous octoate (US Pat. No. 5,770,682A, US Pat. No. 20110306749). Other patents detail the use of new catalysts based on rare earth metals such as scandium, yttrium (US Pat. No. 5,292,859), or lanthanum, while others detail the use of metals such as zirconium or hafnium (EP Pat. No. 2992029B1), zinc (EP Pat. No. 2507289B1), or organometallics (WO Pat. No. 2017128049A1). No patented process has been found that uses an alkali metal catalyst as described in this invention.

[0008] In view of the aforementioned drawbacks present in the prior art, the present invention describes non-toxic alkali metal compounds for use in polymerization reactions, particularly for obtaining high molecular weight polymers such as PLA, on an industrial scale. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present inventors have discovered that certain alkali metal phenolic compounds catalyze polymerization or copolymerization reactions (collectively referred to as (co)polymerization reactions) in quantitative yields to produce highly interesting polymers in a simple manner.

[0010] Thus, in a first aspect, the present invention provides a compound of general formula (I) or (II) as a catalyst in a process for the ring-opening (co)polymerization of heterocycles: [ka] (In the formula, R1 and R2 are independently selected from hydrogen, C3-C8 alkyl, C3-C8 haloalkyl, C3-C8 alkoxide, C3-C8 halo-alkoxide, C3-C8 dialkylamino, C3-C8 halo-dialkylamino, C3-C8 hydroxyalkyl or cyanide; R3 is selected from H, C3-C8 alkyl, C3-C8 haloalkyl, C3-C8 cyanoalkyl, C3-C8 alkoxide, C3-C8 dialkylamino, or cyanide; n is an integer from 1 to 3, M is an alkali metal selected from Li, Na and K. The present invention relates to the use of the compound of the present invention.

[0011] The reactions catalyzed by compounds of formula (I) or (II) can involve a single heterocycle (polymerization reactions) or at least two different heterocycles (copolymerization reactions).

[0012] In the present invention, the term "heterocycle" refers to a compound formed by a cyclic hydrocarbon chain having 3 to 20 links, in which at least one carbon atom of the main chain is substituted with O, N, or S. The heterocycle may be saturated or unsaturated, but is preferably saturated. These heterocycles may optionally be substituted at one or more positions with one or more groups such as hydroxyl groups, amine groups, amide groups, oxo groups, cyano groups, halogen groups, or aryl groups.

[0013] The synthesis of compounds of formula (I) is shown in Scheme 1. The preparation of compounds of general formula (1) and (I) has already been described by DJ Mindiola et al. in patent document US2014 / 0213805A1. Derivatives of type (2) are the corresponding metal precursors, which are commercially available compounds or can be easily prepared by those skilled in the art. Scheme 1: [ka]

[0014] In the MR reagent (2), M is an alkali metal selected from Li, Na, and K; R represents a hydrogen atom, a halogen atom, or an alkyl, cycloalkyl, alkenyl, alkynyl, amido, haloalkyl, alkoxide, cycloalkoxide, halo-alkoxide, aryloxide, thioalkyl, thiocycloalkyl, thioaryl, amino, alkylamino, dialkylamino, halo-dialkylamino, cycloalkylamino, dicycloalkylamino, alkyl(cycloalkyl)amino, arylamino, diarylamino, alkylarylamino, cyanoalkyl, or hydroxyalkyl radical, and any alkyl group present in the radical is preferably C3-C8 alkyl.

[0015] In the compounds of general formula (1), R1, R2 and R3 have the same meanings as for the radicals R1, R2 and R3 in the compounds of formula (I) above.

[0016] The reaction of a compound of general formula (1) with a compound of general formula (2) to obtain a compound of general formula (I) can be carried out as described in patent document US2014 / 0213805A1. Briefly, the reaction is carried out in an aprotic solvent under an inert atmosphere, such as argon or nitrogen, at a temperature of -90 to +50°C. The compound obtained is purified by standard purification methods, such as recrystallization or washing with a non-coordinating solvent, such as n-hexane.

[0017] 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.

[0018] In the presence of coordinating solvents such as THF or other neutral compounds such as crown ethers, compounds of general formula (I) can incorporate them as ligands into the coordination sphere.

[0019] The compound of formula (II) can be obtained in a similar manner to that used to obtain the compound of formula (I), i.e., by reacting the compound of general formula (1) with the compound of general formula (2), as described in patent document US2014 / 0213805A1, but by adding a crown ether to the reaction medium, preferably in a molar ratio of compound of formula (1) to crown ether of 1:1. In a preferred embodiment, the crown ether used is 18-crown-6 ether.

[0020] As used herein, the terms "C3-C8 alkyl" and "C3-C8 cycloalkyl" refer to straight-chain or cyclic carbon groups of 3 to 8 carbon atoms, respectively, which may be branched or unbranched. Examples of unbranched straight-chain alkyls include methyl, ethyl, propyl, pentyl, hexyl, and heptyl. Examples of branched alkyls include 2-propyl and 2-butyl. Cyclic groups include, inter alia, cyclopropyl, cyclobutyl, and cyclohexyl.

[0021] The terms "C3-C8 alkenyl" or "C3-C8 alkynyl" refer to groups having the same definition as used for alkyl groups, but containing one or more C=C double bonds or C≡C triple bonds, respectively. They may be branched or unbranched, and may be straight-chain or cyclic, of 3 to 8 carbon atoms. They may be substituted or unsubstituted, similar to alkyl groups.

[0022] The term "amide" refers to (NH2) - or (N(alkyl)2) - and the like, wherein alkyl is as defined above (C3-C8 alkyl).

[0023] The term "halogen" (or halide) refers to F, Cl, Br, or I.

[0024] The term "aryl" refers to a monocyclic or polycyclic aromatic ring in which a proton has been removed from the ring. Examples of aryl groups are phenyl, naphthyl, and anthracenyl.

[0025] The term "C3-C8 haloalkyl" refers to a C3-C8 alkyl group having one or more halide substituents.

[0026] The term "C3-C8 alkoxide" (or "C3-C8 alkoxy") refers to groups such as O-C3-C8 alkyl.

[0027] The term "C3-C8 cycloalkoxide" refers to groups such as O-C3-C8 cycloalkyl.

[0028] The term "C3-C8 halo-alkoxide" refers to a group in which the C3-C8 alkyl group of the alkoxide has one or more halide substituents.

[0029] The term "aryloxide" refers to a group such as O-aryl, where aryl is as defined above.

[0030] The term "C3-C8 thioalkyl" refers to groups such as S-C3-C8 alkyl.

[0031] The term "C3-C8 thiocycloalkyl" refers to groups such as S-C3-C8 cycloalkyl.

[0032] The term "thioaryl" refers to groups such as S-aryl, where aryl is as defined above.

[0033] The term "amino" refers to groups such as -NH2.

[0034] The term "C3-C8 alkylamino" refers to an amino group in which one of the hydrogens has been replaced with a C3-C8 alkyl group.

[0035] The term "C3-C8 dialkylamino" refers to groups such as -N(alkyl)2, where alkyl is as defined above (C3-C8 alkyl).

[0036] The term "C3-C8 halo-dialkylamino" refers to a dialkylamino group in which at least one alkyl has a halide substituent.

[0037] The term "C3-C8 cycloalkylamino" refers to an amino group in which one of the hydrogens has been replaced with a C3-C8 cycloalkyl group.

[0038] The term "di(cycloalkyl)amino" refers to groups such as -N(cycloalkyl)2, where cycloalkyl is as defined above (C3-C8 cycloalkyl).

[0039] The term "alkyl(cycloalkyl)amino" refers to an amino group in which two hydrogens have been replaced with an alkyl group and a cycloalkyl group, as these terms are defined above (C3-C8 alkyl or cycloalkyl).

[0040] The term "arylamino" refers to an amino group in which one of the hydrogens has been replaced with an aryl group, where aryl is as defined above.

[0041] The term "diarylamino" refers to groups such as -N(aryl)2, where aryl is as defined above.

[0042] The term "C3-C8 alkylarylamino" refers to an amino group in which two hydrogens are replaced with a C3-C8 alkyl group and an aryl group, respectively, where C3-C8 alkyl and aryl are as defined above.

[0043] The term "(cycloalkyl)arylamino" refers to an amino group in which two hydrogens are replaced by a C3-C8 cycloalkyl group and an aryl group, respectively, where cycloalkyl and aryl are as defined above.

[0044] The term "C3-C8 cyanoalkyl" refers to an alkyl group substituted with one or more cyano (-CN) substituents.

[0045] The term "C3-C8 hydroxyalkyl" refers to an alkyl group substituted with one or more hydroxyl substituents.

[0046] In a preferred embodiment of the use of compounds of formula (I) or (II), R1 and R2 are H.

[0047] In another preferred embodiment of the use of compounds of formula (I) or (II), R3 is C3-C8 alkyl, more preferably tert-butyl.

[0048] In another preferred embodiment of the use of compounds of formula (I) or (II), M is sodium or potassium.

[0049] In another preferred embodiment of the use of compounds of formula (II), n is 3.

[0050] In more preferred embodiments, the compound is selected from: [ka]

[0051] In the (co)polymerization reaction, the compounds of formula (I) or (II) also play the role of initiators and / or regulators.

[0052] The compounds of the described general formula (I) or (II) are particularly useful and effective in ring-opening (co)polymerization reactions of heterocycles selected from cyclic esters (including diesters, i.e., where the ring contains two ester groups), ethers, thioethers, amides and carbonates.

[0053] In preferred embodiments, 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 rings a), b), and c) can have 3 to 20 linkages. [ka]

[0054] 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 ethylene brassylate. 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.

[0055] In another preferred embodiment, the heterocycle is selected from epoxides and thioepoxides.

[0056] Another aspect of the present invention relates to a process for the ring-opening polymerization or copolymerization of heterocycles selected from cyclic esters, ethers, thioethers and carbonates, comprising contacting one or more starting heterocycles with a compound of formula (I) or (II) as defined above.

[0057] In a preferred embodiment, the preferred starting heterocycle is a heterocycle as set forth in the first aspect of the present invention.

[0058] In particular, by using lactide as the starting heterocycle in the ring-opening polymerization reaction, PLA can be obtained at room temperature in just one minute. The resulting PLA has a high molecular weight (over 100 kDa), making this method feasible for industrial-scale use. Furthermore, the resulting polymer has a bimodal weight distribution, indicating the presence of two very distinct groups of polymer chains in the material. This bimodal distribution results from the majority group of chains having a molecular weight above 100 kDa, while a second group of chains is composed of PLA oligomers around 500 Da. The use of PLA oligomers as plasticizing additives for bioplastics, especially industrially obtained PLA, which exhibits stiffness and brittleness issues, is well known in the industry and is increasingly being produced and incorporated into plastic formulations. The lactide polymerization method described in this invention makes it possible to obtain materials that already contain a low proportion of PLA oligomers, which act as plasticizers, in their composition, representing a major industrial breakthrough for processing materials without the need for subsequent modification. Furthermore, the conversion of lactide monomer to PLA polymer is complete, i.e., all lactide is converted to polylactic acid at the end of the reaction. This is an improvement over industrial processes that use stannous octoate as a catalyst. These processes do not convert all of the monomer to polymer, leaving a significant proportion of lactide in the material, which significantly deteriorates its physical properties and requires a purification step. The method described in this invention avoids the purification of the material to remove lactide monomer at the end of the reaction, which is required in industrial processes.

[0059] The process can be carried out in the presence of a solvent or in the absence of a solvent if the starting heterocycle is a liquid. If the starting heterocycle is a solid at room temperature, the reaction can be carried out in the melt.

[0060] If the reaction is carried out in the presence of a solvent, said solvent, whether polar or non-polar, is preferably an aprotic solvent such as an aromatic hydrocarbon (toluene), an ether (tetrahydrofuran, THF), or an aliphatic halogenated compound (dichloromethane, DCM) and an aromatic halogenated compound (bromobenzene).

[0061] The (co)polymerization reaction can be carried out over a wide temperature range from 0°C to 200°C, but is preferably carried out at 15°C to 30°C, and more preferably at room temperature (20-25°C) as long as 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 melting temperature of the starting heterocycle(s).

[0062] The reaction time can range from 1 second to 300 hours, but the reaction time is generally from 1 second to 72 hours.

[0063] In a preferred embodiment, the process is carried out in the presence of 0.1 to 2 mol %, more preferably 2 mol %, of a catalyst of formula (I) or (II) relative to the starting heterocycle.

[0064] In a preferred embodiment, the process is carried out in the absence of a co-catalyst, such that the compound of formula (I) or (II) is the sole catalyst for the reaction.

[0065] In another preferred embodiment, the process is carried out in the presence of a co-catalyst. Some examples of co-catalysts to be mentioned are benzyl alcohol or isopropyl alcohol.

[0066] In a preferred embodiment, the process is carried out in dichloromethane or toluene at room temperature starting from L-lactide.

[0067] In another preferred embodiment, the process is carried out starting from L-lactide in the melt at 145° C. in the absence of a solvent.

[0068] In another preferred embodiment, the process is carried out starting from L-lactide in dichloromethane at room temperature in the presence of benzyl alcohol as a cocatalyst.

[0069] In a preferred embodiment, the process is carried out in dichloromethane at room temperature starting from L-lactide and ε-caprolactone.

[0070] In a preferred embodiment, the process is carried out starting from ε-caprolactone in the absence of solvent (molten state) at 80°C.

[0071] In a preferred embodiment, the process is carried out in the absence of solvent (molten state) at 80° C., starting from trimethylene carbonate or ethylene brassylate.

[0072] The method thus described has important advantages, as follows: The compounds of the present invention contain alkali metals such as lithium, sodium, or potassium, which have no inherent toxicity, which is advantageous compared to state-of-the-art catalysts that contain toxic or health-hazardous metals; · Can be performed with purified or unpurified monomers, in an inert atmosphere or in air; The reaction has quantitative yields and all of the starting reagents are converted into product, reducing the need to purify the resulting polymer; The resulting polymer does not undergo racemization or depolymerization reactions; No catalyst deactivator is required at the final stage to prevent depolymerization and racemization reactions; · It is particularly advantageous for obtaining high molecular weight PLA with piezoelectric capacitance potential; The polydispersity (M w / M n ) can be modified by achieving complete conversion of the monomers by intramolecular or intermolecular chain transfer processes and then leaving the reaction mixture at the reaction temperature; the mass of the (co)polymer is hardly affected during these processes (HR Kricheldorf, M. Berl and N. Scharnagl, Macromolecules, 1988, 21, 286.); The uses of the resulting polymers can be similar to those of conventional plastic products such as polypropylene, polystyrene, and polyethylene.

[0073] The final aspect of the present invention relates to the use of compounds of formula (I) or (II) as defined above as catalysts in a depolymerization process to obtain oligomers and derivatives of the monomers that form the polymer. The process requires the presence of an alcohol, such as methanol, ethanol, or benzyl alcohol, in a large excess relative to the catalyst, preferably more than about 50 equivalents. In this reaction, the alcohol is used as a chain transfer agent to obtain derivatives of the starting heterocycle from polymers containing heteroatoms in their structure. The process falls within the concept of chemical recycling.

[0074] The alcohols have the formula ROH, where R represents a C3-C8 alkyl or benzyl group, which can be used as solvents to produce PLA oligomers and products derived from the desired starting heterocycles, such as methyl or ethyl lactate, which are considered superior alternatives to other, more polluting solvents.

[0075] A preferred embodiment of using a compound of formula (I) or (II) as a catalyst in a depolymerization process involves the depolymerization of polylactide in DCM or ethyl acetate solution at 25° C. by an alcoholysis process in the presence of methanol.

[0076] Throughout the specification and claims, the word "comprises" and variations thereof are not intended to exclude other technical features, additives, components, or steps. Other objects, advantages, and features of the present invention will become more apparent to those skilled in the art, partly from the specification and partly from the practice of the present invention. The following examples are offered for illustrative purposes and are not intended to limit the invention. [Example]

[0077] Examples carried out by the inventors that clearly demonstrate the effectiveness of the method of the present invention are given below as non-limiting illustrations of the present invention.

[0078] Example 1: Preparation of the compound of general formula II: potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr-crown) 1000 mg of 2,6-bis(diphenylmethyl)-4-tert-butylphenol (HOAr) of general formula 1 (described in Keith Searles, Ba L. et al. Inorg. Chem. 2013, 52, 19, 11126-11135) was dissolved in 20 mL of diethyl ether in a refrigerator equipped with a magnetic stirrer under an argon atmosphere. This solution was added to a suspension of potassium benzyl (KBn) in a cold bath at -78 °C. After the addition, the red solution was stirred at room temperature for 1 hour, resulting in the formation of an insoluble white solid. Next, 550 mg of 18-crown-6 ether was dissolved in 10 mL of diethyl ether under an argon atmosphere. This solution was added to the white suspension. This produced a clear solution, which was stirred at room temperature for 30 minutes and finally dried under vacuum. 1480 mg of the product was obtained (91% yield). [ka]

[0079] Example 2: Preparation of the compound of general formula I: potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr) 1000 mg of 2,6-bis(diphenylmethyl)-4-tert-butylphenol (HOAr) of general formula 1 is dissolved in 20 mL of diethyl ether in a refrigerator equipped with a magnetic stirrer under an argon atmosphere. This solution is added to a suspension of potassium benzyl (KBn) in a -78 °C cold bath. After the addition, the red solution is stirred at room temperature for 1 hour, resulting in the formation of an insoluble white solid. The solution is then filtered, and the solid is finally dried under vacuum. 992 mg is obtained (yield 92%). [ka]

[0080] Example 3: Preparation of the compound of general formula I: sodium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (NaOAr) 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 refrigerator equipped with a magnetic stirrer under an argon atmosphere. Sodium bis(trimethylsilyl)amide was added to the solution in a -78°C cold bath. After 15 minutes, the solution was stirred at room temperature for 1 hour. The solvent was evaporated under vacuum, and the resulting amine was removed by adding dry hexane. The solution was then filtered, and the solid was finally dried under vacuum. 1830 mg was obtained (95% yield). [ka]

[0081] Example 4: Preparation of lactide polymer in dichloromethane (DCM) solution Dissolve 50 mg of potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr·crown, prepared as described in Example 1) in 10 mL of DCM and add it to 4 g of recrystallized L-lactide in a vial in a dry box. After 15 min of reaction at 25 °C, vacuum dry the resulting polymer. 1 H-NMR spectroscopy indicates a 83% conversion of monomer to polymer. GPC-SEC studies performed in THF using polystyrene standards and correction factors indicate a medium molecular weight (M w = 20.7 kDa) w / M n =1.5) can be obtained.

[0082] Example 5: Preparation of lactide polymer in toluene solution Dissolve 50 mg of potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr·crown, prepared as described in Example 1) in 20 mL of toluene and add it to 4 g of recrystallized L-lactide in a vial in a dry box. After 30 min of reaction at 25 °C, dry the resulting polymer under vacuum. 1H-NMR spectroscopy indicates >99% conversion of monomer to polymer. GPC-SEC studies performed in THF using polystyrene standards and correction factors indicate a medium molecular weight (M w = 30.7 kDa) w / M n =1.3) can be obtained.

[0083] Example 6: Preparation of lactide polymer in the absence of solvent at 145°C 50 mg of potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr·Crown, prepared as described in Example 1) is added to 4 g of recrystallized L-lactide melted in a ROTAFLO ampoule. After 14 hours of reaction at 145 °C, the solution reaches a specific viscosity. 1 H-NMR spectroscopy indicates a 93% conversion of monomer to polymer. GPC-SEC studies performed in THF using polystyrene standards and correction factors indicate a medium molecular weight (M w = 14.4 kDa) w / M n =2.5) can be obtained.

[0084] Example 7: Preparation of lactide polymer in dichloromethane (DCM) solution 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) is dissolved in 10 mL of DCM and added to 6 g of recrystallized L-lactide in a vial in a dry box. After 1 minute of reaction at 25 °C, the solution becomes highly viscous. The resulting polymer is dried under vacuum. 1 H-NMR spectroscopy indicates >99% conversion of monomer to polymer. GPC-SEC studies performed in THF using polystyrene standards and correction factors indicate high molecular weight (M w = 190.3 kDa) w / M n =2.4) can be obtained.

[0085] Example 8: Preparation of lactide polymer in dichloromethane (DCM) solution in the presence of benzyl alcohol as a cocatalyst 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) are dissolved in 10 mL of DCM and added to 6 g of recrystallized L-lactide in a vial in a dry box. After 4 minutes of reaction at 25 °C, the solution becomes highly viscous. The resulting polymer is dried under vacuum. 1 H-NMR spectroscopy indicates >99% conversion of monomer to polymer. GPC-SEC studies performed in THF using polystyrene standards indicate high molecular weight (M w = 43.2 kDa) w / M n =1.3) can be obtained.

[0086] Example 9: Preparation of lactide polymer in the absence of solvent at 145°C 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) is added to 6 g of recrystallized L-lactide melted in a ROTAFLO ampoule. After 14 hours of reaction at 145° C., the solution becomes highly viscous. 1 H-NMR spectroscopy indicates a 95% conversion of monomer to polymer. GPC-SEC studies performed in THF using polystyrene standards reveal a medium molecular weight (M w = 19.4 kDa) w / M n =2.4) can be obtained.

[0087] Example 10: Preparation of polymer from crude lactide in dichloromethane solution 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) was dissolved in 10 mL of DCM and added to 6 g of L-lactide taken directly from an open bottle in a shrink flask connected to a shrink line under an argon atmosphere. After 1 minute of reaction at 25 °C, the solution became highly viscous. The resulting polymer was dried under vacuum. 1 H-NMR spectroscopy shows >99% conversion of monomer to polymer.

[0088] Example 11: Preparation of lactide polymer in dichloromethane (DCM) solution 50 mg of sodium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (NaOAr, prepared as described in Example 3) is dissolved in 10 mL of DCM and added to 6 g of recrystallized L-lactide in a vial in a dry box. After 1 minute of reaction at 25 °C, the solution becomes highly viscous. The resulting polymer is dried under vacuum. 1 H-NMR spectroscopy indicates >99% conversion of monomer to polymer. GPC-SEC studies performed in THF using polystyrene standards indicate high molecular weight (M w = 275.9 kDa) w / M n =2.6) can be obtained.

[0089] Example 12: Preparation of polymer from crude lactide in dichloromethane solution 50 mg of sodium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (NaOAr, prepared as described in Example 3) was dissolved in 10 mL of DCM and added to 6 g of L-lactide taken directly from an open bottle in a shrink flask connected to a shrink line under an argon atmosphere. After 1 minute of reaction at 25 °C, the solution became highly viscous. The resulting polymer was dried under vacuum. 1 H-NMR spectroscopy shows >99% conversion of monomer to polymer.

[0090] Example 13: Preparation of ε-caprolactone polymer in the absence of solvent at 80°C 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) is dissolved in 4.6 mL of ε-caprolactone in a ROTAFLO ampoule connected to a shrink line under argon and placed in a bath at 80 °C. After 2 hours of reaction, the medium becomes highly viscous. The resulting polymer is dried under vacuum. 1 H-NMR spectroscopy indicates a 95% conversion of monomer to polymer. GPC-SEC studies performed in THF using polystyrene standards indicate high molecular weight (M w= 105.1 kDa) w / M n =2.2) can be obtained.

[0091] Example 14: Preparation of lactide and ε-caprolactone diblock copolymer in dichloromethane solution 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) is dissolved in 6 mL of ε-caprolactone in a ROTAFLO ampoule connected to a shrink line under argon atmosphere, which is then placed in a bath at 80 °C. After 2 hours of reaction, a solution of 6 g of L-lactide in 10 mL of DCM is added at room temperature. The resulting polymer is dried under vacuum. 1 H-NMR spectroscopy revealed a 95% conversion of ε-caprolactone to polymer, while L-lactide reached 92% conversion in 3 h. GPC-SEC studies performed in THF using polystyrene standards revealed the formation of high molecular weight (M w = 102.1 kDa) w / M n =2.6) can be obtained.

[0092] Example 15: Preparation of trimethylene carbonate polymer in the absence of solvent at 80°C 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) are added to 4.3 g of trimethylene carbonate melted in a ROTAFLO ampoule. After 14 hours of reaction at 80° C., the medium becomes highly viscous. 1 H-NMR spectroscopy indicates a 93% conversion of monomer to polymer. GPC-SEC studies performed in THF using polystyrene standards reveal a medium molecular weight (M w = 40.5 kDa) w / M n =2.2) can be obtained.

[0093] Example 16: Preparation of polymer from ethylene brassylate in the absence of solvent at 80°C 50 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) are dissolved in 11 mL of ethylene brassylate in a ROTAFLO ampoule connected to a shrink line under an argon atmosphere, which is placed in a bath at 80° C. After 14 hours of reaction, the medium becomes highly viscous. 1 H-NMR spectroscopy indicates >99% conversion of monomer to polymer. GPC-SEC studies performed in THF using polystyrene standards indicate high molecular weight (M w = 83.1 kDa) w / M n =2.3) can be obtained.

[0094] Example 17: Depolymerization of polylactide in dichloromethane (DCM) and methanol solutions at 25°C 200 mg of potassium 18-crown-6-2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr·crown, prepared as described in Example 1) was dissolved in a solvent mixture containing 28 mL of DCM and 7 mL of methanol and added to 4 g of commercially available poly-L-lactide (PLLA) in a shrink flask connected to a shrink line under an argon atmosphere. The reaction was carried out at 25 °C for 10 min. 1 H-NMR spectroscopy revealed a 99% conversion of the polymer to methyl-L-lactic acid, with complete degradation of PLLA and 1% oligomers as by-products, which could be separated from the desired product by distillation.

[0095] Example 18: Depolymerization of polylactide in dichloromethane (DCM) and methanol solutions at 25°C 200 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) was dissolved in a solvent mixture containing 40 mL of DCM and 10 mL of methanol and added to 6 g of commercially available poly-L-lactide (PLLA) in a shrink tube connected to a shrink line under an argon atmosphere. The reaction was carried out at 25°C for 10 min. 1H-NMR spectroscopy revealed a 99% conversion of the polymer to methyl-L-lactic acid, with complete degradation of PLLA and 1% oligomers as by-products, which could be separated from the desired product by distillation.

[0096] Example 19: Depolymerization of polylactide in ethyl acetate (AcOEt) and methanol solutions at 25°C 200 mg of potassium 2,6-bis(diphenylmethyl)-4-tert-butylphenoxide (KOAr, prepared as described in Example 2) was dissolved in a solvent mixture containing 40 mL of AcOEt and 10 mL of methanol and added to 6 g of commercially available poly-L-lactide (PLLA) in a shrink tube connected to a shrink line under an argon atmosphere. The reaction was carried out at 25°C for 60 min. 1 H-NMR spectroscopy revealed a 97% conversion of the polymer to methyl-L-lactic acid, with complete decomposition of PLLA and 3% oligomers as by-products. The proportion of oligomers varied and was related to the proportion of alcohol used; a lower alcohol proportion resulted in a higher proportion of oligomers. It was noted that the by-products could be separated from the desired product by distillation.

Claims

1. Compounds of formula (I) or (II) as catalysts in the ring-opening (co)polymerization process of heterocycles: 【Chemistry 1】 (In the formula, R １ and R ２ is hydrogen, C ３ -C ８ Alkyl, C ３ -C ８ Haloalkyl, C ３ -C ８ Alkoxide, C ３ -C ８ Halo-alkoxides, C ３ -C ８ Dialkylamino, C ３ -C ８ Halo-dialkylamino, C ３ -C ８ independently selected from hydroxyalkyl or cyanide; R ３ is H, C ３ -C ８ Alkyl, C ３ -C ８ Haloalkyl, C ３ -C ８ Cyanoalkyl, C ３ -C ８ Alkoxide, C ３ -C ８ selected from dialkylamino or cyanide; n is an integer from 1 to 3, M is an alkali metal selected from Li, Na and K. Use of compounds.

2. R １ and R ２ The use according to claim 1, wherein is H.

3. R ３ is C ３ -C ８ 3. The use according to claim 1 or 2, wherein the alkyl is alkyl.

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

5. The use according to any one of claims 1 to 4, wherein M is Na or K.

6. The compounds of formula (I) and (II) are as follows: 【Chemistry 2】 The use according to any one of claims 1 to 5, wherein the compound is selected from the group consisting of:

7. The use according to any one of claims 1 to 6, wherein the heterocycle is selected from cyclic esters, diesters, ethers, thioethers, amides and carbonates.

8. 2. The use according to claim 1, wherein the heterocycle is selected from lactide, ε-caprolactone, trimethylene carbonate and ethylene brassylate.

9. 3. The use according to claim 1 or 2, wherein the heterocycle is an epoxide or a thioepoxide.

10. A process for the ring-opening polymerization or copolymerization of heterocycles, comprising contacting one or more starting heterocycles with a compound of formula (I) or (II) according to any one of claims 1 to 6.

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

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

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

14. The process according to any one of claims 10 to 12, carried out in the presence of a polar or non-polar aprotic solvent.

15. 12. The method according to claim 10 or 11, which is carried out in the molten state.

16. 16. The method according to any one of claims 10 to 15, wherein the compound of formula (I) or (II) is present in an amount of 0.1 to 2 mol % relative to the starting heterocycle.

17. The process according to any one of claims 10 to 16, carried out in the presence or absence of a co-catalyst.

18. Use of a compound of formula (I) or (II) according to any one of claims 1 to 6 as a catalyst in a process for depolymerization of polymers having heteroatoms in their structure to obtain oligomers and derivatives of the monomers forming the polymer, said process being carried out in the presence of an alcohol R-OH, where R is C ３ -C ８ alkyl or benzyl radicals), use.

19. Formula (II): 【Transformation 3】 (In the formula, R １ , R ２ , R ３ , n and M are defined in any one of claims 1 to 6. Compound.

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