Process for synthesis of polyester polyols by ring-opening copolymerization of gamma-butyrolactone with other lactones

Abstract

A process for the synthesis of polyester polyols by ring-opening copolymerization of gamma-butyrolactone with other lactones, the use of a kit comprising one or more bases comprising alkali metal cations and one or more alcohols in said process, and the polyester polyols obtainable by said process are described.

Description

[0001] The present application relates to a method for synthesizing polyester polyols by ring-opening copolymerization of γ-butyrolactone with other lactones, including the use in said method of a kit of one or more bases comprising alkali metal cations and one or more alcohols, and to polyester polyols obtainable by said method.

[0002] Polyester polyols are an important class of polyols, which are used, for example, in the synthesis of polyurethanes. In particular, γ-butyrolactone is a highly attractive monomer for the synthesis of polyester polyols by ring-opening polymerization because it is a cheap and readily available material that can be obtained from biomass feedstocks. This provides polymers that are not only biodegradable but also obtainable from renewable resources. Due to the low strain energy of the five-membered ring of γ-butyrolactone, γ-butyrolactone is less prone to polymerization compared to other readily polymerizable lactones such as ε-caprolactone (see: Q. Song et al., Polymer Journal, 2020, 52, 3 - 11). Interestingly, the ring-opening copolymerization of γ-butyrolactone with other lactones proceeds more straightforwardly and can deliver products that are liquid at room temperature (see: Q. Song et al., Progress in Polymer Science, 2020, 110, 101309)).

[0003] Due to the development of catalyst / initiator systems capable of copolymerizing γ-butyrolactone with other lactones into polyester polyols, some progress has been made in the past few years. However, typically harsh reaction conditions using Lewis acid catalysts are required, the catalysts are rather complex, polyols are not obtained, or the yields obtained are only moderate, and the reaction is carried out in a relatively dilute solution, which is disadvantageous from an economic perspective.

[0004] EP 1 041 099 A2 discloses the use of BF3*Et2O as an initiator for copolymerizing γ-butyrolactone with ε-caprolactone and δ-valerolactone respectively into polyesters at a temperature of 130 °C and a pressure of 1.25 GPa. The weight-average molecular weights (M w ) of the polyesters are 31,700 g / mol and 14,600 g / mol respectively, and the yields are 85% and 76% respectively. The required high pressure is a significant drawback because this would require expensive high-pressure equipment to carry out the copolymerization. Nor could it be demonstrated whether the products obtained were polyols.

[0005] Macromol.Chem.Phys.1996, 197, 1273 - 1283 describes the copolymerization of different ratios of γ-butyrolactone with ε-caprolactone at a temperature of 20 °C and atmospheric pressure using Al(OiPr)3 as an initiator. The average molecular weight (M n)Between 950 g / mol and 33,100 g / mol. A disadvantage of this method is that at least one end of the polymer chain of the resulting polyester is capped with an OiPr group from the initiator. Thus, the resulting polyester is not a diol and cannot be used as a polyol in polyurethane synthesis.

[0006] Polymer, 1998, 39, 1213 - 1222 describes the copolymerization of γ-butyrolactone with different lactones such as ε-caprolactone, δ-valerolactone, β-propiolactone or glycolide at 140 °C using tetraphenyltin as the initiator. However, even using a large excess of γ-butyrolactone (5 equivalents compared to other lactones), the highest fraction of structural units derived from γ-butyrolactone in the resulting polyester copolymer that can be achieved by this method is 26 mol%. Another major disadvantage of this method is the use of an organotin compound, which is generally a compound of concern due to its toxicity.

[0007] Polymer, 2005, 46, 12118 - 12129 describes the copolymerization of γ-butyrolactone with ε-caprolactone at 150 °C using decamolybdate as the catalyst. However, even using a 1:1 molar ratio of γ-butyrolactone:ε-caprolactone, the highest fraction of structural units derived from γ-butyrolactone in the resulting polyester copolymer that can be achieved by this method is 10 mol%. Thus, a large amount of γ-butyrolactone remains unreacted.

[0008] J.Mater.Chem.B. 2016, 4, 5394 - 5404 describes the copolymerization of γ-butyrolactone with ε-caprolactone at 110 °C using dioctyltin as the catalyst and ethylene glycol as the initiator. Since a diol is used as the initiator, a polyol that can be further used in polyurethane synthesis is obtained. However, even using a 6:4 molar ratio of γ-butyrolactone:ε-caprolactone, the highest fraction of structural units derived from γ-butyrolactone in the polyester copolymer that can be achieved by this method is 11 mol%. Thus, a large amount of γ-butyrolactone remains unreacted. Another major disadvantage of this method is the use of an organotin catalyst, which is generally a compound of concern due to its toxicity.

[0009] Polym.Chem. 2018, 9, 2936 - 2941 describes the copolymerization of γ-butyrolactone with L-lactide at -50 °C to +25 °C using phosphazene base as the catalyst and benzyl alcohol as the initiator. Since a monohydric alcohol benzyl alcohol is used as the initiator, at least one end of the polymer chain of the resulting polyester is capped with a benzyl group from the initiator. Thus, the resulting polyester is not a diol and cannot be used as a polyol in polyurethane synthesis. Moreover, the use of an expensive and sensitive phosphazene base is a disadvantage of this method.

[0010] Macromolecules, 2017, 50, 8469 - 8479 describes the copolymerization of different ratios of γ - butyrolactone with ε - caprolactone and δ - valerolactone at - 40 °C to + 25 °C using phosphazene base or La(N(SiMe3)2)3 as catalysts and a monohydric alcohol as an initiator. Since a monohydric alcohol is used as an initiator, at least one end of the polymer chain of the resulting polyester polyol is not capped with a hydroxyl group. Therefore, the resulting polyester is not a diol and cannot be used as a polyol in polyurethane synthesis. In addition, the use of expensive and sensitive phosphazene base or La(N(SiMe3)2)3 is a serious drawback of this method.

[0011] CN 114369232 A discloses an ABA triblock copolymer and its preparation method, which uses γ - butyrolactone (γ - BL), α - methylene - γ - butyrolactone (MBL), ε - caprolactone (ε - CL), δ - valerolactone (δ - VL), lactide (LA) and other biomass monomers as raw materials, and a binary catalytic system composed of a strong base and a cocatalyst.

[0012] CN 108250415 A discloses a poly(γ - butyrolactone) - b - polylactic acid block copolymer and its preparation method.

[0013] P. Walther and S. Naumann (Macromolecules 2017, 50, 8406 - 8416) disclose a dual - catalysis method that uses a setup consisting of an N - heterocyclic olefin (NHO) and a Lewis acid (such as MgCl2 or LiCl) to homopolymerize ω - pentadecalactone (PDL) and copolymerize it with five - membered, six - membered and seven - membered lactones (γ - butyrolactone (GBL), 5 - valerolactone (VL) and ε - caprolactone (CL)). The copolymerization of GBL with VL and CL was also studied.

[0014] W0 2022 / 122360A1 discloses a composition for producing polyurethane foams, especially rigid polyurethane foams, which comprises at least one isocyanate component, a polyol component, an optional catalyst for catalyzing the formation of urethane bonds or isocyanurate bonds, and a blowing agent, and the composition comprises a polyester polysiloxane block copolymer.

[0015] The main object of the present invention is to provide a method for synthesizing a polyester polyol by ring-opening copolymerization of γ-butyrolactone with other lactones, which method can be carried out using a catalyst that is simple, readily available, and inexpensive, wherein the method provides the polyester polyol in high yield and enables incorporation of 20 mol% or more, preferably 30 mol% or more, more preferably 40 mol% or more of γ-butyrolactone in the copolymer. Another object is to provide a method for ring-opening copolymerization of γ-butyrolactone with other lactones, which method does not require very high temperatures (above 50 °C) or very low temperatures (below -25 °C), and thus requires less expensive equipment and less energy.

[0016] The main object and other objects of the present invention are achieved by a method for synthesizing a polyester polyol,

[0017] which method comprises a step of ring-opening copolymerization of lactones,

[0018] wherein the lactones are

[0019] (i) γ-butyrolactone (I)

[0020]

[0021] and

[0022] (ii) one or more lactones of formula (II)

[0023]

[0024] wherein

[0025] m is an integer selected from 1 to 12,

[0026] n is an integer selected from 1 to 2,

[0027] each R a 、each R b 、each R c and each R d is independently selected from the group consisting of H and C1-C 10 -alkyl,

[0028] p is an integer selected from 0 and 1,

[0029] with the proviso that m is not 3 when p = 0,

[0030] wherein the ring-opening copolymerization is carried out in the presence of

[0031] (iii) one or more bases containing alkali metal cations

[0032] and

[0033] (iv) one or more alcohols

[0034] The temperature is from -25°C to +50°C,

[0035] wherein

[0036] the total amount of lactones (i) and (ii)

[0037] and the total amount of base (iii) containing an alkali metal cation have a molar ratio of

[0038] ((i)+(ii)):(iii)

[0039] is 50:1 or higher.

[0040] In the process according to the invention, (i) γ-butyrolactone (I) is copolymerized with (ii) one or more lactones of formula (II) as defined above, preferably with a lactone of formula (II) as defined above.

[0041] The lactone according to formula (II) contains m groups CR a R b , where m is an integer selected from 1 to 12. Therefore, the lactone according to formula (II) contains 1 to 12 groups CR a R b . In addition, the lactone according to formula (II) contains p groups -(C=O)-O-[CR c R d n , where p is an integer selected from 0 and 1, and n is an integer selected from 1 and 2. Therefore, the lactone according to formula (II) contains one group -(C=O)-O-[CR c R d n , which contains one or two groups [CR c R d , or does not contain the group -(C=O)-O-[CR c R d n .

[0042] As defined above, when p = 0 in formula (II), then m must not be 3. Therefore, it should be understood that γ-butyrolactone (I) is not a lactone according to formula (II) as defined above.

[0043] The molecule of formula (II) has m groups CR a R b and n groups CR c R d . The m substituents R a 、m substituents R b 、n substituents R c and n substituents R​​​d Each of them is independently selected from the group consisting of H and C1-C 10 -alkyl. As used herein, C1-C 10 -alkyl is intended to include straight-chain C1-C 10 -alkyl and branched-chain C4-C 10 -alkylalkyl, and more specifically n-C1-C 10 -alkyl, sec-C3-C 10 -alkyl and tert-C4-C 10 -alkyl.

[0044] Preferably, the lactone according to formula (II) or one or more or all of the lactones according to formula (II) are selected from the group consisting of ε-caprolactone, ε-decalactone, δ-valerolactone, β-propiolactone, lactide and glycolide. More preferably, γ-butyrolactone (I) is copolymerized with a lactone according to formula (II) selected from the group consisting of ε-caprolactone, ε-decalactone, δ-valerolactone, β-propiolactone, lactide and glycolide.

[0045] In ε-caprolactone, p = 0, m = 5, and each R a and each R b is H.

[0046] In ε-decalactone, p = 0 and m = 5, in the 1st to 4th (counting from the group CR a R b closest to the carbonyl group) CR a R b groups, R a and R b are both H, and in the 5th CR a R b group, R a is H, and R b is C4H9.

[0047] In δ-valerolactone, p = 0, m = 4, and each R a and each R b is H.

[0048] In β-propiolactone, p = 0, m = 2, and each R a and each R b is H.

[0049] In lactide, p = 1, n = m = 1, each of R a and R c is H, and each of R b and R d is CH3.

[0050] In glycolide, p = 1, n = m = 1, and each of R a , R b , R c and R d is H.

[0051] The most preferred lactones of formula (II) are those selected from the group consisting of ε-caprolactone, ε-decalactone, and δ-valerolactone.

[0052] In the process according to the invention, the ring-opening copolymerization is carried out in the temperature range from -25 °C to +50 °C, preferably in the temperature range from -25 °C to +30 °C, more preferably at -25 °C to +20 °C, and most preferably in the temperature range from -25 °C to +10 °C.

[0053] In the process according to the invention, the ring-opening copolymerization is generally carried out at ambient pressure.

[0054] In the process according to the invention, the ring-opening copolymerization is carried out in the presence of

[0055] (iii) one or more bases containing alkali metal cations

[0056] and

[0057] (iv) one or more alcohols

[0058] Without wishing to be bound by any theory, it is currently assumed that the base (iii) acts as a catalyst for the ring-opening copolymerization of (i) γ-butyrolactone and (ii) said one or more lactones of formula (II), and the alcohol (iv) acts as an initiator for the ring-opening copolymerization of (i) γ-butyrolactone and (ii) said one or more lactones of formula (II).

[0059] In the process according to the invention, the molar ratio of the total amount of lactones (i) and (ii) to the total amount of the base (iii) containing alkali metal cations

[0060] ((i)+(ii)):(iii)

[0061] is 50:1 or higher. Preferably, the molar ratio of the total amount of lactones (i) and (ii) to the total amount of the base (iii) containing alkali metal cations ranges from 100:1 to 800:1, preferably 100:1 to 400:1. Thus, the amount of the base (iii) required as a catalyst for the ring-opening copolymerization of a given amount of lactones (i) and (ii) is quite low, which is advantageous from an economic point of view.

[0062] Base (iii) is a base containing an alkali metal cation. The anion of base (i) can be a proton acceptor (Bronsted base) and / or an electron pair donor (Lewis base). Preferably, the alkali metal cation is selected from the group consisting of Li + 、Na + 、K + 、Rb + and Cs + and most preferably is selected from the group consisting of Li + 、Na + and K + .

[0063] Preferably, base (iii) containing an alkali metal cation or one or more or all of bases (iii) containing an alkali metal cation are selected from the group consisting of lithium alkoxides, sodium alkoxides and potassium alkoxides. The alkoxides can be derived from monohydric alcohols, dihydric alcohols or trihydric alcohols. More preferably, base (iii) containing an alkali metal cation or one or more or all of bases (iii) containing an alkali metal cation are selected from the group consisting of lithium methoxide, sodium methoxide, potassium methoxide, lithium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide, lithium benzylate, sodium benzylate, potassium benzylate, dipotassium phthalate and disodium phthalate.

[0064] More preferably, each base (iii) containing an alkali metal cation is selected from the group consisting of lithium alkoxides, sodium alkoxides and potassium alkoxides, preferably selected from the group consisting of lithium methoxide, sodium methoxide, potassium methoxide, lithium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide, lithium benzylate, sodium benzylate and potassium benzylate.

[0065] The most preferred bases (iii) are lithium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide and potassium benzylate.

[0066] Preferably, alcohol (iv) or one or more or all of alcohols (iv) are selected from monohydric alcohols, dihydric alcohols, trihydric alcohols and tetrahydric alcohols. However, in some cases, especially for the production of polyester polyols suitable for polyurethane synthesis, preferably, alcohol (iv) is not a monohydric alcohol.

[0067] Preferably, alcohol (iv) or one or more or all of alcohols (iv) are selected from the group consisting of ethylene glycol, diethylene glycol, polyethylene glycol (PEG), 1,2-propanediol, dipropylene glycol, polypropylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, polybutylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, mannitol, sorbitol, xylitol, threitol

[0068] and benzyl alcohol according to formula (III)

[0069]

[0070] wherein

[0071] n is an integer from 1 to 4, preferably 2 or 3,

[0072] m is an integer from 0 to 3,

[0073] o is 0 or 1

[0074] m + n + o ≤ 6;

[0075] R 1 and R 2 are each independently selected from the group consisting of:

[0076] F, Cl, Br, OH, CN, NH2, NO2,

[0077] C1-C 10 -alkyl

[0078] C3-C 10 -cycloalkyl,

[0079] C3-C containing at least one heteroatom selected from N, O, and S 10 -heterocyclic group,

[0080] C5-C 14 -aryl,

[0081] C5-C containing at least one heteroatom selected from N, O, and S 10 -heteroaryl,

[0082] wherein the C1-C 10 -alkyl, C3-C 10 -cycloalkyl, C3-C 10 -heterocyclic group, C5-C 14 -aryl or C5-C 10 -heteroaryl optionally has one or more additional substituents selected from the group consisting of F, Cl, Br, OH, CN,

[0083] NH2 and C1-C 10 -alkyl,

[0084] wherein the benzyl alcohol according to formula (III) is preferably selected from the group consisting of benzyl alcohol, 1,4-benzenedimethanol, 2,6-dichlorobenzyl alcohol, 4-methylbenzyl alcohol, and 2,4,6-trimethylbenzyl alcohol.

[0085] As used herein, C1-C 10 -alkyl is intended to include straight-chain C1-C 10 -alkyl and branched-chain C4-C 10 -alkylalkyl, and more specifically n-C1-C 10 -alkyl, sec-C3-C 10 -alkyl and tert-C4-C10 -alkyl

[0086] More preferably, each alcohol (iv) is selected from the group defined above.

[0087] Among the benzyl alcohols according to formula (III), 1,4-benzenedimethanol, 2,6-dichlorobenzyl alcohol, 4-methylbenzyl alcohol and 2,4,6-trimethyl-benzyl alcohol are preferred.

[0088] The most preferred alcohols (iv) are methanol, ethanol, polyethylene glycol, 1,4-butanediol, 1,6-hexanediol, benzyl alcohol, 1,4-benzenedimethanol, 2,6-dichlorobenzyl alcohol, 4-methylbenzyl alcohol and 2,4,6-trimethylbenzyl alcohol.

[0089] Most preferably, one or more of the base (iii) containing an alkali metal cation or the base (iii) containing an alkali metal cation are selected from the group defined above of the preferred base (iii), and one or more of the alcohol (iv) or the alcohol (iv) are selected from the group defined above of the preferred alcohol (iv). More preferably, each base (iii) containing an alkali metal cation is selected from the group defined above of the preferred base (iii), and each alcohol (iv) is selected from the group defined above of the preferred alcohol (iv).

[0090] In a particularly preferred method

[0091] (iii) one, more or all of the base containing an alkali metal cation or the base (iii) containing an alkali metal cation are selected from the alkali metal alcoholates of the formula MOR 3 wherein M is selected from the group consisting of Li,

[0092] Na and K

[0093] (iv) one, more or all of the alcohol or the alcohol (iv) are selected from the alcohols of the formula R 3 OH, where the R 3 of (iii) is 3 the same as the R of (iv) and is preferably selected from the group consisting of methyl, ethyl, isopropyl, sec-butyl, tert-butyl and benzyl.

[0094] In the process according to the invention, the molar ratio of the total amount of the base (iii) containing an alkali metal cation to the total amount of the OH groups (v) in the alcohol (iv)

[0095] (iii):(v)

[0096] is preferably in the range from 1:6 to 12:1, more preferably from 1:2 to 8:1.

[0097] In the process according to the invention, the molar ratio of (i) γ-butyrolactone to (ii) the lactone according to formula (II) can vary, resulting in a variation in the molar ratio of the structural units derived from (i) γ-butyrolactone (I) to the structural units derived from (ii) one or more lactones according to formula (II) in the final polyester polyol. Thereby, the properties of the resulting polyester polyol can be adjusted. For example, the molar ratio of the structural units derived from (i) γ-butyrolactone to the structural units derived from (ii) the lactone according to formula (II) can have a strong influence on the melting point or glass transition temperature of the resulting polyester polyol. Preferably, in the process according to the invention, the molar ratio of the total amount of (i) γ-butyrolactone (I) to (ii) the lactone of formula (II)

[0098] (i):(ii)

[0099] is in the range from 5:95 to 95:5, more preferably from 85:15 to 15:85.

[0100] In the process according to the invention, the ring-opening copolymerization is generally carried out in a reaction mixture comprising the reactants (i), (ii), a catalyst (iii) and an initiator (iv). Accordingly, a reaction mixture comprising the reactants (i), (ii), a catalyst (iii) and an initiator (iv) can be provided for the process according to the invention.

[0101] In certain cases, preferably, the ring-opening copolymerization is carried out in a solvent or in one or more solvents. Suitable solvents are those solvents in which the reactants (i) and (ii), the catalyst (iii) and the initiator (iv) and the product polyester polyol are respectively miscible and soluble. Accordingly, the copolymerization is carried out in a reaction mixture comprising the reactants (i), (ii), a catalyst (iii), an initiator (iv) and a solvent. The presence of one or more solvents in the reaction mixture enables the reactants (i), (ii), (iii) and (iv) as defined above to be evenly distributed and promotes their interaction. Accordingly, in such cases, a reaction mixture comprising the reactants (i), (ii), a catalyst (iii), an initiator (iv) and one or more solvents is generally provided for the process according to the invention.

[0102] Preferably, one or more or all of the solvents are selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, ethers, esters, N,N-dialkylamides, dialkyl sulfoxides and nitriles. More preferably, each solvent is selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, ethers, esters, N,N-dialkylamides, dialkyl sulfoxides and nitriles.

[0103] As used herein, the term "hydrocarbon" is intended to include halogenated hydrocarbons.

[0104] Further preferably, one, more or all of the solvents are selected from the group consisting of dichloromethane, toluene, 2-methyl-tetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, dimethylformamide, dimethyl sulfoxide and acetonitrile. Most preferably, each solvent is selected from the group consisting of dichloromethane, toluene, 2-methyl-tetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, dimethylformamide, dimethyl sulfoxide and acetonitrile.

[0105] For ring-opening copolymerization, there can be provided

[0106] - a premix comprising (i) γ-butyrolactone (I) and (ii) one or more lactones of formula (II) as defined above and optionally one or more solvents, and

[0107] - a premix comprising (iii) one or more bases containing alkali metal cations and (iv) one or more alcohols and one or more solvents.

[0108] In the process according to the invention, a reaction mixture can be formed and the ring-opening copolymerization can be initiated by adding a first premix comprising (iii) one or more bases containing alkali metal cations and (iv) one or more alcohols and one or more solvents to a second premix comprising (i) γ-butyrolactone (I) and (ii) one or more lactones of formula (II) as defined above and optionally one or more solvents.

[0109] After initiating the ring-opening copolymerization

[0110] - one or more additional portions of the premix comprising (iii) said one or more bases containing alkali metal cations and (iv) said one or more alcohols and one or more solvents as in the above first premix

[0111] and / or

[0112] - (i) γ-butyrolactone (I) and (ii) as defined above in the second premix as

[0113] one or more additional portions of the premix of said one or more lactones of formula (II) and optionally one or more solvents

[0114] can be added.

[0115] Said one or more additional portions of the premix comprising (iii) said one or more bases containing alkali metal cations and (iv) said one or more alcohols and one or more solvents may contain the base (iii) and said one or more alcohols (iv) in the same or different molar ratios as in the above first premix.

[0116] Said one or more additional portions of the premix comprising (i) γ-butyrolactone (I) and (ii) one or more lactones of formula (II) as defined above may contain (i) γ-butyrolactone (I) and (ii) said one or more lactones of formula (II) in the same molar ratio or a different molar ratio as in the second premix above, in order to adjust the molar ratio of (i) γ-butyrolactone (I) and (ii) one or more lactones of formula (II) as defined above in the copolymer to be formed.

[0117] In some cases, in order to reduce the complexity of the method, it may be preferred that, after the initiation of ring-opening copolymerization, no additional portion of the premix comprising (iii) said one or more bases containing alkali metal cations and (iv) said one or more alcohols and one or more solvents is added, and no additional portion of the premix comprising (i) γ-butyrolactone (I) and (ii) said one or more lactones of formula (II) as defined above and optionally one or more solvents is added.

[0118] The solvent or one or more or all of the solvents are preferably selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, ethers, esters, N,N-dialkylamides, dialkyl sulfoxides, and nitriles, and most preferably selected from the group consisting of dichloromethane, toluene, 2-methyl-tetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, dimethylformamide, dimethyl sulfoxide, and acetonitrile. More preferably, each solvent is selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, ethers, esters, N,N-dialkylamides, dialkyl sulfoxides, and nitriles, and most preferably selected from the group consisting of dichloromethane, toluene, 2-methyl-tetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, and acetonitrile.

[0119] In some cases, the method as defined above further comprises the steps of drying lactones (i) and (ii) by adding a desiccant before ring-opening copolymerization, and optionally separating the dried lactones (i) and (ii) from the desiccant. The drying can be achieved by any suitable desiccant.

[0120] The desiccant is preferably selected from the group consisting of:

[0121] CaH2,

[0122] tosyl isocyanate,

[0123] and oxazolidine.

[0124] The oxazolidine is preferably selected from the group consisting of oxazolidine of formula (III), oxazolidine of formula (IV), and oxazolidine of formula (V)

[0125]

[0126] wherein

[0127] R 4 、R 5 、R 6 and R 7 are each independently selected from the group consisting of H- and C1-C 10 -alkyl

[0128] and R 8 is a bridging unit comprising from 1 to 20 -CH2- units (methylene units) and optionally one or more moieties selected from the group consisting of:

[0129] -NH-

[0130] -O- (ether bridge),

[0131] -CO- (carbonyl)

[0132] -COO- (carboxyl)

[0133] and -NH-COO- (urethane).

[0134] As used herein, C1-C 10 -alkyl is intended to include straight-chain C1-C 10 -alkyl as well as branched C4-C 10 -alkylalkyl, and more specifically n-C1-C 10 -alkyl, sec-C3-C 10 -alkyl and tert-C4-C 10 -alkyl.

[0135] In certain preferred oxazolidines of formula (VI), the bridging unit R 8 is

[0136]

[0137] In certain preferred oxazolidines of formulas (IV) and (V) respectively, R 4 is selected from branched alkyl, such as sec-C3-C 10 -alkyl or tert-C4-C 10 , R 5 is selected from n-C1-C 10 -alkyl, and R 6 in formula (V) is methyl.

[0138] Most preferably, the oxazolidine has formula (VII)

[0139]

[0140] The oxazolidine of formula (VII) is sold by Incorez under the trade name "INCOZOL 2".

[0141] The above substances can act as desiccants for (i) γ-butyrolactone and (ii) the lactones of formula (II).

[0142] Before the ring-opening copolymerization, especially before preparing the reaction mixture containing the reactants (i), (ii), catalyst (iii) and initiator (iv) defined above, the dry γ-butyrolactone (I) and the dry lactones of formula (II) can be separated from the desiccant by distillation to avoid the presence of the desiccant and its reaction products with water in the target product polyester polyol. Especially when CaH2 is used as the desiccant, it is preferred to use distillation to separate the dried γ-butyrolactone (I) and the dried lactones of formula (II) from the spent CaH2. Regardless of the desiccant applied, the distillation must be carried out under a protective atmosphere (such as nitrogen or argon) to prevent the dried γ-butyrolactone (I) and the dried lactones of formula (II) from absorbing atmospheric moisture.

[0143] Preferably, the water content of (i) γ-butyrolactone (I) and (ii) one or more lactones of formula (II) used in the ring-opening copolymerization method according to the invention is 0.1 wt% or lower, preferably 0.05 wt% or lower, and most preferably 0.01 wt% or lower, as measured by the Karl Fischer titration method. The low water content can be achieved by applying a desiccant, preferably one of the preferred desiccants described above.

[0144] In certain cases, preferably, the method for synthesizing polyester polyol defined above further includes a step of quenching the ring-opening copolymerization by adding a quenching solution containing one or more acids and one or more solvents. The base (iii) can be neutralized by quenching. In the absence of quenching, there is a risk of decomposition when the obtained polyester polyol is separated from the reaction mixture at ambient temperature.

[0145] In the added quenching solution, one or more or all of the acids or the acids are preferably selected from the group consisting of hydrohalic acids, oxoacids of Cl, S, N, P and B, alkylsulfonic acids, arylsulfonic acids, mono-, di- and trifunctional carboxylic acids. The mono-, di- and trifunctional carboxylic acids include hydroxy-functionalized mono-, di- and trifunctional carboxylic acids and unsaturated mono-, di- and trifunctional carboxylic acids.

[0146] Most preferably, in the quenching solution, each acid is selected from the group consisting of hydrohalic acids, oxoacids of Cl, S, N, P and B, alkylsulfonic acids, arylsulfonic acids, mono-, di- and trifunctional carboxylic acids as defined above.

[0147] The most preferred acids are selected from the group consisting of hydrochloric acid HCl, perchloric acid HClO4, nitric acid HNO3, sulfuric acid H2SO4, phosphoric acid H3PO4, boric acid B(OH)3, formic acid, acetic acid, acrylic acid, oxalic acid, propionic acid, lactic acid, citric acid, methanesulfonic acid, and toluenesulfonic acid.

[0148] The quenching solution contains one or more solvents. Suitable solvents are those in which the polyester polyol is soluble.

[0149] In the quenching solution, one or more or all of the solvents are preferably selected from the group consisting of aliphatic and aromatic hydrocarbons, ketones, ethers, dialkyl carbonates, and dialkyl sulfoxides. Most preferably, in the quenching solution, each solvent is selected from the group consisting of aliphatic and aromatic hydrocarbons, ketones, ethers, dialkyl carbonates, and dialkyl sulfoxides.

[0150] As used herein, the term "hydrocarbon" is intended to include halogenated hydrocarbons.

[0151] The most preferred solvents are those selected from the group consisting of dichloromethane (DCM), chloroform, deuterated chloroform (CDCl3), 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, 1,4-dioxane, anisole, dimethyl ether, acetone, acetophenone, dihydrolevoglucosenone, dimethyl carbonate, diethyl carbonate, dimethyl sulfoxide, and acetonitrile.

[0152] The added quenching solution preferably has a temperature in the range of -25°C to 20°C.

[0153] In the quenching solution, the total concentration of the acid is preferably in the range of 0.001 mol / l to 1 mol / L, preferably in the range of 0.016 mol / L to 0.081 mol / L.

[0154] The quenching solution is preferably added in such an amount that the acid concentration provided by the quenching solution corresponds to an amount of 1 to 50 equivalents of acid per 1 equivalent of base, preferably 4 to 20 equivalents of acid per 1 equivalent of base.

[0155] Work-up of the reaction mixture and separation of the resulting polyester polyol can be carried out in any conventional manner, for example using filtration or aqueous extraction work-up, precipitation, removal of the solvent by distillation, or a combination of some or all of these steps, such as first hydrolytic work-up to remove any basic base (iii) and alcohol (iv), and then removal of the organic solvent and any unreacted γ-butyrolactone (I) and unreacted lactone according to formula (II) from the organic phase by evaporation or distillation. By applying these measures or combinations thereof, polyester polyols of generally sufficient purity can be obtained such that no additional purification steps are required.

[0156] The method for synthesizing a polyester polyol according to the present invention can be carried out continuously, semi - continuously or discontinuously. The reaction can be carried out in all reactors known to those skilled in the art suitable for this type of reaction. Suitable reactors are described and reviewed in the relevant literature, for example, K. Henkel, “Reactor Types and Their Industrial Applications”, Ullmann’s Encyclopedia of Industrial Chemistry, 2005, Wiley - VCH Verlag GmbH & Co. KGaA, chapter 3.3: “Reactors for gas - liquid reactions”.

[0157] A particularly preferred method for synthesizing a polyester polyol comprises the following steps:

[0158] (A) Ring - opening copolymerization of the following substances:

[0159] (i) γ - butyrolactone (I)

[0160] and

[0161] (ii) One or both of ε - caprolactone, ε - decalactone and δ - valerolactone

[0162] in the presence of

[0163] (iii) One or more bases containing alkali metal cations selected from the group consisting of lithium tert - butoxide, sodium tert - butoxide, potassium tert - butoxide, dipotassium phthalyl alcoholate and disodium phthalyl alcoholate

[0164] and

[0165] (iv) One or more alcohols selected from the group consisting of 1,4 - benzenedimethanol, 1,3,5 - benzenetriol, glycerol, trimethylolethane, pentaerythritol, benzyl alcohol, ethylene glycol, polyethylene glycol and 1,5 - pentanediol

[0166] at a temperature of - 25 °C to + 30 °C,

[0167] wherein the molar ratio of the total amount of γ - butyrolactone (I), ε - caprolactone, ε - decalactone and δ - valerolactone to the total amount of the base (iii) containing alkali metal cations

[0168] ((i)+(ii)):(iii)

[0169] is from 100:1 to 800:1

[0170] and

[0171] The molar ratio of the total amount of base (iii) containing an alkali metal cation to the total amount of OH groups (v) in the alcohol (iv)

[0172] (iii):(v)

[0173] is in the range of 1:2 to 8:1,

[0174] and

[0175] wherein the molar ratio of γ-butyrolactone (i) to the total amount of ε-caprolactone and δ-valerolactone (ii) is in the range of 85:15 to 15:85,

[0176] and

[0177] wherein the ring-opening copolymerization is carried out in a solvent selected from the group consisting of dichloromethane, toluene, 2-methyl-tetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, dimethylformamide, dimethyl sulfoxide, acetonitrile, and mixtures thereof,

[0178] and

[0179] wherein the water content of γ-butyrolactone (I), ε-caprolactone, ε-decalactone, and δ-valerolactone is 0.01 wt% or less, as measured by the Karl-Fischer titration method,

[0180] and (B) quenching the ring-opening copolymerization by adding a quenching solution containing an acid and a solvent,

[0181] wherein

[0182] - the acid is selected from the group consisting of hydrochloric acid, perchloric acid, nitric acid, sulfuric acid, phosphoric acid, boric acid, formic acid, acetic acid, acrylic acid, oxalic acid, propionic acid, lactic acid, citric acid, methanesulfonic acid, and toluenesulfonic acid,

[0183] - the solvent is selected from the group consisting of dichloromethane, chloroform, deuterated chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, 1,4-dioxane, anisole, dimethyl ether, acetone, acetophenone, dihydrolevoglucosenone, dimethyl carbonate, diethyl carbonate, dimethyl sulfoxide, acetonitrile, and mixtures thereof,

[0184] - the quenching solution has a temperature in the range of -25 °C to +50 °C.

[0185] In another aspect, the use of a kit in the method for synthesizing a polyester polyol as defined above is disclosed, the kit comprising

[0186] (iii) one or more bases containing an alkali metal cation

[0187] (iv) one or more alcohols.

[0188] Specific and preferred bases (iii) containing alkali metal cations are as described above. Specific and preferred alcohols (iv) are as described above. Specific and preferred combinations of bases (iii) containing alkali metal cations and alcohols (iv) are as described above. Preferably, the kit is used in one of the specific and preferred methods for synthesizing polyester polyols defined above.

[0189] In another aspect, a polyester polyol obtainable by the method defined above is disclosed. Preferably, the polyester polyol is obtainable by one of the specific and preferred methods defined above.

[0190] The polyester polyol obtainable by the method defined above contains structural units derived from (i) γ-butyrolactone (I) and structural units derived from (ii) one or more lactones according to formula (II). Preferably, the polyester polyol contains structural units derived from (i) γ-butyrolactone (I) and structural units derived from (ii) one or more lactones selected from the group consisting of ε-caprolactone, ε-decalactone, δ-valerolactone, β-propiolactone, lactide, and glycolide. In certain cases, the preferred polyester polyol contains structural units derived from (i) γ-butyrolactone (I) and structural units derived from (ii) one lactone selected from the group consisting of ε-caprolactone, ε-decalactone, δ-valerolactone, β-propiolactone, lactide, and glycolide. Most preferably, the polyester polyol contains structural units derived from (i) γ-butyrolactone (I) and structural units derived from (ii) one lactone selected from the group consisting of ε-caprolactone, ε-decalactone, and δ-valerolactone.

[0191] Preferably, one, more, or all of the lactones according to formula (II) are selected from the group consisting of ε-caprolactone, ε-decalactone, δ-valerolactone, β-propiolactone, lactide, and glycolide.

[0192] Preferably, the polyester polyol obtainable by the method defined above, wherein the fraction of the structural units derived from (i) γ-butyrolactone (I) is 20 mol% or more, preferably 30 mol% or more, more preferably 40 mol% or more.

[0193] The polyester polyol obtainable by the method defined above preferably has one or more of the following properties:

[0194] - Number average molecular weight (M n ) in the range of 1000 g / mol to 20000 g / mol

[0195] - Weight average molecular weight (Mw ) in the range of 1500 g / mol to 40000 g / mol

[0196] - Molecular weight distribution determined by gel permeation chromatography (GPC) (Mw w / Mn n )

[0197] in the range of 1.3 to 5.0

[0198] - The decomposition onset temperature (T5%) determined by thermogravimetric analysis (TGA) is in the range of 220 °C to 250 °C

[0199] - The glass transition temperature (Tg) determined by differential scanning calorimetry is in the range of -70 °C to

[0200] +80 °C

[0201] - The crystallization temperature (Tc) determined by differential scanning calorimetry is in the range of -30 °C to +35 °C

[0202] - The melting temperature (Tm) determined by differential scanning calorimetry is in the range of -20 °C to 120 °C.

[0203] The methods for determining the above parameters are known in the art. For details, see the Examples section.

[0204] Preferred polyester polyols obtainable by the methods defined above are soluble in one or more solvents selected from the group consisting of: tetrahydrofuran, 2-methyltetrahydrofuran, acetone, acetonitrile, dichloromethane, dimethyl sulfoxide (DMSO), chlorobenzene, chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, dimethylformamide, ethyl acetate, γ-butyrolactone (GBL), dimethyl carbonate, diethyl carbonate, dimethoxyethane (glyme), dihydrolevoglucosenone (cyrene), and toluene.

[0205] The fields of application of the polyester polyols obtainable by the methods defined above include, for example, adhesives, such as hot melt adhesives or compostable adhesives, and encapsulation of crop protection products.

[0206] The polyester polyols obtainable by the methods defined above can be used in seed treatment compositions and methods for treating seeds. Accordingly, the present invention also relates to the use of these polymers in seed treatment compositions. Seed treatment is a method of applying active ingredients to seeds to support germination and / or growth. Seed treatment is applicable to a variety of crops. Typical examples include the application of pesticides, such as fungicides, insecticides, and plant growth regulators, and other active ingredients, such as fertilizers.

[0207] The polyester polyols obtainable by the method defined above can be used in the form of a blend with one or more other polymers, in a way that increases the content of renewable materials in the final part.

[0208] In addition to these applications, the polyester polyols obtainable by the method defined above can be used as intermediates for the preparation of other polymers or elastomers, such as for home care or cosmetic applications or for technical polymers such as polyurethanes.

[0209] In particular, the polyester polyols (which are polyols) obtainable by the method defined above can be used for the preparation of:

[0210] - Thermoplastic polyurethanes, for example for extrusion applications, preferably for extruded articles, more preferably extruded articles selected from the group consisting of cable sheaths, pipe fittings and hoses, injection molding applications, preferably for injection molded articles, more preferably for injection molded articles selected from the group consisting of rolls, gaskets, seals, rail pads and conveyor belts, preferably having improved compression set, having improved heat resistance and creep properties,

[0211] - Polyurethane foams

[0212] - Cast elastomers

[0213] - Thermoplastic copolyesters and other specialty polymers.

[0214] The polyester polyols obtainable by the method defined above can also be used as binders in coating applications, such as

[0215] - Conventional primers,

[0216] - Water-based coating layers,

[0217] - Liquid primers that are substantially free of solvents and water (so-called 100% systems),

[0218] - Solid anhydrous primers, such as powder coatings and pigmented powder coatings,

[0219] - Solvent-free, possibly pigmented powder coating dispersions, such as powder slurry primers.

[0220] Such coatings can be cured by heat treatment, radiation or dual-curing hardening methods. They are self-crosslinking or crosslinked by external crosslinking agents.

[0221] These coatings are suitable for coating substrates such as wood, paper, textiles, leather, nonwovens, plastics, glass, ceramics, mineral products, for example for constructing such as cement stone or fiber cement boards, and especially metals or coated metals.

[0222] The coating method is carried out according to methods known in the art, wherein a coating containing at least one or more polyester polyols obtainable by the methods defined above is applied to a substrate in a desired thickness, and then the volatile components are removed. If desired, the method can be repeated one or more times. The coating can be applied to the substrate according to known methods such as spraying, stopping, applying with a doctor blade, brushing, roll coating or casting. The strength of such coatings is typically 3 g / m 2 to 1000 g / m 2 and preferably 10 g / m 2 to 200 g / m 2 .

[0223] The polyester polyols obtainable by the methods defined above can also be used in the production of printing inks or printing coatings, as additives such as dispersion aids, stabilizers or binders. The preferred application is as a binder for printing inks or printing coatings.

[0224] Furthermore, the polyester polyols obtainable by the methods defined above can be used as rheology modifiers in cosmetic and dermatological preparations, especially as thickeners, especially as oil-thickening polymers suitable for cosmetic applications. Examples:

[0225] The following examples are intended to further explain and illustrate the invention, and not to limit its scope.

[0226] The conversion rates (Conv.) of the lactones given in the following table also represent their incorporation percentages in the copolymer.

[0227] Preparation of poly(GBL-co-DVL), Table 1, Example 1 :

[0228] The ring-opening copolymerization of γ-butyrolactone (GBL) and δ-valerolactone (DVL) was carried out in a 100 mL round-bottom flask dried by flame. In an argon-filled glove box, GBL (10 mL, 130 mmol, 0.66 eq) and DVL (6 mL, 65 mmol, 0.33 eq) were charged into the round-bottom flask and sealed with a septum. Potassium tert-butoxide (110.5 mg, 0.985 mmol, 0.005 eq) was charged into a separate 5 mL vial, and then the solvent 2-MeTHF (4 mL, resulting in a concentration of GBL + DVL in the reaction mixture to be formed of 50 M) and the initiator 1,4-benzenedimethanol (272.2 mg, 1.97 mmol, 0.01 eq) were charged and the vial was sealed. The round-bottom flask and the vial were taken out of the glove box. The premix of the base, the initiator, and the solvent was sonicated for 10 minutes until a homogeneous suspension was obtained. The round-bottom flask was immersed in a cooling bath at -21 °C. After equilibrating at the said temperature for 40 minutes, the reaction mixture was formed, and the ring-opening copolymerization of GBL and DVL was initiated by a one-time addition of the base / initiator / solvent premix via an airtight syringe. After 45 minutes at -21 °C, the copolymerization was quenched by adding a cold (-21 °C) solution of acetic acid in DCM (5 μL / mL) of 40 mL, and the resulting product was immediately homogenized thoroughly with a spatula until the precipitated polymer redissolved. The volatile components of the quenched reaction mixture were evaporated using a rotary evaporator (at 35 °C until 20 mbar was reached). The remaining viscous liquid was precipitated using cold methanol:water 9:1, filtered, washed with cold methanol:water 9:1, and dried under high vacuum (0.1 mbar) for 24 hours.

[0229]

[0230] Table 1 (Example 1)

[0231]

[0232] 1,4-BDM = 1,4-benzenedimethanol;

[0233] CP = composition of the resulting copolymer (mol GBL:mol DVL)

[0234] [a] M = GBL + DVL

[0235] [b] Determined by 1 1H NMR.

[0236] [c] By 11H-NMR was determined by comparing the integral value of the signal from the initiator 1,4-BDM [5.09 ppm] as A with the CH2 signal from poly-γ-butyrolactone [1.95 ppm] as B and the 2CH2 signal from poly-δ-valerolactone [1.67 ppm] as C; the protons were denoted as N A , N B and N c , which corresponded to the number of protons integrated for the initiator A, pGBL B, and pDVL C; and N OH represented the number of -OH in the initiator (N OH (diol)=2). M n was calculated by the following equation:

[0237]

[0238] Application of the polyester polyol according to Example 1 in the formation of polyurethane foam

[0239] The polyurethane foam was obtained by reacting the polyol obtained in Example 1 with 4,4'-diisocyanatodicyclohexylmethane (H12MDI, IUPAC name 1-isocyanato-4-[(4-isocyanatocyclohexyl)methyl]cyclohexane) as a diisocyanate according to the following reaction equation:

[0240]

[0241] Water was used as the blowing agent.

[0242] Table 2

[0243]

[0244] These experiments showed that the polyester polyol according to Example 1 could be used as the polyol in the synthesis of polyurethane foam.

[0245] Preparation of poly(GBL-co-DVL), Table 3, Examples 2 to 28 :

[0246] The ring-opening polymerization of γ-butyrolactone (GBL) and δ-valerolactone (DVL) was carried out in a sealed 10 mL vial. In an argon-filled glove box, both monomer GBL (8 mmol to 13 mmol, 0.4 eq to 0.66 eq) and DVL (6.5 mmol to 12 mmol, 0.33 eq to 0.6 eq) were charged into a 10 mL vial and sealed with a septum. Potassium tert-butoxide (0.0025 eq to 0.02 eq) was charged into a separate 1 mL vial, and then the solvent 2-MeTHF (400 μL, resulting in a concentration of GBL + DVL in the reaction mixture to be formed of 50 M) and the initiator 1,4-benzenedimethanol (0.01 eq) were added and the vial was sealed. The vial was taken out of the glove box. The base / initiator / solvent premix was sonicated for 5 minutes until a homogeneous suspension was obtained. The vial containing GBL and DVL was immersed in a cooling bath at the temperature shown in Table 3 (-21 to +25). After equilibration at the said temperature for 30 minutes, the reaction mixture was formed, and the ring-opening copolymerization of GBL and DVL was initiated by a one-time addition of the base / initiator / solvent premix via an airtight syringe. After the time shown in Table 3, the copolymerization was quenched by adding a solution (5 μL / mL) of 4 mL acetic acid in CDCl3 (at the temperature shown in Table 3), and the resulting product was immediately homogenized thoroughly with a spatula until the precipitated polymer redissolved. By 1 1H-NMR analysis of the quenched reaction mixture to obtain the percentage and yield of the converted monomers.

[0247] Table 3

[0248]

[0249] [a] M = GBL + DVL

[0250] [b] Determined by 1 1H NMR.

[0251] Preparation of poly(GBL-co-DVL), Table 4, Examples 29 to 33 :

[0252] The ring-opening polymerization of γ-butyrolactone (GBL) and δ-valerolactone (DVL) was carried out in a sealed 10 mL vial. In an argon-filled glove box, two monomers GBL (10 mmol, 0.5 eq), DVL (10 mmol, 0.5 eq) were loaded into a 10 mL vial and sealed with a septum. Potassium tert-butoxide (0.0025 eq to 0.01 eq) was loaded into a separate 1 mL vial, and then the solvent 2-MeTHF (400 μL, resulting in a concentration of GBL + DVL in the reaction mixture to be formed of 50 M) and the initiator shown in Table 4 (0.01 eq) were added and sealed. The vial was taken out of the glove box. The base / initiator / solvent premix was sonicated for 5 minutes until a homogeneous suspension was obtained. The vial containing GBL and DVL was immersed in a cooling bath at -10 °C. After equilibrating at this temperature for 30 minutes, the ring-opening copolymerization of GBL and DVL was initiated by a one-time addition of the base / initiator / solvent premix via an airtight syringe. After 45 minutes, the reaction mixture was formed, and the copolymerization was quenched by adding a solution of 4 mL acetic acid in CDCl3 (5 μL / mL) at -10 °C, and the product was immediately homogenized thoroughly with a spatula until the precipitated polymer redissolved. By 1 1H-NMR analysis of the quenched reaction mixture to obtain the percentage and yield of the converted monomers.

[0253] Table 4

[0254]

[0255] 1,3,5-BTM: 1,3,5-benzenetriol; Gly: glycerol; TMOE: trimethylolethane;

[0256] PETP: pentaerythritol; BnOH: benzyl alcohol.

[0257] [a] M = GBL + DVL

[0258] [b] Determined by 1 1H NMR.

[0259] Preparation of poly(GBL-co-DVL), Table 5, Example 34 :

[0260] The ring-opening copolymerization of γ-butyrolactone (GBL) and δ-valerolactone (DVL) was carried out in a flame-dried 100 mL round-bottom flask. In an argon-filled glove box, GBL (100 mmol, 0.5 eq) and DVL (100 mmol, 0.5 eq) were loaded into the round-bottom flask and sealed with a septum. Potassium tert-butoxide (2 mmol, 0.01 eq) was loaded into a separate 5 mL vial, followed by the solvent 2-MeTHF (4 mL, resulting in a concentration of GBL + DVL in the reaction mixture to be formed of 50 M) and the initiator pentaerythritol (2 mmol, 0.01 eq), and the vial was sealed. The round-bottom flask and the vial were taken out of the glove box. The base / initiator / solvent premix was sonicated for 10 minutes until a homogeneous suspension was obtained. The round-bottom flask was immersed in a cooling bath at -10 °C. After equilibration at this temperature for 40 minutes, the reaction mixture was formed, and the ring-opening copolymerization of GBL and DVL was initiated by a one-time addition of the base / initiator / solvent premix via an airtight syringe. After 45 minutes at -10 °C, the copolymerization was quenched by adding a cold (-10 °C) solution of acetic acid in DCM (5 μL / mL) (40 mL), and the resulting product was immediately homogenized thoroughly with a spatula until the precipitated polymer redissolved. The volatile components of the quenched reaction mixture were evaporated using a rotary evaporator (at 35 °C until 20 mbar was reached). The remaining viscous liquid was precipitated using cold methanol:water 9:1, filtered, washed with cold methanol:water 9:1, and dried under high vacuum (0.1 mbar) for 24 hours.

[0261] Table 5

[0262]

[0263] PETP: Pentaerythritol;

[0264] CP = Composition of the resulting copolymer (mol GBL:mol DVL).

[0265] [a] M = GBL + DVL

[0266] [b] Determined by 1 1H NMR.

[0267] Preparation of poly(GBL-co-DVL), Tables 6 and 7, Examples 35 to 38 :

[0268] The ring-opening copolymerization was carried out in a 50 mL Schlenk tube that had been pre-dried overnight in an oven at 120 °C under N2 atmosphere. After three high vacuum / N2 cycles, the dried Schlenk tube was sealed and charged with GBL (0.33 eq to 0.91 eq) and DVL (0.09 eq to 0.67 eq). The water scavenger (desiccant) Incozol 2 (0.002 eq) was added to the GBL / DVL mixture via a gastight syringe and stirred for 1 hour at room temperature under N2 atmosphere. Then the sealed Schlenk tube was immersed in a cooling bath at -10 °C for 30 minutes for temperature equilibration. A separate vial was dried in an oven at 120 °C and the air was evacuated by three high vacuum / N2 cycles before sealing. Then it was charged via a gastight syringe with anhydrous 2-MeTHF (resulting in a concentration of GBL + DVL in the reaction mixture to be formed of 100 M), an anhydrous solution of the base potassium tert-butoxide in 2-MeTHF (2 M, 25 wt%, 0.005), and the initiator benzyl alcohol (0.01 eq). The base / initiator / solvent mixture was sonicated for 10 minutes until a homogeneous suspension was obtained. The reaction mixture was formed and the ring-opening copolymerization of GBL and DVL was initiated by a one-time addition of the base / initiator / solvent premix via a gastight syringe.

[0269] After 4 hours, the ring-opening copolymerization was quenched by adding a cold (-10 °C) solution of acetic acid in DCM (5 μL / mL) of 40 mL, and then the formed white solid polymer was gently crushed with a spatula. Then the quenched mixture was warmed to room temperature. Then it was washed with distilled water (3 x 50 mL) in a separatory funnel and then the volatiles were evaporated on a rotary evaporator (40 °C until 20 mbar was reached). The remaining viscous liquid was precipitated using cold methanol (0 °C). In the case where the resulting precipitate was a viscous liquid, it was washed several times with methanol by continuous centrifugation / redispersion (4000 rpm, 2 minutes, 10 °C) and separated by centrifugation, and then dried under reduced pressure. In the case where the resulting precipitate was a solid, it was filtered, washed with cold methanol, and dried in vacuo on a rotary evaporator to obtain the corresponding copolymer.

[0270] Table 6

[0271]

[0272] CP = Composition of the resulting copolymer (mol GBL:mol DVL)

[0273] [a] Determined by 1H-NMR

[0274] The copolymers obtained in Examples 35 to 38 had the following properties:

[0275] Table 7

[0276]

[0277] Determination of M from GPC in THF n 、M w and (M w / M n ).

[0278] The glass transition temperature (T g ), crystallization temperature (T c ), and melting temperature (T m ) are measured by DSC

[0279] Preparation of poly(GBL-co-DVL), Tables 8 and 9, Examples 39 to 44 :

[0280] Ring-opening copolymerization is carried out in a 50 mL Schlenk tube that has been pre-dried overnight at 120 °C in an oven under N2 atmosphere. After three high vacuum / N2 cycles, the dried Schlenk tube is sealed and charged with GBL (0.67 eq to 0.83 eq) and DVL (0.17 eq to 0.33 eq). The water scavenger (drying agent) Incozol 2 (0.002 eq) is added to the GBL / DVL mixture via a gastight syringe and stirred for 1 hour at room temperature under N2 atmosphere. Then the sealed Schlenk tube is immersed in a cooling bath at -10 °C for 30 minutes for temperature equilibration.

[0281] Separate vials are dried in an oven at 120 °C and the air is evacuated by three high vacuum / N2 cycles before sealing. Then they are charged via a gastight syringe with anhydrous 2-MeTHF (resulting in a concentration of GBL + DVL in the reaction mixture to be formed of 100 M), an anhydrous solution of the base potassium tert-butoxide in 2-MeTHF (2 M, 25 wt%, 0.01 eq to 0.02 eq), and the initiator shown in Table 8 (0.01 eq). The base / initiator / solvent premix is sonicated for 10 minutes until a homogeneous suspension is obtained. The reaction mixture is formed and the ring-opening copolymerization of GBL and DVL is initiated by a one-time addition of the base / initiator / solvent premix via a gastight syringe.

[0282] After 4 h, the copolymerization was quenched by adding a cold (−10 °C) solution of 40 mL acetic acid in DCM (5 μL / mL), and the resulting white solid polymer was then gently crushed with a spatula. The quenched mixture was then warmed to room temperature. It was then washed in a separatory funnel with distilled water (3×50 mL) and the volatiles were then evaporated on a rotary evaporator (40 °C until 20 mbar was reached). The remaining viscous liquid was precipitated using cold methanol (0 °C). In the case where the resulting precipitate was a viscous liquid, it was washed several times with methanol by successive centrifugation / redispersion (4000 rpm, 2 min, 10 °C), separated by centrifugation, and then dried under reduced pressure. In the case where the resulting precipitate was a solid, it was filtered, washed with cold methanol, and dried in vacuo on a rotary evaporator to obtain the corresponding copolymer.

[0283] Table 8

[0284]

[0285]

[0286] CP = composition of the resulting copolymer (mol GBL:mol DVL)

[0287] 1,5P-PDO: 1,5-pentanediol; PEG400: polyethylene glycol 400; 1,4-BDM: 1,4-benzenedimethanol; EG: ethylene glycol [a] M = GBL + DVL

[0288] [b] Determined by 1H-NMR

[0289] The copolymers obtained in Examples 42 to 44 had the following properties:

[0290] Table 9

[0291]

[0292] M was determined from GPC in THF n 、M w and (M w / M n ).

[0293] The glass transition temperature (T g ), crystallization temperature (T c ), and melting temperature (T m ) were measured by DSC

[0294] Preparation of poly(GBL-co-ECL), Table 10, Example 45 :

[0295] The ring-opening polymerization of γ-butyrolactone (GBL) and ε-caprolactone (ECL) was carried out in a sealed 10 mL vial. In an argon-filled glove box, the two monomers GBL (10 mmol, 0.5 eq), ECL (10 mmol, 0.5 eq) were loaded into a 10 mL vial and sealed with a septum. Potassium tert-butoxide (0.005 eq) was loaded into a separate 1 mL vial, and then the solvent 2-MeTHF (400 μL, resulting in a concentration of GBL + ECL in the reaction mixture to be formed of 50 M) and the initiator 1,4-benzenedimethanol (0.01 eq) were added and the vial was sealed. The vial was taken out of the glove box. The base / initiator / solvent premix was sonicated for 5 minutes until a homogeneous suspension was obtained. The vial containing GBL and ECL was immersed in a cooling bath at -10 °C. After equilibration for 30 minutes, the reaction mixture was formed and the ring-opening copolymerization of GBL and ECL was initiated by a one-time addition of the base / initiator / solvent premix via an airtight syringe. After 45 minutes, the copolymerization was quenched by adding a solution (5 μL / mL) of 4 mL acetic acid in CDCl3 (at the temperature shown in Table 10), and the resulting product was immediately homogenized thoroughly with a spatula until the precipitated polymer redissolved. By 1 1H-NMR analysis of the quenched reaction mixture was performed to obtain the percentage and yield of the converted monomers.

[0296]

[0297] Table 10 (Example 45)

[0298]

[0299] [a] M = GBL + ECL

[0300] [b] Determined by 1 1H NMR.

[0301] Preparation of poly(GBL-co-ECL), Table 11, Examples 46 to 47 :

[0302] The ring-opening copolymerization of γ-butyrolactone (GBL) and ε-caprolactone (ECL) was carried out in a 100 mL round-bottom flask dried by flame. In an argon-filled glove box, GBL (100 mmol, 0.5 eq), ECL (100 mmol, 0.5 eq) were charged into the round-bottom flask and sealed with a septum. Potassium tert-butoxide (1 mmol, 0.005 eq) was charged into a separate 5 mL vial, and then the solvent 2-MeTHF (4 mL, resulting in a concentration of GBL + ECL in the reaction mixture to be formed of 50 M) and the initiator shown in Table 11 (2 mmol, 0.01 eq) were charged and the vial was sealed. The round-bottom flask and the vial were taken out of the glove box. The base / initiator / solvent premix was sonicated for 10 minutes until a homogeneous suspension was obtained. The round-bottom flask was immersed in a cooling bath at -10 °C. After equilibration at this temperature for 40 minutes, the reaction mixture was formed, and the ring-opening copolymerization of GBL and ECL was initiated by a one-time addition of the base / initiator / solvent premix via an airtight syringe. After 45 minutes at -10 °C, the copolymerization was quenched by adding a cold (-10 °C) solution of acetic acid in DCM (5 μL / mL) of 40 mL, and the resulting product was immediately homogenized thoroughly with a spatula until the precipitated polymer redissolved. The volatile components of the quenched reaction mixture were evaporated using a rotary evaporator (at 35 °C until 20 mbar was reached). The remaining viscous liquid was precipitated using cold methanol:water 9:1, filtered, washed with cold methanol:water 9:1, and dried under high vacuum (0.1 mbar) for 24 hours.

[0303] Table 11

[0304]

[0305] 1,4-BDO = 1,4-butanediol;

[0306] CP = Composition of the resulting copolymer (mol GBL:mol ECL)

[0307] [a] M = GBL + ECL

[0308] [b] Determined by 1 H NMR.

[0309] [c] By 1 H-NMR of the pure copolymer, determined by comparing the integral value of the signal from the initiator 1,4-BDM [5.09 ppm] as A with the CH2 signal from poly-γ-butyrolactone [1.95 ppm] as B and the 2CH2 signal from poly-ε-caprolactone [1.66 ppm] as C; the protons are denoted as N A 、N B and N c, which correspond to the number of protons integrated for initiator A, pGBL B, and pECL C; and N OH represents the number of -OH in the initiator (N OH (diol)=2). M n is calculated by the following equation:

[0310]

[0311] Preparation of poly(GBL-co-ECL), Tables 12 and 13, Examples 48 to 50 :

[0312] Ring-opening copolymerization was carried out in a 50 mL Schlenk tube that had been pre-dried overnight in an oven at 120 °C under N2 atmosphere. After 3 high vacuum / N2 cycles, the dried Schlenk tube was sealed and charged with GBL (0.67 eq to 0.83 eq) and ECL (0.17 eq to 0.33 eq). The water scavenger Incozol 2 (0.002 eq) was added to the GBL / ECL mixture via a gastight syringe and stirred for 1 hour at room temperature under N2 atmosphere. Then the sealed Schlenk tube was immersed in a cooling bath at -10 °C for 30 minutes for temperature equilibration.

[0313] Separate vials were dried in an oven at 120 °C and the air was evacuated by 3 high vacuum / N2 cycles before sealing. Then they were charged via a gastight syringe with anhydrous 2-MeTHF (resulting in a concentration of GBL + ECL in the reaction mixture to be formed of 100 M), an anhydrous solution of the base potassium tert-butoxide in 2-MeTHF (2 M, 25 wt%, 0.005 eq to 0.02 eq), and the initiator shown in Table 12 (0.01 eq). The base / initiator / solvent premix was sonicated for 10 minutes until a homogeneous suspension was obtained. The reaction mixture was formed and the ring-opening copolymerization of GBL and ECL was initiated by a one-time addition of the base / initiator / solvent premix via a gastight syringe.

[0314] After 4 hours, the copolymerization was quenched by adding a cold (-10 °C) solution of 40 mL acetic acid in DCM (5 μL / mL), and then the formed white solid polymer was gently crushed with a spatula. Then the quenched mixture was warmed to room temperature. Then it was washed with distilled water (3 x 50 mL) in a separatory funnel and then the volatiles were evaporated on a rotary evaporator (40 °C until 20 mbar was reached). The remaining viscous liquid was precipitated using cold methanol (0 °C). In the case where the resulting precipitate was a viscous liquid, it was washed several times with methanol by continuous centrifugation / redispersion (4000 rpm, 2 minutes, 10 °C) and then centrifuged and dried under reduced pressure. In the case where the resulting precipitate was a solid, it was filtered, washed with cold methanol, and dried in vacuo on a rotary evaporator to obtain the corresponding copolymer.

[0315] Table 12

[0316]

[0317] CP = Composition of the resulting copolymer (mol GBL:mol ECL)

[0318] [a] M = GBL + ECL

[0319] [b] Determined by 1 1H-NMR

[0320] The copolymers obtained in Examples 48 to 50 have the following properties:

[0321] Table 13

[0322]

[0323] M was determined from GPC in THF n 、M w and (M w / M n ).

[0324] The glass transition temperature (T g ), crystallization temperature (T c ), and melting temperature (T m ) were measured by DSC.

[0325] Preparation of poly(GBL-co-EDL), Table 14, Example 51 :

[0326] The ring-opening copolymerization of γ-butyrolactone (GBL) and ε-decalactone (EDL) was carried out in a 100 mL round-bottom flask dried by flame. In an argon-filled glove box, GBL (100 mmol, 0.5 eq) and EDL (100 mmol, 0.5 eq) were charged into the round-bottom flask and sealed with a septum. Potassium tert-butoxide (1 mmol, 0.005 eq) was charged into a separate 5 mL vial, and then the solvent 2-MeTHF (4 mL, resulting in a concentration of GBL + EDL in the reaction mixture to be formed of 50 M) and the initiator 1,4-benzenedimethanol (2 mmol, 0.01 eq) were added and sealed. The round-bottom flask and the vial were taken out of the glove box. The base / initiator / solvent premix was sonicated for 10 minutes until a homogeneous suspension was obtained. The round-bottom flask was immersed in a cooling bath at -10 °C. After equilibration at this temperature for 40 minutes, the reaction mixture was formed, and the ring-opening copolymerization of GBL and EDL was initiated by a one-time addition of the base / initiator / solvent premix via an airtight syringe. After 45 minutes at -10 °C, the copolymerization was quenched by adding a cold (-10 °C) solution of 40 mL acetic acid in DCM (5 μL / mL), and the product was immediately homogenized thoroughly with a spatula until the precipitated polymer redissolved. The volatile components of the quenched reaction mixture were evaporated using a rotary evaporator (at 35 °C until a pressure of 20 mbar was reached). The remaining viscous liquid was precipitated using cold methanol:water 9:1, filtered, washed with cold methanol:water 9:1, and dried under high vacuum (0.1 mbar) for 24 hours.

[0327]

[0328] Table 14 (Example 51)

[0329]

[0330] CP = composition of the resulting polymer (mol GBL:mol EDL)

[0331] [a] M = GBL + EDL

[0332] [b] Determined by 1 1H NMR.

[0333] [c] By 1H-NMR of the pure copolymer, determined by comparing the integral value of the signal from the initiator 1,4-BDM [5.09 ppm] as A with the CH2 signal from poly-γ-butyrolactone [2.37 ppm] as B and the 2CH2 signal from poly-ε-decalactone [2.30 ppm] as C; the protons are denoted as N 1 、N A 、N B and N c, which correspond to the number of protons integrated for initiator A, pGBL B, and pEDL C; and N OH represents the number of -OH in the initiator (N OH (diol)=2). M n is calculated by the following equation:

[0334]

Claims

1. A method for synthesizing a polyester polyol, The method comprises a ring-opening copolymerization step of lactones, wherein the lactones are (i) γ-butyrolactone (I) and (ii) one or more lactones of formula (II) wherein m is an integer selected from 1 to 12, n is an integer selected from 1 to 2, Each R a 、 each R b 、 each R c and each R d is independently selected from the group consisting of H and C1-C 10 -alkyl. p is an integer selected from 0 and 1, with the proviso that m is not 3 when p = 0, wherein the ring-opening copolymerization is carried out in the presence of: (iii) one or more bases containing alkali metal cations, selected from the group consisting of lithium alcoholates, sodium alcoholates and potassium alcoholates and (iv) one or more alcohols at a temperature of -25 °C to +50 °C, wherein the total amount of lactones (i) and (ii) and the total amount of the base (iii) containing alkali metal cations ((i)+(ii)):(iii) is 50:1 or higher, wherein a reaction mixture is formed, and the ring-opening copolymerization is initiated by adding a first premix containing (iii) one or more bases containing alkali metal cations and (iv) one or more alcohols and one or more solvents to a second premix containing (i) γ-butyrolactone (I) and (ii) one or more lactones of formula (II).

2. The method according to claim 1, wherein the one or more lactones (ii) are selected from the group consisting of ε-caprolactone, ε-decalactone, δ-valerolactone, β-propiolactone, lactide and glycolide.

3. The method according to claim 1, wherein the base (iii) containing alkali metal cations or one or more or all of the bases (iii) containing alkali metal cations are selected from the group consisting of lithium methoxide, sodium methoxide, potassium methoxide, lithium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide, lithium benzylate, sodium benzylate, potassium benzylate, dipotassium phthalate and disodium phthalate.

4. The method according to any one of the preceding claims, wherein the alcohol (iv) or one or more or all of the alcohols (iv) are selected from the group consisting of ethylene glycol, diethylene glycol, polyethylene glycol, 1,2-propanediol, dipropylene glycol, polypropylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, polybutylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, mannitol, sorbitol, xylitol, threitol, and benzyl alcohol according to formula (III) wherein n is an integer from 1 to 4, preferably 2 or 3, m is an integer from 0 to 3, o is 0 or 1 m + n + o ≤ 6; R 1 and R 2 are each independently selected from the group consisting of: F, Cl, Br, OH, CN, NH2, NO2, C1-C 10 -alkyl C3-C 10 -cycloalkyl, C3-C containing at least one heteroatom selected from N, O, and S 10 -heterocyclic group, C5-C 14 -aryl, C5-C containing at least one heteroatom selected from N, O, and S 10 -heteroaryl, wherein the C1-C 10 -alkyl, C3-C 10 -cycloalkyl, C3-C 10 -heterocyclic group, C5-C 14 -aryl or C5-C 10 -heteroaryl optionally has one or more additional substituents selected from the group consisting of F, Cl, Br, OH, CN, NH2, and C1-C 10 -alkyl, wherein the benzyl alcohol according to formula (III) is preferably selected from the group consisting of benzyl alcohol, 1,4-benzenedimethanol, 2,6-dichlorobenzyl alcohol, 4-methylbenzyl alcohol and 2,4,6-trimethylbenzyl alcohol.

5. The method according to any one of the preceding claims, wherein the ring-opening copolymerization is carried out in the temperature range of -25 °C to +30 °C.

6. The method according to any one of the preceding claims, wherein the total amount of lactones (i) and (ii) The molar ratio to the total amount of base (iii) containing an alkali metal cation is in the range of 100:1 to 800:1, preferably 100:1 to 400:

1.

7. The method according to any one of the preceding claims, wherein the total amount of base (iii) containing an alkali metal cation and the molar ratio to the total amount of OH groups (v) in the alcohol (iv) (iii):(v) is in the range of 1:6 to 12:1, preferably 1:2 to 8:

1.

8. The method according to any one of the preceding claims, wherein (i) γ-butyrolactone (I) and the molar ratio to the total amount of the lactone (ii) is in the range of 5:95 to 95:5, and preferably 85:15 to 15:

85.

9. The method according to any one of the preceding claims, wherein the ring-opening copolymerization is carried out in a solvent or one or more solvents, wherein the solvent or one or more or all of the solvents are selected from the group consisting of aliphatic hydrocarbons, aromatic hydrocarbons, ethers, esters, N,N-dialkylamides, dialkyl sulfoxides, and nitriles, wherein preferably, the solvent or one or more or all of the solvents are selected from the group consisting of dichloromethane, toluene, 2-methyl-tetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, dimethylformamide, dimethyl sulfoxide, and acetonitrile, and mixtures thereof.

10. The method according to any one of the preceding claims, the method further comprising drying the lactones (i) and (ii) by adding a drying agent before the ring-opening copolymerization, and optionally separating the dried lactones (i) and (ii) from the drying agent, wherein the drying agent is preferably selected from the group consisting of CaH2, tosyl isocyanate, and oxazolidine wherein the oxazolidine is preferably selected from the group consisting of oxazolidine of formula (IV), oxazolidine of formula (V), and oxazolidine of formula (VI) wherein R 4 , R 5 , R 6 and R 7 are each independently selected from the group consisting of H- and C1-C 10 -alkyl and R 8 is a bridging unit comprising from 1 to 20 -CH2- units and optionally one or more moieties selected from the group consisting of -NH-, -O-, -CO-, -COO- and -NH-COO-.

11. The method according to any one of the preceding claims, wherein the lactones (i) and (ii) have a water content of 0.1 wt% or less, preferably 0.05 wt% or less, and most preferably 0.01 wt% or less, as measured by the Karl Fischer titration method.

12. The method according to any one of the preceding claims, the method further comprising quenching the ring-opening copolymerization by adding a quenching solution comprising one or more acids and one or more solvents, wherein preferably - the one or more acids are selected from the group consisting of hydrohalic acids, oxoacids of Cl, S, N, P, and B, alkyl sulfonic acids, aryl sulfonic acids, mono-, di-, and trifunctional carboxylic acids, and / or - the one or more solvents are selected from the group consisting of halogenated aliphatic and aromatic hydrocarbons, ketones, ethers, dialkyl carbonates, dialkyl sulfoxides, and nitriles and / or - the quenching solution has a temperature in the range of -25°C to +50°C.

13. The method for synthesizing a polyester polyol according to any one of the preceding claims, the method comprising the steps of: (A) Ring-opening copolymerization of the following substances: (i) γ-butyrolactone (I) and (ii) one or both of ε-caprolactone, ε-decalactone and δ-valerolactone in the presence of the following substances (iii) one or more bases containing an alkali metal cation, selected from the group consisting of lithium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide, dipotassium phthalyl alcoholate and disodium phthalyl alcoholate, and (iv) one or more alcohols, selected from the group consisting of 1,4-benzenedimethanol, 1,3,5-benzenetriol, glycerol, trimethylolethane, pentaerythritol, benzyl alcohol, ethylene glycol, polyethylene glycol and 1,5-pentanediol the temperature is from -25 °C to +30 °C, wherein the total molar ratio of γ-butyrolactone (I), ε-caprolactone and δ-valerolactone to the base (iii) containing an alkali metal cation ((i)+(ii)):(iii) is from 100:1 to 800:1 and the total molar ratio of the base (iii) containing an alkali metal cation to the total amount of OH groups (v) in the alcohol (iv) (iii):(v) is in the range of 1:2 to 8:1, and wherein the molar ratio of γ-butyrolactone (i) to the total amount of ε-caprolactone and δ-valerolactone (ii) is in the range of 85:15 to 15:85, and wherein the ring-opening copolymerization is carried out in a solvent selected from the group consisting of dichloromethane, toluene, 2-methyl-tetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethyl acetate, dimethylformamide, dimethylformamide, dimethyl sulfoxide and acetonitrile and mixtures thereof, and wherein the water content of γ-butyrolactone (I), ε-caprolactone and δ-valerolactone is 0.01 wt% or less, as measured by the Karl Fischer titration method, and (B) quenching the ring-opening copolymerization by adding a quenching solution containing an acid and a solvent, wherein - the acid is selected from the group consisting of hydrochloric acid, perchloric acid, nitric acid, sulfuric acid, phosphoric acid, boric acid, formic acid, acetic acid, acrylic acid, oxalic acid, propionic acid, lactic acid, citric acid, methanesulfonic acid and toluenesulfonic acid, - the solvent is selected from the group consisting of dichloromethane, chloroform, deuterated chloroform, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, 1,4-dioxane, anisole, dimethyl ether, acetone, acetophenone, dihydrolevoglucosenone, dimethyl carbonate, diethyl carbonate, dimethyl sulfoxide, acetonitrile and mixtures thereof, - the quenching solution has a temperature in the range of -25 °C to +50 °C.

14. The method according to any one of the preceding claims, wherein after initiating the ring-opening copolymerization, - one or more additional portions of a premix containing (iii) the one or more bases containing an alkali metal cation and (iv) the one or more alcohols and one or more solvents as in the first premix and / or - one or more additional portions of a premix containing (i) γ-butyrolactone (I) and (ii) the one or more lactones of formula (II) as defined above and optionally one or more solvents as in the second premix are added.

15. A kit comprising the following items - one or more bases containing an alkali metal cation (iii) and -one or more alcohols (iv) Use in the process according to any one of claims 1 to 14.

16. A polyester polyol obtainable by a process according to any one of claims 1 to 14.

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