Synthesis of di(hydroxymethyl)tetrahydrofuran and its application in polyesters and polyurethanes.

Abstract

The present invention relates to the synthesis of di(hydroxymethyl)tetrahydrofuran (DHMTHF) and the preparation of trans-enriched mixtures of DHMTHF. The present invention further relates to polyester polyols obtained by reacting cis / trans DHMTHF mixtures with dicarboxylic acids. The present invention further relates to compositions containing polyurethanes and polyester polyols containing DHMTHF, particularly such polyurethane-containing (adhesive) compositions.

Description

[Technical field]

[0001] The present invention relates to the synthesis of di(hydroxymethyl)tetrahydrofuran (DHMTHF) and the preparation of trans-enriched mixtures of DHMTHF. The present invention further refers to polyester polyols obtained by reacting cis / trans DHMTHF mixtures with dicarboxylic acids. The present invention further relates to compositions containing polyurethanes and polyester polyols containing DHMTHF, in particular such polyurethane-containing (adhesive) compositions. [Background technology]

[0002] Due to the diverse requirements of the wide range of applications that adhesives have to fulfill, there is a constant demand for new polymers in the adhesive technology field. In this regard, great progress has been made in recent decades through the development of new synthetic polymers. However, the latter are mainly derived from fossil sources and are consequently characterized by low sustainability. On the contrary, the use of renewable raw materials allows to reduce the carbon footprint of the final product, while at the same time giving access to new chemical structures that are not available from traditional petroleum-based sources.

[0003] Among the various types of adhesives, hot melts are characterized by a growth rate 1.5 to 2 times higher than those registered in other types. Typical components of reactive polyurethane hot melt adhesives are industrially produced by the reaction of polyisocyanates with polyether polyols or polyester polyols. It is noteworthy that bio-based polyester polyols, polyether polyols, and polyurethanes have increasingly been reported in both industry and academia. However, there are few studies on the influence of different stereoisomers of bio-based polyols on the properties of the resulting polymers and materials.

[0004] The use of different diastereomers of the biobased diol di(hydroxymethyl)tetrahydrofuran (DHMTHF) for the synthesis of polyesters has been reported in the art (Moore & Kelly, Macromolecules 1978, 11, 568-573). However, in the reported method, the authors obtained these polymers in the presence of excess triethylamine, using chloroform, a non-innocent solvent, carboxylic acid chlorides as comonomers. Moreover, the polymerization process took two weeks and the product consisted only of low molecular weight substances. Finally, the cis and trans DHMTHF isomers were synthesized by a multi-step process that included reduction with sodium amalgam, stoichiometric reactions with toxic and explosive diazomethane and lithium aluminum hydride, respectively.

[0005] Recently, DHMTHF was used to synthesize copolyesters of 1,4-cyclohexanedimethanol and furandicarboxylic acid (FDCA), revealing that increasing the content of cis-DHMTHF in the synthesized polymers could result in increased stiffness, storage modulus, and hydrophobicity of the latter (Jin et al., ACS Sustainable Chem. Eng. 2021, 9, 39, 13287-13302). It is noteworthy that even if the authors used only the cis isomer of DHMTHF, the corresponding trans isomer is speculated to have resulted in different properties due to changes in the spatial shape and arrangement of the resulting polymer. For FDCA polyesters, cis / trans-DHMTHF mixtures have been disclosed (WO 2017 / 091435; WO 2017 / 091412), but no economically viable method is currently known for synthesizing pure or trans-enriched DHMTHF. In fact, these disclosures only yielded DHMTHF with moderate selectivity of 58% and a maximum trans content of 29% from the hydrogenation of levoglucosenone (LGO) in the presence of supported palladium catalysts at 150 °C (Figure 1). Furthermore, a series of homogeneous ruthenium precursors in combination with NHC or diphosphorus-containing ligands were reported for the hydrogenation of 5-HMF to DHMTHF, which was obtained in a very poor yield of 17% but with a maximum trans content of 44% (Cadu et al. Green Chem. 2018, 20, 3386-3393). In this latter case, the authors used high catalyst loadings, and both reported procedures yielded product mixtures that made the isolation of DHMTHF problematic. Moreover, both LGO and 5-HMF were employed as high-purity crystalline starting materials, which would undoubtedly make DHMTHF too expensive as a polymer building block. The higher cost of the latter is a result of the purification steps required to remove impurities such as formic acid, levulinic acid and oligomers.

[0006] Here, we found that low-purity aqueous 5-HMF solution, obtained as a by-product of the hydrothermal carbonization process of sugars or lignocellulosic materials (Thoma et al. ChemSusChem 2020, 13, 3544-3564), can be utilized to synthesize DHMTHF and its corresponding polymers.

[0007] Current research has shown that the introduction of linear molecules containing ether bonds has a favorable effect on the polarity, hydrophilicity, degradability, and biocompatibility of polyesters, but they usually have a significant negative effect on strength and thermal properties. We hypothesized that replacing linear monomers containing ether bonds with cyclic monomers from the molecular structure perspective may be a means to overcome these problems. To date, several cyclic diols, such as 1,4-cyclohexanedimethanol (CHDM), 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO), and isosorbide (IS), have been reported to improve the properties of synthesized polyesters, but of these cyclic diols, only isosorbide is currently available from biomass feedstocks.

[0008] DHMTHF may be a promising new bio-based monomer that allows the synthesis of new materials with attractive properties, but to date, no scalable method is known to synthesize trans-enriched DHMTHF that reliably results in differences in the properties of the resulting polymers compared to the corresponding cis-DHMTHF analogues. Furthermore, the use of DHMTHF as the main diol in polyester polyols is not known to be suitable for polyurethane adhesives that simultaneously exhibit good tensile strength and high elongation. It would be desirable to be able to use these in other systems to benefit from the advantageous properties of polyester polyols derived from DHMTHF. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Application Publication No. 2017 / 091435 [Patent Document 2] International Application Publication No. 2017 / 091412 [Non-patent literature]

[0010] [Non-Patent Document 1] Moore & Kelly, Macromolecules 1978, 11, 568-573 [Non-Patent Document 2] Jin et al. ACS Sustainable Chem. Eng. 2021, 9, 39, 13287-13302 [Non-Patent Document 3] Cadu et al. Green Chem. 2018, 20, 3386-3393 [Non-Patent Document 4] Thoma et al. ChemSusChem 2020, 13, 3544-3564 Summary of the Invention

[0011] It is therefore an object of the present invention to provide polyester polyols comprising bio-based monomers that can be used in liquid systems for ambient temperature applications, such as polyurethane adhesives, in particular two-part polyurethane adhesives, the latter of which further need to meet the requirements of industrial applications, for example for joining materials with different thermal expansion coefficients.

[0012] Surprisingly, it has been found that the above mentioned objectives are achieved by the development of a new synthetic route to obtain DHMTHF with a high trans isomer content and further by its use for the synthesis of polyester polyols obtained from reaction mixtures comprising defined cis / trans DHMTHF mixtures and dicarboxylic acids preferentially obtained from biomass. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the prior art and the present invention. [Diagram 2]FIG. 2 is a schematic diagram of a hydrogen borrowing reaction in one embodiment. [Diagram 3] FIG. 3 is an example of a ruthenium catalyst that may be selected in various embodiments. [Figure 4] FIG. 4 shows the results of differential scanning calorimetry (DSC) of each polymer. [Diagram 5] FIG. 5 shows the results of thermogravimetric analysis of each poly(urethane-urea) polymer. [Figure 6] FIG. 6 shows the results of differential scanning calorimetry (DSC) of each PU film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] In a first aspect, the present invention thus relates to a process for producing di(hydroxymethyl)tetrahydrofuran (DHMTHF) from 5-hydroxymethylfurfural (5-HMF), comprising hydrogenating a solution of 5-HMF, such as an aqueous solution, in the presence of a heterogeneous catalyst, wherein the 5-HMF is crude 5-HMF.

[0015] "Aqueous solution", as used herein, refers to a solution in which water is the predominant solvent, i.e., a solution in which water constitutes at least 50% by weight or volume, such as at least 70, at least 80 or at least 90% by weight or volume, of the total solvent used.

[0016] In various embodiments, the heterogeneous catalyst is a syn-surface hydrogenation catalyst, preferably selected from Raney nickel, Ru / C (ruthenium on carbon), Pd / Al (palladium on alumina), Pd / C (palladium on carbon), more preferably Raney nickel. Further suitable catalysts include, but are not limited to, Pd / Si (palladium on silica), Ru / Al (ruthenium on alumina), Raney cobalt, and Raney copper.

[0017] In various embodiments, the hydrogenation reaction is carried out in the presence of ethanol in an amount of at least 1.3 mL of ethanol per mmol of 5-HMF, preferably in an amount of 1.4 to 3.0 mL of ethanol per mmol of 5-HMF.

[0018] In various embodiments, the hydrogenation reaction is carried out at a pressure of at least 10 bar or at least 20 bar, preferably at least 50 bar, more preferably 80-100 bar H 2 and / or at a temperature of 80-120° C., preferably about 100° C.; and / or for a reaction time of at least 5 hours, preferably 5-60 hours.

[0019] In these methods, the 5-HMF used is crude 5-HMF. Such crude 5-HMF can be, for example, a by-stream product in a hydrothermal carbonization process of sugar or lignocellulosic materials. In general, the crude 5-HMF can have a purity of less than 95%, e.g., less than 94%, less than 93%, less than 92%, less than 91%, less than 90%, less than 89%, less than 88%, less than 87% (all by weight) based on the total organic content. In various embodiments, the 5-HMF purity ranges from 70-95%, e.g., 75-90%, e.g., 80-90%. "Purity" as used in this context relates to the purity of the solid or organic fraction, i.e., free of any potentially present aqueous phase / water. The crude 5-HMF can be provided in the form of an aqueous solution, e.g., containing 15-25% by weight of 5-HMF solids. The impurities contained in the crude 5-HMF may optionally include those selected from formic acid, levulinic acid, oligomers of 5-HMF, and combinations thereof in an amount of at least 1 wt%, at least 2 wt%, at least 3 wt%, at least 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 wt% of the total weight of organic matter in the crude 5-HMF.

[0020] In various embodiments, these methods provide cis-enriched DHMTHF, i.e., the content of the cis diastereomer is higher than the content of the trans diastereomer, preferably the molar ratio is greater than 1, more preferably greater than 1.5, greater than 2, greater than 3, greater than 4, greater than 5, greater than 6, greater than 7, greater than 8, greater than 9, greater than 10, greater than 11, greater than 12, greater than 13, greater than 14, greater than 15, greater than 16, greater than 17, greater than 18, greater than 19, or greater than 20. In various embodiments, the cis to trans ratio is at least 80:20, preferably at least 85:15, more preferably at least 90:10, e.g., about 92:8.

[0021] In another aspect, the present invention relates to a method for concentrating a mixture of cis- / trans-DHMTHF to trans-DHMTHF, the method comprising reacting the mixture of cis- / trans-DHMTHF at elevated temperature in the presence of a suitable metal catalyst for metal-catalyzed hydrogen borrowing reaction, a base and a suitable solvent.

[0022] "Elevated temperature" as used herein relates to temperatures above ambient, ie temperatures of 30°C or greater, such as at least 40, at least 50, at least 60 or at least 70°C.

[0023] In such processes, the mixture of cis- / trans-DHMTHF used as starting material has a cis to trans ratio of at least 1, preferably at least 2, more preferably 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20, or from 1 to 20, from 2 to 20, from 3 to 20. In various embodiments, it may be DHMTHF obtained according to the hydrogenation processes described herein.

[0024] Trans-enriched DHMTHF obtained according to the method described herein refers to a mixture of cis / trans DHMTHF in which the content of the trans diastereomer is at least 30 mol%, preferably at least 35 mol% or at least 40 mol% based on the total amount of cis and trans diastereomers. These are considered to be trans-enriched with respect to the cis / trans mixture used as starting material (which usually contains an excess of cis diastereomer). Such enrichment typically means that the amount of trans diastereomer relative to the starting material is increased by at least 5 mol%, preferably at least 10 mol%, more preferably 20 mol% or more. For example, using a cis / trans DHMTHF mixture having a cis / trans ratio of 90:10, the enrichment method described herein can provide a trans-enriched mixture having a trans content of at least 30 mol%, i.e., a cis / trans ratio of 70:30 or less, e.g., 60:40.

[0025] In various embodiments, the catalyst for the metal-catalyzed hydrogen-borrowing reaction is a metal complex catalyst, such as a ruthenium complex catalyst, a cobalt complex catalyst, a manganese complex catalyst, or an iron complex catalyst.

[0026] In various embodiments, it is a ruthenium complex catalyst, preferably a ruthenium complex having a tridentate pincer ligand. Such catalysts can be selected from, but are not limited to: Carbonylchlorohydrido[bis(2-di-cyclohexylphosphinoethyl)amine]ruthenium(II); Carbonylchlorohydrido[bis(2-di-i-propylphosphinoethyl)amine]ruthenium(II), Carbonylchlorohydride[bis(2-di-t-butylphosphinoethyl)amine]ruthenium(II), Dichloro[rel-N(S)]-N-[2-[(R)-phenylthio-κS]ethyl]-4-morpholineethanamine-κN-N,κN](triphenylphosphine)ruthenium(II), Dichloro[rel-[N(R)]-N-[2-[(R)-(phenylmethyl)thio-κS]ethyl]-4-morpholineethanamine-κN-N,κN](triphenylphosphine)ruthenium(II), Dichloro[N-[2-(phenylthio-κS)ethyl]-[4-morpholineethanamine-κN-N,κN](tricyclohexylphosphine)ruthenium(II), Dichloro[rel-[N(S)]-N-[2-[(R)-phenylthio-κS]ethyl]-[1-pyrrolidineethanamine-κN-N,κN](triphenylphosphine)ruthenium(II), Dichloro[N1,N1-dimethyl-N2-[2-(phenylthio-κS)ethyl]-1,2-ethanediamine-κN1,κN2](tricyclohexylphosphine)ruthenium(II), Dichloro[N-[2-(diphenylphosphino-κP)ethyl]-2-(methylthio-κS)ethanamine-κN](triphenylphosphine)ruthenium, Dichloro[rel-[N(S)]-N-[2-(diphenylphosphinyl-κO)ethyl]-2-[(R)-methylthio-κS]ethanamine-κN](triphenylphosphine)ruthenium, Carbonylchlorohydride[bis(2-(diphenylphosphinoethyl)amino)]ruthenium(II), Carbonylchlorohydride[6-(di-t-butylphosphinomethyl)-2-(N,N-diethylaminomethyl)pyridine]ruthenium(II), Carbonylchlorohydridotris(triphenylphosphine)ruthenium(II), Carbonyl(dihydrido)tris(triphenylphosphine)ruthenium(II), Carbonylhydrido[6-(di-t-butylphosphinomethylene)-2-(N,N-diethylaminomethyl)-1,6-dihydropyridine]ruthenium(II), Carbonylhydrido(tetrahydroborate)[bis(2-diphenylphosphinoethyl)amino]ruthenium(II), Chlorocarbonylhydrido[4,5-bis-(di-i-propylphosphinomethyl)acridine]ruthenium(II), Chlorohydridotris(triphenylphosphine)ruthenium(II), 1-Hydroxytetraphenylcyclopentadienyl(tetraphenyl-2,4-cyclopentadiene-1-one)-μ-hydrotetracarbonyldiruthenium(II), Dichloro(benzene)ruthenium(II) dimer, Carbonyl(dihydrido)tris(triphenylphosphine)ruthenium(II), Chlorohydridotris(triphenylphosphine)ruthenium(II), and [Ru(1,1,1-tris(diphenylphosphinomethyl)ethane)TMM] (TMM = trimethylenemethane).

[0027] In various embodiments, the ruthenium catalyst is selected from the following: [ka] [ka] [ka] , preferably Ru-2 and Ru-3, for example Ru-3.

[0028] Other suitable catalysts include, but are not limited to, the following: [N2,N4-bis(diisopropylphosphino)-6-phenyl-1,3,5-triazine-2,4-diamine]cobalt dichloride, [N2,N4-bis(diisopropylphosphino)-6-cyclopropylamino-1,3,5-triazine-2,4-diamine]-cobalt dichloride, [N2,N4-bis(diisopropylphosphino)-6-methyl-1,3,5-triazine-2,4-diamine]-manganese(dicarbonyl) bromide, [N2,N4-Bis(diisopropylphosphino)-6-phenyl-1,3,5-triazine-2,4-diamine]-manganese dichloride; [N2,N4-bis(diisopropylphosphino)-6-cyclopropylamino-1,3,5-triazine-2,4-diamine]manganese dichloride, [N2,N4-bis(diisopropylphosphino)-6-diethylamino-1,3,5-triazine-2,4-diamine]-manganese(dicarbonyl) bromide, and Carbonylhydrido(tetrahydroborate)[bis(2-diphenylphosphinoethyl)amino]iron(II).

[0029] The catalyst can be used in an amount of 1 mol% or less, preferably about 0.5 mol% or less, for example about 0.5 mol%, 0.4 mol%, 0.3 mol%, 0.2 mol% or 0.1 mol%, It has been found that 0.1 mol% also provides good catalytic action and can be more advantageous than higher concentrations such as 1 mol% or more.

[0030] In various embodiments, the reaction temperature is 50-150°C, for example 80°C or higher, preferably 80-120°C.

[0031] In various embodiments, the base is a strong base. Such a strong base may be an alkoxide, particularly a metal alkoxide. Suitable bases include, but are not limited to, potassium tert-butoxide, sodium tert-butoxide, potassium tert-pentoxide, sodium tert-pentoxide, sodium methoxide, potassium methoxide, sodium ethoxide, and potassium ethoxide. In various embodiments, the base may be potassium tert-butoxide (KOtBu) or potassium tert-pentoxide (KOtPen). The base may be used in any suitable amount, for example, at least 6, 7, 8, 9, or at least 10 mole %. It has been found that low concentrations adversely affect the reaction, while high concentrations do not provide additional benefits.

[0032] In various embodiments, the solvent is an organic solvent, preferably selected from heptane, THF, 1,4-dioxane, toluene, sulfolane, acetonitrile, 2-MeTHF, and mixtures thereof, such as, but not limited to, toluene.

[0033] The process can be carried out under a nitrogen or argon atmosphere. It may be advantageous not to carry out the reaction under a hydrogen atmosphere.

[0034] In various embodiments, the reaction time is from 2 to 48 hours, preferably from about 4 to 24 hours.

[0035] In another aspect, the present invention provides an alternative method for concentrating trans-DHMTHF from a mixture of cis- / trans-DHMTHF, comprising the steps of: (a) acetylating the mixture of cis- and trans-DHMTHF, for example with acetic anhydride, optionally at elevated temperature, to obtain a mixture of diacetyl esters of cis- and trans-DHMTHF; (b) crystallizing the diacetyl ester of trans-DHMTHF from a solution of a mixture of the diacetyl esters of cis- and trans-DHMTHF in a suitable solvent at a temperature that allows preferential crystallization of trans-DHMTHF, preferably from −5 to −20° C., more preferably at about −15° C.; (c) isolating the crystallized diacetyl ester of trans-DHMTHF; and (d) hydrolyzing the diacetyl ester of trans-DHMTHF under basic conditions to obtain concentrated trans-DHMTHF. The present invention relates to a method comprising the steps of:

[0036] When acetic acid is produced in step (a), a step of removing acetic acid may be carried out after step (a).

[0037] In these processes, the mixture of cis- / trans-DHMTHF used as the starting material has a cis to trans ratio of 3 or less, preferably 2.5 or less, more preferably 2 or less, and most preferably 1.5 or less, but typically greater than 1. In various embodiments, it may be DHMTHF obtained according to the hydrogenation methods described herein. In various other embodiments, the mixture used in these processes is produced by the catalytic trans enrichment method described above.

[0038] The definition of trans-enriched DHMTHF above also applies to this method.

[0039] In various embodiments, the diacetyl ester remaining after removal of acetic acid in step (b) is dissolved in a suitable solvent to crystallize / precipitate the trans diastereomer. The solvent may be, but is not limited to, diethyl ether, THF, 2-MeTHF, 1,4-dioxane, methyl-tert-butyl ether, cyclopentyl methyl ether, tert-amyl ethyl ether, acetonitrile, and ethyl acetate. Enrichment of the trans diastereomer is based on the finding that the trans isomer crystallizes at higher temperatures than the cis diastereomer. In the described methods and in the described solvents, the temperature at which the trans diastereomer of diacetyl DHMTHF precipitates from solution ranges from about -5 to about -20°C, preferably about -15°C. At lower temperatures, for example about -30°C, both diastereomers have been found to precipitate from solution. It is understood that these temperature ranges may be different in other solvent systems and under different conditions. In various embodiments, a solvent system is used in which the temperature at which one of the two diastereomers crystallizes is at least 5°C, preferably at least 10°C, higher than the temperature at which the other diastereomer crystallizes. Generally, the temperatures used for crystallization are all below 5°C or below 0°C.

[0040] As used herein, "about" in relation to numerical values ​​refers to the reference value ±10%, preferably ±5%.

[0041] Isolation of the trans-enriched diacetyl-DHMTHF can be achieved by centrifugation and decantation or filtration followed by drying. The crystalline precipitate can be washed multiple times, for example with diethyl ether, to remove impurities before drying. Drying can be performed in vacuum, i.e. under reduced pressure. The trans-enriched diacetyl-DHMTHF thus obtained has a cis:trans ratio of 30:70 or less, preferably 20:80 or less, for example about 15:85.

[0042] The trans-enriched diacetyl-DHMTHF can then be hydrolyzed to give trans-enriched DHMTHF. For this reaction, the crystalline material can be dissolved in a suitable solvent, such as ethanol, and then a base, e.g., NaOH, can be added as an aqueous solution. Suitable reaction conditions are known to those skilled in the art and may involve slow addition of the base over an extended period of time and extensive stirring for an extended period of time, such as 48 hours. The resulting water can be removed under reduced pressure and the residue filtered and eluted with a suitable solvent, such as ethyl acetate. All volatiles can then be removed again under reduced pressure to give trans-enriched DHMTHF as a colorless liquid.

[0043] The trans-enriched DHMTHF thus obtained can retain the previous cis / trans ratio and may have a cis:trans ratio of 30:70 or less, preferably 20:80 or less, or even 10:90 or less, for example about 15:85.

[0044] In these acetylation methods, the supernatant remaining from step (d) containing cis-enriched diacetyl-DHMTHF can be subjected to a hydrolysis step similar to that of the trans-enriched diacetyl-DHMTHF to obtain cis-enriched DHMTHF, which can have a cis / trans ratio of 60 or more:40, such as 70 or more:30. This cis-enriched DHMTHF can then be subjected to a hydrogen borrowing process to provide trans-enriched DHMTHF, which can again be subjected to an acetylation process to obtain trans-enriched. This sequence of steps can be repeated multiple times to achieve nearly stereoselective production of trans-DHMTHF. Such techniques include both trans-enrichment methods described herein.

[0045] The present invention also relates to the trans-enriched DHMTHF mixtures thus obtained, in particular cis / trans DHMTHF mixtures having a molar ratio of cis to trans diastereomers of less than 70:30, preferably 70:30 to 30:70, for example 60:40 to 40:60.

[0046] Another aspect of the invention relates to polyester polyols obtained by reacting a diastereomeric mixture of cis- / trans-DHMTHF with an appropriate diacid. The cis / trans mixture of DHMTHF is obtained by the method described herein above. In various embodiments, the diastereomeric mixture of cis- / trans-DHMTHF has a cis to trans DHMTHF ratio of about 70:30 or less, such as about 30:70 to about 70:30, preferably about 40:60 to about 60:40. Such mixtures are also referred to herein as trans-enriched cis / trans DHMTHF mixtures.

[0047] In various embodiments, the diacid is at least one dicarboxylic acid. The dicarboxylic acid may be an aliphatic or aromatic dicarboxylic acid and may contain from 4 to 30 carbon atoms. If it is an aliphatic dicarboxylic acid, it may be a saturated or unsaturated aliphatic dicarboxylic acid. In various embodiments, it is an aliphatic dicarboxylic acid, for example an aliphatic dicarboxylic acid having a carbon chain of at least 2 carbon atoms, which may be saturated or unsaturated. In various embodiments, it is a saturated aliphatic C 4 -C 24-dicarboxylic acids, such as 1,6-hexanedioic acid, 1,7-heptanedioic acid, 1,8-octanedioic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1,11-undecanedioic acid, 1,12-dodecanedioic acid, 1,13-tridecanedioic acid, 1,14-tetradecanedioic acid, 1,15-pentadecanedioic acid, 1,16-hexadecanedioic acid, 1,17-heptadecanedioic acid, 1,18-octadecanedioic acid, 1,19-nonadecanedioic acid, 1,20-eicosanediocic acid, 1,21-heneicosanediocic acid, 1,22-docosanediocic acid, 1,23-tricosanediocic acid, and 1,24-tetracosanediocic acid, as well as anhydrides, halides (chlorides), and esters derived from said acids. In other embodiments, the acids used may include, but are not limited to, succinic acid, adipic acid, sebacic acid, azelaic acid, isophthalic acid, orthophthalic acid, terephthalic acid, furandicarboxylic acid, itaconic acid, and anhydrides, halides (chlorides) and esters derived from said acids. It is understood that mixtures and salts of all the above acids, as well as their derivatives such as esters, halides, anhydrides, etc., may also be used.

[0048] The term "carbon chain" when used in reference to a dicarboxylic acid refers to a linear carbon chain separating two carboxylic acid groups, the chain being terminated at both ends by a carboxylic acid group, with the carbons of each carboxylic acid group forming the start and end points that determine the length of the carbon chain.

[0049] In various embodiments, the polymerization reaction is carried out using a two-stage melt condensation process comprising a pre-condensation step at gradually increasing temperature from about 120° C. to about 220° C. at normal pressure (i.e., about 1 bar), followed by a condensation step under reduced pressure, optionally in the presence of a suitable catalyst, preferably a polycondensation catalyst, such as a metal alkoxide, more preferably a titanium alkoxide catalyst, even more preferably titanium (IV) isopropoxide.

[0050] Examples of suitable polycondensation metal catalysts include, but are not limited to, aluminum, titanium, magnesium and zirconium alkoxides, tin compounds, more specifically organotin carboxylates such as dibutyltin dilaurate, dibutyltin diacetate, dibutyltin bis-(2-ethylhexanoate), or other organotin compounds such as dibutyltin oxide, dibutyltin dimethoxide, dibutyltin dibromide, dibutyltin dichloride, di-tert-butyltin dichloride, dimethyltin dibromide, dimethyltin dichloride, diphenyltin dichloride, or tin octoate, iron acetate, iron benzoate, iron naphthenate; iron acetylacetonate, manganese acetate, manganese naphthenate, and manganese acetylacetonate.

[0051] The molecular weights of the components contained in the reaction mixture are determined according to standard procedures, for example by GPC or end group titration (OH number determination).

[0052] In a further aspect, the present invention relates to compounds of formula (Ia) and (Ib): [ka] The present invention relates to polyester polyols comprising monomer units of formula (Ia) and (Ib) in a molar ratio of 70:30 or less, preferably 70:30 to 30:70. In some embodiments, the monomer units of formula (Ia) and (Ib) constitute at least 5 mol %, at least 10, 15, 20, 25, 30, 35, 40, 45, or at least 50 mol %, or at least 60, 70, 80, 90, or at least 95 mol % of the total polyol units in said polyester polyol. In various embodiments, the ratio of units of formula (Ia) to units of formula (Ib) is about 30:70 to about 70:30, preferably about 40:60 to about 60:40. In various embodiments, the polyester polyol does not contain polyol units other than formula (Ia) and (Ib), or these other polyols are present in an amount of 10 mol % or less of the total polyol units. In addition to these polyol-derived monomeric units, the polyester polyols also contain diacid-derived monomeric units linking the polyol-derived units. These acid units can be derived from the diacids disclosed above. The polyester polyols can be made according to the methods described herein.

[0053] More surprisingly, it has been found that some of the polyester polyols of the present invention are semi-crystalline and at the same time have a low melting point, making them particularly suitable for temperature-sensitive applications. In one embodiment, the polyester polyols of the present invention have a (semi)crystalline form at or below room temperature. Room temperature as used in the present invention refers to a temperature of 23 to 25° C. at a pressure of 1000 to 1020 hPa.

[0054] The polyester polyols exhibiting semi-crystalline morphology as described herein refer to polyester polyols in which the polymer chains are at least partially aligned. The morphology of polyester polyols can be determined, for example, by DSC, and the degree of crystallinity is usually represented by distinct melting and crystallization peaks in the diagram. In contrast, amorphous materials are characterized by the absence of distinct peaks in the DSC diagram.

[0055] Those skilled in the art are aware of various methods for preparing (semi)crystalline polyester polyols. However, said crystalline polyester polyols usually have a melting point or softening point significantly higher than room temperature. Surprisingly, it has been found that the melting point of the polyester polyols of the present invention can be adapted by using an appropriate amount of trans-DHMTHF.

[0056] The melting point of the polyester polyol of the present invention can also be adjusted as required by selecting an appropriate dicarboxylic acid.

[0057] In particularly preferred embodiments, the DHMTHF and dicarboxylic acids from which the polyester polyols of the present invention are derived are derived from renewable resources. Generally, such compounds derived from renewable resources are referred to as "bio-based" compounds, in contrast to typical petroleum-based compounds.

[0058] Some of the polyester polyols of the invention are particularly distinguished by their (semi)crystalline morphology and at the same time exhibit low melting points. In contrast to state-of-the-art crystalline polyester polyols, which usually exhibit high melting points of 80° C. or higher, these polyester polyols were found to have melting points in the low temperature range below 60° C., allowing more flexible applications in many technical fields. In one embodiment, the polyester polyols of the invention have a melting point of −10 to 50° C., preferably −5 to 30° C., measured by DSC at a heating rate of 10 K / min.

[0059] In addition to the DHMTHF mixture and at least one dicarboxylic acid, other components may be included in the reaction mixture to adjust the properties of the polyester polyol of the present invention.Thus, the reaction mixture may further include a diol.Examples of such polyols include monoethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol (including R-, S- and racemic forms), 1,4-butanediol, 1,4-pentanediol, 3-methylpentane-1,5-diol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1,5-pentanediol, 1,6-hexanediol, 1,8-octaneglycol, cyclohexanedimethanol, 2-methylpropane-1,3-diol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol and polybutylene glycol.

[0060] However, it may be preferred that such diols not constitute more than 50 mol % of the total amount of polyols used, preferably no more than about 30 mol %, or no more than 20 mol %, or no more than 10 mol %.

[0061] The reactivity of the polyester polyol of the present invention can also be adjusted as necessary depending on the subsequent use. In various embodiments, the polyester polyol of the present invention thus has a hydroxyl number (OH number) of 5 to 250 mg KOH / g, 5 to 150, 10 to 100 mg KOH / g, or 20 to 50 mg KOH / g, or 25 to 34 mg KOH / g.

[0062] The hydroxyl number is a measure of the content of free hydroxyl groups in a chemical, usually expressed as the mass of potassium hydroxide (KOH) in milligrams equivalent to the hydroxyl group content in one gram of chemical. The analytical method used to determine the hydroxyl number traditionally involves acetylating the free hydroxyl groups of a substance with acetic anhydride in pyridine solvent. The hydroxyl number can be determined according to DIN 53240.

[0063] The hydroxyl number of the polyester polyol of the present invention can be adjusted, for example, by the ratio of diol to dicarboxylic acid in the reaction mixture. In a preferred embodiment, the molar ratio of at least one diol to at least one dicarboxylic acid in the reaction mixture is 1.5:1 to 1:1, preferably 1.2:1 to 1:1.

[0064] When the polyester polyol is -OH terminated, the acid number is at most 20 mg / g, preferably at most 10, for example 0.5 to 10 or 1 to 3 mg / g.

[0065] In various embodiments, the polyester polyols may be acid terminated, in which case the acid number is from 5 to 250, preferably from 10 to 150 mg / g.

[0066] In a preferred embodiment, the polyester polyol of the present invention has an average molecular weight Mn of 1000 to 25000 g / mol, preferably 2000 to 10000 g / mol, as measured by GPC. The molecular weight of the polyester polyol of the present invention can be measured by GPC, particularly using THF as an eluent.

[0067] The present invention also relates in another aspect to a process for the preparation of polyester polyols as described above, which process comprises reacting a diastereomeric mixture of cis- / trans-DHMTHF with an appropriate diacid, and all of the embodiments disclosed above with respect to the polyester polyols also apply to these processes.

[0068] Some of the polyester polyols of the present invention are particularly suitable for adhesive applications, especially for low melting systems, whose presence in the adhesive allows one to benefit from the advantageous properties of crystalline polyester polyols without the need to melt the adhesive at high temperatures.

[0069] A further aspect of the invention is a composition, such as an adhesive or coating composition, comprising the DHMTHF mixture or polyester polyol of the invention. In these compositions, the molar ratio of cis to trans DHMTHF, either as a monomer or as a monomer unit in a polymer, may be 70:30 or less, such as 70:30 to 30:70 or 60:40 to 40:60. Also included is the use of the DHMTHF mixtures and polyester polyols described herein in adhesive or coating compositions.

[0070] The polyester polyols of the present invention can be applied to many adhesive systems. Preferably, the adhesive system is a polyurethane adhesive, in particular a two-part polyurethane adhesive (2K system) or a one-part polyurethane adhesive (1K system). In various embodiments, the polyester polyols are therefore used in polyurethane adhesives and other PU applications, such as foams, thermoplastic PU (TPU), PU dispersions (PUD) and all other PU systems. In addition, they are also useful in other applications where polyesters are used, such as reactive prepolymers of acrylic resins and toughening agents in epoxy resins.

[0071] The present invention therefore also relates in a particular embodiment to the use of the mixture of polyester polyols obtained from the cis / trans DHMTHF of the present invention as a component of thermoplastic materials or adhesives and / or sealants. The mixture of polyester polyols of the present invention can be used in thermoplastics as deformation and extrusion means or as melt means for physically bonding adhesives and / or sealants, but due to the low application temperature and the high elasticity and mechanical stability of the adhesives, the polymeric material of the present invention can be used both in thermoplastics and as a tackifier in adhesives, preferably hot melt adhesives, as well as in crosslinking reactive adhesives.

[0072] In one aspect, the present invention therefore relates to polyurethanes obtained by reacting a polyester polyol as described herein or obtainable according to the process of the present invention with a polyisocyanate. Also included is a process for the synthesis / production of such polyurethanes, comprising reacting a polyester polyol of the present invention or obtainable according to the process of the present invention with a polyisocyanate.

[0073] In addition to the polyester polyols of the invention, further polyols can also be used, in particular polyols that are typically used in the production of polyurethanes.However, it may be preferred that the polyester polyols of the invention constitute at least 5 mol%, at least 10 mol%, at least 15 mol%, at least 20 mol%, at least 25 mol%, at least 30 mol%, at least 35 mol%, at least 40 mol%, at least 45 mol%, at least 50 mol%, or at least 70 mol%, or at least 80 mol%, 90 mol%, or 95 mol% of the total amount of polyols used.

[0074] Suitable additional polyols include, but are not limited to, polyhydroxyethers (substituted or unsubstituted polyalkylene ether glycols or polyhydroxypolyalkylene ethers), polyhydroxypolyesters, ethylene or propylene oxide adducts of polyols and mono-substituted esters of glycerol, and "polymer polyols" (i.e., graft polyols that contain a portion of vinyl monomer polymerized in situ), and mixtures thereof. Such compounds are commercially available, and methods of synthesizing such compounds are well known in the art. In various embodiments of the present invention, the polyol is selected from additional polyester polyols, polyether polyols, and combinations thereof.

[0075] Suitable polyether polyols include linear and / or branched polyethers having multiple ether bonds and at least two hydroxyl groups, and substantially no functional groups other than hydroxyl groups. Examples of polyether polyols include polyoxyalkylene polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, and the like. In addition, homopolymers and copolymers of polyoxyalkylene polyols, or mixtures thereof, can also be used. Particularly preferred copolymers of polyoxyalkylene polyols include adducts of at least one compound selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, 2-ethylhexanediol-1,3, glycerin, 1,2,6-hexanetriol, trimethylolpropane, trimethylolethane, tris(hydroxyphenyl)propane, triethanolamine, triisopropanolamine, and at least one compound selected from the group consisting of ethylene oxide, propylene oxide, and butylene oxide. Such compounds are commercially available and methods for synthesizing such compounds are well known in the art.Non-limiting examples of commercially available polyols that can be used in the practice of the present invention include polyethers such as polyether triols, e.g., those with a molecular weight of about 3000-9000, e.g., 4000-8000, e.g., about 6000, OH-terminated polybutadienes, e.g., those with a molecular weight of about 2000-4000, e.g., 25000-3500, e.g., about 2800, castor oil, and OH-terminated prepolymers available under the trade name Loctite UK 8201 HF (Henkel).

[0076] Further suitable polyester polyols are formed from the condensation of one or more polyhydric alcohols having from about 2 to about 15 carbon atoms with one or more polycarboxylic acids having from about 2 to about 14 carbon atoms. Examples of suitable polyhydric alcohols include ethylene glycol, propylene glycols such as 1,2-propylene glycol and 1,3-propylene glycol, glycerol, pentaerythritol, trimethylolpropane, 1,4,6-octanetriol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,4-pentanediol, hexanediol, dodecanediol, octanediol, chloropentanediol, glycerol monoallyl ether, glycerol monoethyl ether, diethylene glycol, 2-ethylhexanediol, 1,4-cyclohexanediol, 1,2,6-hexanetriol, 1,3,5-hexanetriol, 1,3-bis-(2-hydroxyethoxy)propane, and the like. Such compounds are commercially available and methods for synthesizing such compounds are well known in the art. Commercially available semi-crystalline polyester polyols useful in the present invention include, for example, Dynacoll 7380, 7360 (Creanova), Fomrez 66-32 (Crompton), and Rucoflex S-105-30 (Bayer).

[0077] Suitable hydroxyl polycarbonates can be obtained by reacting carbon acid derivatives, such as diphenyl carbonate, dimethyl carbonate or phosgene, with diols. Suitable examples of such diols include ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, 2-methyl-1,3-propanediol, 2,2,4-trimethylpentanediol-1,3, dipropylene glycol, polypropylene glycol, dibutylene glycol, polybutylene glycol, bisphenol A, tetrabromobisphenol A, and lactone-modified diols. The diol component preferably contains 40-100% by weight of hexanediol, preferably 1,6-hexanediol and / or hexanediol derivatives. More preferably, the diol component includes examples that exhibit ether or ester groups in addition to terminal OH groups. The hydroxyl polycarbonate should be substantially linear. However, it can be optionally slightly branched by the incorporation of multifunctional components, especially low molecular weight polyols. Suitable examples include glycerol, trimethylolpropane, hexanetriol-1,2,6, butanetriol-1,2,4, trimethylolpropane, pentaerythritol, quinitol, mannitol, sorbitol, methyl glycoside, 1,3,4,6-dianhydrohexyte. Suitable polycarbonate polyols are available, but are not limited to, under the trade names Desmophen® C3200 (Bayer) and Kuraray® C2050 (poly-(3-methyl-1,5-pentanediol, 1,6-hexanediol) carbonate; Kuraray).

[0078] Polyurethanes can be produced using commonly used polyisocyanates. Organic polyisocyanates that can be used in the practice of the present invention include alkylene diisocyanates, cycloalkylene diisocyanates, aromatic diisocyanates, and aliphatic-aromatic diisocyanates. Specific examples of suitable isocyanate-containing compounds include ethylene diisocyanate, ethylidene diisocyanate, propylene diisocyanate, butylene diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, cyclopentylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate, cyclohexylene-1,2-diisocyanate, and 4,4'-diphenylmethane diisocyanate. , 2,2-diphenylpropane-4,4'-diisocyanate, xylylene diisocyanate, 1,4-naphthylene diisocyanate, 1,5-naphthylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, diphenyl-4,4'-diisocyanate, azobenzene-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, 2,4-tolylene diisocyanate, dichlorohexamethylene diisocyanate Such compounds are commercially available and methods of synthesizing such compounds are well known in the art. Preferred isocyanate-containing compounds are those that are (crystalline) solids at room temperature, including but not limited to methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI) polymers, such as dimers or trimers, especially TDI dimers with urea or uretdione bridges. In various embodiments, the polyisocyanate used is, but is not limited to, 4,4'-, 2,2'- or 2,4'-MDI.

[0079] Polyurethanes can be obtained by using a molar excess of polyisocyanates with respect to the NCO / OH ratio. In such embodiments, the resulting polyurethanes can be NCO-terminated polyurethanes. To this end, the molar ratio of NCO groups of the polyisocyanate(s) to the sum of hydroxyl groups of the polyol(s) can be greater than 1.00:1.00, such as 1.1:1, but can range, for example, up to 3:1 or 2:1. In some embodiments, the ratio of hydroxyl groups to NCO groups can be in any combination of upper limits selected from less than 0.99:1, 0.975:1, 0.95:1, 0.9:1, 0.85:1, 0.8:1, 0.75:1, or 0.7:1, and lower limits selected from 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1. In some embodiments, the ratio is in the range of 0.65 to 0.95:1. In a specific embodiment, the ratio is 0.7-0.9:1.

[0080] Alternatively, the NCO to hydroxyl group ratio may be less than 1:1, for example up to 1:3, or up to 1:2. In various embodiments, the ratio may be in a range having an upper limit selected from less than 0.99:1, 0.975:1, 0.95:1, 0.9:1, 0.85:1, 0.8:1, 0.75:1, or 0.7:1, with any combination of lower limits selected from 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1. In some embodiments, the NCO to hydroxyl ratio is in the range of 0.65 to 0.95:1. The excess of hydroxyl groups means that the resulting PU after curing is preferably hydroxyl terminated.

[0081] These polyurethanes of the invention may be part of adhesive and coating compositions which are also part of the invention and which may further comprise all the additives known and conventional for such adhesive and coating compositions.

[0082] The PU composition may optionally contain from 0% to about 40% by weight, for example up to about 20% by weight, of such additives which are inert to other components contained in the PU composition of the present invention and are conventionally used in the technical field of PU formulations to meet various properties and specific application requirements, such as diluents, plasticizers, fillers, drying agents, rheology modifiers, pigments, dyes, curing catalysts, adhesion promoters, etc., which may be incorporated in small or large amounts into the adhesive formulation depending on the purpose.

[0083] In various embodiments, the composition is an adhesive composition, such as a reactive hot melt adhesive composition. EXAMPLES

[0084] method Catalytic testing for hydrogenation of aqueous 5-HMF solutions. In a typical screening of catalysts and reaction conditions, oven-dried 4 mL glass vials equipped with a magnetic stir bar were used. Each vial was loaded with a specific amount of heterogeneous catalyst for a final metal content of 1.26 mg, corresponding to 1 wt.% with respect to the 5-HMF used. Then, 560 μL (1 mmol) of crude aqueous 5-HMF solution (c = 1.79 mol / L) and 1–2 mL of ethanol were added to each vial. The vials were placed in an aluminum injection port and closed with a PTFE / rubber septum pierced with a needle. Three vials were placed in the same aluminum injection port and transferred to a Parr 300 mL stainless steel autoclave. The latter was heated at 20 bar N 2 3 times at 10 bar H 2 Finally, the autoclave was purged twice with H2O at 25 bar or 90 bar. 2 The reactor was pressurized at 1000 rpm and placed in an aluminum block preheated at 100 °C. After the desired time, the reactor was allowed to cool to room temperature and carefully depressurized. The reaction mixture was filtered over a short pad of Celite using ethanol as the eluent. The solvent was evaporated from the collected solution, and 1,4-dinitrobenzene was added as an internal standard to determine the conversion and yield, as well as the cis / trans ratio, by NMR spectroscopy.

[0085] Reaction conditions for screening catalysts and borrowing hydrogen. A typical reaction used an oven-dried 10 mL pressure Schlenk tube from FengTecEx (product number: F580810) equipped with a magnetic stir bar. In a glove box, the Schlenk tube was filled with the respective amount of catalyst and base under argon atmosphere, sealed with a Teflon screw cap and removed from the glove box. The desired solvent (4.0 mL or 2.0 mL) and 1.0 mmol (132 mg) of degassed cis-enriched DHMTHF (92% / 8% cis:trans) were then added under a constant argon flow. The Schlenk tube was again sealed with a Teflon screw cap and placed in a preheated oil bath at the desired temperature, in which the mixture was stirred (500 rpm) for 24 h. The reaction was then stopped and allowed to cool at room temperature. The mixture was filtered over a short pad of silica under a flow of argon using diethyl ether as the eluent. The solvent was then removed using a rotary evaporator, and the yield of DHMTHF was determined.Finally, an aliquot of the resulting product was analyzed by NMR spectroscopy to determine the cis / trans ratio.

[0086] Acetylation of cis / trans-DHMTHF. A round-bottom flask equipped with a reflux condenser was charged with 20.0 g (151 mmol) of DHMTHF with a trans isomer content of 44% and acetic anhydride (34.0 mL, 360 mmol). The mixture was heated to 140° C. under stirring and continued for an additional 3 h after reaching this temperature. The mixture was then allowed to cool and the formed acetic acid was removed under high vacuum at 70° C. The resulting brownish liquid was the corresponding diacetyl ester of DHMTHF and was used in the next step without further purification. Yield: 32.3 g (99%).

[0087] Crystallization of trans-DHMTHF. Transfer 245.0 g of diacetyl-DHMTHF (61% cis / 39% trans) into a round-bottom flask and add 80 mL of dry diethyl ether (Et 2After storing the crude mixture at -15 °C for >12 h, trans-enriched diacetyl-DHMTHF precipitated from solution as a white crystalline solid. This crystalline precipitate was filtered through a Büchner funnel with filter paper (both pre-chilled in the refrigerator) and dissolved in cold Et 2 The crystalline solid was washed three times with O. Finally, the crystalline solid was dried under high vacuum. Yield: 63.0 g (66%), cis / trans ratio: 15% / 85%.

[0088] Hydrolysis of diacetyl-DHMTHF ester (using the example of trans-enriched diacetyl-DHMTHF). A 1000 mL two-necked round bottom flask equipped with a condenser was charged with a magnetic stir bar and 63.0 g of trans-enriched diacetyl-DHMTHF (291 mmol). 40.0 mL of ethanol was added to predissolve the crystalline material. Then, 600 mL of 4 M aqueous NaOH was added dropwise over 2 h with stirring at 40 °C. After complete addition, the mixture was stirred for another 48 h. Then, the water was removed on a rotary evaporator and the resulting viscous suspension was filtered over silica using ethyl acetate (EtOAc) as eluent. After removal of volatiles under reduced pressure, trans-enriched DHMTHF was obtained as a colorless liquid by vacuum (0.3 mbar) distillation at 130 °C. Yield: 27.6 g (72%), cis / trans ratio: 15% / 85%.

[0089] Synthesis of polyester-polyol. Dodecanedioic acid and DHMTHF were placed in a 250 mL three-neck flask equipped with a mechanical stirrer, a Vigreux column, and a distillation bridge fitted with another 250 mL round-bottom flask to collect water. The entire apparatus was purged with nitrogen for 1 hour before the mixture was heated to 120 °C. The reaction was held at this temperature for 1 hour, after which the temperature was further increased to 140 °C. The temperature was then increased successively in 20 °C increments to 220 °C, holding at least 1 hour after each increase. At 220 °C, a vacuum was applied and slowly reduced from 850 mbar to 15 mbar. After 27 hours at 220 °C and 15 mbar, the reaction mixture was cooled at 120 °C and the vacuum was released. Titanium (IV) isopropoxide was added as catalyst, the mixture was again heated to 220 °C, and a vacuum (15 mbar) was applied. Finally, after an additional 7 hours at 220° C. under vacuum, the reaction mixture was cooled and the achievement of conversion was assessed by acid value titration using 0.1 M KOH in water and phenolphthalein as indicator.

[0090] Formation of polyurethane films. 50 g of polyester (ex. OH number 27) was placed in a 250 mL three-neck flask equipped with a mechanical stirrer and a condenser. The polymer was heated to 80 °C and kept under vacuum (<0.001 mbar) for 1.5 h. Then 2.2 equivalents of 4,4'-MDI (6.64 g) were added and the mixture was stirred under nitrogen atmosphere for 1 h. The resulting polymer was used to cast a 1 mm thick film and stored at ambient conditions for 1 week.

[0091] Example 1: Hydrogenation of 5-HMF in water 56.0 mL (100 mmol) of 5-HMF aqueous solution (c = 1.79 mol / L) and 140.0 mL of ethanol were added to a 300 mL stainless steel autoclave (Parr) equipped with a PTFE cross stirrer (length: 38 mm). Then, Raney nickel catalyst (2.5 g of solid catalyst) in the form of an aqueous suspension was added to the mixture. The autoclave was then closed and heated under 20 bar N 2 3 times at 20 bar H 2 and finally purged with 90 bar H 2The mixture was stirred at 650 rpm for 12 h, after which the autoclave was cooled to room temperature and pressurized at 90 bar H 2 The mixture was then repressurized at 100°C, placed again in an aluminum block and stirred at 100°C for another 12 hours. After a total of 24 hours, the reactor was carefully depressurized at room temperature. The reaction mixture was filtered on a pleated filter by taking special care to continuously rinse the filter paper with ethanol. After evaporation of the solvent, a brown liquid was obtained. DHMTHF was then recovered in 92% (12.1 g) yield by distillation under vacuum (0.4 mbar) at 130°C as a viscous colorless liquid with a cis content of 92%.

[0092] [Table 1]

[0093] Example 2: Isomerization of cis- to trans-DHMTHF using the borrowed hydrogen method A 300 mL autoclave (Parr) was charged with a PTFE cross stir bar and 23.8 g of cis-enriched DHMTHF-diol (180 mmol). The autoclave was then closed and vacuum was applied for 30 min. Then, 263.9 mg of Ru-3 (0.25 mol%), weighed in a vial inside the glove box, was added to the autoclave under a constant argon flow. Finally, 180.0 mL of toluene and 11.7 mL of KO were added. t Pen (10 mol %; 1.7 mol / L in toluene) was added under argon. The autoclave was then pressurized under 20 bar N 2 After purging three times with 500 rpm, the mixture was placed in a preheated aluminum block at 100 °C and stirred (600 rpm) for 16 h. The reaction mixture was then allowed to cool at room temperature and transferred to a round-bottom flask. The toluene was removed on a rotary evaporator and the final mixture was filtered through silica using diethyl ether as eluent under a constant argon flow. The diethyl ether was removed on a rotary evaporator and distilled under vacuum at 0.3 mbar and 130 °C to give the cis / trans DHMTHF mixture as a viscous colorless liquid in 94% yield (22.3 g).

[0094] [Table 2]

[0095] [Table 3]

[0096] Example 3: Effect of DHMTHF diastereomers on the properties of polyesters and polyurethanes To investigate the effect of blending two diastereomers of DHMTHF into adhesive polymers, novel potentially 100% biobased polyester polyols were synthesized using pre-prepared diastereomeric mixtures (92:8, 57:43, 15:85) in combination with dodecanedioic acid (DDA). The polyesters were prepared following a two-stage melt condensation process in which (I) pre-condensation at ambient pressure with a gradual temperature ramp from 120°C to 220°C and (II) condensation under vacuum in the presence of catalytic amounts of titanium(IV) isopropoxide were performed. The hydroxyl values ​​of the synthesized polyesters were in the desired range (OH-N = 25-34 mg / mol). -1 ) with only minor by-product formation. Thus, DHMTHF has been successfully used as a monomer in an industrially favorable melt condensation process to produce low acid values ​​(AN = 1-3 mg -1 ) resulting in a polyester polyol with high viscosity at room temperature and honey-like viscosity at 80° C. (see Table 4).

[0097] To investigate the influence of the two different diastereomers on the thermal behavior of the resulting polymers, differential scanning calorimetry (DSC) was performed (Figure 4). Interestingly, regardless of the diastereomeric mixture used, all the synthesized polyester polyols showed semi-crystalline nature indicated by the presence of at least two melting points. The integrated area of ​​the latter in particular was proportional to the mole fraction of cis- and trans-DHMTHF in the diol mixture. In particular, the polyester polyol obtained from cis-enriched DHMTHF showed one major crystalline domain with a peak temperature at 1 °C, probably associated with the cis isomer, and two small melting peaks centered at 11 °C and 21 °C, which could be the result of crystalline phases containing mixed enrichment and trans enrichment, respectively (Figure 4, bottom curve). Thus, for the polymers based on trans-enriched DHMTHF, the crystalline phase with a melting peak at 21 °C was found to be the major crystalline phase (Figure 4, top curve).

[0098] Surprisingly, the polymer obtained from the 57:43 cis / trans DHMTHF mixture also showed two characteristic melting points (Figure 4, middle curve). Interestingly, the use of more excess trans-DHMTHF in the synthesized polyester resulted in a higher degree of crystallinity of the latter. Notably, the crystallization temperatures (T c ) were all nearly identical, and only one peak was observed in each case (data not shown).

[0099] To use the synthesized polyester polyols for the preparation of moisture-curable polyurethane prepolymers, 4,4'-diphenylmethane diisocyanate (4,4'-MDI) was reacted in slight excess with the polyester polyols to produce isocyanate-terminated polymers, which were then post-cured in a climatic chamber (23 °C, 50% relative humidity) to give poly(urethane-urea) polymers (PU's). Thermogravimetric analysis of the latter showed good thermal stability with a mass loss of 5% in each case at about 300 °C (see Figure 5).

[0100] Furthermore, the mechanical properties of the obtained polymers were investigated by performing stress-strain tests. As summarized in Table 5, the PU films obtained from cis / trans DHMTHF polyester polyols showed good tensile strength and at the same time a significantly higher elongation. This combination of properties is highly desired in many applications, for example, joining materials with different thermal expansion coefficients or gluing windows and other components in automotive interiors. The PU obtained from cis- and trans-enriched DHMTHF polyester polyols also showed acceptable values ​​of both tensile strength and elongation at break, although they were lower than those obtained with cis / trans DHMTHF polyester polyols. It can therefore be concluded that a balanced blend of cis / trans DHMTHF in polyester polyols improves the mechanical performance.

[0101] [Table 4]

[0102] [Table 5]

[0103] In summary, the synthesis of various cis / trans DHMTHF mixtures from aqueous 5-HMF was demonstrated on a multigram scale. In particular, Raney Nickel proved active for the direct hydrogenation of 5-HMF to cis-enriched DHMTHF, not only starting from pure 5-HMF but also in the presence of rather large amounts of impurities. Furthermore, cis-DHMTHF was tested for the first time in a borrowed hydrogenation reaction, which significantly increased the content of the trans isomer along with high isolated yields. Surprisingly, a commercially available ruthenium complex was found to efficiently catalyze the isomerization of DHMTHF from cis to trans under basic conditions at 100 °C. Interestingly, acetylation of the cis / trans mixture allowed the separation of the trans isomers, for example in diethyl ether, by crystallization at −15 °C. Moreover, the remaining liquid containing the cis-enriched DHMTHF diacetate could be subjected to another isomerization / crystallization sequence after hydrolysis, the latter being considered as a suitable cascade for the synthesis of trans-DHMTHF. Finally, novel polyester polyols were synthesized from various mixtures of DHMTHF and diacids, preferably also available from renewable sources. DSC analysis showed that the higher the amount of trans-DHMTHF, the higher the crystallinity of the resulting polymer.

Claims

1. (A) a polyester polyol obtained by reacting a diastereomeric mixture of cis- / trans-DHMTHF with a suitable diacid, wherein said diastereomeric mixture of cis- / trans-DHMTHF has a cis- to trans-DHMTHF ratio of about 70:30 or less; or (B) Formulas (Ia) and (Ib): 【Chemistry 1】 in a molar ratio of (Ia) to (Ib) of 70:30 or less, preferably 70:30 to 30:70, wherein said monomer units of formula (Ia) and (Ib) preferably constitute at least 5 mol %, preferably at least 20 mol %, more preferably at least 50 mol % of all polyol units in said polyester polyol.

2. A method for making polyester polyols comprising reacting a diastereomeric mixture of cis- / trans-DHMTHF with an appropriate diacid.

3. a) the diacid is a dicarboxylic acid, preferably an aromatic or aliphatic dicarboxylic acid having from 4 to 30 carbon atoms; b) the diastereomeric mixture of cis- / trans-DHMTHF has a cis to trans DHMTHF ratio of about 30:70 to 70:30, preferably about 40:60 to about 60:40; c) the reaction is carried out using a two-stage melt condensation process comprising a pre-condensation step at a gradually increasing temperature from about 120°C to about 220°C at atmospheric pressure, followed by a condensation step under reduced pressure; and / or d) the polyester polyol has a hydroxyl number of 10 to 150 mg KOH / g; The polyester polyol according to claim 1 .

4. A polyurethane obtained by reacting the polyester polyol according to claim 1 or 3 or the polyester polyol obtained by the method according to claim 2 with a polyisocyanate.

5. A method for producing a polyurethane, which comprises reacting the polyester polyol according to claim 1 or 3 or the polyester polyol obtained by the method according to claim 2 with a polyisocyanate.

6. (a) the polyisocyanate is used in molar excess relative to the NCO to OH ratio; and / or (b) the polyisocyanate is a diisocyanate, optionally 4,4'-MDI; The polyurethane of claim 4.

7. A process for producing di(hydroxymethyl)tetrahydrofuran (DHMTHF) from 5-hydroxymethylfurfural (5-HMF), comprising hydrogenating a solution, optionally an aqueous solution, of 5-HMF in the presence of a heterogeneous catalyst, wherein the 5-HMF is crude 5-HMF.

8. The 5-HMF is (a) 5-HMF, optionally obtained as a by-stream product of a hydrothermal carbonization process of sugar and / or lignocellulosic material; and / or (b) has a purity of less than 95%; The method of claim 7.

9. 9. The method according to claim 7 or 8, wherein the heterogeneous catalyst is a syn-face hydrogenation catalyst, preferably selected from Raney nickel, Ru / C (ruthenium on carbon), Pd / Al (palladium on alumina), Pd / C (palladium on carbon), Pd / Si (palladium on silica), Ru / Al (ruthenium on alumina), Raney cobalt, Raney copper, more preferably Raney nickel.

10. The hydrogenation reaction is (a) in the presence of ethanol in an amount of at least 1.3 mL per millimole of 5-HMF, preferably in an amount of 1.4 to 3.0 mL per millimole of 5-HMF; (b) H of at least 10 or at least 20 bar, preferably at least 50 bar, more preferably 80 to 100 bar ２ Under pressure; (c) at a temperature of 80-120°C, preferably about 100°C; and / or (d) a reaction time of at least 5 hours, preferably 5 to 60 hours The method according to claim 7 or 8, wherein

11. 1. A method for concentrating trans-DHMTHF from a mixture of cis- / trans-DHMTHF, comprising: (A) reacting a mixture of cis- / trans-DHMTHF at elevated temperature in the presence of a suitable metal catalyst for metal-catalyzed hydrogen borrowing reaction, a base, and a suitable solvent; or (B) (i) acetylating the mixture of cis- and trans-DHMTHF, optionally with acetic anhydride, optionally at elevated temperature, to obtain a mixture of diacetyl esters of cis- and trans-DHMTHF; (ii) crystallizing the diacetyl ester of trans-DHMTHF from a solution of a mixture of the diacetyl esters of cis- and trans-DHMTHF in a suitable solvent at a temperature that allows preferential crystallization of trans-DHMTHF; (iii) isolating the crystallized diacetyl ester of trans-DHMTHF; and (iv) Hydrolyzing the diacetyl ester of trans-DHMTHF under basic conditions to obtain concentrated trans-DHMTHF. A method comprising:

12. (a) the mixture of cis- / trans-DHMTHF has a cis to trans ratio of at least 1, preferably at least 2, more preferably from 3 to 20; (b) the catalyst is a ruthenium, cobalt, manganese or iron complex catalyst, preferably a ruthenium complex having a tridentate pincer ligand, more preferably a ruthenium complex selected from Ru-2, Ru-3, Ru-5 and Ru-8; (c) the reaction temperature is 80°C or higher, preferably 80 to 120°C; (d) the base is a strong base, preferably selected from metal alkoxides, more preferably potassium tert-butoxide, sodium tert-butoxide, potassium tert-pentoxide, sodium tert-pentoxide, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide; (e) the solvent is selected from the group consisting of heptane, THF, 1,4-dioxane, toluene, sulfolane, acetonitrile, 2-MeTHF, and mixtures thereof; (f) a reaction time of 2 to 48 hours, preferably about 4 to 24 hours; (g) the base is used in an amount of at least 7 mol %, preferably at least 10 mol %; (h) the catalyst is used in an amount of 1 mol % or less, preferably about 0.5 mol % or less; (i) the reaction is not carried out under a hydrogen atmosphere; (j) the content of the trans diastereomer in the trans-enriched product is at least 10 mol % higher, preferably at least 20 mol % higher, than in the mixture of cis- / trans-DHMTHF used as starting material; The method of claim 11(A).

13. (1) the mixture of cis- / trans-DHMTHF has a cis to trans ratio of 3 or less, preferably 2.5 or less, more preferably 2 or less, and most preferably 1.5 or less; and / or (2) hydrolyzing the concentrated solution of cis-DHMTHF remaining after step (iv) under basic conditions and subjecting it first to the process of claim 11(A), and subjecting the resulting mixture of cis- and trans-DHMTHF again to the process of claim 11(B), and repeating this sequence of steps optionally multiple times to achieve nearly stereoselective production of trans-DHMTHF. The method of claim 11(B).

14. (a) a diastereomeric mixture of cis- / trans-DHMTHF obtainable according to the process of any one of claims 7, 8 or 11 to 13; (b) a diastereomeric mixture of cis- / trans-DHMTHF having a molar ratio of cis to trans diastereomers of 70:30 or less, preferably 70:30 to 30:70; (c) a polyester polyol according to claim 1 or 3, or a polyester polyol obtainable by the process of claim 2; or (d) a composition comprising the polyurethane according to claim 4.

15. The composition of claim 14, wherein the composition is an adhesive composition.

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