Sorbitan esters and process for enzymatically preparing the same

Abstract

To provide a process for enzymatically preparing sorbitan carboxylic acid esters, and to provide the sorbitan carboxylic acid esters obtained by this process.SOLUTION: A method for producing sorbitol carboxylic acid esters using an enzyme comprises: a process step A) of providing sorbitol and at least one acyl donor; and a process step B) of reacting sorbitol with the at least one acyl donor in the presence of a lipase at a temperature between 75°C and 110°C to obtain sorbitol carboxylic acid esters. The process step A) comprises blending the sorbitol with the at least one acyl donor at a temperature between 80°C and 120°C for at least 10 minutes.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The subject of the present invention is a process for the enzymatic preparation of sorbitan carboxylic acid esters, and the sorbitan carboxylic acid esters obtainable by said process.

[0002] prior art Sorbitol carboxylic acid esters are important products for the food and cosmetics industry, on the one hand because of their surface-active properties and, on the other hand, because they can be obtained from natural and renewable raw materials.

[0003] DE 102009001748 A1 describes a sorbitan ester obtained by the solvent-free reaction of 1 mole of sorbitol (also called glucitol) with 1.55 moles of caprylic acid, and the use of the sorbitan ester thus obtained as a thickener for aqueous surfactant systems. A disadvantage of this process is that under the reaction conditions described, sorbitol is almost completely, but at least partially, dehydrated to form the so-called sorbitan (product mixture).

[0004] Four degradation products of sorbitol frequently occur under these conditions: the anhydrohexitols 1,4-anhydrosorbitol, 2,5-anhydrosorbitol, and 1,5-anhydrosorbitol (Advances in Carbohydrate Chemistry and Biochemistry, 1983, 41, 27-66), and isosorbide (1,4:3,6-dianhydrosorbitol; ChemSusChem. 5(1): 167-176). A further drawback of these sorbitan esters is their dark color, which requires post-treatment, for example with activated carbon, to achieve a product quality usable in the cosmetic field.

[0005] Japanese Patent Publication No. 63-133991 describes the reaction of 1.0 equivalent of oleic acid with 1.0 equivalent of sorbitol in the presence of >9% lipase (Candida sp.) at 40-50°C and 100 mmHg (133 mbar). A drawback of this process described in the prior art is that only about 70% esterification is achieved. A further drawback is that only pure oleic acid is used, which is too costly and therefore uneconomical for industrial applications in the food and cosmetics sectors.

[0006] German Patent Application Publication No. 3430944 describes the reaction of ≥ 4.0 equivalents of oleic acid or stearic acid with 1.0 equivalent of sorbitol in the presence of approximately 7% lipase at 40°C for 72 hours, with the reactants and enzyme reacting with each other in an aqueous buffer system at a weight concentration of approximately 28g per 1000mL. A drawback of this process described in the prior art is the use of an aqueous phosphate buffer, which results in a salt load in the product that is undesirable for use in cosmetics. Another drawback is that the weight concentration of the reactants and lipase in the buffer system is only approximately 3%, which means that the space-time yield of the industrial reaction is too low. Another drawback is that only pure oleic acid and pure stearic acid are used.

[0007] Lorie et al., Biotechnol. Bioeng. 1995, 48, 214-221, describe the reaction of sorbitol with 1.0 equivalent of oleic acid in the presence of 15% Novozym 435 (a lipase from Candida antarctica; approximately 494,000 PLU per mole of fatty acid) at 90°C and a pressure of <0.7 kPa (<7 mbar). One drawback of the process described in the prior art is that the sorbitol used remains as a highly viscous semi-solid at the bottom of the reaction vessel, with the oleic acid layer on top. This behavior makes the already difficult mixing of the reactants even more difficult.

[0008] EP 1755545 describes a mixture of sorbitan esters and sorbitol esters, in which the chain length of the fatty acid in the sorbitan ester is longer than that in the sorbitol ester, and always more than 80% saturated fatty acids are used. The sorbitan esters make up at least 50% of the mixture. The sorbitol esters consist exclusively of monoesters and diesters, with at least 40% monoesters and less than 60% diesters, and are used to influence emulsion stability and viscosity. Starting with lauric acid, a mixture consisting of 7% sorbitan esters, 68% C12 sorbitol esters, and 25% polyols is obtained. A drawback of the production methods described in the prior art is the fact that sorbitan esters are formed in this case as well, resulting in a reduction in the hydrophilic portion of the surfactant and, further, in poor color.

[0009] The object of the present invention was to provide a process for the preparation of sorbitan esters which makes it possible to overcome at least one of the disadvantages of the prior art processes.

[0010] Detailed Description of the Invention Surprisingly, it has been found that the sorbitol carboxylic acid esters described below and the methods described below are able to solve the problems set out in the present invention.

[0011] An advantage of the present invention is that the sorbitol carboxylic acid esters according to the present invention are superior thickeners for aqueous surfactant systems compared to the prior art.

[0012] A further advantage in this case is that the sorbitol carboxylic acid esters according to the invention also have an excellent color and a very good odor compared to the prior art.

[0013] An advantage of the present invention is that only very small amounts of sorbitol degradation products or esters of degradation products are obtained as reaction products.

[0014] An advantage of the present invention is that the process according to the invention can be carried out in the absence of a solvent.

[0015] A further advantage of the present invention is that the sorbitol carboxylic acid esters are obtained in a homogeneous reaction mixture, so that no additional process steps, such as extraction, crystallization, filtration or distillation, are necessary.

[0016] An advantage of the present invention is that the process can be carried out at high temperatures, which results in improved miscibility of the reaction partners while also providing a surprisingly high recyclability of the enzymes used.

[0017] A further advantage of the present invention is that the resulting sorbitol carboxylic acid esters can be very easily incorporated into formulations, especially cosmetic formulations.

[0018] The subject of the present invention is therefore a process for the enzymatic production of sorbitol carboxylic acid esters, comprising: A) providing sorbitol and at least one acyl donor, preferably a fatty acid acyl donor, in particular a fatty acid acyl donor selected from fatty acid esters and fatty acids, particularly preferably a fatty acid, B) reacting sorbitol with at least one acyl donor in the presence of a lipase at a temperature between 75°C and 110°C, preferably between 77°C and 100°C, and even more preferably between 80°C and 95°C, to obtain sorbitol carboxylic acid esters; and optionally C) a process step for purifying the sorbitol carboxylic acid ester; wherein process step A) comprises blending sorbitol and at least one acyl donor at a temperature in the range of 80°C to 120°C, preferably 90°C to 120°C, even more preferably 95°C to 120°C, even more preferably 100°C to 120°C for at least 10 minutes, preferably at least 30 minutes, even more preferably at least 60 minutes.

[0019] The term "sorbitol carboxylic acid ester" as used herein encompasses compositions that contain a majority of sorbitol carboxylic acid esters, particularly at least 40% by weight, preferably at least 50% by weight, and even more preferably at least 60% by weight of the entire composition, but may also contain by-products from the respective production processes, such as 1,4-anhydrosorbitol carboxylic acid esters, 2,5-anhydrosorbitol carboxylic acid esters, 1,5-anhydrosorbitol carboxylic acid esters, and isosorbide carboxylic acid esters, as well as unreacted reactants.

[0020] The terms "sorbitol carboxylic acid ester" and "sorbitan carboxylic acid ester" are used interchangeably in the present invention.

[0021] The use of this term is based on the conventional nomenclature of polyol esters. Polyol esters are known to be prone to dehydration during their synthesis, and therefore the resulting products are mixed compositions. For example, those skilled in the art will understand the term "sorbitan ester" to mean a mixture containing not only esters of 1,4-anhydrosorbitol and esters of 1,5-anhydrosorbitol, but also esters of isosorbide and sorbitol, and free sorbitol; see, for example, Food emulsifiers and their applications, 1997, p. 26.

[0022] The term "carboxylic acid ester of sorbitol" in the present invention refers to a pure sorbitol compound.

[0023] The term "carboxylic acid ester of 1,4-anhydrosorbitol" in the present invention refers to a pure 1,4-anhydrosorbitol compound.

[0024] The term "carboxylic acid ester of 2,5-anhydrosorbitol" in the present invention means a pure 2,5-anhydrosorbitol compound.

[0025] The term "carboxylic acid ester of 1,5-anhydrosorbitol" in the present invention refers to a pure 1,5-anhydrosorbitol compound.

[0026] The term "carboxylic acid ester of isosorbide" in the present invention refers to the pure isosorbide compound.

[0027] Unless otherwise specified, all percentages (%) listed are by weight.

[0028] According to the present invention, any acyl group donor can be used, such as carboxylic acid esters or carboxylic acids themselves, and mixtures thereof.

[0029] According to the invention, it is preferred that the acyl group donor provided in process step A) provides an acyl group which is derived from a carboxylic acid, in particular a natural fatty acid or a mixture thereof, containing 2 to 34, preferably 4 to 24, particularly preferably 6 to 22 carbon atoms.

[0030] Preferably, according to the invention, the carboxylic acid esters used as acyl group donors are selected from esters based on alkanols and polyols having up to 6 carbon atoms, particularly preferably esters based on alkanols and polyols having up to 3 carbon atoms, and very particularly preferably glycerol esters. Particularly preferably, according to the invention, the carboxylic acid esters used as acyl group donors are selected from triglycerides, in particular natural fats and oils, particularly preferably from the group including, and preferably consisting of, coconut oil, palm kernel oil, olive oil, palm oil, argan oil, castor oil, linseed oil, babassu oil, rapeseed oil, algae oil, sesame oil, soybean oil, avocado oil, jojoba oil, safflower oil, almond oil, cottonseed oil, shea butter, sunflower oil, cupuaçu butter, and oils with a high proportion of polyunsaturated fatty acids (PUFAS). Sorbitan esters, monoglycerides, and diglycerides containing acyl groups, in particular those described below, can also be used with preference.

[0031] Particularly preferably, according to the present invention, the acyl donor is selected from fatty acid acyl donors, which provide acyl groups selected from the group of acyl groups of natural fatty acids, or mixtures thereof. In this context, preferred fatty acids are mixtures of natural fatty acids, especially mixtures in which no carboxylic acid chain length has a proportion of more than 95% by weight, especially more than 99% by weight, in the overall chain length distribution. Natural fatty acids can be prepared based on naturally occurring vegetable or animal oils and preferably have 6 to 30 carbon atoms, especially 8 to 22 carbon atoms. Natural fatty acids are generally unbranched and usually consist of an even number of carbon atoms. Any double bonds have a cis configuration. Examples are caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, pelargonic acid (obtained, for example, by ozonolysis or oxidative cleavage of oleic acid), isostearic acid, stearic acid, 12-hydroxystearic acid, dihydroxystearic acid, undecylenic acid (obtained by thermal decomposition of ricinoleic acid), oleic acid, linoleic acid, linolenic acid, petroselinic acid, elaidic acid, arachidic acid, behenic acid, erucic acid, gadoleic acid, linolenic acid, eicosapentaenoic acid, docosahexaenoic acid and arachidonic acid.

[0032] Particularly preferably, according to the invention, the acyl donor is selected from fatty acid acyl donors, characterized in that they provide an acyl mixture comprising at least two acyl groups of a carboxylic acid selected from the group consisting of caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, pelargonic acid (obtained, for example, by ozonolysis or oxidative cleavage of oleic acid), isostearic acid, stearic acid, 12-hydroxystearic acid, dihydroxystearic acid, undecylenic acid (obtained, for example, by thermal decomposition of ricinoleic acid), oleic acid, linoleic acid, linolenic acid, petroselinic acid, elaidic acid, arachidic acid, behenic acid, erucic acid, gadoleic acid, linolenic acid, eicosapentaenoic acid, docosahexaenoic acid and arachidonic acid.

[0033] Preferably, according to the invention, carboxylic acids, in particular fatty acids, are used as acyl group donors. Preferred fatty acids in this context are those mentioned above in connection with the fatty acids preferably provided.

[0034] Alternatively, according to the present invention, a mixture of fatty acids and glycerol fatty acid esters is preferably used as the acyl group donor, with the fatty acids described above in relation to the preferred fatty acids being preferably used with equal priority in both the fatty acid and glycerol fatty acid component. The mixture of fatty acids and glycerol fatty acid esters used preferably has a weight ratio of fatty acid to glycerol fatty acid ester of 80:20 to 99:1, preferably 90:10 to 99:1, particularly preferably 95:5 to 99:1.

[0035] A preferred process according to the invention is characterized in that sorbitol and at least one acyl donor make up at least 80% by weight, preferably at least 90% by weight, particularly preferably at least 95% by weight, of the total reaction batch at the start of process step B).

[0036] In this context, the entire reaction batch may contain very little, if any, solvent, since it consists largely of the reactants, i.e., sorbitol and the acyl donor. Based on the above, it is clear that the acyl donor is not encompassed by the term "solvent" in the process according to the invention.

[0037] Possible solvents include, for example, ketones such as methyl isobutyl ketone or cyclohexanone, sterically hindered secondary alcohols such as 2-butyl-1-octanol, methylcyclohexanol, 1-methoxy-2-propanol, 2,3-butanediol, 2-octanol, diacetone alcohol, 2-methyl-2-butanol, and ethers such as 1,4-dioxane, tetrahydrofuran, and Varonic APM. The solvent is contained in a total amount of less than 20% by weight, preferably less than 10% by weight, and particularly less than 5% by weight, based on the total reaction batch. The expression "contains less than X% by weight at most" can be considered as "having a content of less than X% by weight."

[0038] Particularly preferably, the process according to the invention is carried out solvent-free.

[0039] A preferred process according to the invention is therefore characterized in particular in that in process step B) the water content, based on the total reaction batch, is less than 15% by weight, preferably less than 5.0% by weight, particularly preferably less than 1.0% by weight.

[0040] According to the invention, the lipase preferably used in process step B) is immobilized on a solid support.

[0041] Lipases preferably used according to the invention in process step B) are lipase from Thermomyces lanuginosus (accession number O59952), lipases A and B from Candida antarctica (accession number P41365), lipase from Mucor miehei (accession number P19515), lipase from Humicola sp. (accession number O59952), lipase from Rhizomucor javanicus (accession number S32492), lipase from Rhizopus oryzae (accession number P61872), lipase from Candida rugosa ... Lipases from Rhizopus niveus (accession number P61871), Penicillium camemberti (accession number P25234), Aspergillus niger (ABG73613, ABG73614, and ABG37906), and Penicillium cyclopium (accession number P32949, P20261, P32946, P32947, P3294, and P32949). and lipases having at least 60%, preferably at least 80%, preferably at least 90%, particularly preferably at least 95%, 98% or 99% homology thereto at the amino acid level, respectively, wherein lipases A and B from Candida antarctica (accession number P41365) are particularly preferred.

[0042] The accession numbers cited in this invention correspond to entries in the NCBI ProteinBank database as of January 1, 2017, and as a general rule, the version number of an entry is displayed as a ".number" such as ".1".

[0043] Enzymes that are homologous at the amino acid level preferably have an enzymatic activity at the propyl laurate unit (PLU) as defined in the present invention of at least 50%, in particular at least 90%, compared to the reference sequence.

[0044] To measure enzyme activity in PLU (propyl laurate units), 1-propanol and lauric acid are mixed uniformly at an equimolar ratio at 60°C. The enzyme is added to initiate the reaction, which is then timed. Samples are taken from the reaction mixture at regular intervals, and the content of reacted lauric acid is measured by titration with potassium hydroxide solution. The enzyme activity in PLU is determined by the rate at which 1 g of the enzyme synthesizes 1 micromole of propyl laurate per minute at 60°C. See U.S. Patent Application Publication No. 20070087418, especially paragraph

[0185] .

[0045] Examples of commercially available lipases, which are also preferably used in the method according to the invention, are the commercially available products Lipozyme TL IM, Novozym 435, Lipozyme IM 20, Lipase SP382, Lipase SP525, Lipase SP523 (all commercially available from Novozymes A / S, Bagsvaer, Denmark), Chirazyme L2, Chirazyme L5, Chirazyme L8, Chirazyme L9 (all commercially available from Roche Molecular Biochemicals, Mannheim, Germany), CALB Immo Plus™ from Purolite, and Lipase M "Amano", Lipase F-AP. 15 “Amano”, Lipase AY “Amano”, Lipase N “Amano”, Lipase R “Amano”, Lipase A “Amano”, Lipase D “Amano”, and Lipase G “Amano” (all commercially available products from Amano Co., Ltd., Japan).

[0046] "Homology at the amino acid level" in the present invention is understood to mean "amino acid identity", which can be determined by known methods. Generally, specific computer programs with algorithms that take into account specific requirements are used. A preferred method for determining identity first generates a maximum alignment between the sequences to be compared. Computer programs for determining identity include, but are not limited to, the GCG program package, including: - GAP(Deveroy, J. et al., Nucleic Acid Research 12 (1984), p.387, Genetics Computer Group University of Wisconsin, Medicine (WI), and - BLASTP, BLASTN and FASTA (Altschul, S. et al., Journal of Molecular Biology 215 (1990), p. 403-410. BLAST programs are available from the National Center for Biotechnology Information (NCBI) and other sources (BLAST Handbook, Altschul S. et al., NCBI NLM NIH Bethesda ND 22894; Altschul S. et al., supra).

[0047] Those skilled in the art will recognize that various computer programs are available for calculating the similarity or identity between two nucleotide sequences or amino acid sequences.For example, the identity percentage between two amino acid sequences can be determined by, for example, the algorithm by Needleman and Wunsch (J. Mol. Biol. (48). 444-453 (1970)), which is integrated into the GAP program of the GCG software package (available at http: / / www.gcg.com), and uses Blossom 62 matrix or PAM250 matrix, gap weight of 16, 14, 12, 10, 8, 6 or 4, and length weight of 1, 2, 3, 4, 5 or 6.Those skilled in the art will recognize that although the use of different parameters will produce slightly different results, the overall identity percentage between two amino acid sequences will not be significantly different.The Blossom 62 matrix is ​​usually used with default settings (gap weight: 12, length weight: 1).

[0048] In the present invention, 60% identity according to the above algorithm means 60% homology, and the same applies to higher identities.

[0049] Preferably, according to the invention, in process step B) 500 PLU to 2000 PLU, preferably 200 PLU to 1500 PLU, particularly preferably 25 PLU to 1250 PLU of lipase are used per g of sorbitol to be converted.

[0050] Preferably, according to the invention, process step B) is carried out at a pressure of less than 1 bar, preferably less than 0.5 bar, particularly preferably less than 0.1 bar.

[0051] Alternatively and preferably according to the invention, process step B) is carried out in a bubble column reactor in which the reaction batch is passed through with at least one inert gas, this gas being preferably selected from the group comprising nitrogen and argon, preferably selected from the group consisting of nitrogen and argon. In this context, it is preferred according to the invention that the gas flow is between 1 and 60 kg / h, preferably between 5 and 25 kg / h, even more preferably between 10 and 14 kg / h.

[0052] Preferably, according to the invention, process step B) is characterized in that process step B) is terminated at the latest 180 hours, preferably 120 hours, particularly preferably 100 hours after addition of the lipase.

[0053] A preferred process according to the present invention is characterized in that the molar ratio of the provided sorbitol to the acyl groups contained in all the provided acyl group donors is within the range of 1.00:0.50 to 1.00:5.00, preferably 1.00:0.70 to 1.00:3.00, particularly preferably 1.00:1.00 to 1.00:2.25, or particularly preferably 1.00:2.3 to 1.00:4.50.

[0054] A preferred process according to the invention is characterized in that the by-products formed in process step B), such as water if the acyl donor used is an acid or the corresponding alcohol if the acyl donor used is an ester, are removed, for example by distillation.

[0055] Process step C) of the method according to the invention involves the purification of the sorbitol carboxylic acid esters. For this purpose, any methodology can be employed which allows obtaining sorbitol carboxylic acid esters in higher concentrations.

[0056] Preferably, according to the invention, the process according to the invention comprises, in process step C), the removal of the lipase used in the process according to the invention.

[0057] When the lipase is immobilized on a carrier, according to the present invention, it is preferable to remove the lipase by filtration using a filter having openings of 0.1 μm to 1250 μm, preferably 0.5 μm to 100 μm, particularly a bag filter.

[0058] Preferably, according to the invention, the process of the invention is characterized in that no molecular sieves are used in the process.

[0059] Preferably, according to the invention, the method of the invention is characterized in that the substrate is used in a state where it is not immobilized on a solid support, such as for example silica.

[0060] A further subject of the present invention are sorbitol carboxylic acid esters obtainable by the process according to the invention.

[0061] Preferably, according to the present invention, sorbitol carboxylic acid esters include carboxylic acid esters of sorbitol, carboxylic acid esters of 1,4-anhydrosorbitol, carboxylic acid esters of 2,5-anhydrosorbitol, carboxylic acid esters of 1,5-anhydrosorbitol, and carboxylic acid esters of isosorbide, and the sorbitol residue contained in the sorbitol carboxylic acid ester is a 1,4-anhydrosorbitol residue, a 2,5-anhydrosorbitol residue, a 1,5 ... Sorbitol carboxylic acid esters having a weight ratio of the sum of all sorbitol residues and isosorbide residues greater than 90:10, preferably greater than 93:7, particularly preferably greater than 95:5, and most preferably greater than 96:4, are characterized in that the molar ratio of esterified primary hydroxyl groups to esterified secondary hydroxyl groups in the sorbitol carboxylic acid ester is 80:20 to 20:80, preferably 70:30 to 30:70, even more preferably 60:40 to 40:60, and even more preferably 55:45 to 45:55.

[0062] The term "sorbitol carboxylic acid esters including sorbitol carboxylic acid esters, 1,4-anhydrosorbitol carboxylic acid esters, 2,5-anhydrosorbitol carboxylic acid esters, 1,5-anhydrosorbitol carboxylic acid esters, and isosorbide carboxylic acid esters, wherein the weight ratio of sorbitol residues contained in the carboxylic acid ester to the total of all 1,4-anhydrosorbitol residues, 2,5-anhydrosorbitol residues, 1,5-anhydrosorbitol residues, and isosorbide residues contained in the carboxylic acid ester is greater than 90:10" clearly and unambiguously indicates that in the sorbitol carboxylic acid esters according to the present invention, the content of at least one selected from 1,4-anhydrosorbitol carboxylic acid esters, 2,5-anhydrosorbitol carboxylic acid esters, 1,5-anhydrosorbitol carboxylic acid esters, and isosorbide carboxylic acid esters must not be 0 (zero), because division by 0 is not defined.

[0063] The weight ratio of sorbitol residues in a sorbitol carboxylic acid ester according to the present invention to the total weight of all 1,4-anhydrosorbitol residues, 2,5-anhydrosorbitol residues, 1,5-anhydrosorbitol residues, and isosorbide residues in a sorbitol carboxylic acid ester according to the present invention can be determined by high-performance liquid chromatography (HPLC). This method involves alkaline hydrolysis of the sorbitol carboxylic acid ester to be analyzed, removing the carboxylic acid, and analyzing sorbitol and its degradation products, 1,4-anhydrosorbitol, 2,5-anhydrosorbitol, 1,5-anhydrosorbitol, and isosorbide. To this end, 150 mg of the sorbitol carboxylic acid ester to be analyzed is added to 2.00 mL of 1 M aqueous KOH solution and hydrolyzed at 95°C for 30 minutes with stirring. The reaction mixture is then cooled to room temperature and adjusted to pH 2-3 with 2 M aqueous hydrochloric acid. The resulting carboxylic acid is then extracted with diethyl ether (3 x 3.00 mL), and the organic supernatant is removed after each extraction using a pipette. After extraction, the remaining ether is removed by heating the aqueous solution to 50°C with stirring for 20 minutes (boiling point of diethyl ether: 34.6°C). The resulting solution is filled to 10.0 mL with distilled H2O and then diluted 1:10, and an aliquot of the solution is analyzed by HPLC. The analysis is performed under the following conditions: Column: Aminex HPX-87C column 300 x 7.8 mm Eluent: H2O Injection volume: 10.0μL Flow rate: 0.60mL / min Column temperature: 50℃ Detector: G1362A / 1260 RID (Agilent), 35°C Measurement time: 30.0 minutes

[0064] An ion exchange process separates sorbitol and its degradation products.

[0065] For evaluation, the ratio of the sorbitol peak area to the sum of the peak areas of 1,4-anhydrosorbitol, 2,5-anhydrosorbitol, 1,5-anhydrosorbitol, and isosorbide is calculated. Reference substances for sorbitol degradation products are commercially available, but can alternatively be obtained by heating neat sorbitol in the presence of an acidic (>140°C) or basic (>180°C) catalyst.

[0066] The molar ratio of esterified primary hydroxyl groups to esterified secondary hydroxyl groups in the carboxylic acid ester of sorbitol can be determined by: 13 This is performed by C-NMR spectroscopy. For sample preparation, 50-70 mg of material is dissolved in 1 mL of a deuterated solvent with the addition of a relaxation promoter (chromium(III) acetylacetonate, 1%). Depending on the product characteristics, DMSO-d6, CDCl3, and methanol-d4 have been found to be suitable solvents. If the sample does not dissolve completely in one of the solvents, a solvent mixture must be found. The prepared sample solution is transferred to a 5 mm NMR tube and introduced into the NMR spectrometer. NMR spectroscopy can, in principle, be performed using commercially available NMR instruments. For this NMR spectroscopy, a Bruker Avance 400 instrument was used. The spectra were recorded with the following parameters: Temperature: T = 295 K, delay time: D1 = 2 s, number of scans: NS = 2048, transmitter frequency offset: O1P = 110 ppm, sweep width: SW = 300 ppm, sample head: PA BBI 400 S1 H-BB-D-05-Z. Resonance signals are recorded relative to the chemical shifts of tetramethylsilane (TMS = 0 ppm) as an internal standard. Equivalent results can be obtained with other commercially available NMR instruments using the same operating parameters. Quantification is performed by determining the area under each resonance signal, i.e., the area enclosed by the signal from the baseline. For this NMR spectroscopy measurement, integration was performed using TOPSPIN (version 3.0) software. For accurate identification of esterified primary and secondary hydroxyl groups, DEPT spectra were primarily recorded. The molar ratio of esterified primary to secondary hydroxyl groups was determined by subtracting the integral P (signals of esterified primary hydroxyl groups) from the integral C (signals of ester carbonyl groups). This yields the integral S of the signals of esterified secondary hydroxyl groups, which cannot be determined directly due to overlap with other signals.

[0067] P = esterified primary hydroxyl group [R- C H2-OC(O)R group integral value C = integral value of ester carbonyl group S = CP = esterified secondary hydroxyl group [R2- C Integral value of H-OC(O)R group The calculated P to S ratio corresponds to the molar ratio of esterified primary hydroxyl groups to esterified secondary hydroxyl groups in the carboxylic acid ester of sorbitol.

[0068] According to the present invention, preferred is a sorbitol carboxylic acid ester having an average degree of esterification of the sorbitol carboxylic acid ester contained therein of 0.3 to 4.0, preferably 1.0 to 3.0, particularly preferably 1.1 to 2.7, and particularly preferably 1.3 to 2.6. Alternatively, preferred is a sorbitol carboxylic acid ester having an average degree of esterification of the sorbitol carboxylic acid ester contained therein of 2.7 to 4.0.

[0069] The average degree of esterification of the sorbitol carboxylic acid esters contained in the sorbitol carboxylic acid esters according to the present invention can be determined, for example, by first determining the content of free sorbitol and its degradation products, 1,4-anhydrosorbitol, 2,5-anhydrosorbitol, 1,5-anhydrosorbitol, and isosorbide, in a sample of the sorbitol carboxylic acid ester by GC or HPLC. Furthermore, the saponification value, acid value, and content of free fatty acids and neutralized fatty acids (e.g., by GC as described below in the section "Determination of the Free Carboxylic Acid Content") must be determined. Determining the carboxylic acid composition after alkaline saponification provides the average molar mass of the esterified carboxylic acid mixture, which can then be used to calculate the average degree of esterification.

[0070] According to the present invention, the sorbitol carboxylic acid esters contained therein preferably include sorbitol monoesters, sorbitol diesters, and sorbitol triesters, and the sorbitol triesters are contained in an amount of 10 to 50% by weight, preferably 15 to 45% by weight, and particularly preferably 20 to 40% by weight, based on the total amount of sorbitol carboxylic acid esters contained. In this regard, further according to the present invention, the sorbitol carboxylic acid esters contained therein preferably include sorbitol monoesters, sorbitol diesters, sorbitol triesters, and sorbitol tetraesters.

[0071] According to the invention, sorbitol carboxylic acid esters are preferred, characterized in that they contain 0.05% to 40% by weight, preferably 0.2% to 25% by weight, particularly preferably 0.5% to 10% by weight of free sorbitol, the weight percentages being based on the total sorbitol carboxylic acid ester.

[0072] To quantify the sorbitol content of the sorbitol carboxylic acid esters of the present invention by GC, a portion of the sample is dissolved in pyridine:chloroform (4:1). 0.25 mL of this solution is mixed with 0.5 mL of MSTFA [N-methyl-N-(trimethylsilyl)trifluoroacetamide] and 0.5 mL of a mixture of N-trimethylsilylimidazole and pyridine (11:39). The alcohol is quantitatively converted to its trimethylsilyl ether by reaction at 80°C (30 min) and then analyzed by GC / FID. This is performed using a gas chromatograph equipped with a split / splitless injector, a capillary column, and a flame ionization detector under the following conditions:

[0073] Injector: 290℃, split 30mL Injection volume: 1μL Column: 50m x 0.32mm HP5 1.05μm Carrier gas: Hydrogen, constant flow, 2 mL / min Temperature program: 100°C to 140°C at 10°C / min, then 140°C to 300°C at 5°C / min, then conditioning at 300°C for 5 minutes Detector: FID, at 310°C Hydrogen 30mL / min Air 400mL / min Make-up gas 12mL / min

[0074] Sorbitol is separated and its weight percentage is determined by the internal standard method, for which the GC system is calibrated by analyzing a mixture of sorbitol and an internal standard of known composition.

[0075] According to the invention, sorbitol carboxylic acids are preferred, characterized in that they contain less than 25% by weight, preferably 0.01% to 20% by weight, particularly preferably 0.05% to 10% by weight, of at least one free carboxylic acid, the percentages being based on the total sorbitol carboxylic acid esters, whereby the at least one free carboxylic acid can be present in protonated or neutralized form.

[0076] To determine the content of free carboxylic acids in the sorbitol carboxylic acid esters of the present invention, the acid value is first determined. The weight percentage can be determined from the acid value and the molecular weight of the fatty acid. Suitable methods for determining the acid value are, in particular, those according to DGF CV 2, DIN EN ISO 2114, Ph.Eur.2.5.1, ISO 3682, and ASTM D 974. Those skilled in the art will recognize that, in the case of a mixture of carboxylic acids, GC analysis can be additionally performed after saponification of the sorbitol carboxylic acid ester to determine the average molecular weight of the carboxylic acid mixture present. For this purpose, 0.6 g of the sorbitol carboxylic acid ester of the present invention is boiled under reflux for 4 hours in 25 mL of a 0.5 M KOH solution in ethanol. The pH is then adjusted to 2-3 with sulfuric acid, and the free carboxylic acids are separated by extraction three times with 1 volume each of petroleum ether. The combined extracts are concentrated to approximately 10 mL by evaporation. Suitable methods for determining the fatty acid distribution are those according to DGF C VI 11a, DGF C-VI 10a, and GAT Ring Test 7 / 99. A 0.5 mL aliquot of the petroleum ether extract obtained above is mixed with 0.5 mL of MTBE and 1 mL of trimethylanilinium hydroxide (0.2 M in methanol) in an autosampler vial and analyzed by GC. This is performed using a gas chromatograph equipped with a split / splitless injector, a capillary column, and a flame ionization detector under the following conditions: Injector: 290℃, split 30mL Injection volume: 1μL Column: 30m x 0.32mm HP1 0.25μm Carrier gas: Helium, head pressure 70kPa Temperature program: 80°C to 300°C at 8°C / min, followed by conditioning at 300°C for 20 min Detector: FID, at 320°C Hydrogen 35mL / min Air 240mL / min Make-up gas 12mL / min

[0077] The carboxylic acids are separated into their methyl esters according to their carbon chain length. By evaluating the peak areas, the weight ratios of these carboxylic acid methyl esters to each other can be determined, from which the ratios of the amounts of substance of the related carboxylic acids can be determined using their respective molecular weights. Furthermore, the average molecular weight of this fatty acid mixture can be determined: [Table 1]

[0078] According to the present invention, a sorbitol carboxylic acid ester characterized in that the secondary ester positional isomer is contained in an amount of 5 to 25% by weight, preferably 7 to 15% by weight, and particularly preferably 9 to 13% by weight, of the total monoester component of the sorbitol carboxylic acid ester is preferred.

[0079] According to the present invention, sorbitol carboxylic acid esters characterized in that all monoester components of sorbitol carboxylic acid esters and all diester components of sorbitol carboxylic acid esters each contain at least two positional isomers are preferred.

[0080] According to the present invention, a sorbitol carboxylic acid ester characterized in that the positional isomer in which at least one secondary hydroxyl group is esterified accounts for 25% by weight to 45% by weight, preferably 28% by weight to 39% by weight, and particularly preferably 30% by weight to 37% by weight of the total diester component of the sorbitol carboxylic acid ester.

[0081] The determination of the content of secondary ester positional isomers in all monoester components of sorbitol carboxylic acid esters according to the present invention, the content of triester species relative to the sum of all sorbitol carboxylic acid esters contained, and the content of positional isomers in all diester components in which at least one secondary hydroxyl group is esterified can be carried out by gas chromatography, optionally combined with mass spectrometry (GC-FID and GC-MS): First, 10 mg of a sample of the corresponding sorbitol carboxylic acid ester is dissolved in 1.5 mL of trichloromethane, and then 0.15 mL of N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) is added. Derivatization is carried out at 80 °C for 30 minutes. A sample of the resulting clear solution is analyzed by GC-FID and GC-MS. The measurement parameters are as follows: Gas chromatograph: Agilent 7890 Column: Agilent HP-5 (50 m, 0.32 mm, 0.5 μm) Flow rate: Hydrogen at a constant 2 mL / min (GC-MS: Helium) Temperature control: 80°C, 8°C / min; 300°C, 30 min, injector 1 μL, split 1:20, detector 310°C Detector: FID, 310℃ / GC-MS Scan 35-650 d

[0082] In GC-FID analysis, the esters in a sample are separated according to their total chain length. The proportion of each ester species relative to one another is determined by the area ratio of the GC-FID peaks. Peaks are identified / assigned to individual ester species by GC-MS and, if necessary, by comparison with the retention times of separately prepared and separated standards, e.g., mono- and diesters in which only the primary hydroxyl groups are esterified. This method also allows the content of free protonated carboxylic acids and, in addition, free neutralized carboxylic acids, to be determined, since these are also derivatized.

[0083] A further subject of the present invention is the use of the sorbitol carboxylic acid esters according to the invention as viscosity modifiers, care active ingredients, foam boosters or solubilizers, antibacterial agents, antistatic agents, binders, corrosion inhibitors, dispersants, emulsifiers, film-forming agents, humectants, opacifiers, oral care agents, preservatives, skin care agents, hydrophilic emollients, foam stabilizers and non-ionic surfactants, preferably as viscosity modifiers, emulsifiers, antibacterial agents and hydrophilic emollients, particularly preferably as viscosity modifiers, in particular as thickeners, in particular in cleaning or care formulations.

[0084] The following examples are provided to illustrate the present invention, and are not intended to limit the scope of the present invention, the scope of which is clear from the entire specification and claims, to the embodiments given in the examples.

[0085] Working Example: Various sorbitol carboxylic acid esters were prepared as described below.

[0086] How to determine the number of colors A 25% solution in a mixture of concentrated acetic acid and toluene (3:1) was prepared from the sample to be analyzed and, if necessary, filtered to clarify. An aliquot of this solution (approximately 10 g; enough to fill the cuvette) was measured at room temperature in an 11 mm round cuvette in a Lico 690 spectrophotometer, and the color number indicated was recorded.

[0087] Example 1: Enzymatic esterification of sorbitol with 1.55 eq. of caprylic acid (according to the invention) A mixture of sorbitol (96.5 g, 0.529 mol, 1.00 eq.) and caprylic acid (acid value 389 mg KOH / g, >98%, 118.34 g, 0.821 mol, 1.55 eq.) was heated to 100 °C with stirring and N2 flow. After 1 h, the mixture was cooled to 85 °C, and immobilized Candida antarctica lipase B (6.44 g; Purolite D5619, equivalent to 55747 PLU) was added. The mixture was further stirred at 85 °C and 15 mbar for 24 h, during which the water produced was continuously distilled off. The mixture was then filtered at 80 °C using a Buchner funnel with a black ribbon filter to remove the enzyme. The resulting product had an acid value of 3.0 mg KOH / g.

[0088] Example 1B: Sorbitan ester according to "Example 0" of DE 102009001748 A1 (not according to the invention) A mixture of sorbitol (70% aqueous solution, 390.45 g, 1.50 moles, 1.00 eq.), phosphoric acid (2.9 g), and sodium hydroxide (5.0 g) was dehydrated at 140° C. for 30 minutes. Then, caprylic acid (acid number 389 mg KOH / g, >98%, 334.8 g, 2.32 moles, 1.55 eq.) was added, and the mixture was stirred at 200° C. until the acid number reached 8.1 mg KOH / g.

[0089] Example 1C: Enzymatic esterification of sorbitol with 1.55 eq. caprylic acid according to Biotechnol Bioeng 1995 48 214-221 (not according to the invention) A mixture of sorbitol (96.5 g, 0.529 mol, 1.00 eq.), caprylic acid (acid value 389 mg KOH / g, >98%, 118.34 g, 0.821 mol, 1.55 eq.), and Novozym 435 (57.9 g, 405475 PLU) was stirred at 90 °C and <7 mbar for 24 h, with the water formed being continuously distilled off. The mixture was then filtered at 85 °C through a Büchner funnel equipped with a black ribbon filter to remove the enzyme. The resulting product had an acid value of 2.0 mg KOH / g.

[0090] Example 2: Enzymatic esterification of sorbitol with 2.00 eq. of technical grade oleic acid (according to the invention) A mixture of sorbitol (51.3 g, 0.282 mol, 1.00 eq.) and oleic acid (acid value 200 mg KOH / g, iodine value 92.3 g I2 / 100 g, 157.9 g, 0.563 mol, 2.00 eq.) was heated to 100 °C with stirring and N2 flow. After 1 h, the mixture was cooled to 85 °C, and immobilized enzyme Candida antarctica lipase B (6.28 g; Purolite D5619, equivalent to 54361 PLU) was added. The mixture was further stirred at 85 °C and 20 mbar for 24 h, during which the water produced was continuously distilled off. The mixture was then filtered at 80 °C using a Buchner funnel with a black ribbon filter to remove the enzyme. The resulting product had an acid value of 4.2 mg KOH / g.

[0091] Example 2B: Enzymatic esterification of sorbitol with 1.00 eq. oleic acid according to Biotechnol Bioeng 1995 48 214-221 (not according to the invention) A mixture of sorbitol (100.1 g, 0.549 mol, 1.00 eq.), oleic acid (>99%, 155.1 g, 0.549 mol, 1.00 eq.), and Novozym 435 (38.7 g, 271126 PLU) was stirred at 90 °C and <7 mbar for 24 h, continuously distilling off the water produced. The mixture was then filtered at 85 °C through a Buchner funnel equipped with a black ribbon filter to remove the enzyme. The resulting product had an acid value of 12.8 mg KOH / g.

[0092] Example 3: Enzymatic esterification of sorbitol with 1.50 eq. of stearic acid (according to the invention) A mixture of sorbitol (62.6 g, 0.344 mol, 1.00 eq.) and stearic acid (acid value 198 mg KOH / g, ≥92%, 146.7 g, 0.516 mol, 1.50 eq.) was heated to 115 °C with stirring and N2 sparging. After 1 h, the mixture was cooled to 90 °C, and the immobilized enzyme Candida antarctica lipase B (6.28 g; Purolite D5619, equivalent to 54350 PLU) was added. The mixture was further stirred at 90 °C and <7 mbar for 24 h, during which the water produced was continuously distilled off. The mixture was then filtered at 85 °C using a Buchner funnel with a black ribbon filter to remove the enzyme. The resulting product had an acid value of 6.5 mg KOH / g.

[0093] Example 3B: Enzymatic esterification of sorbitol with 1.50 eq. stearic acid according to Biotechnol Bioeng 1995 48 214-221 (not according to the invention) A mixture of sorbitol (62.6 g, 0.344 mol, 1.00 eq.), stearic acid (acid value 198 mg KOH / g, ≥ 92%, 146.7 g, 0.516 mol, 1.50 eq.), and Novozym 435 (7.77 g, 54393 PLU) was stirred at 90 °C and < 7 mbar for 24 h, continuously distilling off the water formed. The mixture was then filtered at 85 °C through a Büchner funnel equipped with a black ribbon filter to remove the enzyme. The resulting product had an acid value of 10.4 mg KOH / g.

[0094] Example 4: Enzymatic esterification of sorbitol with 1.80 eq. of lauric acid (according to the invention) A mixture of sorbitol (71.4 g, 0.392 mol, 1.00 eq.) and lauric acid (acid value 280 mg KOH / g, ≥99%, 141.3 g, 0.705 mol, 1.80 eq.) was heated to 100 °C with stirring and N2 flow. After 1 h, the mixture was cooled to 95 °C, and immobilized Candida antarctica lipase B (6.38 g; Purolite D5619, equivalent to 55227 PLU) was added. The mixture was further stirred at 95 °C and 20 mbar for 24 h, during which the water produced was continuously distilled off. The mixture was then filtered at 80 °C using a Buchner funnel with a black ribbon filter to remove the enzyme. The resulting product had an acid value of 3.5 mg KOH / g.

[0095] Example 4B: Sorbitol ester according to "Preparation (ii), (a)" of EP 1 755 545 (not according to the invention) A mixture of sorbitol (70% aqueous solution, 390.0 g, 1.50 mol, 1.00 eq.), lauric acid (acid value 280 mg KOH / g, ≥ 99%, 330.0 g, 1.65 mol, 1.10 eq.), and K2CO3 (16 g) was heated to 180 °C with N2 sparging while stirring, and the water produced was continuously distilled off until the acid value reached 3.5 mg KOH / g.

[0096] Example 4C: Sorbitol ester according to "Preparation (ii), (b)" of EP 1755545 (not according to the invention) A mixture of sorbitol (99.0 g, 0.54 mol, 1.00 eq.), methyl laurate (140.0 g, 0.65 mol, 1.20 eq.) and KCO (6 g) was heated with stirring to 160 °C at 50 mbar over 5 hours, while the methanol formed was continuously distilled off.

[0097] Example 4D: Enzymatic esterification of sorbitol with 1.80 eq. of lauric acid according to Biotechnol Bioeng 1995 48 214-221 (not according to the invention) A mixture of sorbitol (71.4 g, 0.392 mol, 1.00 eq.), lauric acid (acid value 280 mg KOH / g, ≥99%, 141.3 g, 0.705 mol, 1.80 eq.), and Novozym 435 (49.8 g, 348253 PLU) was stirred at 90 °C and <7 mbar for 24 h, continuously distilling off the water produced. The mixture was then filtered at 85 °C through a Büchner funnel equipped with a black ribbon filter to remove the enzyme. The resulting product had an acid value of 2.8 mg KOH / g.

[0098] Example 5: Characterization of sorbitol carboxylic acid esters Table 1 compares the parameters determined for examples according to the invention and examples not according to the invention. In particular, it is clear from Examples 4, 4B and 4C that the sorbitol carboxylic acid esters produced by the method according to the invention have a better color than those produced by classical chemical synthesis.

[0099] [Table 2]

[0100] Example 6: Thickening performance in cosmetic formulations The thickening effect of the inventive examples was evaluated in two different formulations compared with the corresponding non-inventive examples. Formulation 1 consisted of 9% SLES, 3% cocamidopropyl betaine, and 0.7% NaCl in water. The pH of Formulation 1 was adjusted to 5.2 with citric acid. Then, 1.1% of each of the above examples was blended over 30 minutes at 60°C with stirring, and the viscosity was measured at 22°C using a Brookfield viscometer (spindle 62, 30 rpm for Examples 1, 1B, 1C, 2, and 2B; spindle 2, 60 rpm for Examples 3, 3B, 4, 4B, 4C, and 4D). Formulation 2 consisted of 5.6% AMC, 4.4% lauryl glucoside, 1.2% coconut glucoside, and 3.6% glutamate in water. The pH of Formulation 2 was adjusted to 5.2 with citric acid. Then, 1.0% of each of the above example materials was added to each formulation at 60°C for 30 minutes while stirring, and the viscosity was measured at 22°C using a Brookfield viscometer (spindle 62, 30 rpm for Examples 1, 1B, 1C, 2, and 2B; spindle 2, 60 rpm for Examples 3, 3B, 4, 4B, 4C, and 4D).

[0101] The viscosity measurement results are shown in Table 2.

[0102] [Table 3]

[0103] The results in Table 2 show that in both formulations, Example 1 according to the present invention has a higher viscosity than Examples 1B and 1C not according to the present invention. The same can be seen in comparisons between Example 2 according to the present invention and Example 2B not according to the present invention, between Example 3 and 3B, and between Example 4 and 4B, 4C, and 4D.

[0104] Example 7: Accelerated Enzyme Reactions The publication Biotechnol Bioeng 1995 48 214-221 describes the use of extremely high amounts of enzyme, i.e., about 494,000 PLU per mole of fatty acid used. Such high enzyme loadings are uneconomical. A preferred loading is about 100,000 PLU or less per mole of fatty acid used. In Example 3 (according to the invention) and Example 3B (not according to the invention), after the reaction was completed and the enzyme was removed, the acid value was determined, and an aliquot (about 30 g) in a 100 mL glass graduated cylinder was left in a heating cabinet at 90 °C for 24 hours. After successful phase separation, the ratio (v / v) of the upper ester phase to the lower sorbitol phase was determined. The results are shown in Table 2.

[0105] [Table 4]

[0106] As is clear from the data shown in Table 2, the process according to the invention has the advantage over the processes described in the prior art that a desirable low acid number is achieved already after a reaction time of 24 hours, as well as a smaller proportion of sorbitol phase separating out in the melt.

[0107] A further advantage of the process according to the invention is found in the comparison of Example 1 with Example 1C, namely that after a reaction time of 24 hours, in the prior art process, the conversion determined by the acid number is in the same range as the conversion according to the invention, despite a 7-fold higher amount of lipase.

[0108] [Table 5]

[0109] A similar picture is found in the comparison of Example 2 and Example 2B, i.e., with the same amount of lipase, after a reaction time of 24 hours, the conversion rate determined by the acid number in the prior art process is clearly lower than the conversion rate according to the invention.

[0110] [Table 6]

[0111] A similar picture is found in comparing Example 4 and Example 4D, i.e., with the same amount of lipase, after 24 hours of reaction time, the conversion rate in the prior art process is in the same range as the conversion rate according to the present invention.

[0112] [Table 7]

[0113] Example formulation [Table 8-1]

[0114] [Table 8-2]

[0115] [Table 8-3]

[0116] [Table 8-4]

[0117] [Table 8-5]

[0118] [Table 8-6]

[0119] [Table 8-7]

[0120] Table 8-8

[0121] Table 8-9

[0122] Table 8-10

[0123] Table 8-11

[0124] Table 8-12

[0125] Table 8-13

[0126] Table 8-14

[0127] Table 8-15

[0128] Table 8-16

[0129] Table 8-17

[0130] Table 8-18

[0131] Table 8-19

[0132] Table 8-20

[0133] Table 8-21

[0134] Table 8-22

[0135] Table 8-23

[0136] Table 8-24

[0137] Table 8-25

[0138] Table 8-26

[0139] Table 8-27

[0140] Table 8-28

[0141] Table 8-29

[0142] Table 8-30

[0143] Table 8-31

[0144] Table 8-32

[0145] Table 8-33

[0146] Table 8-34

[0147] Table 8-35

[0148] Table 8-36

[0149] Table 8-37

[0150] Table 8-38

Claims

1. A method for producing sorbitol carboxylic acid esters using an enzyme, comprising the steps of: A) providing sorbitol and at least one acyl donor, preferably a fatty acid acyl donor, in particular a fatty acid acyl donor selected from fatty acid esters and fatty acids, particularly preferably a fatty acid, B) reacting sorbitol with said at least one acyl donor in the presence of a lipase at a temperature of 75°C to 110°C, preferably 77°C to 100°C, even more preferably 80°C to 95°C to obtain sorbitol carboxylic acid esters; and optionally C) a process step of purifying the sorbitol carboxylic acid ester. characterized in that process step A) comprises blending said sorbitol and said at least one acyl donor at a temperature range of from 80°C to 120°C, preferably from 90°C to 120°C, even more preferably from 95°C to 120°C, even more preferably from 100°C to 120°C for at least 10 minutes, preferably at least 30 minutes, even more preferably at least 60 minutes.

2. 2. The process according to claim 1, wherein the acyl group donor provided in process step A) provides an acyl group derived from a carboxylic acid, in particular a natural fatty acid or a mixture thereof, containing 2 to 34, preferably 4 to 24, particularly preferably 6 to 22, carbon atoms.

3. 3. The process according to claim 1, wherein the sorbitol and the at least one acyl donor make up at least 80% by weight, preferably at least 90% by weight, particularly preferably at least 95% by weight, of the total reaction batch at the start of process step B).

4. 4. The process according to claim 1, wherein in process step B), the water content of the reaction batch as a whole is less than 15% by weight, preferably less than 5.0% by weight, particularly preferably less than 1.0% by weight.

5. The lipases include lipase derived from Thermomyces lanuginosus (accession number O59952), lipase A and B derived from Candida antarctica (accession number P41365), lipase derived from Mucor miehei (accession number P19515), lipase derived from Humicola sp. Lipases derived from Humicola sp. (accession number O59952), Rhizomucor javanicus (accession number S32492), Rhizopus oryzae (accession number P61872), Candida rugosa (accession numbers P20261, P32946, P32947, P3294, and P32949), Rhizopus niveus (accession number P61871), Penicillium camemberti (accession number P25234), Aspergillus niger (accession number P25235), and the like.

5. The method according to claim 1, wherein the lipase is selected from the group consisting of lipases derived from Penicillium niger (ABG73613, ABG73614 and ABG37906) and lipase derived from Penicillium cyclopium (Accession No. P61869), and lipases having at least 60% homology thereto at the amino acid level.

6. 6. The method according to claim 1, wherein process step B) is carried out at a pressure of less than 1 bar, preferably less than 0.5 bar, particularly preferably less than 0.1 bar.

7. 7. The process according to claim 1, wherein process step B) is terminated at the latest 180 hours, preferably 120 hours, particularly preferably 100 hours after the addition of the lipase.

8. 8. The process of claim 1, wherein the molar ratio of provided sorbitol to acyl groups contained in all provided acyl donors is in the range of 1.00:0.50 to 1.00:5.00, preferably 1.00:0.70 to 1.00:3.

00.

9. Sorbitol carboxylic acid ester obtainable by the process according to any one of claims 1 to 8.

10. The sorbitol carboxylic acid ester includes a carboxylic acid ester of sorbitol, a carboxylic acid ester of 1,4-anhydrosorbitol, a carboxylic acid ester of 2,5-anhydrosorbitol, a carboxylic acid ester of 1,5-anhydrosorbitol, and a carboxylic acid ester of isosorbide, and the sorbitol residue contained in the sorbitol carboxylic acid ester is preferably a 1,4-anhydrosorbitol residue, a 2,5-anhydrosorbitol residue, a 1,5 ... and a 2,5-anhydrosorbitol residue.

10. The sorbitol carboxylic acid ester according to claim 9, wherein the weight ratio of the sum of all of the groups and isosorbide residues is greater than 90:10, preferably greater than 93:7, particularly preferably greater than 95:5, and most preferably greater than 96:4, and the molar ratio of esterified primary hydroxyl groups to esterified secondary hydroxyl groups in the carboxylic acid ester of sorbitol is from 80:20 to 20:80, preferably from 70:30 to 30:70, even more preferably from 60:40 to 40:60, and even more preferably from 55:45 to 45:

55.

11. The sorbitol carboxylic acid ester according to claim 9 or 10, wherein the average degree of esterification of the sorbitol carboxylic acid ester contained therein is 0.3 to 4.0, preferably 1.0 to 3.0, particularly preferably 1.1 to 2.7, and especially preferably 1.3 to 2.

6.

12. 12. The sorbitol carboxylic acid ester according to claim 9, wherein the sorbitol carboxylic acid ester contains 0.05 to 40% by weight, preferably 0.2 to 25% by weight, particularly preferably 0.5 to 10% by weight, of free sorbitol.

13. 13. The sorbitol carboxylic acid ester according to claim 9, wherein the sorbitol carboxylic acid ester comprises less than 25% by weight, preferably 0.01% to 20% by weight, particularly preferably 0.05% to 10% by weight, of at least one free carboxylic acid.

14. The sorbitol carboxylic acid ester according to any one of claims 9 to 13, wherein the secondary ester positional isomer is contained in an amount of 5 to 25% by weight, preferably 7 to 15% by weight, particularly preferably 9 to 13% by weight, of the total monoester component of the sorbitol carboxylic acid ester.

15. 15. Use of at least one sorbitol carboxylic acid ester according to any one of claims 9 to 14 as viscosity modifier, care active ingredient, foam booster or solubilizer, antibacterial agent, antistatic agent, binder, corrosion inhibitor, dispersant, emulsifier, film former, humectant, opacifier, oral care agent, preservative, skin care agent, hydrophilic emollient, foam stabilizer and non-ionic surfactant, preferably as viscosity modifier, emulsifier, antibacterial agent and hydrophilic emollient, particularly preferably as viscosity modifier, in particular as thickener, in particular in cleaning or care formulations.

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