FR2974803A1 - PROCESS FOR THE PREPARATION OF A PARTIALLY PURIFIED GLYCOLIC ACID - Google Patents

Abstract

The subject of the invention is a process for preparing a glycolic acid of fermentative origin, having a colorimetric quality of between 300 and 1000 APHA, and comprises the following steps: clarifying the fermentation medium containing the glycolates so as to obtain a solution of glycolates freed from its insoluble organic impurities, converting the glycolates to glycolic acid, so as to obtain a free glycolic acid solution, optionally eliminating all or part of the organic and / or mineral impurities soluble using a technology separator selected from the group consisting of weak anionic resins and activated carbon or granular black, taken alone or in combination, distilling the free glycolic acid solution, previously concentrated to a solids content of more than 60% by dry weight, preferably between 60 and 80% by dry weight, using a distillation technology allowing a temperature s stay very short, less than 5 min, preferably between 0 and 2 minutes, and recover the glycolic acid thus distilled.

Description

PROCESS FOR THE PREPARATION OF A PARTIALLY PURIFIED GLYCOLIC ACID

The present invention relates to a process for the partial purification of a glycolic acid produced by fermentation. Glycolic acid (HOCH2COOH), or hydroxyacetic acid, is the first compound in the family of alpha-hydroxy carboxylic acids. According to its degree of purity, glycolic acid can be used: for applications requiring very high purity: as a synthesis intermediate, in particular for the manufacture of polymers, for applications requiring a lower purity, so-called "partial": in cosmetology, in textiles, in food or in various industries. This level of purity of glycolic acid is determined by measuring a colorimetric index which reflects its thermal stability. This colorimetric test consists of measuring the coloration of purified glycolic acid after treatment at 180 ° C. for 2 hours. This colorimetric measurement is carried out on a spectrocolorimeter and is expressed in APHA unit. The lower the level of impurities, the lower will be the coloration of glycolic acid. For the purposes of the invention, a "partially purified" glycolic acid then means a glycolic acid having between 300 and 1000 APHA. High purity glycolic acid has less than 300 APHA. The partially purified glycolic acid according to the invention can be used in the following applications: in cosmetology, as a skin care product, most often as a chemical "desquamation" agent, thanks to its small size and its excellent ability to penetrate the skin, - in the textile industry as a dyeing and tanning agent, - in the food processing industry as a flavoring agent and as a preservative, - in the building industry as a cleaning agent for concrete, - in various industries, for the preparation of emulsions, solvents and additives for ink and paint to improve flow and gloss properties. From a commercial point of view, the important derivatives of glycolic acid include methyl glycolate and butyl glycolate. The latter is used as a solvent in certain varnishes because it is nonvolatile and has a good dissolution capacity. Glycolic acid is conventionally prepared chemically. from chloroacetic acid and sodium hydroxide, by hydrogenation of oxalic acid, or by hydrolysis of cyanohydrin derived from formaldehyde. Glycolic acid can also be isolated from natural sources such as sugar cane, sugar beet, pineapple, melons and unripe grapes. Finally, glycolic acid can be prepared enzymatically ("enzymatic bioconversion") but also by fermentation, technical field to which the present invention relates. The production of glycolic acid by fermentation is generally carried out with a microorganism of the genus Escherichia, Aureobasidium, Williopsis, Nocardia or Rhodococcus. It is especially here to use these cells for their natural or acquired ability to perform enzymatic bioconversions. In the patent application WO 2002/068659, there is described, for example, an E. coli expressing a nitrilase or nitrile hydratase activity enabling it to hydrate glycolonitrile to glycolate. This microorganism is then placed in a solution of potassium phosphate containing glycolonitrile to obtain an ammonium glycolate. The pathways of production by Escherichia, Aureobasidium, Williopsis, Nocardia or Rhodococcus prefer the glycolic acid production route from ethylene glycol. In the patent application EP 1,947,079, there is described for example a recombinant Escherichia coli capable of oxidizing ethylene glycol to glycolic acid. This microorganism has thus acquired the ability to convert ethylene glycol to glycolaldehyde by a first enzyme, and the glycolaldehyde thus produced is then converted into glycolic acid by a second enzyme. In the present invention, glycolic acid is more particularly produced by a recombinant E. coli such as for example described by international patent applications WO 2007 / 140,816 and WO 2007 / 141,316. Unlike conventional enzymatic bioconversion routes from glycolonitrile or ethylene glycol as presented above, the production of glycolic acid is achieved by fermentation of a renewable carbon source, such as glucose (used as a source carbonaceous fermentable model). This E. coli host cell is genetically modified to: i) attenuate its glyoxylate consumption pathways to compounds other than glycolate, ii) use NADPH glyoxylate reductase to convert glyoxylate to glycolate, iii) reduce its levels expressing all the glycolate-degrading enzymes, and iv) increasing the flow in the glyoxylate synthesis pathway. This recombinant E. coli is also genetically engineered to increase the bioavailability of intracellular NADPH.

Reduction of glyoxylate consumption pathways is achieved by attenuating at least one of the aceB, glcB, gcl and eda genes. The NADPH glyoxylate reductase cloned into the recombinant host strain is preferably endogenous, or is selected from the group consisting of the ycdW and yiaE genes. Mitigation of the glycolate consumption pathways is achieved by mutation of g1cDEF genes encoding glycolate oxidase or a1dA encoding glycoaldehyde dehydrogenase.

The metabolic flux is increased in the sense of the glyoxylate synthesis pathway by: attenuation of the gene encoding the isocitrate dehydrogenase activity, or attenuation of at least the pta gene coding for the phospho-transacetylase, the ack gene, coding for the acetate kinase, or the poxB gene, encoding pyruvate oxidase, or stimulating the expression of the aceA gene by overexpression of the gene as such, or by attenuation of the iclR or fadR genes.

Finally, the bioavailability of NADPH is increased by attenuation of at least the pgi gene coding for glucose-6-phosphate isomerase, udhA, coding for soluble transhydrogenase, or edd, coding for phosphogluconate dehydratase. .

These glycolic acid production routes by enzymatic bioconversion or by fermentation are accompanied by the search for improved new processes for the purification of glycolic acid, transposable industrially, and adapted to the desired quality of glycolic acid.

The two key unitary stages of the multi-stage purification processes of the state of the art are conventionally: distillation, crystallization.

The first route concerns mainly the distillation of the esterified derivatives of glycolic acid, rather than glycolic acid as such.

Indeed, if the relatively low boiling point of glycolic acid (ca 170 ° C) naturally directs the skilled person to choose distillation as a unit purification step, the difficulty inherent in this technology is that At high temperature, the natural tendency of hydroxy carboxylic acids in general, and glycolic acid in particular, is to polycondensation. Conventional distillation technologies therefore do not make it possible to distill free glycolic acid since there is competition between distillation and condensation of glycolic acid molecules (see international patent applications WO 1992/05138, WO2006 / 069110 and WO 2006/069129). Therefore, the skilled person often ends up giving up using this technology to purify glycolic acid as such, too restrictive in terms of control of heating conditions, and prefer the distillation of esters of the acid glycoly, or its amines or amides derived, the esterification step prior to distillation to block the condensation of glycolic acid.

For example, in EP 2,050,733 it is recommended to produce a cyclic ester of glycolic acid. The operating conditions must, however, be controlled: use a starting aqueous solution containing a mixture of 20 to 50% free glycolic acid and glycolic acid dimer and add a hydroxyl derivative of high boiling point, which will lead to the formation cyclic esters to the detriment of that of oligomers. The addition of compounds of 1-octadecanol, 1-tridecanol, diphenylmethanol, dodecanol, polyalkene alcohol or phenol derivatives of 1-naphthol, 2-naphthol and pyrodecanol or even compounds having two hydroxyl functions of the propylene glycol type However, butylene glycol ... do not make this process particularly attractive. The distillation of amine, amide or dialkylammonium derivatives of glycolic acid in the presence of azeotropic agent is also proposed in the patent application WO 02/074403, but here too, the complexity and heaviness of the technology used are damaging. Purification of glycolic acid by crystallization is therefore often preferred over distillation.

This crystallization is carried out by cooling an aqueous solution of glycolic acid, to obtain glycolic acid of high purity. The crystallization of glycolic acid as such, or conventionally obtained from glycolate, is thus carried out by a prior acidification step using a cation exchange resin, a bipolar electrodialysis or by addition of sulfuric acid, as follows: - crystallization in one step, such as for example described in patent applications WO 2003 / 643,366 or WO 2006/064611, which allows the production of high purity glycolic acid, but in low yield, - so-called "multi-loop" series crystallization, as described in patent application US 2008/0091047, which solves the recovery of a high purity glycolic acid with a satisfactory yield but by complexes and heavy stages of multi-stage crystallization. For the preparation of a partially purified glycolic acid, it may be envisaged to implement less complex crystallization steps.

However, even simplified, this method is far from being considered a method of choice. Indeed, in principle, since the solubility of the glycolic acid in solution in water is very high, a high crystallization yield is obtained only if the temperature is lowered to at least 10 ° C below the point of freezing of the crystal. This requires the implementation of large scale refrigeration systems, incompatible with an industrially profitable process.

In addition, the recovery of the crystals involves solid / liquid separation systems on a large scale, such as the centrifuge.

From all the foregoing, it follows that none of the unit steps of crystallization or distillation is really satisfactory, each step retaining the limitations of its own.

It also results that there remains an unmet need for an effective and economically viable process for even partial purification of glycolic acid. The applicant company has found that this need could be met, against all odds, by the implementation of a main stage of distillation of free glycolic acid, in the presence of water, under particular conditions. As stated above, the purity level of the glycolic acid thus purified is determined by measuring a colorimetric index (HAZEN or APHA color index) which reflects the thermal stability of the glycolic acid produced. This colorimetric measurement is carried out using a spectrocolorimeter scanning wavelengths of the visible range from 380 nm to 780 nm, and is expressed in APHA unit. The measurement protocol is as follows: - Concentrate the glycolic acid solution at 70% dry matter, - Condition 10 g in a clogged hydrolysis tube, - Place the tube in an oven for 2 hours at 180 ° C. Allow the tube to cool to room temperature then measure APHA staining using the spectrocolorimeter. The method according to the invention for preparing a glycolic acid of fermentative origin, having a colorimetric quality of between 300 and 1000 APHA comprises the following steps. 1) to clarify the fermentation medium containing the glycolates, 2) to convert the glycolates to glycolic acid, so as to obtain a free glycolic acid solution, 3) optionally to eliminate in whole or in part the soluble organic and / or inorganic impurities at 1 using a separation technology selected from the group consisting of weak anionic resins and activated carbon, taken alone or in combination, 4) distilling the free glycolic acid solution, previously concentrated to a solids content of more than 60% by weight dry, preferably between 60 and 80 dry weight, using a distillation technology allowing a very short residence time, less than 5 min, preferably between 0 and 2 minutes, and 5) recovery glycolic acid thus distilled.

The first step of this process according to the invention consists in clarifying the fermentation medium containing the glycolates, so as to obtain a solution of glycolates essentially free of its insoluble organic impurities.

The fermentation medium can come from any fermentation producing glycolates, especially bacterial cultures, for example E. coli. As will be exemplified below, according to a preferred embodiment, the selected glycolic acid-producing microorganism is a recombinant Escherichia coli strain as described in WO 2007 / 140,816 and WO 2007 / 141,316, strain of genotype : MG165 AaceB Agcl Ag1cDEFGB AaldA AiclR Apgi :: Cm Aeddeda :: Cm 4udhA :: Cm (pME101-ycdW). Clarification of the fermentation medium refers to the removal of "insoluble organic impurities", i.e., biomass, residual insoluble proteins and insoluble particles. The clarified solution is typically a clear solution.

This elimination of insoluble organic impurities is carried out by any method known as such by those skilled in the art, a method chosen for example from the group consisting of microfiltration, centrifugation and rotary drum filtration.

The second step of the process according to the invention consists in converting glycolates to glycolic acid, so as to obtain a free glycolic acid solution.

This acidification step is carried out by any method known as such by the person skilled in the art, a method chosen for example from the group consisting of electrodialysis on bipolar membranes, ion exchange resins or the addition of strong acid. In the preamble of this second step, if the bipolar electrodialysis is chosen (the bipolar membrane ensuring the dissociation of the water proton and hydroxyl ion), the Applicant Company recommends eliminating the divalent cations (in particular the Mg-2 + ions). and residual Cal-1 that may degrade the membranes of the bipolar electrodialyzer used This preliminary step may be carried out by passing the glycolate solution through a weak cation exchange resin in the presence of an aminophosphoric chelating agent. or diacetic so as to complex the divalent cations.Both the effectiveness of this bipolar electrodialysis step, and in order to increase the conversion yields of glycolate ions to free glycolic acid, it may be proposed to complete this second step process according to the invention by a strong cation exchange resin treatment. entaire can thus allow the conversion of 5 to 20 residual glycolates.

The applicant company then recommends using a strong polystyrenic DVB type cation exchange resin with sulfonic groups. As will be exemplified below, the Applicant Company converts 90% of the glycolates by bipolar electrodialysis and the residual 10% by treatment with strong cation exchange resin. The third step of the process according to the invention consists in optionally eliminating all or part of the soluble organic and / or mineral impurities using a separation technology chosen from the group consisting of weak anionic resins and activated carbon, taken alone or in combination.

Advantageously, the Applicant Company recommends indeed after the total conversion step glycolates in free glycolic acid to perform a step of removing soluble mineral impurities such as inorganic anions by passing on a weak anionic resin having as a skeleton structure polystyrenic (for example a Lewatit S4528 resin in free base form). This step also allows the elimination in part of soluble organic impurities such as amino acids.

In addition to this treatment, it may be then recommended a decolorization step with activated carbon (for example 5% dry matter), having the effect of significantly reducing the levels of soluble organic impurities (coloring precursors and organic nitrogen).

This treatment makes it possible to improve the thermal stability of the glycolic acid produced, as will be exemplified hereinafter. The fourth step of the process according to the invention consists in distilling the free glycolic acid solution, previously concentrated to one dry matter of more than 60% by dry weight, preferably between 60 and 80% by dry weight, using a distillation technology allowing a very short residence time, less than 5 min, preferably between 0 and 2 minutes. The Applicant Company has found that surprisingly and unexpectedly it was possible to purify by distillation of free glycolic acid in aqueous solution (ie still having up to 20% water, more particularly still up to 40% of water), without risk of condensation, if one chooses a technology allowing a distillation of glycolic acid at high temperature in a very short residence time, less than 5 min, preferably between 0 and 2 min. The applicant company recommends carrying out a continuous distillation of thin film, falling stream or scraped film (technology called "short path" by the Anglo-Saxons), preferably a continuous distillation scraped film as will be exemplified below.

The Applicant Company has indeed found that reducing the exposure time of glycolic acid at high temperature advantageously reduces the phenomenon of condensation. The Applicant Company has also found that concentrating the glycolic acid solution, for example at 70% dry matter, makes it possible to avoid the polymerization of glycolic acid while guaranteeing a glycolic acid recovery yield of at least 70%. and a significant reduction in color and its precursors.

Thanks to this particular conduct of the distillation step, it is therefore no longer necessary, as is also generally taught in the state of the art, to distill a glycolic acid of very high dry matter (ie of the order 99.5 dry weight).

The fifth step of the process according to the invention finally consists in recovering the glycolic acid thus distilled. Other features and advantages of the invention will become apparent on reading the nonlimiting examples described below.

Presentation of the analysis methods Measurement of HAZEN staining The measurement of HAZEN staining is carried out directly on a LICO 200 spectrocolorimeter (DR LANGE). The coloration of a 70% glycolic acid solution after thermal test is measured using 10 mm single-use plastic vats and read directly. The HAZEN or APHA color index is used to evaluate the color of almost colorless products. In the light yellow field it is more selective than the iodine color scale, for example, and allows to detect a point of color in an almost colorless liquid. In the 200 to 1000 APHA color range, 10 mm rectangular cuvettes are used; for colorings below 200 APHA, 50 mm cuvettes are used.

Cation determination Cations are measured by atomic emission spectrometry using plasma detection.

Anion Determination Anions such as sulfate, chlorine and phosphate are separated on an anion exchange column, Dionex AS11-HC type, heated to 36 ° C. The detection is carried out using a conductivity meter. The eluent increases its concentration of NaOH gradually. Trifluoroacetic acid is used as an internal standard. Determination of organic acids The organic acids are separated by ion exchange chromatography: 3 columns of Biorad HPX-87H type in series, heated to 85 ° C. and with UV detection at 210 nm. The eluent is 5 mM sulfuric acid. Quantitative analysis is performed by external calibration. Pyruvic, malic, fumaric, lactic, formic and acetic acids are used as standards. Determination of free sugars The determination of glucose and fructose is carried out using solutions prepared according to the protocol of the "glucose, fructose" kit R-Biopharm reference 10139106035. The glucose contents assayed by this method must be less than 1 g / 1 similarly for fructose contents, the amounts of glucose + fructose should be less than 1g / l. Assaying Total Sugars The total glucose assay is performed by hydrochloric hydrolysis. This method makes it possible to quantify the total glucose contained in a sample: acid hydrolysis of the sample with hydrochloric acid for 1 hour at 100 ° C., neutralization, hexokinase determination of glucose released by acid hydrolysis . EXAMPLE 1 Preparation of a glycolic acid having a colorimetric index of 900 APHA Glycolic acid is produced by fermentation of glucose by the strain MG165 AaceB Agcl Ag1cDEFGB AaldA AiclR Apgi :: Cm Aedd-eda :: Cm AudhA :: Cm (pME101-ycdW) cited above (see International Patent Applications WO 2007 / 140,816 and WO 2007 / 141,316). A fermentation must obtained according to the protocol described in the above international patent applications is purified according to the 3 main stages according to the invention: Elimination of biomass and insoluble Acidification Distillation Biomass and insolubles are eliminated by microfiltration tangential having a cutoff threshold of 0.14} gym. The permeate thus obtained is clear and of composition presented in Table 1.

Table 1: Composition of the fermentation broth Compounds Typical content (% / sec) Glycolic acid 58 Citric acid 4,6 Lactic acid 0,3 Succinic acid 1,1 Acetic acid 2,6 Formic acid 0,3 Free glucose 0,1 Total Glucose 0.9 Organic Nitrogen 0.5 NH4 1.3 Na 21.6 K 0.9 Sulfates 1.9 Phosphates 2.4 Cl 0.4 Mg 0.1 Ca Traces Fe Traces The solution thus obtained is treated with resin chelating (Rôhm & Haas IRC 747) at a rate of 2 BV / h to remove divalent cations that would damage bipolar membranes. The fermentation must is then acidified to 90% by bipolar electrodialysis (EUR6 5.55m2 of EURODIA®) then the residual 10% of cations are removed by passage over a strong cationic resin styrenic skeleton (PUROLITE® C150H +) at a rate of 2 BV / h. The acidified solution has the composition given in Table 2.

Table 2: Composition of the Acidified Solution Compounds Typical Content (% / sec) Glycolic Acid 80.5 Citric Acid 7.8 Lactic Acid 1.3 Succinic Acid 1.1 Acetic Acid 0.5 Formic Acid 0.6 Free Glucose (ppm) ) 75 Total glucose (ppm) 500 Organic nitrogen 0.3 NH4 G 0.1 Na G 0.1 KG 0.1 Sulfates 2.7 Phosphates 2.3 Cl 0.5 Mg G 0.1 Ca traces Fe Traces APHA staining 1000 (out of range) after thermal test This solution is then concentrated to 70% of MS before being distilled on short-path evaporator (VTA 0.045m ') under the following conditions: supply at ambient Tp, flow rate 450 g / h , Tp evaporator 140 ° C and 30mBar. The recovery yield of glycolic acid is 70 o. Table 3. Distillate Composition Compounds Typical Content (% / sec) Glycolic Acid 91.3 Citric Acid 0.5 Lactic Acid 3.2 Succinic Acid 2.1 Acetic Acid 2 Formic Acid 0.4 Free Glucose (ppm) <20 Total glucose (ppm) <20 Organic nitrogen 80 ppm dry APHA 900 coloring after thermal test The process according to the invention allows a significant improvement in the thermal stability of the glycolic acid produced.

In addition, the short residence time imposed by short path distillation technology, allowing the presence of water in the raw material makes it possible to obtain a distillate with a very low content of oligomers (2% of dimers).

Finally, glycolic acid is of satisfactory purity for industrial applications (the main impurities are organic acids which are not harmful for industrial cleaning, for example).

EXAMPLE 2 Preparation of a glycolic acid having a colorimetric quality of 700 APHA The fermentation wort is acidified as described in Example 1. It is then passed over anionic resin with a styrene skeleton (Lewatit® S4528 in free base form) . The composition of the medium at the anionic resin outlet is shown in Table 4 below.

Table 4: Composition of the acidified solution treated with anionic resin Compounds Typical content (% / sec) Glycolic acid 89.3 Citric acid <0.02 Lactic acid 1.3 Succinic acid 1.3 Acetic acid 4.5 Formic acid G 1 , 0 Free Glucose (ppm) 75 Total Glucose (ppm) 500 Organic Nitrogen 410 ppm / sec NH4 G 0.1 Na G 0.1 KG 0.1 Sulfates <0.02 Phosphates <0.02 Cl <0.02 Mg G 0.1 Ca Traces Fe Traces This solution is then concentrated to 70% of MS before being distilled on short-path evaporator (VTA 0.045m2) under the following conditions: feed at ambient Tp, flow rate 450 g / h, Tp evaporator 140 ° C and 30mBar. The recovery yield of the glycolic acid is 70 and the thermal stability of the distillate is improved as shown in Table 5. Table 5: Composition of the distillate Compounds Typical content (% / sec) Glycolic acid 98 Citric acid <0.02 Lactic Acid 1 Succinic Acid 0.5 Acetic Acid 0.3 Formic Acid 0.2 Free Glucose (ppm) <20 Total Glucose (ppm) <20 Total Nitrogen (ppm) 44 APHA 700 Color After Thermal Test Addition of resin anion removal step also made it possible to retain staining precursors. The quality of the distillate is thus improved. EXAMPLE 3 Preparation of a glycolic acid having a colorimetric quality of 400 APHA The fermentation broth is clarified, acidified and demineralized under the conditions described in Examples 1 and 2. A fading step with 5% (w / w dry) particulate activated charcoal (Norit SX +) is performed to remove more soluble organic impurities and staining precursors. The contact time is 1 hour at room temperature, then the activated carbon is filtered. The composition of the filtrate is shown in Table 6.

Table 6: Composition of the activated carbon treated demineralized solution Compounds Typical content (% / sec) Glycolic acid 92.7 Citric acid <0.02 Lactic acid 1 Succinic acid 0.5 Acetic acid 0.2 Formic acid 0.2 Free Glucose (ppm) 50 Total Glucose (ppm) 200 Organic Nitrogen 200 (ppm) NH4 G 0.1 Na G 0.1 KG 0.1 Sulfates <0.02 Phosphates <0.02 Cl <0.02 Mg G 0 This solution is then concentrated to 70% of MS before being distilled on short-path evaporator (VTA 0.045 m 2) under the following conditions: feeding at ambient Tp, flow rate 450 g / h, Tp evaporator 140 ° C and 30mBar.5 The recovery yield of glycolic acid is 70 and the thermal stability of the distillate is improved as shown in Table 7. Table 7: Composition of the distillate Compounds Typical content (% / sec) Glycolic acid 98 Citric Acid <0.02 Lactic Acid 1 Succinic Acid 0.5 Acetic Acid 0.3 Formic Acid 0.2 Free Glucose (ppm) Total glucose (ppm) 100 Total nitrogen (ppm) <20 APHA 400 coloring after thermal test These operating conditions make it possible to considerably improve, within the limit imposed by the Applicant Company, the thermal stability of the glycolic acid.

Claims (6)

REVENDICATIONS1. Process for the preparation of a glycolic acid of fermentative origin, having a colorimetric quality of between 300 and 1000 APHA, comprising the following steps: 1) clarifying the fermentation medium containing the glycolates so as to obtain a solution of glycolates freed from its insoluble organic impurities, 2) convert the glycolates to glycolic acid, so as to obtain a solution of free glycolic acid, 3) optionally eliminating all or part of the soluble organic and / or mineral impurities using a separation technology chosen from the group consisting of weak anionic resins and activated carbon or granular black, taken alone or in combination, 4) distilling the free glycolic acid solution, previously concentrated to a dry matter of more than 60 by dry weight, preferably between 60 and 80 by dry weight, using a distillation technology allowing a time of very short stay, less than 5 minutes, preferably between 0 and 2 minutes, and 5) recover the glycolic acid thus distilled. 2. Method according to claim 1, characterized in that the step 1) of clarifying the fermentation medium is carried out using a method selected from the group consisting of microfiltration, centrifugation and rotary drum filtration. . 3. Method according to either of claims 1 and 2, characterized in that the step 2) of converting glycolates to glycolic acid is carried out using a method selected from the group consisting of electrodialysis on bipolar membranes, ion exchange resins or the addition of strong acid.4. Process according to any one of Claims 1 to 3, characterized in that the distillation step with a very short residence time is carried out using a method chosen from the group consisting of continuous thin-film distillation, falling stream and scraped film. 5. Use of the glycolic acid obtained according to the process of any one of the preceding claims as a skin peeling agent, dyeing and tanning agent, as a preservative, as a cleaning agent, and as an ink additive and painting. 6. Use of the glycolic acid obtained according to the process of any one of claims 1 to 4 in the cosmetic, food, textile, building and various industries.