Process for obtaining acetoin

Abstract

A process for obtaining acetoin from a medium containing it is provided, the process comprising a dehydration step by pervaporation using a hydrophilic membrane. This process allows for the satisfactory isolation and purification of acetoin, both in terms of quality and yield. Furthermore, it eliminates the need for solvents and avoids the generation of impurities. Figure 1

Description

Title of the invention: Process for obtaining acetoin FIELD OF THE INVENTION

[0001] The present invention relates to a process for obtaining acetoin from a medium comprising it, the process comprising a step of dehydration by pervaporation using a hydrophilic membrane. This process makes it possible to isolate and purify acetoin satisfactorily, both from the point of view of quality and yield. In addition, it makes it possible to dispense with the use of solvents and to avoid the generation of impurities. TECHNICAL BACKGROUND

[0002] Acetoin (3-hydroxybutanone) is a chiral organic molecule of formula C4H8O2 belonging to the class of hydroxylated ketones and comprising two enantiomeric forms. Acetoin comprises two functional groups, a hydroxyl group and a carbonyl group, which make it particularly reactive and prone to decomposition, in particular into acetaldehyde.

[0003] Acetoin is present in trace amounts in many foods, including grapes, raspberries, apples, bananas, corn, honey, and coffee. This molecule is also present in certain cheeses and meats. Finally, this molecule is also a synthetic intermediate in the metabolism of sugars in certain microorganisms.

[0004] Acetoin is, along with diacetyl (2,3-butanedione), one of the molecules that gives butter its characteristic flavor. It can be used as a flavoring agent.

[0005] Acetoin is frequently used in particular in the food industry, particularly in the fields of dairy products, beverages, bakery, Viennese pastries and pastry, to give a "buttery flavor" to products containing it. In this field, regulations require the use of acetoin with a high degree of purity, for example at least 95% (see EC Regulation No. 1334 / 2008).

[0006] Acetoin is also used in other fields, particularly in the fields of perfumery, pharmacy and tobacco.

[0007] Acetoin can be obtained from chemical synthesis processes or biological processes.

[0008] Chemical synthesis processes may use, for example, 2,3-butanedione and 2,3-butanediol as raw materials.

[0009] Biological methods may use wild microorganisms, selected microorganisms or recombinant microorganisms. Microorganisms Recombinant organisms are known which do not naturally produce acetoin or produce it in too low a yield and / or as a synthetic intermediate. For example, recombinant microorganisms have been obtained from the following microorganisms: Bacillus subtilis, Bacillus pumilus, Bacillus methanolicus, Bacillus licheniformis, Corynebacterium glutamicum, Escherichia coli, Eactococcus lactis, Saccharomyces cerevisiae and Serratia marcescens.

[0010] Regardless of the method of production, the quantity and quality of the product obtained may not be sufficient, in particular for use in the food and pharmaceutical fields. In addition, a medium may be obtained comprising impurities, in particular by-products of acetoin, organic residues (biomass) in the case of production with a biological process, as well as other molecules. It is therefore necessary to isolate and purify the acetoin from the medium comprising it.

[0011] A number of purification techniques are known, for example distillation, liquid-liquid extraction or salting-out extraction.

[0012] The effectiveness of these techniques, in particular distillation, may be limited by the fact that acetoin forms an azeotropic mixture with water, the separation then being hindered or limited as soon as the liquid phase and the gaseous phase reach the same water / acetoin composition.

[0013] The use of solvents is not recommended, particularly when the acetoin is intended for the food industry. Indeed, for regulatory reasons, only certain solvents can be used for a product containing acetoin to be labeled "natural". Among the available solvents, only ethyl acetate is both compliant with European regulations and particularly suitable for the purification of acetoin. However, the use of this solvent requires large quantities, which makes the process less economically viable on an industrial scale for efficient extraction. In addition, this solvent does not allow the use of the American NOP (for "national organic program") label.

[0014] International application WO 2021 / 060334 A1 published on April 1, 2021 discloses a purification process using tangential filtration technology implemented by a nanofiltration step, followed by a reverse osmosis step. However, this process does not efficiently achieve residual moisture contents below 50%.

[0015] Thus, there is a real need to provide a process for obtaining acetoin that can be used directly in agri-food preparations. There is also a real need to provide a process for obtaining acetoin in a high yield and at an affordable cost. There is also a real need to provide a process carried out without using solvents, in particular ethyl acetate. There is also a real need to provide a process for obtaining acetoin that can be labeled "natural". Summary of the invention

[0016] The invention relates firstly to a process for obtaining acetoin from a medium to be treated, the process comprising a step of dehydration by pervaporation using a hydrophilic membrane, to obtain a dehydrated medium comprising at least 70% acetoin, by total weight of the treated medium.

[0017] In embodiments, the hydrophilic membrane is selected from the group consisting of hydrophilic polymeric membranes, hydrophilic inorganic membranes, hydrophilic two-dimensional material-based membranes, hydrophilic mixed matrix membranes, or membranes derived therefrom.

[0018] In embodiments, the hydrophilic membrane is a hydrophilic silica-based membrane or a hydrophilic membrane derived therefrom.

[0019] In embodiments, the hydrophilic silica-based membrane is obtained from organoalkoxysilane precursors.

[0020] In embodiments, a negative pressure of -700.105 mPa or more is applied at the permeation surface of the hydrophilic membrane.

[0021] In embodiments, the dehydration step is carried out in the absence of solvents and / or inorganic salts.

[0022] In embodiments, the method comprises a step of pretreatment of the medium to be treated carried out, before the dehydration step, by a technique chosen from the group consisting of centrifugation, frontal filtration and microfiltration.

[0023] In embodiments, the method comprises a step of post-treatment of the treated medium carried out, after the dehydration step, by distillation.

[0024] In embodiments, the medium comprising acetoin is obtained by a biological process carried out using recombinant microorganisms.

[0025] In embodiments, the recombinant microorganisms are yeasts belonging to the genus Saccharomyces.

[0026] The invention relates secondly to acetoin, obtained from the process described opposite.

[0027] The invention relates thirdly to the use of a hydrophilic membrane, as described opposite, to obtain acetoin.

[0028] The present invention makes it possible to meet the needs expressed above.

[0029] Surprisingly, the inventors have demonstrated that acetoin can be isolated and purified satisfactorily, both in terms of quality and yield, by selecting hydrophilic membranes. By using such membranes, only Water and hydrophilic compounds migrate through the membrane into the permeate (filtrate), while acetoin remains in the retentate (treated medium), resulting in a progressive and satisfactory dehydration of the acetoin. This pervaporation dehydration technique also overcomes the separation constraints associated with the formation of azeotropic mixtures.

[0030] The commonly used liquid-liquid extraction technique has the disadvantage of being carried out with solvents, for example ethyl acetate, used in large quantities. Furthermore, disadvantageously, the inventors have demonstrated that this technique leads to the formation of impurities, for example methylallyl acetate, a reaction product between acetoin and ethyl acetate. Finally, this technique does not make it possible to obtain acetoin that can be labeled "natural".

[0031] The technique according to PCT application WO 2021 / 060334 A1 makes it possible to avoid the use of solvents, but is not economically viable, in that the yield of acetoin is too low, due to the formation of a water-acetoin azeotropic mixture and the elimination of a significant part of the acetoin with the water.

[0032] The use of the pervaporation dehydration technique according to the invention, using a hydrophilic membrane, makes it possible to avoid the use of solvent, to avoid the generation of impurities in the final product, to circumvent the separation difficulties linked to the formation of an azeotropic mixture and to obtain a satisfactory yield of acetoin.

[0033] Furthermore, and counter-intuitively, the inventors have also demonstrated that the use of a hydrophilic membrane makes it possible to obtain a process having improved performance compared to a process using an organophilic membrane, i.e. a higher yield and degree of dehydration, even though water is initially the majority in the medium. BRIEF DESCRIPTION OF THE FIGURES

[0034] [Fig. 1] represents a graph concerning the concentration of acetoin and water (mass %) in the retentate as a function of time (min).

[0035] [Fig.2] represents a graph concerning the concentration of acetoin in the retentate (% by mass) and the underpressure at the permeation surface (.105 mPa) as a function of time (min). DETAILED DESCRIPTION

[0036] The invention is now described in more detail and in a non-limiting manner in the following description.

[0037] In the description, unless otherwise indicated, all percentages indicated are mass percentages.

[0038] In a first aspect, the present invention relates to a method for obtaining acetoin from a medium comprising it (medium to be treated), the method comprising a step of dehydration by pervaporation using a hydrophilic membrane. Dehydration step

[0039] The dehydration step consists of bringing the medium to be treated into contact with a first surface of the hydrophilic membrane and applying a negative pressure at the permeation surface (second surface) of the hydrophilic membrane.

[0040] The underpressure applied at the permeation surface of the hydrophilic membrane is -700.105 mPa or more, preferably -300.105 to -0.1.105 mPa, very preferably -100.105 to -105 mPa. The underpressure is defined relative to the pressure at the surface in contact with the medium to be dehydrated.

[0041] The temperature applied at the power supply is 150°C or less, preferably 5 to 100°C, very preferably 30 to 90°C.

[0042] A permeate is therefore gradually formed comprising the water and the hydrophilic compounds having migrated through the hydrophilic membrane (medium to be eliminated), while the residual medium, comprising the acetoin, forms the retentate (treated medium). Hydrophilic membrane

[0043] By "hydrophilic membrane" is meant a membrane which preferentially allows water and hydrophilic molecules to pass through the permeate.

[0044] The hydrophilic membrane may be selected from the group consisting of hydrophilic polymeric membranes, hydrophilic inorganic membranes, membranes based on hydrophilic two-dimensional materials, hydrophilic mixed-matrix membranes or hydrophilic membranes derived therefrom; preferably the hydrophilic membrane is an inorganic membrane or a hydrophilic membrane derived therefrom.

[0045] The hydrophilic inorganic membrane may be chosen from the group consisting of hydrophilic zeolite-based membranes, hydrophilic silica-based membranes, hydrophilic metal-organic framework (MOF) membranes, hydrophilic covalent organic framework (COF) membranes or hydrophilic membranes derived therefrom; preferably the hydrophilic inorganic membrane is a hydrophilic silica-based membrane or a hydrophilic membrane derived therefrom; very preferably the hydrophilic inorganic membrane is a hydrophilic silica-based hybrid membrane. The silica-based hybrid membranes are referred to interchangeably as organic-inorganic silica membranes, organo-silica membranes or organo-silica membranes. ("organosilica membrane") or organosilica hybrid membranes ("organosilica hydrid membrane").

[0046] The hydrophilic silica-based hybrid membrane may be selected from the group consisting of hydrophilic pendant-type organosilica membranes or hydrophilic bridged-type organosilica membranes; preferably hydrophilic bridged silica-based hybrid membranes.

[0047] Silica-based hybrid membranes are known (see the review by X. Ren entitled “Organosilica-based membranes in gas and liquid-phase separation”, Membranes, 2019, 9, 107; the work entitled “Pervaporation, vapourpermeation and membrane distillation - Principles and applications”, Ed. Woodhead Publishing Series in Energy, 2015, in particular chapter 5 entitled “Next-generation pervaporation membranes: recent trends, challenges and perspectives”, 107-141; article by G. Liu entitled “Pervaporation membrane materials: Recent trends and perspectives”, Journal of Membrane Science, 2021, 636).

[0048] Bridged silica-based hybrid membranes can be obtained from organoalkoxysilane precursors (monomers), i.e. alkoxysilane precursors comprising organic groups.

[0049] The organoalkoxysilane precursor may be chosen from organoalkoxysilane precursors comprising one, two, three or more silica atoms.

[0050] The organoalkoxysilane precursor comprising a silica atom may be selected from the group consisting of methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), phenyltriethoxysilane (PhTES), hydroxymethyl(triethoxy)silane (HMTES), 3-aminopropyltriethoxysilane (APTES) and mixtures thereof.

[0051] The organoalkoxysilane precursor comprising two silica atoms may be selected from the group consisting of bis(triethoxysilyl)methane (BTESM), l-2-bis(triethoxysilyl)ethane (BTESE), l,3-bis(triethoxysilyl)propane (BTESP), l,8-bis(triethoxysilyl)octane (BTESO), l-2-Bis(triethoxysilyl)ethylene (BTESEthy), l,2-bis(triethoxysilyl)acetylene (BTESA), l,4-bis(triethoxysilyl)diacetylene (BTESDA), bis(trimethoxysilyl)norbornane (BTMS-Nor), l,2-bis(triethoxysilyl)benzene (BTESB), 2,5-bis[2-triethoxysilyl)ethyl]-1,4-dioxane (BTES-ED), bis[3-(triethoxysilyl)propyl]amine (BTESPA), l,6-diacetoxy-3,4-bis(triethoxysilyl)hexa-2,4-diene (BTES-Ac), 4,6-bis(3-triethoxysilyl-l-propoxy)-l,3-pyrimidine (BTPP), bis(triethoxysilyldimethyl / dipropyl-N,N'-oxalylurea (BTESMOU / BTESMPU) and mixtures thereof; preferably the organoalkoxysilane precursor comprising two silica atoms is chosen from the group consisting of BTESM, BTESE and their mixture; very preferably the organoalkoxysilane precursor comprising two silica atoms is BTESE.

[0052] The organoalkoxysilane precursor may be chosen from the group consisting of TTESPT, TESE-POSS, MTMS, MTES, PhTES, HMTES, APTES, BTESM, BTESE, BTESP, BTESO, BTESEthy, BTESA, BTESDA, BTMS-Nor, BTESB, BTES-ED, BTESPA, BTES-Ac, BTPP, BTESMOU / BTESMPU, TTESPT, TESE-POSS and mixtures thereof; preferably the organoalkoxysilane precursor is chosen from the group consisting of BTESM, BTESE and mixtures thereof; very preferably the organoalkoxysilane precursor is BTESE.

[0053] The organic group can be used to functionalize the al-koxysilane precursors.

[0054] The organic group used to form organic bridges between the organoalkoxysilane precursors can be chosen from the group consisting of methane (CH4), ethane (CH3-CH3), propane (CH3-CH2-CH3), hexane (CH3-(CH2)4-CH3), octane (CH3-(CH2)6-CH3), phenyl, ethylene (CH2= CH2), acetylene (CHCH), diethylenedioxane, norbomane, triazine, pyrimidine and mixtures thereof. For example, organic bridges such as -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -(CH2)6-, -(CH2)8, phenyl, -CH=CH-, an acetylene bridge, a diethylenedioxane bridge, a norbomane bridge, a triazine bridge, a pyrimidine bridge and their mixtures are obtained.

[0055] Silica-based hybrid membranes can be further treated, for example with metals.

[0056] Hydrophilic membranes are commercially available, for example, under the name Hybsi® from Hybsi® (Pervatech®). Environment to be treated

[0057] The medium to be treated corresponds to the starting product (non-pretreated medium) or alternatively to the intermediate product (pretreated medium) which has previously undergone a pretreatment step. The terms “medium”, “composition”, “solution” and “substrate” can be used interchangeably to designate the medium to be treated (and the treated medium where appropriate).

[0058] The medium to be treated may comprise from 2 to 50%, preferably from 6 to 30%, of acetoin, by total weight of the medium. For example, the medium to be treated may comprise from 1 to 5%, or from 5 to 10%, or from 10 to 15%, or from 15 to 20%, or from 20 to 25%, or from 25 to 30%, or from 30 to 35%, or from 35 to 40%, or from 40 to 45%, or from 45 to 50%, of acetoin, by total weight of the medium.

[0059] Acetoin may be present in the form of its (3R)-3-hydroxybutanone enantiomer (natural enantiomer), its (3S)-3-hydroxybutanone enantiomer or the mixture of these two enantiomers (including their racemic mixture).

[0060] The medium to be treated is an aqueous medium. The medium to be treated may comprise at least 15%, preferably at least 45%, very preferably at least 65%, of water, by total weight of the medium.

[0061] The medium to be treated can be obtained from a chemical synthesis process or from a biological process. Treated environment

[0062] After carrying out the dehydration step, a treated medium (corresponding to the retentate) is obtained.

[0063] The treated medium may comprise at least 70% (from 70 to 99%), preferably at least 80% (from 80 to 99%), very preferably at least 90% (from 90 to 99%), of acetoin, by total weight of the medium. For example, the dehydrated medium may comprise from 70 to 75%, or from 75 to 80%, or from 80 to 85%, or from 85 to 90%, or from 90 to 95%, or from 95 to 99%, of acetoin, by total weight of the medium.

[0064] As a corollary, the treated medium may comprise 30% or less (from 1 to 30%), preferably 20% or less (from 1 to 20%), very preferably 10% or less (from 1 to 20%), of water and additional compounds (impurities), by total weight of the medium. Filtration agents (absence)

[0065] The dehydration step is carried out in the absence of solvents, for example ethyl acetate, methyl tert-butyl ether, butyl acetate, dimethyl carbonate, diethyl ether, diethyl carbonate, ethanol, methanol, acetone, isopropanol, acetonitrile, dichloromethane and / or chloroform. In particular, the dehydration step is carried out in the absence of ethyl acetate.

[0066] The dehydration step is carried out in the absence of inorganic salts, for example ammonium sulfate, magnesium sulfate, sodium sulfate, copper sulfate, calcium chloride, potassium hydrogen phosphate (dipotassium phosphate), potassium pyrophosphate, sodium carbonate and / or potassium carbonate. Pre-processing step

[0067] The method may comprise a step of pretreating the medium to be treated, carried out before the dehydration step. In this embodiment, the medium to be treated is pretreated and the pretreated medium, thus obtained, is subsequently dehydrated.

[0068] A pretreatment step may be implemented in order to remove suspended solids in the medium to be treated. In particular, a pretreatment step may be implemented when the acetoin is produced by a biological process and the medium to be treated therefore comprises biomass.

[0069] When the medium comprising acetoin is obtained from a biological process, it may comprise biomass. By "biomass" is meant the material organic of bacterial or fungal, plant or animal origin, preferably organic matter of bacterial or fungal origin. When the medium is obtained from a biological process using bacteria or fungi including yeasts, the biomass may comprise whole microorganisms (living or dead), residues of these microorganisms (residues of nuclei, organelles, cytoplasm, membrane, etc.) and molecules produced by them (proteins, carbohydrates, lipids, etc.). The medium to be treated (not pretreated) may comprise from 1 to 20%, preferably from 1 to 10%, of dry biomass, by total weight of the medium.

[0070] The pretreatment step can make it possible to eliminate at least 80%, preferably at least 90%, of the dry biomass contained in the medium to be dehydrated.

[0071] The pretreatment step can be chosen by the techniques consisting of centrifugation, frontal filtration, microfiltration, ultrafiltration or any other conventional clarification technique. Post-processing step

[0072] The method may comprise a step of post-treatment of the treated medium (retentate), carried out after the dehydration step.

[0073] A post-treatment step may be implemented in order to increase the purity of the acetoin.

[0074] The post-treatment step can be carried out by distillation.

[0075] The process according to the invention is particularly advantageous, in that it makes it possible to overcome the difficulties encountered during the implementation of direct distillation, due to the formation of a water-acetoin azeotropic mixture. Chemical synthesis process of acetoin

[0076] The medium comprising acetoin can be obtained by a chemical synthesis process. Biological process for obtaining acetoin

[0077] The medium comprising acetoin can be obtained by a biological process.

[0078] The biological process can be carried out using microorganisms, including wild microorganisms, selected microorganisms or recombinant microorganisms.

[0079] Wild microorganisms are microorganisms that naturally produce acetoin at usable concentrations. Selected (non-genetically modified) microorganisms are microorganisms with improved performance in terms of acetoin production.

[0080] Recombinant (genetically modified) microorganisms - not naturally producing acetoin or producing it at too low a yield and / or as a synthesis intermediate - may be chosen from the group consisting of Bacillus subtilis, Bacillus pumilus, Bacillus methanolicus, Bacillus licheniformis, Corynebacterium glutamicum, Escherichia coli, Lactococcus lactis, Serratia marcescens and yeasts of the genus Saccharomyces; preferably a microorganism being a yeast of the genus Saccharomyces; very preferably Saccharomyces cerevisiae. Acetoin thus obtained

[0081] The process according to the invention makes it possible to obtain a product comprising at least 70% acetoin, by total weight of the treated medium. EXAMPLES

[0082] Example according to the invention: Process for obtaining acetoin using a hydrophilic membrane Materials

[0083] Medium to be purified: Aqueous solution comprising 10% acetoin, by total weight of the aqueous solution

[0084] Hydrophilic membrane: Hybsi® AR membrane marketed by Hybsi®

[0085] Dehydration device: Device PTU-044 Settings

[0086] Medium temperature: 100°C

[0087] Linear speed (velocity) of feed in medium: 1-2 m / s

[0088] Permeate underpressure (vacuum pressure): -20.105 mPa Water content measurement

[0089] The water content in the retentate and in the filtrate is measured by the Karl Fischer filtration method (KF titration). Measurement of acetoin content

[0090] The acetoin content is measured by HPLC and / or gas chromatography. Dehydration process

[0091] The objective of this process is to obtain the permeation of water from the medium to be treated through the hydrophilic membrane to the permeate and as a corollary the dehydration of acetoin (retentate).

[0092] As illustrated in [Fig. 1], which represents a graph concerning the concentration of acetoin and water (% by mass) in the retentate as a function of time (min), the concentration of water (white squares) decreases and conversely the concentration of acetoin (black circles) increases in the retentate over time. After 485 min of treatment, the concentration of water decreases to about 1.1%, by total weight of the retentate, while the concentration of acetoin increases to about 77%, the difference corresponding to organic residues other than acetoin.

[0093] Comparative example: Process for obtaining acetoin using a organophilic membrane materials

[0094] Medium to be purified: Aqueous solution comprising 10% acetoin, by total weight of the aqueous solution

[0095] Organophilic membrane: PDMS-FS membrane marketed by Pervatech®

[0096] Extraction device: PTU-044 device Settings

[0097] Environment temperature: 55°C

[0098] Medium feed rate: 200 L / h

[0099] Permeate vacuum pressure: from 20.105 mPa to 4.105 mPa Liquid-liquid extraction process

[0100] The objective of this method is to obtain the permeation of acetoin from the medium comprising it through the organophilic membrane towards the filtration agent.

[0101] As illustrated in [Fig.2], which represents a graph concerning the concentration of acetoin in the retentate (left ordinate, mass %) and the underpressure at the permeation surface (right ordinate, X.105 mPa) as a function of time (min), the filtration is not sufficiently selective, in that the migration of acetoin (black circles) through the membrane is also accompanied by a migration of water, despite the organophilic property of the membrane used and despite the application of increasing underpressures (white circles). This insufficient selectivity therefore does not allow acetoin dehydration to be obtained at a useful level. Conclusion

[0102] The tests carried out demonstrate that efficient purification of acetoin is possible by selecting a hydrophilic membrane. Conversely and counter-intuitively, the tests carried out with an organophilic membrane did not give conclusive results, in the absence of sufficient selectivity of the membrane.

Claims

Claims

1. A method for obtaining acetoin from a medium to be treated comprising acetoin, the method comprising a step of dehydration by pervaporation using a hydrophilic membrane to obtain a treated medium comprising at least 70% acetoin, by total weight of the treated medium, in that the hydrophilic membrane is a hydrophilic silica-based membrane or a hydrophilic membrane derived therefrom.

2. A process for obtaining acetoin, according to claim 1, in that the hydrophilic silica-based membrane is a hydrophilic bridged silica-based hybrid membrane.

3. Process for obtaining acetoin, according to claim 2, in that the hydrophilic bridged silica-based membrane is obtained from organoalkoxysilane precursors.

4. A process for obtaining acetoin, according to claim 3, in that the organoalkoxysilane precursor comprises a silica atom and is selected from the group consisting of methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), phenyltriethoxysilane (PhTES), hydroxymethyl(triethoxy)silane (HMTES), 3-aminopropylriethoxysilane (APTES) and mixtures thereof.

5. A process for obtaining acetoin, according to claim 3, in that the organoalkoxysilane precursor comprises two silica atoms and is selected from the group consisting of bis(triethoxysilyl)methane (BTESM), l-2-bis(triethoxysilyl)ethane (BTESE), l,3-bis(triethoxysilyl)propane (BTESP), l,8-bis(triethoxysilyl)octane (BTESO), l-2-Bis(triethoxysilyl)ethylene (BTESEthy), l,2-bis(triethoxysilyl)acetylene (BTESA), l,4-bis(triethoxysilyl)diacetylene (BTESDA), bis(trimethoxysilyl)norbornane (BTMS-Nor), l,2-bis(triethoxysilyl)benzene (BTESB), 2,5-bis[2-triethoxysilyl)ethyl]-1,4-dioxane (BTES-ED), bis[3-(triethoxysilyl)propyl]amine (BTESPA), l,6-diacetoxy-3,4-bis(triethoxysilyl)hexa-2,4-diene (BTES-Ac), 4,6-bis(3-triethoxysilyl-l-propoxy)-l,3-pyrimidine (BTPP), bis(triethoxysilyldimethyl / dipropyl-N,N'-oxalylurea (BTESMOU / BTESMPU) and mixtures thereof.

6. Process for obtaining acetoin, according to one of claims 3-5, in that the organoalkoxysilane precursor is functionalized by a organic grouping.

7. Process for obtaining acetoin, according to claim 6, in that the organic group is chosen from the group consisting of methane (CH4), ethane (CH3-CH3), propane (CH3-CH2-CH3), hexane (CH3-(CH2)4-CH3), octane (CH3-(CH2)6-CH3), phenyl, ethylene (CH2= CH2), acetylene (CHCH), diethylenedioxane, norbomane, triazine, pyrimidine and mixtures thereof.

8. A method for obtaining acetoin, according to one of the preceding claims, in that a sub-pressure of -700.105 mPa or more is applied at the permeation surface of the hydrophilic membrane.

9. Process for obtaining acetoin, according to one of the preceding claims, in that the dehydration step is carried out in the absence of solvents and / or inorganic salts.

10. Process for obtaining acetoin, according to one of the preceding claims, comprising a step of pretreatment of the medium to be treated carried out, before the dehydration step, by a technique chosen from the group consisting of centrifugation, frontal filtration and microfiltration.

11. Process for obtaining acetoin, according to one of the preceding claims, comprising a step of post-treatment of the treated medium carried out, after the dehydration step, by distillation.

12. Process for obtaining acetoin, according to one of the preceding claims, in that the medium comprising the acetoin is obtained by a biological process carried out using recombinant microorganisms.

13. Process for obtaining acetoin, according to the preceding claim 12, in that the recombinant microorganisms are yeasts belonging to the genus Saccharomyces.

14. Use of a hydrophilic membrane, according to one of claims! to 13, for obtaining acetoin.

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