Process for the preparation of low-color alkyl polyglycosides involving prior neutralization of the reaction medium

Abstract

A process for preparing alkyl polyglycosides having a color equal to or less than 1.5 VCS is disclosed, which comprises successively: (a) a glycosylation step (a) consisting in a reaction between at least one alcohol of formula (I) and at least one reducing sugar of formula (III): HO-(G)-H(III) in the presence of at least one acid catalyst (CA) at a minimum temperature of 100° C. and a maximum temperature of 120° C.; (b) a step (b) of pre-neutralizing the reaction medium from step (a); (c) a step (c) of removing the reducing sugar of formula (III) that did not react in step (a) from the pre-neutralized reaction medium obtained in step (b); (d) a step (d) of neutralizing the reaction medium from step (c) with an aqueous solution containing a base agent (Ab); and (e) a step (e) of recovering at least one composition (C) having a color equal to or less than 1.5 VCS.

Description

[Technical field]

[0001] The present invention relates to a method for preparing low color alkyl polyglycosides (color less than 1.5 VCS) with a carbonate neutralizing agent.

[0002] Alkyl polyglycosides, or APGs, are perhaps the best example of bio-based surfactants currently available on the market. Their molecular structure is characterized by the simultaneous presence of a hydrophilic head derived from a reducing sugar (D-glucose, D-xylose, or D-rhamnose are the reducing sugars that are mainly available on an industrial scale) and a lipophilic hydrocarbon chain of various lengths (see formula I: simplified structure of APGs). [ka] [Background technology]

[0003] Their industrial-scale production methods are relatively simple, using as raw materials: i) crystalline glucose, or xylose, or rhamnose, obtained respectively from the complete hydrolysis of wheat, corn, or potato starch, or from the hydrolysis of wood hemicellulose, and ii) fatty alcohols from the petrochemical industry (hydrogenation of the methyl esters obtained in the transesterification of vegetable triglycerides).The Fischer glycosylation reaction then consists in linking these two raw materials together by forming a covalent chemical bond, for example in the reaction (II) between glucose and an alcohol. [ka]

[0004] To carry out this glycosylation reaction, an acid catalyst of inorganic or organic origin is required, and an excess of alcohol is purposefully introduced, thus acting as reactant and solvent. At the end of the reaction, the APG is dispersed or dissolved in the excess of unreacted alcohol. APGs are differentiated by the nature and length of the hydrocarbon alkyl chain R, and by their average degree of polymerization DP, which is greater than 1 but less than or equal to 2.5.

[0005] At the end of the glycosylation reaction stage, a neutralization step is carried out to deactivate the catalyst and stop the reaction.

[0006] Depending on the length of the alkyl chain of the alcohol and the associated use, the alcohol is either removed or retained.

[0007] The neutralization step depends on the length of the hydrocarbon alkyl chain. If the latter has less than 12 carbon atoms, neutralization is carried out with aqueous sodium hydroxide. The excess fatty alcohol present at the end of glycosylation is removed by high vacuum or molecular distillation or by evaporation, generally using falling or short-path thin-film evaporators, and the collected APG concentrate is finally dissolved in water. The commercial product thus obtained is therefore in the form of an aqueous APG solution with a weight concentration between 40% and 80%.

[0008] When the hydrocarbon alkyl chain R has a number of carbon atoms greater than or equal to 12, neutralization is generally carried out with sodium or potassium hydroxide alone or in combination with a reducing agent, such as sodium borohydride (NaBH4) or sodium hypophosphite (NaH2PO2), as described in the European patent published under the number EP 0 077 167, the European patent application published under the number EP 0 338 151 A1, and the European patent application published under the number EP 0 388 857 B1. The mixture of APG and excess fatty alcohol is isolated after neutralization and is solid as such. The ratio of APG to fatty alcohol depends on the molar stoichiometry initially adopted with respect to the raw materials and their reactivity. However, a ratio of 5% to 30% by weight of APG and 70% to 95% by weight of fatty alcohol is generally found. For example, the resulting composition may be in the form of a solid, for example in the form of flakes or beads, or in the form of a liquid, depending on the nature of the hydrocarbon alkyl chain R.

[0009] However, the neutralization step with bases (e.g. NaOH, KOH) from the prior art of APGs having a hydrocarbon alkyl chain R with a number of carbon atoms greater than or equal to 12 to achieve a pH of a 5 wt. % dispersion in water of the neutralization medium between 5.5 and 7.5 leads to a noticeable coloration of the product.

[0010] For the purposes of the present invention, "measurement of the pH of a 5% by weight dispersion in water" means an analytical method for measuring the pH of a dispersion of an APG-based composition according to the proviso of NF EN 1262, said measurement being carried out by potentiometric measurements using a combined pH electrode (aqueous medium) and a pH meter.

[0011] This coloration can impair the organoleptic properties of the final product into which the APG composition is incorporated. For this reason, a solution is provided to minimize the coloration of compositions containing APGs having a hydrocarbon alkyl chain R with a carbon number of 12 or more. To obtain such low color (<1.5 VCS) compositions based on APGs having a hydrocarbon alkyl chain R with a carbon number of 12 or more, two solutions known in the prior art are conventionally used.

[0012] For the purposes of the present invention, a "low color composition" means a composition having a Gardner color scale defined by DIN-ISO 4630 of 1.5 VCS or less. The Gardner color scale is measured using a LICO 200 / Dr LANGE (or equivalent) colorimeter, which measures light transmission on any medium. Such a colorimeter is operated with a halogen lamp corresponding to standard illuminant C defined by DIN 5033 and with a standard observer having a 2° field of view. During the measurement, a reference radiation beam compensates for the variations in the recorded values ​​due to lamp and temperature differences.

[0013] The first solution consists in combining the base used with a reducing agent. Among these reducing agents, sodium borohydride (NaBH4) or sodium hypophosphite (NaH2PO2) can be mentioned. This solution is not entirely problem-free. Although very effective, especially in minimizing the coloration of the treated composition, NaBH4 is a reducing agent that is dangerous to handle and use (corrosive products, release of hydrogen). NaH2PO2 itself is not very effective, even when introduced in high concentrations.

[0014] A second solution, commonly used to minimize the color of compositions based on APG with a hydrocarbon chain R with a number of carbon atoms greater than or equal to 12, and described in the prior art, involves decolorization with hydrogen peroxide (H2O2) during a final step. Although effective, this step is however time-consuming, since it is necessary to adjust the pH value of a 5% by weight dispersion in water to between 7.0 and 7.5, while maintaining the oxidizing power of the medium by adding H2O2. This step, which is difficult to carry out, can last several hours, thus significantly increasing the production time and reducing productivity. Summary of the Invention [Problem to be solved by the invention]

[0015] Therefore, the technical problem to be solved is to find an alternative to the neutralization of APG compositions having a hydrocarbon alkyl chain R with a number of carbon atoms equal to or greater than 12. This alternative needs to be effective and easy to implement while guaranteeing a color of 1.5 VCS or less without a bleaching step. [Means for solving the problem]

[0016] One of the solutions of the present invention is a composition (C) having a color of 1.5 VCS or less, which, for 100% of its weight, comprises: i) an amount of ≧40% and ≦95% by weight, preferably ≧50% and ≦95% by weight, and even more preferentially ≧70% and ≦90% by weight, of formula (I): an alcohol of formula (I) R-OH (wherein R represents a linear or branched, saturated or unsaturated hydrocarbon group which may contain at least one hydroxyl functional group and may contain from 12 to 22 carbon atoms), or a mixture of alcohols of formula (I); ii) in an amount of ≧5% by weight and ≦60% by weight, preferably ≧5% by weight and ≦50% by weight, and even more preferentially ≧10% by weight and ≦30% by weight, of formula (II): a composition (C1) represented by RO-(G)xH (II) (wherein residue G represents a residue of a reducing sugar, R represents a group as defined in formula (I), and x, which indicates the average degree of polymerization of residue G, represents a decimal number greater than 1.05 and less than or equal to 2.5), or a mixture of compositions (C1) of formula (II); A method for preparing composition (C), in which the sum of the weight proportions of the compounds of formulae (I) and (II) in composition (C) is understood to be 100% by weight, comprising the steps of: The above method: a) a glycosylation step a) consisting of a reaction between at least one alcohol of formula (I) and at least one reducing sugar of formula (III): HO-(G)-H (III) in the presence of at least one acid catalyst (CA) at a temperature of ≧100° C. and ≦120° C., preferentially ≧100° C. and ≦115° C., even more preferentially ≧100° C. and ≦110° C., wherein the acid catalyst (CA) is selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, hypophosphorous acid, methanesulfonic acid, para-toluenesulfonic acid, trifluoromethanesulfonic acid and acidic ion exchange resins; b) pre-neutralizing the reaction medium from step a), the pre-neutralization being carried out so as to obtain a reaction medium in which a 5 wt. % dispersion in water has a pH of 3.5 to 5.5; c) removing the reducing sugar of formula (III) that has not reacted in step a) from the preneutralized reaction medium obtained in step b); d) a base agent (Ab) which is: ·Formula (IVa): XnCO3(IVa) wherein X represents a sodium or potassium atom and n is an integer equal to 2, or X represents a calcium or magnesium atom and n is an integer equal to 1, ·Formula (IVb): Y(HCO3)m (IVb) wherein Y represents a sodium or potassium atom and m is an integer equal to 1, or Y represents a calcium or magnesium atom and m is an integer equal to 2, Step d) of neutralizing the reaction medium from step c) with an aqueous solution containing a basic agent (Ab) selected from the group consisting of: Step d) in which the neutralization is carried out so as to obtain a reaction medium in which a 5% by weight dispersion of the reaction medium in water has a pH between 5.5 and 7.5; e) recovering at least one composition (C) having a color of 1.5 VCS or less; The preparation method comprises the steps of: DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The color number characterizing the composition (C) prepared by the method that is the subject of the present invention is the Gardner color number defined by DIN-ISO 463. The Gardner color number is measured using a LICO 200 / Dr LANGE (or equivalent) colorimeter that performs light transmission measurements on any medium. Such a colorimeter is operated with a halogen lamp that corresponds to the standard illuminant C defined by DIN 5033 and with a standard observer with a 2° field of view. During the measurement, a reference radiation beam compensates for the variations in the recorded values ​​due to lamp and temperature differences.

[0018] The unit expressing the Gardner color scale characterizing the compositions (C) prepared by the process that is the subject of the present invention is the VCS.

[0019] Optionally, the method according to the invention may have one or more of the following features: said composition (C1) ■ Sum: a1+a2+a3+a4+a5 is equal to 1, Formulas (II1), (II2), (II3), (II4) and (II5) in respective molar ratios a1, a2, a3, a4 and a5 such that the sum a1+2a2+3a3+4a4+5a5 is equal to x: RO-(G)1-H(II1), RO-(G)2-H(II2), RO-(G)3-H(II3), RO-(G)4-H(II4), RO-(G)5-H(II5), consisting of a mixture of compounds represented by: composition (C) comprises a reducing sugar of formula (III) in an amount equal to or less than 2% by weight, more particularly equal to or less than 1% by weight, HO-(G)-H(III); It is understood that the sum of the weight proportions of the compounds of formulae (I), (II) and (III) in composition (C) is equal to 100% by weight; - the basic agent (Ab) contained in the aqueous solution used in the neutralization step d) is selected from sodium carbonate (Na2CO3) or sodium bicarbonate (NaHCO3); the pre-neutralization step b) is carried out with at least one of the following compounds: sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH4OH), monoethanolamine, diethanolamine, triethanolamine and triethylamine; - the pre-neutralization step b) is carried out with one of the following compounds: sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3) and calcium carbonate (CaCO3); - the reducing sugar of formula (III) selected for glycosylation in step a) is selected from the members of the group consisting of glucose, xylose, arabinose and rhamnose; - step c) of removing the reducing sugar of formula (III) is carried out by filtration, centrifugation or sedimentation; - in step d), the aqueous solution of the basic agent (Ab) comprises 10% by weight to 25% by weight of said basic agent (Ab); step a) comprises the following successive sub-steps: i) introducing an alcohol of formula (I) or a mixture of alcohols of formula (I) into a reactor (Re) equipped with a mechanical stirrer and a vacuum device; ii) heating the alcohol of formula (I) to a temperature of 80° C. to 90° C. with mechanical stirring; iii) charging a reducing sugar of formula (III) into a reactor (Re); iv) introducing an acid catalyst (CA) into the reactor (Re); v) heating, under partial vacuum, the reaction medium from substep iv) present in the reactor (Re) to a temperature between 100° C. and 110° C. for the duration of the reaction; vi) cooling the reaction medium from substep v) to a temperature of 70° C. to 80° C.; Contains; the group R is selected from the following groups: lauryl (or n-dodecyl), myristyl (or n-tetradecyl), n-pentadecyl, cetyl (or n-hexadecyl), n-heptadecyl, stearyl (or n-octadecyl), palmitoleyl (or 9-hexadecenyl), oleyl (or 9-octadecenyl), linoleyl (9,12-octadecadienyl), linolenyl (or 6,9,12-octadecatrienyl), nonadecyl, arachidyl (or n-eicosyl), behenyl (or n-docosyl), erucyl (13-docosenyl) or 12-hydroxystearyl; the group R is selected from the following groups: 2-hexyloctyl, 2-hexyldecyl, 2-hexyldodecyl, 2-octyldecyl, 2-octyldodecyl, 2-decyltetradecyl, isostearyl (or 16-methylheptadecyl) or isomyristyl (or 13-methyltridecyl); - the acid catalyst (CA) is selected from the members of the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, hypophosphorous acid, methanesulfonic acid, para-toluenesulfonic acid, trifluoromethanesulfonic acid and acidic ion exchange resins; - during substeps ii) to iv), the reactor (Re) is inerted under nitrogen; - the method comprises, between substeps ii) and iii), a vacuum step, preferably at a pressure equal to or less than 50 mbar; - substep vi) is carried out at atmospheric pressure.

[0020] The use of the carbonate of formula (IVa) or the hydrogen carbonate of formula (IVb) does not contribute to an increase in the color of composition (C) (so the presence of a reducing agent is unnecessary), but neutralizes a 5% by weight dispersion of composition (C) to the desired pH (values ​​between 5.5 and 7.5). The use of a base agent (Ab) makes it possible to avoid a decolorization step involving the use of peroxide agents or the like, since it allows a color of 1.5 VCS or less to be achieved.

[0021] The term "reducing sugar" in the definition of formula (II) and the definition of formula (III) refers to saccharide derivatives that do not have in their structure a glycosidic bond formed between the anomeric carbon and the oxygen of the acetal group, as defined in the reference publication: "Biochemistry", Daniel Voet / Judith G. Voet, page 250, John Wiley & Sons, 1990.

[0022] The oligomeric structure (G)x present in formula (II) may be any isomer relating to either optical isomerism, geometric isomerism or positional isomerism, and it may also represent a mixture of isomers.

[0023] In formula (II) as defined above, the group R is attached to G via the anomeric carbon of the saccharide residue to form an acetal functionality.

[0024] According to a particular aspect of the invention, in the definition of the compounds of formula (II) and formula (III), G represents the residue of a reducing sugar selected from glucose, dextrose, sucrose, fructose, idose, gulose, galactose, maltose, isomaltose, maltotriose, lactose, cellobiose, mannose, ribose, xylose, arabinose, lyxose, allose, altrose, rhamnose, dextran or talose.

[0025] According to one particular aspect of the invention, in the definition of the compound of formula (II), G represents the residue of a reducing sugar chosen from the residues of glucose, xylose, arabinose or rhamnose, and x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.5.

[0026] According to a further particular aspect of the invention, in the definition of the compound of formula (II), G represents the residue of a reducing sugar chosen from the residues of glucose, xylose, arabinose or rhamnose and x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.0, more particularly greater than or equal to 1.25 and less than or equal to 2.0.

[0027] According to another particular aspect of the invention, the reducing sugar of formula (III) is selected from the members of the group consisting of glucose, dextrose, sucrose, fructose, idose, gulose, galactose, maltose, isomaltose, maltotriose, lactose, cellobiose, mannose, ribose, xylose, arabinose, lyxose, allose, altrose, rhamnose, dextran or talose.

[0028] According to a more particular embodiment of the invention, the reducing sugar of formula (III) is chosen from glucose, xylose, arabinose or rhamnose.

[0029] The method according to the invention consists in pre-neutralizing the medium at the end of the glycosylation reaction in order to achieve a pH of a 5% by weight dispersion of said medium in water of between 3.5 and 5.5. This pre-neutralization can be carried out using alkali metal or alkaline earth metal carbonates, alkali metal or alkaline earth metal hydrogen carbonates or any other base known to those skilled in the art. The remaining reducing sugars of formula (II) are subsequently removed by filtration and an aqueous solution of a basic agent (Ab) is added to achieve a pH of a 5% by weight dispersion of composition (C) in water of between 5.5 and 7.5.

[0030] According to a particular embodiment, one of the subjects of the above method is a composition (C) having a color of less than or equal to 1.5 VCS and comprising, for 100% of its weight: - a mixture (M1) of 45% to 55% by weight of alcohols of formula (I), which comprises, relative to 100% of the weight of said mixture (M1), 50% by weight of alcohols of formula (I) in which R represents an n-hexadecyl group and 50% by weight of alcohols of formula (I) in which R represents an n-octadecyl group, - 45% to 54% by weight of at least one composition (C1) represented by formula (II) in which G represents a glucosyl or α,β-D-glucopyranosyl radical obtained by removal of the hemiacetal hydroxyl group of α,β-D-glucopyranose, x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.0, and R represents an n-hexadecyl radical and an n-octadecyl radical, - less than 1% by weight of glucose, The present invention relates to the preparation of a composition (C) comprising:

[0031] According to a particular embodiment, one of the subjects of the above method is a composition (C) having a color of less than or equal to 1.5 VCS and comprising, for 100% of its weight: - a mixture (M'1) of 45% to 55% by weight of alcohols of formula (I), which contains, relative to 100% of the weight of said mixture (M'1), 70% by weight of alcohols of formula (I) in which R represents an n-hexadecyl group and 30% by weight of alcohols of formula (I) in which R represents an n-octadecyl group, - 45% to 54% by weight of at least one composition (C1) represented by formula (II) in which G represents a glucosyl or α,β-D-glucopyranosyl radical obtained by removal of the hemiacetal hydroxyl group of α,β-D-glucopyranose, x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.0, and R represents an n-hexadecyl radical and an n-octadecyl radical, - less than 1% by weight of glucose, The present invention relates to the preparation of a composition (C) comprising:

[0032] According to a particular embodiment, one of the subjects of the above method is a composition (C) having a color of less than or equal to 1.5 VCS and comprising, for 100% of its weight: a mixture (M''1) of 75% to 90% by weight of alcohols of formula (I), which comprises, relative to 100% of the weight of said mixture (M''1), 50% by weight of alcohols of formula (I) in which R represents an n-hexadecyl group and 50% by weight of alcohols of formula (I) in which R represents an n-octadecyl group, - 10% to 24% by weight of at least one composition (C1) represented by formula (II) in which G represents a glucosyl or α,β-D-glucopyranosyl radical obtained by removal of the hemiacetal hydroxyl group of α,β-D-glucopyranose, x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.0, and R represents an n-hexadecyl radical and an n-octadecyl radical, - less than 1% by weight of glucose, The present invention relates to the preparation of a composition (C) comprising:

[0033] According to a particular embodiment, one of the subjects of the above method is a composition (C) having a color of less than or equal to 1.5 VCS and comprising, for 100% of its weight: - a mixture (M'''1) of 75% to 90% by weight of alcohols of formula (I), which comprises, relative to 100% of the weight of said mixture (M'''1), 70% by weight of alcohols of formula (I) in which R represents an n-hexadecyl group and 30% by weight of alcohols of formula (I) in which R represents an n-octadecyl group, - 10% to 24% by weight of at least one composition (C1) represented by formula (II) in which G represents a glucosyl or α,β-D-glucopyranosyl radical obtained by removal of the hemiacetal hydroxyl group of α,β-D-glucopyranose, x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.0, and R represents an n-hexadecyl radical and an n-octadecyl radical, - less than 1% by weight of glucose, The present invention relates to the preparation of a composition (C) comprising:

[0034] According to a particular embodiment, one of the subjects of the above method is a composition (C) having a color of less than or equal to 1.5 VCS and comprising, for 100% of its weight: - 75% to 90% by weight of an alcohol of formula (I) in which R represents an n-tetradecyl group, - 10% to 24% by weight of at least one composition (C1) represented by formula (II) in which G represents a glucosyl or α,β-D-glucopyranosyl group obtained by removal of the hemiacetal hydroxyl group of α,β-D-glucopyranose, x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.0, and R represents an n-tetradecyl group; - less than 1% by weight of glucose, The present invention relates to the preparation of a composition (C) comprising:

[0035] According to a particular embodiment, one of the subjects of the above method is a composition (C) having a color of less than or equal to 1.5 VCS and comprising, for 100% of its weight: - from 75% to 90% by weight of a mixture of alcohols of formula (I) in which R represents the n-dodecyl, n-tetradecyl, n-hexadecyl and n-octadecyl radicals, - 10% to 24% by weight of at least one composition (C1) represented by formula (II) in which G represents a glucosyl or α,β-D-glucopyranosyl group obtained by removal of the hemiacetal hydroxyl group of α,β-D-glucopyranose, x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.0, and R represents an n-dodecyl group, an n-tetradecyl group, an n-hexadecyl group, or an n-octadecyl group, - less than 1% by weight of glucose, The present invention relates to the preparation of a composition (C) comprising:

[0036] According to a particular embodiment, one of the subjects of the above method is a composition (C) having a color of less than or equal to 1.5 VCS and comprising, for 100% of its weight: - from 75% to 90% by weight of a mixture of alcohols of formula (I) in which R represents an n-eicosyl and n-docosyl radical, - 10% to 24% by weight of at least one composition (C1) represented by formula (II) in which G represents a glucosyl or α,β-D-glucopyranosyl radical obtained by removal of the hemiacetal hydroxyl group of α,β-D-glucopyranose, x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.0, and R represents an n-eicosyl or n-docosyl radical, - less than 1% by weight of glucose, The present invention relates to the preparation of a composition (C) comprising:

[0037] According to a particular embodiment, one of the subjects of the above method is a composition (C) having a color of less than or equal to 1.5 VCS and comprising, for 100% of its weight: - 75% to 90% by weight of a mixture of alcohols of formula (I) in which R represents the n-dodecyl, n-tetradecyl, n-hexadecyl, n-eicosyl and n-docosyl radicals, - 10% to 24% by weight of at least one composition (C1) represented by formula (II) in which G represents a glucosyl or α,β-D-glucopyranosyl radical obtained by removal of the hemiacetal hydroxyl group of α,β-D-glucopyranose, x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.0, and R represents an n-dodecyl radical, an n-tetradecyl radical, an n-hexadecyl radical, an n-eicosyl radical, or an n-docosyl radical, - less than 1% by weight of glucose, The present invention relates to the preparation of a composition (C) comprising:

[0038] According to a particular embodiment, one of the subjects of the above method is a composition (C) having a color of less than or equal to 1.5 VCS and comprising, for 100% of its weight: - from 70% to 90% by weight of a mixture of alcohols of formula (I) in which R represents the n-dodecyl, n-tetradecyl, n-hexadecyl, n-eicosyl and n-docosyl radicals, - 10% to 29% by weight of a composition (C1) represented by formula (II), in which G represents a xylosyl group or an α,β-D-xylopyranosyl group obtained by removal of the hemiacetal hydroxyl group of α,β-D-xylopyranose, x represents a decimal number greater than or equal to 1.05 and less than or equal to 2.0, and R represents a 2-octyldodecyl group, - less than 1% by weight of xylose, The present invention relates to the preparation of a composition (C) comprising:

[0039] According to one particular embodiment, the basic agent (Ab) present in the aqueous solution is potassium carbonate of formula (IVa) in which X represents a potassium atom and n is equal to 2.

[0040] According to one particular embodiment, the basic agent (Ab) present in the aqueous solution is sodium hydrogen carbonate of formula (IVb) in which Y represents a sodium atom and m is equal to 1.

[0041] According to one particular embodiment, the acid catalyst (CA) is selected from the members of the group consisting of sulfuric acid, phosphoric acid, hypophosphorous acid, methanesulfonic acid and p-toluenesulfonic acid. EXAMPLES

[0042] Comparison of the effect of neutralizing agents on the color of compositions of fatty alcohols and alkyl polyglucosides when the neutralizing base agent used is a carbonate according to the invention or sodium hydroxide (comparative neutralizing agent). A comparison was made between carbonate and sodium hydroxide as neutralizing agents. For this purpose, glycosylation reactions were carried out starting from crystalline glucose and various fatty alcohols in cut or pure form: C16 / 18 cetearyl cut, C20 / 22 arachidyl / behenyl cut, 1-tetradecanol (C14 alcohol) and 1-dodecanol (C12 alcohol).

[0043] 1. Examples of the Invention Example 1.1 According to the invention (16 / 18 alcohol cut and Na2CO3 as pre-neutralizer and neutralizer) Step 1: Glycosylation reaction: 967.4 g of cetearyl alcohol (C16 / 18) are charged into a reactor equipped with a mechanical stirrer and a vacuum distillation apparatus. The alcohol is melted at 85° C., stirred and sparged with nitrogen. The medium is placed under vacuum at a pressure of less than 50 Torr. An amount of anhydrous glucose in powder form is added so that the molar ratio of fatty alcohol to glucose is 6 / 1. The medium is inerted under nitrogen. To start the etherification reaction, 0.9 g of a 50% aqueous solution of H3PO2 is added, followed by 1.1 g of a 98% aqueous solution of H2SO4, and the temperature is increased and maintained at 105° C. The reaction is allowed to continue for a period of 5 hours and 45 minutes.

[0044] Step 2: Neutralization of the reaction medium: The medium is then cooled to 80°C at atmospheric pressure and then preneutralized by introducing 2.21 g of a 25% aqueous solution of Na2CO3. The product is then introduced into a glass vial and placed in an oven at 80°C for 5 hours to precipitate the remaining glucose. The product (upper phase) is then filtered on a filter paper (approximately 10 μm). A 5% by weight dispersion in water has a pH of 4.7 and the product has a color of 0.6 VCS. The product is then neutralized by introducing 4.61 g of a 25% aqueous solution of Na2CO3. The product is then introduced into a glass vial and placed in an oven at 80°C for 24 hours to precipitate the remaining glucose. The product (upper phase) is collected and referred to (composition 1).

[0045] analysis: - the pH of a 5% by weight dispersion of composition 1 in water is 6.8; - Composition 1 has a color measurement of 0.5 VCS.

[0046] Example 1.2 (16 / 18 alcohol cut and NaOH as pre-neutralizer and Na2CO3 as neutralizer according to the invention) Step 1: Glycosylation reaction: A reactor equipped with a mechanical stirrer and a vacuum distillation apparatus is charged with 1364.8 g of cetearyl alcohol (C16 / 18). The alcohol is melted at 85°C, stirred and sparged with nitrogen. The medium is placed under vacuum at a pressure of less than 50 Torr. 179.2 g of anhydrous glucose in powder form are added. The medium is inerted under nitrogen. To start the etherification reaction, 1.2 g of a 50% aqueous solution of H3PO2 and then 1.6 g of a 98% aqueous solution of H2SO4 are added, the temperature is increased and maintained at 105°C. The reaction is allowed to continue for 5 hours and 45 minutes.

[0047] Step 2: Neutralization of the reaction medium: The medium is cooled to 80° C. at atmospheric pressure and then preneutralized by introducing, with stirring, 3.4 g of a 25% aqueous solution of NaOH. The product is then introduced into a glass vial and placed in an oven at 80° C. for 5 hours in order to precipitate the remaining glucose. The product (upper phase) is then filtered on a filter paper (approximately 10 μm).

[0048] A 5% by weight dispersion in water has a pH of 4.5 and the product has a color of 1.0 VCS. The product (880 g) is subsequently neutralized in a reactor with stirring at 85° C. by introducing 3.57 g of a 10% aqueous solution of Na2CO3. The product is collected and referred to (composition 2).

[0049] analysis: the pH of a 5% by weight dispersion of composition 2 in water is 7.2; - The colour measurement of composition 2 is 0.9 VCS.

[0050] Example 1.3 According to the invention (16 / 18 alcohol cut and NaOH as pre-neutralizer and NaHCO3 as neutralizer) Step 1: Glycosylation reaction: 271.1 g of cetearyl alcohol (C16 / 18) are charged into a reactor equipped with a mechanical stirrer and a vacuum distillation apparatus. The alcohol is melted at 85° C., stirred and sparged with nitrogen. The medium is placed under vacuum at a pressure of less than 50 Torr. 35.7 g of anhydrous glucose in powder form are added. The medium is inerted under nitrogen. To start the etherification reaction, 0.2 g of a 50% aqueous solution of H3PO2, then 0.3 g of a 98% aqueous solution of H2SO4 are added, the temperature is increased and maintained at 105° C. The reaction is allowed to continue for 5 hours and 45 minutes.

[0051] Step 2: Neutralization of the reaction medium: The medium is cooled to 85°C at atmospheric pressure and then preneutralized by introducing 0.4g of a 25% aqueous solution of NaOH with stirring. The product is then introduced into a glass vial and placed in an oven at 80°C for 24 hours to precipitate the remaining glucose. A 5% by weight dispersion in water has a pH of 3.5 and the product has a color of 0.5 VCS. The product (173.8g) is then neutralized in a reactor at 85°C with stirring by introducing 1.9g of an 8% aqueous solution of NaHCO3. The product is recovered and referred to (composition 3).

[0052] analysis: the pH of a 5% by weight dispersion of composition 3 in water is 6.3; - The color measurement of composition 3 is 0.4 VCS.

[0053] Example 1.4 According to the invention (20 / 22 alcohol cut and NaOH as pre-neutralizer and Na2CO3 as neutralizer) Step 1: Glycosylation reaction: 284.7 g of behenyl / arachidyl alcohol (C20 / 22) are charged into a reactor equipped with a mechanical stirrer and a vacuum distillation apparatus. The alcohol is melted at 85° C., stirred and sparged with nitrogen. The medium is placed under vacuum at a pressure of less than 50 Torr. 29.2 g of anhydrous glucose in powder form are added. The medium is inerted under nitrogen. To start the etherification reaction, 0.3 g of a 50% aqueous solution of H3PO2, then 0.4 g of a 98% aqueous solution of H2SO4 are added, the temperature is increased and maintained at 105° C. The reaction is allowed to continue for 4 hours and 30 minutes.

[0054] Step 2: Neutralization of the reaction medium: The medium is cooled to 90° C. at atmospheric pressure and then preneutralized by introducing, with stirring, 0.89 g of a 25% aqueous solution of NaOH. The product is subsequently introduced into a glass vial and placed in an oven at 80° C. for 24 hours in order to precipitate the remaining glucose. A 5% by weight dispersion in water has a pH of 5.1 and the product has a color of 0.3 VCS.

[0055] 175.4 g of product (upper phase) are subsequently neutralized in a reactor with stirring at 90° C. by introducing 0.61 g of a 10% aqueous solution of Na2CO3.

[0056] The product is collected and referenced (composition 4).

[0057] analysis: the pH of a 5% by weight dispersion of composition 4 in water is 6.8; - The colour measurement of composition 4 is 0.5 VCS.

[0058] Example 1.5 According to the invention (20 / 22 alcohol cut and Na2CO3 as pre-neutralizer and Na2CO3 as neutralizer) Step 1: Glycosylation reaction: 391.9 g of behenyl / arachidyl alcohol (C20 / 22) are charged into a reactor equipped with a mechanical stirrer and a vacuum distillation apparatus. The alcohol is melted at 85° C., stirred and sparged with nitrogen. The medium is placed under vacuum at a pressure of less than 50 Torr. 40.1 g of anhydrous glucose in powder form are added. The medium is inerted under nitrogen. To start the etherification reaction, 0.4 g of a 50% aqueous solution of H3PO2, then 0.6 g of a 98% aqueous solution of H2SO4 are added, the temperature is increased and maintained at 105° C. The reaction is allowed to continue for 4 hours and 30 minutes.

[0059] Step 2: Neutralization of the reaction medium: The medium is cooled to 90° C. at atmospheric pressure and then preneutralized by introducing 2.1 g of a 25% aqueous solution of Na2CO3 with stirring. The product is then introduced into a glass vial and placed in an oven at 105° C. for 24 hours to precipitate the remaining glucose. A 5% by weight dispersion in water has a pH of 5.2 and the product has a color of 0.7 VCS. The product (266 g) is then neutralized in a reactor at 90° C. with stirring by introducing 0.1 g of a 25% aqueous solution of Na2CO3.

[0060] The product is collected and referenced (composition 5).

[0061] analysis: the pH of a 5% by weight dispersion of composition 5 in water is 6.5; - The color measurement of composition 5 is 0.7 VCS.

[0062] Example 1.6 According to the invention (1-tetradecanol and Na2CO3 as pre-neutralizing agent and Na2CO3 as neutralizing agent) Step 1: Glycosylation reaction: 428.7 g of myristyl C14 alcohol (or 1-tetradecanol) are charged into a reactor equipped with a mechanical stirrer and a vacuum distillation apparatus. The alcohol is melted at 80° C., stirred and sparged with nitrogen. The medium is placed under vacuum at 35 Torr. 59.9 g of anhydrous glucose in powder form are added. The medium is inerted under nitrogen. To start the etherification reaction, 1.0 g of a 50% aqueous solution of H3PO2 is added, followed by 0.7 g of a 98% aqueous solution of H2SO4, and the temperature is increased and maintained at 105° C. The reaction is allowed to continue for 5 hours.

[0063] Step 2: Neutralization of the reaction medium: The medium is cooled to 70° C. at atmospheric pressure and then preneutralized by introducing 1.6 g of a 25% aqueous solution of NaOH with stirring. The product is then introduced into a glass vial and placed in an oven at 80° C. for 24 hours to precipitate the remaining glucose. A 5% by weight dispersion in water has a pH of 5.2 and the product has a color of 0.6 VCS. The product (337 g) is then neutralized in a reactor at 70° C. with stirring by introducing 0.7 g of a 10% aqueous solution of Na2CO3. The product is recovered and referred to (composition 6).

[0064] analysis: the pH of a 5% by weight dispersion of composition 6 in water is 7.3; - The colour measurement of composition 6 is 0.7 VCS.

[0065] Example 1.7 According to the invention (1-dodecanol and Na2CO3 as pre-neutralizing agent and Na2CO3 as neutralizing agent) Step 1: Glycosylation reaction: A reactor equipped with a mechanical stirrer and a vacuum distillation apparatus is charged with 414.5 g of lauryl alcohol (C12) (or 1-dodecanol). The alcohol is melted at 85°C, stirred and sparged with nitrogen. The medium is placed under vacuum at a pressure of 30 Torr. 57.9 g of anhydrous glucose in powder form are added. The medium is inerted under nitrogen. To start the etherification reaction, 0.4 g of a 50% aqueous solution of H3PO2, then 0.7 g of a 98% aqueous solution of H2SO4 are added, the temperature is increased and maintained at 105°C. The reaction is allowed to continue for 5 hours.

[0066] Step 2: Neutralization of the reaction medium: The medium is subsequently cooled to 67°C at atmospheric pressure and then pre-neutralized by introducing 3.55 g of a 10% aqueous solution of Na2CO3. The product is filtered on a filter plate (approximately 100 μm) to remove residual glucose. A 5% by weight dispersion in water has a pH of 3.7 and the product has a color of 1.1 VCS. The product (197 g) is subsequently neutralized in a reactor at 67°C by introducing, with stirring, 2.97 g of a 10% aqueous solution of Na2CO3.

[0067] The product is collected and referenced (composition 7).

[0068] analysis: the pH of a 5% by weight dispersion of composition 7 in water is 6.1; - The color measurement of composition 6 is 1.5 VCS.

[0069] 2. Comparative Example Example 2.1: Comparative Example (16 / 18 Alcohol Cut and NaOH as Pre-Neutralizer and NaOH as Neutralizer) Step 1: Glycosylation reaction: 778.1 g of cetearyl alcohol (C16 / 18) are charged into a reactor equipped with a mechanical stirrer and a vacuum distillation apparatus. The alcohol is melted at 85°C, stirred and sparged with nitrogen. The medium is placed under vacuum at a pressure of less than 50 Torr. 102.2 g of anhydrous glucose in powder form are added. The medium is inerted under nitrogen. To start the etherification reaction, 0.7 g of a 50% aqueous solution of H3PO2, then 0.9 g of a 98% aqueous solution of H2SO4 are added, the temperature is increased and maintained at 105°C. The reaction is allowed to continue for 5 hours and 45 minutes.

[0070] Step 2: Neutralization of the reaction medium: The medium is subsequently cooled to 80° C. at atmospheric pressure and then preneutralized by introducing 1.86 g of a 25% aqueous solution of NaOH. The product is subsequently introduced into a glass vial and placed in an oven at 80° C. for 3 hours to precipitate the remaining glucose. A 5% by weight dispersion in water has a pH of 3.3 and the product has a color of 0.6 VCS.

[0071] The product is subsequently neutralized at 80° C. by introducing 0.28 g of a 25% aqueous solution of NaOH. The product is recovered and referenced (composition 1′).

[0072] analysis: the pH of a 5% by weight dispersion of composition 1′ in water is 6.2; The colour measurement of composition 1' is 3.8 VCS.

[0073] Example 2.2: Comparative Example (C12 Alcohol and NaOH as Pre-Neutralizer and NaOH as Neutralizer) Step 1: Glycosylation reaction: 190.6 g of lauryl alcohol (C12) (or 1-dodecanol) are charged into a reactor equipped with a mechanical stirrer and a vacuum distillation apparatus. The alcohol is melted at 85° C., stirred and sparged with nitrogen. The medium is placed under vacuum at 30 Torr. 26.6 g of anhydrous glucose in powder form are added. The medium is inerted under nitrogen. To start the etherification reaction, 0.2 g of a 50% aqueous solution of H3PO2, then 0.3 g of a 98% aqueous solution of H2SO4 are added, the temperature is increased and maintained at 105° C. The reaction is allowed to continue for 5 hours.

[0074] Step 2: Neutralization of the reaction medium: The medium is subsequently cooled to 75° C. at atmospheric pressure and then preneutralized by introducing, with stirring, 0.70 g of a 25% aqueous solution of NaOH. A 5% by weight dispersion in water has a pH of 5.6 and the product has a color of 2.0 VCS. To remove residual glucose, the product is filtered on a K200 filter (approximately 3-6 μm). The product (78 g) is subsequently neutralized in a reactor at 80° C. by introducing, with stirring, 0.08 g of a 25% aqueous solution of NaOH.

[0075] The product is collected and referenced (composition 2').

[0076] analysis: the pH of a 5% by weight dispersion of composition 2' in water is 6.5; The colour measurement of composition 2' is 4.5 VCS.

[0077] 3. Observation and analysis of results Table 1 below summarizes the results of the process for preparing composition (C) obtained by reaction between glucose and C16 / 18 alcohol (mixture of 1-hexadecanol and 1-octadecanol). The different parameters studied are i) the nature of the pre-neutralization agent (Na2CO3 or NaOH) and ii) the nature of the final neutralization agent (Na2CO3, NaHCO3 or NaOH).

[0078] The compositions referred to as "Composition 1", "Composition 2" and "Composition 3" are obtained by carrying out the method according to the present invention, and the composition referred to as "Composition 1'" is obtained by carrying out a comparative method of the prior art.

[0079] [Table 1]

[0080] These tests show that the presence of a pre-neutralization step with an aqueous solution of NaOH and a neutralization step with an aqueous solution of NaOH results in excellent coloration of the resulting compositions (up to 3.8 VCS for composition 1'). In comparison, when the pre-neutralization step is performed with a solution of NaOH (composition 2) or Na2CO3 (composition 1) and the neutralization step is performed with an aqueous solution of Na2CO3, the color of the resulting product is very low (<1 VCS).

[0081] For the preparation of composition 3, the method according to the invention was carried out by carrying out a step of pre-neutralization with an aqueous solution of NaOH (to achieve a pH of 3.5-5.5), followed by a step of neutralization after filtration with a solution of NaHCO3 (to achieve a pH of 5.5-7.5).

[0082] This test shows that it is possible to use sodium bicarbonate during the neutralization step of the method according to the invention in order to ensure a low coloration of the desired composition (since the final color obtained is 0.4 VCS for composition 3).

[0083] Table 2 summarizes the results of the methods for preparing compositions (C) obtained by reaction between glucose and a C20 / 22 alcohol (a mixture of 1-eicosanol and 1-docosanol), between glucose and a C14 alcohol (or 1-tetradecanol), between glucose and a C12 alcohol (or 1-dodecanol), studying the same parameters as those involved in the above studies.

[0084] [Table 2]

[0085] The process according to the invention makes it possible to obtain low-color compositions (C) (color equal to or less than 1.5 VCS), prepared by reaction of glucose with fatty alcohols containing 12, 14, 20 and 22 carbon atoms.

[0086] On the other hand, by carrying out the method for preparing composition 2' (reaction between glucose and 1-dodecanol) using sodium hydroxide for both the pre-neutralization and neutralization steps, the analytical results obtained show that the color of the final mixture is 4.5 VCS, i.e., significantly higher than 1.5 VCS.

[0087] Finally, the process according to the invention makes it possible to obtain a low-color composition (color equal to or less than 1.5 VCS) comprising a fatty alcohol and an alkyl polyglucoside from the reaction of at least one reducing sugar with a fatty alcohol containing from 12 to 22 carbon atoms.

Claims

1. For 100% of its weight: i) an amount greater than or equal to 40% by weight and less than or equal to 95% by weight of an alcohol of formula (I): R-OH(I) wherein R represents a linear or branched, saturated or unsaturated hydrocarbon group containing from 12 to 22 carbon atoms, which may contain at least one hydroxyl functional group, or a mixture of alcohols of formula (I); ii) an amount greater than or equal to 5% by weight and less than or equal to 60% by weight of a composition (C1) represented by formula (II): RO-(G)x-H(II) wherein residue G represents a residue of a reducing sugar, R represents a group as defined in formula (I), and x, which indicates the average degree of polymerization of said residue G, represents a decimal number greater than 1.05 and less than or equal to 2.5, or a mixture of compositions (C1) of formula (II):

1. A method for preparing a composition (C) having a color equal to or less than 1.5 VCS, comprising: It is understood that the sum of the weight proportions of the compounds of formulae (I) and (II) in composition (C) is equal to 100% by weight, The method comprises: a) a glycosylation step a) consisting of a reaction between at least one alcohol of formula (I) and at least one reducing sugar of formula (III): H-O-(G)-H(III) in the presence of at least one acid catalyst (CA) at a temperature equal to or greater than 100°C and equal to or less than 120°C, wherein said at least one acid catalyst (CA) is selected from a member of the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, hypophosphorous acid, methanesulfonic acid, para-toluenesulfonic acid, trifluoromethanesulfonic acid and acidic ion exchange resins; b) pre-neutralizing the reaction medium from step a), said pre-neutralization being carried out so as to obtain a reaction medium in which a 5 wt. % dispersion of said reaction medium in water has a pH of 3.5 to 5.5; c) removing the reducing sugar of formula (III) that has not reacted in step a) from the pre-neutralized reaction medium obtained in step b); d) Carbonate of formula (IVa): XnCO ３ (IVa) wherein X represents a sodium or potassium atom and n is an integer equal to 2, or wherein X represents a calcium or magnesium atom and n is an integer equal to 1; or hydrogen carbonate of formula (IVb): Y(HCO ３ )m(IVb) wherein Y represents a sodium or potassium atom and m is an integer equal to 1, or Y represents a calcium or magnesium atom and m is an integer equal to 2. a step d) of neutralizing the reaction medium from step c) with an aqueous solution comprising a basic agent (Ab) selected from the group consisting of: e) recovering at least one composition (C) having a color less than or equal to 1.5 VCS; The method of claim 1, wherein the

2. The composition (C1) is represented by the formulas (II1), (II2), (II3), (II4), and (II5): RO-(G)1-H (II1), RO-(G)2-H (II2), RO-(G)3-H (II3), RO-(G)4-H (II4), RO-(G)5-H (II5), The molar ratios a1, a2, a3, a4, and a5 of the compounds represented by the formula: Sum: a1+a2+a3+a4+a5 is equal to 1, - The sum a1 + 2a2 + 3a3 + 4a4 + 5a5 is equal to x, 2. The method of claim 1, wherein the mixture comprises:

3. The composition (C) contains an amount of a reducing sugar of formula (III) equal to or less than 2% by weight, more particularly equal to or less than 1% by weight: H-O-(G)-H(III); 3. The method according to claim 1 or 2, characterized in that it comprises:

4. The basic agent (Ab) contained in the aqueous solution used in the neutralization step d) is sodium carbonate (Na ２ CO ３ ) or sodium bicarbonate (NaHCO ３ 3. The method according to claim 1, wherein the compound is selected from the group consisting of:

5. The pre-neutralization step b) is carried out with the following compounds: sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH ４ 3. The method according to claim 1, wherein the method is carried out with at least one of the following amines: monoethanolamine, diethanolamine, triethanolamine, and triethylamine.

6. The pre-neutralization step b) is carried out with the following compound: sodium carbonate (Na ２ CO ３ ), sodium bicarbonate (NaHCO ３ ), and calcium carbonate (CaCO ３ 3. The method according to claim 1, wherein the method is carried out by one of the following methods:

7. 3. The method of claim 1, wherein the reducing sugar of formula (III) selected for glycosylation in step a) is selected from the group consisting of glucose, xylose, arabinose, and rhamnose.

8. 3. The method according to claim 1 or 2, wherein step c) of removing the reducing sugar of formula (III) is carried out by filtration, centrifugation or sedimentation.

9. 3. The method according to claim 1, wherein in step d) the aqueous solution of basic agent (Ab) comprises 10% to 25% by weight of the basic agent (Ab).

10. Step a) comprises the following successive sub-steps: i) introducing an alcohol of formula (I) or a mixture of alcohols of formula (I) into a reactor (Re) equipped with a mechanical stirrer and a vacuum; ii) heating said alcohol of formula (I) to a temperature between 80°C and 90°C under mechanical stirring; iii) charging said reducing sugar of formula (III) into said reactor (Re); iv) introducing an acid catalyst (CA) into said reactor (Re); v) heating, during the reaction, the reaction medium from substep iv) present in the reactor (Re) to a temperature between 100°C and 110°C under partial vacuum; vi) cooling the reaction medium from substep v) to a temperature between 70°C and 80°C; 2. The method of claim 1, comprising:

11. 11. The method according to claim 10, wherein the radical R is selected from the following groups: lauryl (or n-dodecyl), myristyl (or n-tetradecyl), n-pentadecyl, cetyl (or n-hexadecyl), n-heptadecyl, stearyl (or n-octadecyl), palmitoleyl (or 9-hexadecenyl), oleyl (or 9-octadecenyl), linoleyl (9,12-octadecadienyl), linolenyl (or 6,9,12-octadecatrienyl), nonadecyl, arachidyl (or n-eicosyl), behenyl (or n-docosyl), erucyl (13-docosenyl) or 12-hydroxystearyl.

12. 11. The method according to claim 10, wherein the radical R is selected from the following radicals: 2-hexyloctyl, 2-hexyldecyl, 2-hexyldodecyl, 2-octyldecyl, 2-octyldodecyl, 2-decyltetradecyl, isostearyl (or 16-methylheptadecyl), or isomyristyl (or 13-methyltridecyl).

13. 13. The method according to any one of claims 10 to 12, characterized in that during substeps ii) to iv), the reactor (Re) is inerted under nitrogen.

14. 13. A method according to any one of claims 10 to 12, characterized in that it comprises a vacuum step between substeps ii) to iii), preferably at a pressure of 50 mbar or less.

15. 13. The method according to any one of claims 10 to 12, characterized in that substep vi) is carried out at atmospheric pressure.