METHOD FOR THE PRODUCTION OF LOW-COLOR ALKYLPOLYGLYCOSIDES WITH NEUTRALIZATION OF THE REACTION MEDIUM BEFORE SUGAR REMOVAL

Description

[0001] The present invention relates to a process for preparing lightly coloured Alkyl Polyglycosides (colour less than 1.5 vcs) involving carbonate-type neutralizing agents.

[0002] Alkyl polyglycosides, or APGs, are probably the best examples of bio-based surfactants available on the market today. Their molecular structures are characterized by the simultaneous presence of a hydrophilic head derived from reducing sugars (D-glucose, D-xylose, or D-rhamnose are the reducing sugars mainly available on an industrial scale on the market) and a more or less long lipophilic hydrocarbon chain (see formula I: simplified structure of an APG).

[0003] Their industrial-scale manufacturing process is relatively simple and uses as raw materials i) crystallized glucose, xylose, or rhamnose obtained respectively from the total hydrolysis of wheat, corn, or potato starch, or from the hydrolysis of wood hemicelluloses, and ii) fatty alcohols from the oleochemical process (hydrogenation of methyl esters resulting from the transesterification of vegetable triglycerides). Fischer glycosylation reactions then consist of linking these two raw materials together by creating a covalent chemical bond, as for example in reaction (II) between glucose and an alcohol.

[0004] To carry out this glycosylation reaction, an acid catalyst of mineral or organic origin is required, and an excess of alcohols is systematically introduced, acting as both reactant and solvent. At the end of the reaction, the glycation end products (GAPs) are dispersed or solubilized in the excess alcohols that did not react.

[0005] APGs are distinguished by the nature and length of the hydrocarbon alkyl chain R, as well as by their average Degree of Polymerization DP greater than 1 but less than or equal to 2.5.

[0006] Following the glycolysation reaction phase, a neutralization step is carried out in order to deactivate the catalyst and stop the reaction.

[0007] Depending on the length of the alkyl chain of the alcohol and the associated use, said alcohol is either removed or retained.

[0008] The neutralization step varies depending on the length of the alkyl hydrocarbon chain. If the chain has fewer than 12 carbon atoms, neutralization is carried out with an aqueous solution of sodium hydroxide. The excess fatty alcohols remaining after glycosylation are then removed by high-vacuum distillation or molecular distillation, or by evaporation, generally using a falling-film thin-film evaporator or a short-path thin-film evaporator. The resulting PGA concentrate is then dissolved in water. The commercial products obtained are therefore aqueous PGA solutions with a mass concentration between 40 and 80%.

[0009] In cases where the hydrocarbon alkyl chain R has 12 or more carbon atoms, neutralization is generally carried out with sodium hydroxide or potassium hydroxide, alone or in combination with a reducing agent as described in European Patent EP0077167, European Patent Application EP0338151 A1, and European Patent EP0388857 B1, such as sodium borohydride (NaBH4) or sodium hypophosphite (NaH2PO2). The mixture of PGA and excess fatty alcohols is isolated after neutralization and is marketed as such. The mass proportion of PGA and fatty alcohols depends on the initial molar stoichiometry of the raw materials and their reactivity. However, proportions of 5 to 30% by mass of PGA and 70 to 95% of fatty alcohols are generally observed.The resulting compositions can be in solid form, such as scales or beads, or in liquid form, depending on the nature of the alkyl hydrocarbon chain R.

[0010] However, the neutralization step of PGAs whose hydrocarbon alkyl chain R has a number of carbon atoms greater than or equal to 12) by a state-of-the-art base (e.g. NaOH, KOH), to achieve a pH value of a 5% mass dispersion in water of the neutralized medium between 5.5 and 7.5, causes significant coloring of the product.

[0011] For the purposes of this invention, "measurement of the pH of a 5% mass dispersion in water" refers to the analytical method for measuring the pH of a dispersion of a composition based on APG according to the provisions of standard NF EN 1262, said measurement is carried out by potentiometric measurement using a combined pH electrode (aqueous media) and a pH meter.

[0012] This coloration can alter the organoleptic qualities of finished products in which compositions containing PGAs are introduced. Therefore, solutions are being developed to minimize the coloration of compositions containing PGAs whose alkyl hydrocarbon chain R has 12 or more carbon atoms. Two known prior art techniques are commonly used to obtain such PGA-based compositions with 12 or more carbon atoms in their alkyl hydrocarbon chain R that are only slightly colored (< 1.5 vcs).

[0013] For the purposes of this invention, "low-color composition" means a composition whose Gardner color index, as defined by DIN-ISO 4630, is less than or equal to 1.5 VCS. The Gardner color index is measured using a LICO 200 / Dr. LANGE colorimeter (or equivalent) that performs measurements by light transmission on any medium. Such a colorimeter operates with a halogen lamp corresponding to the standard illuminant C, as defined by DIN 5033, and with a standard 2° observer. During measurement, a reference beam compensates for variations in the recorded values ​​due to differences in lamp and temperature.

[0014] The first approach involves adding a reducing agent to the base being used. Examples of such reducing agents include sodium borohydride (NaBH4) and sodium hypophosphite (NaH2PO2). This solution is not entirely satisfactory. While very effective at minimizing discoloration of the treated composition, NaBH4 is a dangerous reducing agent to handle and use (corrosive product, releases hydrogen). NaH2PO2, on the other hand, is very ineffective, even at high concentrations.

[0015] The second commonly used method, described in the prior art, to minimize the color of APG-based compositions with an alkyl hydrocarbon chain R containing 12 or more carbon atoms, is decolorization with hydrogen peroxide (H₂O₂) during the finishing step. While effective, this step is nonetheless time-consuming because it requires adjusting the pH of a 5% wt% dispersion in water to between 7.0 and 7.5 while maintaining the oxidizing power of the medium through the addition of H₂O₂. This delicate step can take several hours and thus significantly increase production time, thereby reducing productivity.

[0016] Other documents disclose prior art preparation processes. For example, EP0092876A1 describes a transglycosylation preparation including a neutralization step carried out with Na2CO3. US5681938A describes a process for preparing PGAs including a manufacturing step carried out with a tertiary amine. US5576425A discloses a neutralization step including carbonates with MgO as the preferred base. Finally, WO98 / 35975A1 describes a PGA preparation including the use of a binary sulfate catalyst, itself a mixture of H2SO4 and an inorganic base including carbonates. The technical problem to be solved is therefore to find an alternative to the neutralization of emulsifying PGA-based compositions whose hydrocarbon alkyl chain R has 12 or more carbon atoms.This alternative must be effective and easy to implement, while guaranteeing a color less than or equal to 1.5 vcs without implementing a bleaching step. A solution of the present invention is a process for preparing a composition (C), of color less than or equal to 1.5 vcs, comprising for 100% of its mass: . (i) an amount greater than or equal to 40% by mass and less than or equal to 95% by mass of an alcohol of formula (I): R-OH (I), in which R represents a hydrocarbon radical, linear or branched, saturated or unsaturated, which may contain at least one hydroxy function, and which has from twelve to twenty-two carbon atoms, or of a mixture of alcohols of formula (I); (ii) an amount greater than or equal to 5% by mass and less than or equal to 60% by mass of a composition (C1) represented by formula (II): RO-(G)xH (II), in which the remainder G represents the remainder of a reducing sugar, R represents a radical as defined in formula (I) and x, which indicates the average degree of polymerization of the remainder G, represents a decimal number greater than 1.05 and less than or equal to 2.5, or of a mixture of compositions (C1) of formula (II); provided that the sum of the mass proportions of the compounds in composition (C) of formulas (I) and (II) is equal to 100% by mass; said process comprising successively: a) A glycosylation step, 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 (AC), at a temperature greater than or equal to 100°C and less than or equal to 120°C, the acid catalyst (AC) being selected from the elements of the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, hypophosphorous acid, methanesulfonic acid, para-toluenesulfonic acid, trifluoromethanesulfonic acid and acid ion exchange resins,b) A neutralization step b) of the reaction medium obtained from step a) with an aqueous solution comprising a basic agent (Ab) chosen from the elements of the group consisting of: ▪ carbonates of formula (IVa): XnCO3 (IVa), in which 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, or ▪ hydrogen carbonates of formula (IVb): Y(HCO3)m (IVb), in which 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, this neutralization step being carried out so as to obtain a reaction medium of which a 5% mass dispersion of said reaction medium in water has a pH value between 5.5 and 7.5, c) A step c) elimination of sugar of formula (III),which did not react in step a), of the neutralized reaction medium, and d) A step d) of recovery of at least one color composition (C) less than or equal to 1.5 vcs. ,

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

[0018] The unit of expression of the Gardner color index, characterizing the composition (C) prepared according to the process which is the subject of the present invention, is the VCS.

[0019] Depending on the case, the process according to the invention may have one or more of the following characteristics: said composition (C1) consists of a mixture of compounds 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), in the respective molar proportions a1, a2, a3, a4 and a5, such that: ▪ the sum: a1+ a2 + a3 + a4 + a5 is equal to 1, and ▪ the sum a1 + 2a2 + 3a3 + 4a4 + 5a5 is equal to x; composition (C) comprises an amount less than or equal to 2% by mass of the reducing sugar of formula (III): HO-(G)-H (III); provided that the sum of the mass proportions of compounds of formulas (I), (II) and (III) in composition (C) is equal to 100% by mass; the basic agent (Ab) present in the aqueous solution is sodium carbonate of formula (IVa) in which X represents the sodium atom and n is equal to 2; the process comprises after the step c) a further adjustment step of the pH value of a 5% mass dispersion in water of the reaction medium by adding an aqueous solution comprising the basic agent (Ab) as defined previously so as to obtain a value of said pH between 5.5 and 7.5; the reducing sugar of formula (III) chosen for the glycolysation of step a) is chosen from the elements of the group consisting of glucose, xylose, arabinose and rhamnose; step c) of removal of the reducing sugar of formula (III) is carried out by filtration, centrifugation or decantation, or by any other solid-liquid separation technique known to those skilled in the art;When this step of removing unreacted reducing sugar of formula (III) involves filtration, the filter medium may be filter paper of suitable pore size (greater than or equal to 10 micrometers), or a cellulose filter plate, optionally in the presence of at least one filter aid known to those skilled in the art; In step b) the aqueous solution of basic agent (Ab) comprises between 10% and 40% by mass of said basic agent (Ab); step a) comprises the following successive substeps: i) Introduction of an alcohol of formula (I) or a mixture of alcohols of formula (I), into a reactor (Re) equipped with mechanical stirring and a vacuum device; ii) Heating of the alcohol of formula (I) to a temperature between 80°C and 90°C under mechanical stirring; iii) Loading of the reducing sugar of formula (III) into the reactor (Re);iv) Introduction of at least one acid catalyst into the reactor (Re), v) Heating under partial vacuum of the reaction medium from substep iv) and present in the reactor (Re) to a temperature between 100°C and -110°C during the duration of the reaction, and vi) Cooling of the medium from substep v) to a temperature between 70°C and 80°C; in formula (I) and / or in formula (II), the radical R is chosen from the following radicals: lauryl (or n-dodecyl) myristyle (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) n-nonadecyl, arachidyl (or n-eicosyl), behenyl (or n-docosyl), erucyl (13-docosenyl), or 12-hydroxystearyl;in formula (I) and / or in formula (II), the radical R is chosen from the following radicals: 2-hexyl octyl, 2-hexyl decyl, 2-hexyl dodecyl, 2-octyl decyl, 2-octyl dodecyl, 2-decyl tetradecyl, isostearyl (or 16-methyl heptadecyl) or isomyristyle (or 13-methyl tridecyl); during the; sub-steps ii) to iv) The reactor (Re) is inert under nitrogen; The process includes between steps ii) and iii) a vacuum step, preferably at a pressure less than or equal to 50 millibars; Step vi) is carried out at atmospheric pressure.

[0020] The use of carbonates of formula (IVa) or hydrogen carbonates of formula (IVb) does not increase the color of composition (C) (the presence of a reducing agent is therefore unnecessary) while neutralizing a 5% wt% dispersion of composition (C) (with a pH between 5.5 and 7.5) to the desired pH. The use of a basic agent (Ab) avoids a decolorization step involving a peroxide or other agent, as it allows a color of 1.5 vcs or less to be achieved.

[0021] By reducing sugar, we mean in the definition of formula (II) and in the definition of formula (III), the saccharide derivatives which do not have in their structures a glycosidic bond established between an anomeric carbon and the oxygen of an acetal group as defined in the reference work: "Biochemistry", Daniel Voet / Judith G. Voet, p. 250, John Wyley & Sons, 1990.

[0022] The oligomeric structure (G)x present in formula (II) can appear in all forms of isomerism, whether optical isomerism, geometric isomerism or positional isomerism; it can also represent a mixture of isomers.

[0023] In formula (II) as defined above, the radical R is linked to G by the anomeric carbon of the saccharide remainder, so as to form an acetal function.

[0024] According to a particular aspect of the present invention, in the definition of compounds of formula (II) and formula (III), G represents the remainder 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 tallose.

[0025] According to a particular aspect of the present invention, in the definition of compounds of formula (II), G represents the remainder of a reducing sugar selected from the remainders 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 present invention, in the definition of compounds of formula (II), G represents the remainder of a reducing sugar chosen from the remainders 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, and even 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 present invention, the reducing sugar of formula (III) is selected from the elements 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 tallose.

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

[0029] The process according to the invention consists of neutralizing the medium at the end of the glycosylation reaction by adding an aqueous solution comprising a basic agent (Ab) to achieve a pH value of a 5% mass dispersion of said medium in water of between 5.5 and 7.5. The residual reducing sugar of formula (III) is then removed by filtration and, optionally, a further addition of an aqueous solution of a basic agent (Ab) can be made if the pH value of the 5% mass dispersion in water of composition (C) is less than 5.5 (finishing step).

[0030] According to one particular aspect, the process is for the preparation of a color composition (C) of less than or equal to 1.5 VCS, comprising 100% of its mass: 45% to 55% by mass of a mixture (M1) of alcohols of formula (I) comprising, for 100% of the mass of said mixture (M1), 50% by mass of an alcohol of formula (I) in which R represents the n-hexadecyl radical and 50% by mass of an alcohol of formula (I) in which R represents the n-octadecyl radical; 45% to 54% by mass of at least one composition (C1) represented by formula (II) in which G represents the glucosyl or α,β-D-glucopyranosyl radical, obtained from the 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, R represents the n-hexadecyl radical and the n-octadecyl radical; 0% to 1% by mass of glucose.

[0031] According to one particular aspect, the process is for the preparation of a color composition (C) of less than or equal to 1.5 VCS, comprising 100% of its mass: 45% to 55% by mass of a mixture (M'1) of alcohols of formula (I) comprising, for 100% of the mass of said mixture (M'1), 70% by mass of an alcohol of formula (I) in which R represents the n-hexadecyl radical and 30% by mass of an alcohol of formula (I) in which R represents the n-octadecyl radical; 45% to 54% by mass of at least one composition (C1) represented by formula (II) in which G represents the glucosyl or α,β-D-glucopyranosyl radical, obtained from the 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, R represents the n-hexadecyl radical and the n-octadecyl radical; 0% to 1% by mass of glucose.

[0032] According to one particular aspect, the process is for the preparation of a color composition (C) of less than or equal to 1.5 VCS, comprising 100% of its mass: 75% to 90% by mass of a mixture (M"1) of alcohols of formula (I) comprising, for 100% of the mass of said mixture (M"1), 50% by mass of an alcohol of formula (I) in which R represents the n-hexadecyl radical and 50% by mass of an alcohol of formula (I) in which R represents the n-octadecyl radical; 10% to 24% by mass of at least one composition (C1) represented by formula (II) in which G represents the glucosyl or α,β-D-glucopyranosyl radical, obtained from the 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, R represents the n-hexadecyl radical and the n-octadecyl radical; 0% to 1% by mass of glucose.

[0033] According to one particular aspect, the process is for the preparation of a color composition (C) of less than or equal to 1.5 VCS, comprising 100% of its mass: from 75% to 90% by mass of a mixture (M‴1) of alcohols of formula (I) comprising, for 100% of the mass of said mixture (M‴1), 70% by mass of an alcohol of formula (I) in which R represents the n-hexadecyl radical and 30% by mass of an alcohol of formula (I) in which R represents the n-octadecyl radical; from 10% to 24% by mass of at least one composition (C1) represented by formula (II) in which G represents the glucosyl or α,β-D-glucopyranosyl radical, obtained from the 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, R represents the n-hexadecyl radical and the n-octadecyl radical; from 0% to 1% by mass of glucose.

[0034] According to one particular aspect, the process is for the preparation of a color composition (C) of less than or equal to 1.5 VCS, comprising 100% of its mass: 75% to 90% by mass of an alcohol of formula (I) in which R represents the n-tetradecyl radical; 10% to 24% by mass of at least one composition (C1) represented by formula (II) in which G represents the glucosyl or α,β-D-glucopyranosyl radical, obtained from the 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, R represents the n-tetradecyl radical; 0% to 1% by mass of glucose.

[0035] According to one particular aspect, the process is for the preparation of a color composition (C) of less than or equal to 1.5 VCS, comprising 100% of its mass: 75% to 90% by mass of a mixture of alcohols of formula (I) in which R represents the n-dodecyl radical, the n-tetradecyl radical, the n-hexadecyl radical and the n-octadecyl radical; 10% to 24% by mass of at least one composition (C1) represented by formula (II) in which G represents the glucosyl or α,β-D-glucopyranosyl radical, obtained from the 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, R represents the n-dodecyl radical, the n-tetradecyl radical, the n-hexadecyl radical, and the n-octadecyl radical; 0% to 1% by mass of glucose.

[0036] According to one particular aspect, the process is for the preparation of a color composition (C) of less than or equal to 1.5 VCS, comprising 100% of its mass: 75% to 90% by mass of a mixture of alcohols of formula (I) in which R represents the n-eicosyl radical and the n-docosyl radical; 10% to 24% by mass of at least one composition (C1) represented by formula (II) in which G represents the glucosyl or α,β-D-glucopyranosyl radical, obtained from the 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, R represents the n-eicosyl radical and the n-docosyl radical; 0% to 1% by mass of glucose.

[0037] According to one particular aspect, the process is for the preparation of a color composition (C) of less than or equal to 1.5 VCS, comprising 100% of its mass: 75% to 90% by mass of a mixture of alcohols of formula (I) in which R represents the n-dodecyl radical, the n-tetradecyl radical, the n-hexadecyl radical, the n-eicosyl radical and the n-docosyl radical; 10% to 24% by mass of at least one composition (C1) represented by formula (II) in which G represents the glucosyl or α,β-D-glucopyranosyl radical, obtained from the 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, R represents the n-dodecyl radical, the n-tetradecyl radical, the n-hexadecyl radical, the n-eicosyl radical and the n-docosyl radical; 0% to 1% by mass of glucose.

[0038] According to one particular aspect, the process is for the preparation of a color composition (C) of less than or equal to 1.5 VCS, comprising 100% of its mass: 70% to 90% by mass of a mixture of alcohols of formula (I) in which R represents the n-dodecyl radical, the n-tetradecyl radical, the n-hexadecyl radical, the n-eicosyl radical and the n-docosyl radical; 10% to 29% by mass of at least one composition (C1) represented by formula (II) in which G represents the xylosyl or α,β-D-xylopyranosyl radical, obtained from the 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, R represents the 2-octyldodecyl radical; 0% to 1% by mass of xylose.

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

[0040] According to one particular aspect, 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 a particular aspect, the acid catalyst (AC) is chosen from the elements of the group consisting of sulfuric acid, phosphoric acid, hypophosphorous acid, methanesulfonic acid, p-toluenesulfonic acid. Examples HAS- Comparison of the effect of the neutralizing agent on the color of a composition of fatty alcohols and alkyl polyglucosides when the basic neutralizing agent used is a carbonate according to the invention or sodium hydroxide (comparative neutralizing agent).

[0042] Comparisons between a carbonate and sodium hydroxide as a neutralizing agent were carried out. For this, glycosylation reactions were performed using crystallized glucose and various fatty alcohols in the form of cuts or pure: cetearyl C-16 / 18 cut, arachidyl / behenic C-20 / 22 cut, and dodecanol-1 (C-12 alcohol).

[0043] Table 1 below shows neutralization results involving sodium carbonate Na2CO3 (neutralizer of the process according to the invention), on the one hand, and sodium hydroxide NaOH, on the other hand (neutralizer of the comparative process). 1- Examples according to the invention Example 1.1 (Cut of alcohols 16 / 18 and Na2CO3) as a neutralizing agent) according to the invention STEP 1: Glycosylation Reaction:

[0044] 967.4 g of cetearyl alcohol (C-16 / 18) are loaded into a reactor equipped with mechanical stirring and a vacuum distillation apparatus. The alcohol is melted at 85°C and stirred and bubbling with nitrogen. The mixture is then placed under vacuum at pressures below 50 Torrs. Anhydrous glucose powder is added to achieve a molar ratio of 6:1 between fatty alcohols and glucose. The mixture is then inert with nitrogen. To initiate the etherification reaction, 0.9 g of a 50% aqueous H₃PO₂ solution is added, followed by 1.1 g of a 98% aqueous H₂SO₄ solution. The temperature is increased and maintained at 105°C. The reaction is carried out for 5 hours and 45 minutes. STEP 2: Neutralization of the reaction medium:

[0045] The medium is then cooled to 80°C at atmospheric pressure and neutralized by adding 4.61 g of a 25% aqueous Na₂CO₃ solution. The product is then transferred to a glass flask and placed in an oven at 80°C for 24 hours to allow the residual glucose to settle. The product (upper phase) is collected and labeled (Composition 1). Analysis:

[0046] The pH value of a 5% mass dispersion in water Composition 1 is 5.5, and the color measurement of Composition 1 is of 0.7 VCS. Example 1.2 (Coupling of alcohols 20 / 22 and Na2CO3) (as a neutralizing agent) STEP 1: Glycosylation Reaction:

[0047] 240.5 g of a mixture of arachidyl alcohol (C20 alcohol) and benethyl / arachidyl alcohol (C-220 / 22 alcohol), in a C20 / C22 alcohol mass ratio of 70 / 30, are loaded into a reactor equipped with mechanical stirring and a vacuum distillation apparatus. The alcohol mixture is melted at 85°C and stirred and bubbling with nitrogen. The mixture is then evacuated to pressures below 50 Torrs. 24.6 g of anhydrous glucose dextrose powder are added. The mixture is inert under nitrogen. To initiate the etherification reaction, 0.2 g of a 50% aqueous H3PO2 solution followed by 0.4 g of a 98% aqueous H2SO4 solution are added, and the temperature is increased and maintained at 105°C. The reaction continued for 4 hours and 30 minutes. STEP 2: Neutralization of the reaction medium:

[0048] The medium is then cooled to 80°C at atmospheric pressure and neutralized by adding 3.3 g of a 10% aqueous Na₂CO₃ solution. The product has a pH of 5.6 and a color of 0.3 VCS. The product is then transferred to a glass flask and incubated at 80°C for 24 hours to decant the residual glucose and dextrose. The product (upper phase) has a pH of 4.8 and a color of 0.3 VCS. A finishing step is performed at 80°C by adding 0.19 g of a 10% aqueous Na₂CO₃ solution to obtain the final product (Composition 2). Analysis:

[0049] The pH value of a 5% mass dispersion in water of Composition 2 is 7.0, and the color measurement of Composition 2 is 0.6 VCS. Example 1.3 (alcohol C12 and Na2CO3) (as a neutralizing agent)

[0050] The procedure of Example 1.1 is reproduced by substituting the 967.4 g of cetearyl alcohol with 414.5 grams of dodecanol-1, and using an amount of anhydrous glucose in powder form such that the molar ratio between dodecanol-1 and glucose is 6 / 1.

[0051] This gives us the referenced product (Composition 3). STEP 1: Glycosylation Reaction:

[0052] 131.3 g of dodecanol-1 (C-12 alcohol) are loaded into a reactor equipped with mechanical stirring and a vacuum distillation apparatus. The alcohol is heated to 85°C and subjected to stirring and nitrogen bubbling. The mixture is then placed under a 30 Torr vacuum. 18.3 g of anhydrous glucose powder are added. The mixture is inert under nitrogen. To initiate the etherification reaction, 0.14 g of a 50% aqueous H₃PO₂ solution are added, followed by 0.23 g of a 98% aqueous H₂SO₄ solution. The temperature is increased and maintained at 105°C. The reaction is carried out for 5 hours. STEP 2: Neutralization of the reaction medium:

[0053] The mixture is then cooled to 67°C at atmospheric pressure and neutralized by introducing 0.29 g of a 25% aqueous Na₂CO₃ solution with stirring. The product is filtered through filter paper (~< 10 µm) to remove residual glucose and obtain the reference product (Composition 3). Analysis:

[0054] The pH value of a 5% mass dispersion in water of Composition 3 is 6.1, and the color measurement of Composition 3 is 1.5 VCS. Example 1.4 (Cut of alcohols 16 / 18 and Na2CO3) (as a neutralizing agent)

[0055] The operating procedure of example 1.1 is reproduced by substituting the 4.61 grams of a 25% aqueous Na2CO3 solution with the appropriate mass of said 25% Na2CO3 solution so as to obtain a pH value of 7.4 for a 5% dispersion of the final composition (Composition 4) thus obtained. Analysis:

[0056] The pH value of a 5% mass dispersion in water of Composition 4 is 7.4, and the color measurement of Composition 4 is 1.0 VCS. Example 1.5 (Coup of alcohols 16 / 18 and Na2CO3) (as a neutralizing agent)

[0057] The operating procedure of example 1.1 is reproduced by substituting the 4.61 grams of an aqueous solution of Na 2 CO 3 at 25% with the adapted mass of said Na 2 CO 3 solution at 25% so as to obtain a pH value of 8.2 for a 5% dispersion of the final composition (Composition 5) thus obtained.

[0058] This gives us the referenced product (Composition 5). Analysis:

[0059] The pH value of a 5% mass dispersion in water of Composition 5 is 8.2, and the color measurement of Composition 5 is 2.3 VCS. 2- Comparative examples Example 2.1 (Cutting of 16 / 18 alcohols and NaOH as a neutralizing agent) STEP 1: Glycosylation Reaction:

[0060] 240.9 g of cetearyl alcohol (C-16 / 18) are loaded into a reactor equipped with mechanical stirring and a vacuum distillation apparatus. The alcohol is melted at 85°C and stirred and bubbling with nitrogen. The mixture is then evacuated to pressures below 50 Torrs. 31.6 g of anhydrous glucose powder are added. The mixture is inert under nitrogen. To initiate the etherification reaction, 0.22 g of a 50% aqueous H₃PO₂ solution are added, followed by 0.28 g of a 98% aqueous H₂SO₄ solution. The temperature is increased and maintained at 105°C. The reaction is carried out for 5 hours and 45 minutes. STEP 2: Neutralization of the reaction medium:

[0061] The mixture is then cooled to 72°C at atmospheric pressure and neutralized by adding 0.73 g of a 25% aqueous NaOH solution while stirring. The product is then transferred to a glass flask and placed in an oven at 80°C for 24 hours to allow the residual glucose to settle. The product (upper phase) is then collected. (Comparative Composition 1). Analysis:

[0062] The pH value of a 5% mass dispersion in water of Comparative Composition 1 is 6.1, and the color measurement of the Comparative Composition 1 is 4.1 VCS. Example 2.2 (Coupling of 20 / 22 alcohols and NaOH as a neutralizing agent)

[0063] The procedure of Example 2.1 is reproduced by substituting the 240.9 g of cetearyl alcohol with 59.9 grams of a mixture of arachidyl alcohol (C20) and benyl alcohol (C22) in a mass ratio (C20 alcohol / C22 alcohol) of 70 / 30, and using an amount of anhydrous glucose in powder form so that the molar ratio between fatty alcohols and glucose is 6 / 1. This yields the referenced product. (Comparative Composition 2) Analysis:

[0064] The pH value of a 5% mass dispersion in water Comparative Composition 2 is 5.7, and the color measurement of the Comparative Composition 2 is 6.3 VCS. Example 2.3 (alcohol C 12 and NaOH as a neutralizing agent) STEP 1: Glycosylation Reaction:

[0065] 131.3 g of dodecanol-1 (C-12) are loaded into a reactor equipped with mechanical stirring and a vacuum distillation apparatus. The dodecanol-1 is introduced at 85°C and subjected to stirring and nitrogen bubbling. The mixture is then placed under vacuum at 30 Torrs. 18.3 g of anhydrous glucose powder are added. The mixture is inert under nitrogen. To initiate the etherification reaction, 0.14 g of a 50% aqueous H₃PO₂ solution are added, followed by 0.23 g of a 98% aqueous H₂SO₄ solution. The temperature is increased and maintained at 105°C. The reaction is carried out for 5 hours. STEP 2: Neutralization of the reaction medium :

[0066] The medium is then cooled to 67°C at atmospheric pressure and neutralized by introducing 0.29 g of a 25% aqueous NaOH solution while stirring. The product is filtered through filter paper (~< 10 µm) to remove residual glucose and obtain the final reference product. (Comparative Composition 3). Analysis:

[0067] The pH value of a 5% mass dispersion in water Comparative Composition 3 is 6.0, and the color measurement of the Comparative Composition 3 is 1.8 VCS. [Table 1] Reference Comparative Composition 1 Composition 1 Comparative Composition 2 Composition 2 Comparative Composition 3 Composition 3 APG Sugar Glucose Alkyl chain APG C-16 / 18 C-20 / 22 C-12 Basic neutralizing agent NaOH Na2CO3 NaOH Na2CO3 NaOH Na2CO3 pH 5% 6,1 5,5 5,7 7,0 6,0 6,1 Color ( vcs ) 4,1 0,7 6,3 0,6 1,8 1,5 Analyses and observations

[0068] Regardless of the fatty acid chain length studied (from C-12 to C-22), using a NaOH solution as the neutralizing agent for the reaction medium to achieve pH values ​​of 5.5 or higher for a 5 wt% dispersion in water, strongly colors the compositions containing residual fatty alcohols and the alkyl polyglucosides formed. Indeed, the color measured for these tests ranges from 1.8 to 6.3 Vcs after filtration of the residual sugar. In comparison, when the neutralization step is carried out with a Na₂CO₃ solution to obtain pH values ​​of 5.5 or higher for a 5 wt% dispersion in water, the colors of the compositions containing residual fatty alcohols and the alkyl polyglucosides formed show values ​​of 1.5 Vcs or lower. B- Influence of the pH value of a 5% wt% dispersion in water of a composition of fatty alcohols and alkyl polyglucosides on the color of the final product, when the neutralization phase is carried out with a carbonate

[0069] Three experimental tests were carried out by implementing the general process described above. These three tests (Example 1.1, Example 1.4 and Example 1.5) describe the preparation of compositions comprising cetearyl alcohol and alkyl polyglucosides on linear C16 and C18 chains, said compositions (Composition 1, Composition 4 and Composition 5) having been prepared by implementing the process according to the invention and are characterized by different pH values ​​of the 5% dispersion of each composition ( cf Table 2). [Table 2] Essay (Composition 1) Composition 4) (Composition 5) pH (5%) 6,4 7,4 8,2 Color (VCS) 0,7 1,0 2,3 Observations and analyses

[0070] The results obtained show that when the pH value of a 5% mass dispersion of the prepared composition is between 5.5 and 7.5, the process according to the invention makes it possible to achieve a color value less than or equal to 1.5 VCS. Conversely, when the pH value of a 5% mass dispersion of the prepared composition is 8.2, the color of the resulting composition exceeds the desired maximum color of 1.5 VCS.

Claims

1. A process for preparing a composition (C), having a color equal to or less than 1.5 vcs, comprising for 100% of its weight: i) a quantity 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), in which R represents a hydrocarbon radical, linear or branched, saturated or unsaturated, possibly comprising at least one hydroxyl function, and comprising from twelve to twenty-two carbon atoms, or a mixture of alcohols of formula (I); ii) a quantity 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):         R-O-(G)x-H     (II), in which the residue G represents the residue of a reducing sugar, R represents a radical as defined in formula (I) and x, which indicates the average degree of polymerization of the residue G represents a decimal number greater than or equal to 1.05 and less than or equal to 2.5, or a mixture of compositions (C1) of formula (II); provided that the sum of the weight proportions of the compounds of formulas (I) and (II) in composition (C) is equal to 100% by weight; said process successively comprising: a) A step a) of glycosylation, 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 greater than or equal to 100°C and less than or equal to 120°C, the at least one acid catalyst (CA) being chosen from the elements of the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, hypophosphorous acid, methane-sulfonic acid, para-toluene sulfonic acid, trifluoromethane sulfonic acid and acidic ion exchange resins, b) A step b) of neutralizing the reaction medium resulting from step a) with an aqueous solution comprising a basic agent (Ab) chosen from the elements of the group consisting of: - carbonates of formula (IVa): XnCO3 (IVa), in which 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, or - hydrogen carbonates of formula (IVb): Y(HCO3)m (IVb), in which 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, the neutralization being carried out so as to obtain a reaction medium, a 5% by weight dispersion of said reaction medium in water having a pH value comprised between 5.5 and 7.5, c) A step c) of eliminating the sugar of formula (III), which has not reacted in step a), from the neutralized reaction medium, and d) A step d) of recovering at least one composition (C) having a color equal to or less than 1.5 vcs.

2. The process according to claim 1, characterized in that said composition (C1) consists of a mixture of compounds represented by formulas (II1), (II2), (II3), (II4) and (II5):         R-O-(G)1-H     (II1),         R-O-(G)2-H     (II2),         R-O-(G)3-H     (113),         R-O-(G)4-H     (II4),         R-O-(G)5-H     (II5), in the respective molar proportions a1, a2, a3, a4 and a5, such that: - the sum: a1+a2 + a3 + a4 + a5 is equal to 1, and - the sum a1 + 2a2 + 3a3 + 4a4 + 5a5 is equal to x.

3. The process according to one of claims 1 or 2, characterized in that composition (C) comprises a quantity less than or equal to 2% by weight of the reducing sugar of formula (III):         H-O-(G)-H     (III); provided that the sum of the weight proportions of the compounds of formulas (I), (II) and (III) in composition (C) is equal to 100% by weight.

4. The process according to one of claims 1 to 3, characterized in that the basic agent (Ab) present in the aqueous solution is sodium carbonate of formula (IVa) in which X is the sodium atom and n is equal to 2.

5. The process according to one of claims 1 to 4, characterized in that it comprises, after step c), a complementary step of adjusting the pH value of a 5% by weight dispersion of the reaction medium in water by adding an aqueous solution comprising the basic agent (Ab) as defined previously so as to obtain a pH value comprised between 5.5 and 7.5.

6. The process according to one of claims 1 to 5, characterized in that the reducing sugar of formula (III) chosen for the glycosylation of step a) is chosen from the elements of the group consisting of glucose, xylose, arabinose and rhamnose.

7. The process according to one of claims 1 to 6, characterized in that step c) of eliminating the reducing sugar of formula (III) is carried out by filtration, centrifugation or decantation.

8. The process according to one of claims 1 to 7, characterized in that in step b) the aqueous solution of basic agent (Ab) comprises between 10% and 40% by weight of said basic agent (Ab).

9. The process according to one of claims 1 to 8, characterized in that step a) comprises the following successive sub-steps: i) Introduction of an alcohol of formula (I) or a mixture of alcohols of formula (I), into a reactor (Ré) equipped with mechanical stirring and a vacuum device; ii) Heating the alcohol of formula (I) to a temperature comprised between 80°C and 90°C under mechanical stirring; iii) Loading the reducing sugar of formula (III) into the reactor (Ré); iv) Introduction of at least one acid catalyst into the reactor (Ré), v) Heating the reaction medium resulting from sub-step iv) and present in the reactor (Ré) under partial vacuum to a temperature comprised between 100°C and 110°C for the duration of the reaction, and vi) Cooling the medium resulting from sub-step v) to a temperature comprised between 70°C and 80°C.

10. The process according to claim 9, characterized in that in formula (I) and / or in formula (II), the radical R is chosen from the following radicals: 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) n-nonadecyl, arachidyl (or n-eicosyl), behenyl (or n-docosyl), erucyl (13-docosenyl), or 12-hydroxystearyl.

11. The process according to claim 9, characterized in that in formula (I) and / or in formula (II), the radical R is chosen from the following radicals: 2-hexyl octyl, 2-hexyl decyl, 2-hexyl dodecyl, 2-octyl decyl, 2-octyl dodecyl, 2-decyl tetradecyl, isostearyl (or 16-methyl heptadecyl) or isomyristyl (or 13-methyl tridecyl).

12. The process according to one of claims 9 to 11, characterized in that during sub-steps ii) to iv) the reactor (Ré) is inerted under nitrogen.

13. The process according to one of claims 9 to 12, characterized in that it comprises between sub-steps ii) and iii) a sub-step of applying vacuum, preferably at a pressure less than or equal to 50 millibars.

14. The process according to one of claims 9 to 13, characterized in that step vi) is performed at atmospheric pressure.