An amino acid surfactant, its preparation method and application

Abstract

The present invention provides an amino acid surfactant, a preparation method thereof and an application thereof, belonging to the technical field of surfactants. The present invention provides an amino acid surfactant having the structure shown in Formula I or a salt thereof. The amino acid surfactant provided by the present invention contains a branched hydrophobic group, so that the amino acid surfactant has excellent foaming performance and foam stability. In addition, the amino acid surfactant provided by the present invention also has good penetration performance and wetting performance, and can be used as an additive for daily chemical products to improve the use effect of daily chemical products. For example, it can be used as an additive for detergents to improve the washing effect.

Description

Technical Field

[0001] The present invention relates to the technical field of surfactants, and particularly relates to an amino acid surfactant, a preparation method thereof, and an application thereof. Background Art

[0002] Amino acid surfactants are a class of surfactants composed of amino acid head groups and hydrophobic chains. Compared with traditional surfactants, they have low irritation, high biodegradability, and excellent interfacial properties. Amino acid surfactants can be widely used in fields such as daily chemicals and medicine, and have important economic and environmental significance. However, the amino acid surfactant products currently on the market have problems of poor foaming performance and poor foam stability. Summary of the Invention

[0003] The purpose of the present invention is to provide an amino acid surfactant, a preparation method thereof, and an application thereof. The amino acid surfactant provided by the present invention has excellent foaming performance and foam stability.

[0004] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides an amino acid surfactant or a salt thereof, and the amino acid surfactant has a structure shown in Formula I:

[0006]

[0007] In Formula I, R is n is 1, 2 or 3.

[0008] Preferably, the salt is a sodium salt or a potassium salt of the amino acid surfactant.

[0009] Preferably, at least one hydrogen in R is replaced by deuterium.

[0010] Preferably, the deuteration rate of R ≥ 80%.

[0011] The present invention provides a preparation method of the amino acid surfactant according to the above technical solution, including the following steps:

[0012] Mix a saturated fatty acid, dimethyl aspartate hydrochloride, a condensation reagent, a base reagent, and an organic solvent, and carry out a condensation reaction to obtain a methyl ester-protected intermediate; the chemical formula of the saturated fatty acid is RCOOH, and R is as defined in Formula I;

[0013] Carry out a demethyl ester protection group reaction on the methyl ester-protected intermediate to obtain the amino acid surfactant.

[0014] Preferably, the condensation reagent includes benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate; the base reagent includes diisopropylethylamine.

[0015] Preferably, the saturated fatty acid is replaced with a deuterated saturated fatty acid, and the preparation method of the deuterated saturated fatty acid comprises the following steps:

[0016] Mix a saturated fatty acid, a catalyst, sodium hydroxide and D 2 O, and carry out a hydrogen-deuterium exchange reaction to obtain a deuterated saturated fatty acid.

[0017] Preferably, the catalyst is a platinum-carbon catalyst; the temperature of the hydrogen-deuterium exchange reaction is 200-220 °C.

[0018] The present invention provides the application of the amino acid surfactant and / or its salt according to the above technical solution or the amino acid surfactant and / or its salt prepared by the preparation method according to the above technical solution in daily chemical products.

[0019] Preferably, the daily chemical products include detergents or cosmetics; the concentration of the amino acid surfactant and / or its salt in the detergent is 0.4-4 wt%, and the concentration of the amino acid surfactant and / or its salt in the cosmetics is 0.4-20 wt%.

[0020] The present invention provides an amino acid surfactant having the structure shown in Formula I. The amino acid surfactant provided by the present invention contains a branched hydrophobic group, so that the amino acid surfactant has excellent foaming performance and foam stability. The results of the test examples show that when the aqueous solution of the amino acid surfactant in the present invention is treated in a predetermined oscillation manner at room temperature, the initial foam height (the foam height at T = 0 s) is 0.60-15.30 mL, indicating that the amino acid surfactant has excellent foaming performance; the foaming height at 5 min (the foam height at T = 5 min) can be up to 97.10% of the initial foam height, indicating that the amino acid surfactant has excellent foam stability. In addition, the amino acid surfactant provided by the present invention also has good penetration performance and wetting performance, and can be used as an additive for daily chemical products to improve the use effect of daily chemical products. For example, it can be used as an additive for detergents to improve the washing effect.

[0021] The present invention provides a preparation method of the amino acid surfactant. The preparation method provided by the present invention is simple and easy to operate, has low production cost, can be mass-produced, and has important commercial application value.

[0022] The present invention also provides a deuterated amino acid surfactant and a preparation method thereof. Deuterated compounds have wide applications in the fields of modern chemistry, biochemistry, medicinal chemistry, etc. Compared with compounds of conventional isotopes, deuterated compounds have great differences in chemical and physical properties, usually with higher chemical stability, easier detection, etc., and are widely used in the research of the structure and function of biomolecules. Therefore, the study of deuterated amino acid surfactants is of great significance. The deuterated amino acid surfactant provided by the present invention can further explore the interfacial behavior of the surfactant from the molecular scale by means of neutron reflection technology, laying a foundation for in-depth study of the structure and composition of the interface. Description of the Drawings

[0023] Figure 1 1H NMR spectrum of SGA prepared in Example 1;

[0024] Figure 2 1H NMR spectrum of SFA prepared in Example 2;

[0025] Figure 3 1H NMR spectrum of SPA prepared in Example 3;

[0026] Figure 4 Contact angle diagram of SGA aqueous solution at 60 s;

[0027] Figure 5 Contact angle diagram of SFA aqueous solution at 60 s;

[0028] Figure 6 Contact angle diagram of SPA aqueous solution at 60 s;

[0029] Figure 7 Foam height diagram of SPA aqueous solution at T = 0 s (left) and T = 5 min (right); Detailed Description of the Invention

[0030] The present invention provides an amino acid surfactant or a salt thereof, and the amino acid surfactant has the structure shown in Formula I:

[0031]

[0032] In Formula I, R is n is 1, 2 or 3.

[0033] In the present invention, the salt is preferably the sodium salt or potassium salt of the amino acid surfactant. Specifically, the hydrogen ions of the two carboxyl groups in Formula I are replaced by sodium ions or potassium ions.

[0034] In the present invention, when R is the amino acid surfactant is denoted as a hydrogenated amino acid surfactant.

[0035] In the present invention, at least one hydrogen in R is replaced by deuterium, and at this time, the amino acid surfactant is denoted as a deuterated amino acid surfactant. In the present invention, the deuteration rate of R is preferably ≥80%, more preferably 90-91.2%.

[0036] In the present invention, the structural formula of the deuterated amino acid surfactant is specifically as shown in Formula II:

[0037]

[0038] In Formula II, n is 1, 2 or 3.

[0039] The present invention provides a preparation method of the amino acid surfactant and its salt according to the above technical solution, which will be specifically described in different cases below. In the present invention, unless otherwise specified, the raw materials used are commercially available products well-known to those skilled in the art or are prepared by methods well-known to those skilled in the art.

[0040] In the present invention, the preparation method of the hydrogenated amino acid surfactant includes the following steps:

[0041] Mix a saturated fatty acid, dimethyl aspartate hydrochloride, a condensation reagent, a base reagent and an organic solvent, and carry out a condensation reaction to obtain a methyl ester protected intermediate; the chemical formula of the saturated fatty acid is RCOOH, and R is defined as in Formula I;

[0042] Carry out a demethyl protection group reaction on the methyl ester protected intermediate to obtain the hydrogenated amino acid surfactant.

[0043] The present invention obtains the hydrogenated amino acid surfactant by a condensation reaction and a demethyl protection group reaction using a saturated fatty acid and dimethyl aspartate hydrochloride as reactants. In the present invention, the saturated fatty acid is specifically tetrahydrogeranic acid, hexahydrofarnesoic acid or phytanic acid, and the structural formulas are as follows:

[0044]

[0045] First, the preparation method of the saturated fatty acid will be described in detail below.

[0046] In the present invention, the preparation method of the saturated fatty acid preferably includes the following steps:

[0047] Mix an unsaturated fatty alcohol, a palladium-carbon catalyst and an organic solvent, and carry out a hydrogenation reaction in the presence of hydrogen to obtain a saturated fatty alcohol; the unsaturated fatty alcohol is geraniol, farnesol and phytol;

[0048] Mix the saturated fatty alcohol, Jones reagent and an organic solvent, and carry out an oxidation reaction to obtain the saturated fatty acid.

[0049] In the present invention, the structural formulas of geraniol, farnesol and phytol are as follows in sequence:

[0050]

[0051] In the present invention, an unsaturated fatty alcohol, a palladium-carbon catalyst (Pd / C catalyst) and an organic solvent are mixed, and a hydrogenation reaction is carried out in the presence of hydrogen to obtain a saturated fatty alcohol. In the present invention, the mass ratio of the unsaturated fatty alcohol to the palladium-carbon catalyst is preferably 2-5:0.1-0.3, more preferably 3-4:0.15-0.25. In the present invention, the organic solvent preferably includes methanol and tetrahydrofuran, and the volume ratio of the methanol to the tetrahydrofuran is preferably 2-4:1, more preferably 3:1; there is no special limitation on the amount of the organic solvent used in the present invention, and it is only necessary to ensure the smooth progress of the reaction. In the present invention, the temperature of the hydrogenation reaction is preferably 20-30 °C, more preferably room temperature; the time is preferably 2-5 days, more preferably 3 days; the hydrogenation reaction is preferably carried out under stirring conditions. After the hydrogenation reaction, in the present invention, the obtained product system is preferably filtered, the solvent in the filtrate is removed, and then the residue is purified by column chromatography to obtain a saturated fatty alcohol. There is no special limitation on the method for removing the solvent in the filtrate in the present invention, for example, the filtrate can be rotary evaporated. In the present invention, the eluent used for column chromatography purification is preferably petroleum ether and ethyl acetate, and the volume ratio of the petroleum ether to the ethyl acetate is preferably 30:1.

[0052] After obtaining the saturated fatty alcohol, in the present invention, the saturated fatty alcohol, Jones reagent and an organic solvent are mixed to carry out an oxidation reaction to obtain the saturated fatty acid. In the present invention, the Jones reagent is preferably prepared from CrO 3 and H 2 O; the dosage ratio of the CrO 3 to the H 2 O is preferably 1.5-5 g:2-6 mL, more preferably 2.4-3.79 g:3-4 mL. In the present invention, the saturated fatty alcohol and CrO 3The mass ratio is preferably 2-4:2-6.5, more preferably 2.5-3:2.4-3.79. In the present invention, the organic solvent is preferably acetone and acetic acid, and the volume ratio of the acetone and acetic acid is preferably 40-80:10-30, more preferably 50-65:20-25; the present invention has no special limitation on the dosage of the organic solvent, and it is only necessary to ensure the smooth progress of the reaction. In the present invention, the saturated fatty alcohol is preferably dissolved in the organic solvent, and then Jones reagent is added at 0 °C until the obtained mixture solution turns red (the purpose is to ensure that the added Jones reagent is in excess to ensure complete reaction), and then the temperature is raised for the oxidation reaction. In the present invention, the temperature of the oxidation reaction is preferably 20-30 °C, more preferably room temperature; the time is preferably 4-24 h, more preferably 12 h; the oxidation reaction is preferably carried out under stirring conditions. After the oxidation reaction, in the present invention, water and sodium metabisulfite are preferably added to the obtained product system until the system turns green (the purpose is to react with the excess Jones reagent), and then the obtained liquid is extracted with ethyl acetate, the organic phase is collected and dried with anhydrous sodium sulfate, filtered, the solvent in the filtrate is removed, and then the residue is purified by column chromatography to obtain the saturated fatty acid. In the present invention, the eluent used for the column chromatography purification is preferably petroleum ether and ethyl acetate, and the volume ratio of the petroleum ether and ethyl acetate is preferably 20:1.

[0053] After obtaining the saturated fatty acid, the present invention mixes the saturated fatty acid, dimethyl aspartate hydrochloride, a condensing reagent, a base reagent, and an organic solvent, and conducts a condensation reaction to obtain a methyl ester-protected intermediate. In the present invention, the dimethyl aspartate hydrochloride is preferably L-dimethyl aspartate hydrochloride; the mass ratio of the saturated fatty acid to dimethyl aspartate hydrochloride is preferably 1-4:0.8-2, more preferably 1.2-3:1.13-1.63. In the present invention, the condensing reagent preferably includes benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (pyBOP); the base reagent preferably includes diisopropylethylamine; the dosage ratio of the saturated fatty acid, the condensing reagent, and the base reagent is preferably 1-4 g:2-6.4 g:2.85-7 mL, more preferably 1.2-3 g:2.5-5.43 g:3.45-5 mL. In the present invention, the organic solvent is preferably acetonitrile and N,N-dimethylformamide (DMF), and the volume ratio of acetonitrile to DMF is preferably 3-8:1.2-2.6, more preferably 5:1.7; the present invention has no special limitation on the dosage of the organic solvent, as long as the reaction proceeds smoothly. In the present invention, the temperature of the condensation reaction is preferably 20-30 °C, more preferably room temperature; the time is preferably 10-16 h, more preferably 12 h; the condensation reaction is preferably carried out under stirring conditions. After the condensation reaction, the present invention preferably adds hydrochloric acid to the obtained product system, then filters, removes the solvent in the filtrate, and then purifies the residue by column chromatography to obtain a methyl ester-protected intermediate. The present invention preferably removes the solvent in the filtrate under vacuum conditions, specifically, the filtrate can be vacuum concentrated. In the present invention, the eluent used for column chromatography purification is preferably petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate is preferably 5:1.

[0054] After obtaining the methyl ester protected intermediate, the present invention conducts a demethyl protection reaction on the methyl ester protected intermediate to obtain the hydrogenated amino acid surfactant. In the present invention, the demethyl protection reaction is preferably carried out under alkaline conditions; the present invention preferably mixes the methyl ester protected intermediate, an alkaline reagent, water and an organic solvent to conduct the demethyl protection reaction. In the present invention, the alkaline reagent is preferably an alkali metal hydroxide, more preferably sodium hydroxide; the organic solvent is preferably an alcohol solvent, more preferably ethanol. The present invention preferably mixes the methyl ester protected intermediate with the organic solvent to obtain a methyl ester protected intermediate solution; mixes the alkaline reagent with water to obtain an alkaline reagent aqueous solution; and mixes the methyl ester protected intermediate solution with the alkaline reagent aqueous solution. In the present invention, the concentration of the alkaline reagent aqueous solution is preferably 0.5 - 1.5 mol / L, more preferably 1 mol / L; the dosage ratio of the methyl ester protected intermediate, the organic solvent and the alkaline reagent aqueous solution is preferably 0.5 - 2 g: 5 - 30 mL: 2 - 14 mL, more preferably 1 - 1.5 g: 11 - 24 mL: 4.4 - 9.5 mL. In the present invention, the temperature of the demethyl protection reaction is preferably 20 - 30 °C, more preferably room temperature; the time is preferably 2 - 6 h, more preferably 4 h; the demethyl protection reaction is preferably carried out under stirring conditions. In the present invention, after the demethyl protection reaction, the present invention preferably adjusts the pH of the obtained product system to acidic and then extracts with ethyl acetate, collects the organic phase, dries it with anhydrous sodium sulfate, filters, removes the solvent in the filtrate, and then washes the residue to obtain the hydrogenated amino acid surfactant. In the present invention, the reagent used for adjusting the acidity is preferably hydrochloric acid, and the concentration of the hydrochloric acid is preferably 0.5 - 1.5 mol / L, more preferably 1 mol / L; the adjustment of the acidity preferably adjusts the pH value of the system to 1 - 3, more preferably 2; the role of adjusting the acidity in the present invention is to protonate all the sodium salts into acids. The present invention preferably removes the solvent in the filtrate under vacuum conditions, specifically, the filtrate can be concentrated under vacuum. In the present invention, the reagents used for washing are preferably ether and acetone; specifically, the residue is washed 2 - 3 times each with ether and acetone.

[0055] The present invention has no special limitation on the preparation method of the salt of the hydrogenated amino acid surfactant, and the methods well-known to those skilled in the art can be adopted. Taking the preparation of the sodium salt or potassium salt of the hydrogenated amino acid surfactant as an example, it preferably includes the following steps:

[0056] Dissolve the hydrogenated amino acid surfactant in ethanol to obtain a hydrogenated amino acid surfactant solution; mix NaOH or KOH with ethanol to obtain an alkali metal hydroxide solution; mix the hydrogenated amino acid surfactant solution with the alkali metal hydroxide solution, precipitate will be generated, after centrifugation, collect the precipitate and wash it to obtain the sodium salt or potassium salt of the hydrogenated amino acid surfactant.

[0057] In the present invention, the molar ratio of the hydrogenated amino acid surfactant to NaOH or KOH is preferably 1 to 1.2:0.8 to 1.5, more preferably 1:1. In the present invention, the reagents used for washing are preferably ether and acetone; specifically, the residue is washed 2 to 3 times with ether and acetone in sequence.

[0058] In the present invention, the preparation method of the deuterated amino acid surfactant comprises the following steps:

[0059] Mix a saturated fatty acid, a catalyst, sodium hydroxide and D 2 O to carry out a hydrogen-deuterium exchange reaction to obtain a deuterated saturated fatty acid; the chemical formula of the saturated fatty acid is RCOOH, and R is defined as in Formula I;

[0060] Mix the deuterated saturated fatty acid, dimethyl aspartate hydrochloride, a condensation reagent, a base reagent and an organic solvent to carry out a condensation reaction to obtain a methyl ester-protected deuterated intermediate;

[0061] Carry out a demethyl ester protection reaction on the methyl ester-protected deuterated intermediate to obtain the deuterated amino acid surfactant.

[0062] In the present invention, a saturated fatty acid, a catalyst, sodium hydroxide and D 2 O are mixed to carry out a hydrogen-deuterium exchange reaction to obtain a deuterated saturated fatty acid. In the present invention, the saturated fatty acid is preferably the saturated fatty acid described in the above technical solution, which will not be elaborated here. In the present invention, the catalyst is preferably a platinum-carbon catalyst (Pt / C catalyst), and the mass content of Pt in the Pt / C catalyst is preferably 10%. In the present invention, the dosage ratio of the saturated fatty acid, Pt / C catalyst, sodium hydroxide and D 2 O is preferably 1 to 5 g:0.2 to 0.5 g:0.12 to 1.16 g:10 to 20 mL, more preferably 2 g:0.3 to 0.35 g:0.26 to 0.47 g:6 to 15 mL. In the present invention, it is preferred to mix the saturated fatty acid, the catalyst and D 2 O, place the obtained mixture in a high-pressure reaction kettle, repeatedly evacuate and replace with argon 2 to 3 times to ensure that there is no oxygen in the reaction system, and then seal the high-pressure reaction kettle to carry out the hydrogen-deuterium exchange reaction. In the present invention, the number of times of the hydrogen-deuterium exchange reaction is preferably 2 to 5 times, more preferably 3 times; the temperature of each hydrogen-deuterium exchange reaction is independently preferably 200 to 220 °C, more preferably 210 to 220 °C; the time of each hydrogen-deuterium exchange reaction is independently preferably 3 to 6 days, more preferably 4 days; the hydrogen-deuterium exchange reaction is preferably carried out under stirring conditions. In the present invention, after each hydrogen-deuterium exchange reaction is completed, it is preferred to stop heating, open the high-pressure reaction kettle when it cools to room temperature, freeze-dry the obtained product system to remove water, and then re-add D2 Perform the next hydrogen-deuterium exchange reaction. In the present invention, after the last hydrogen-deuterium exchange reaction is completed, the present invention preferably stops heating. When cooled to room temperature, the high-pressure reactor is opened, the obtained product system is mixed with water, and then adjusted to a pH value of 1-2 with concentrated hydrochloric acid. The obtained mixed system is extracted with ethyl acetate. The organic phase containing the catalyst is filtered to remove the catalyst. The filtrate is dried with a desiccant (such as anhydrous sodium sulfate), and then the desiccant is filtered off. The filtrate is concentrated to obtain deuterated saturated fatty acid.

[0063] After obtaining the deuterated saturated fatty acid, the present invention mixes the deuterated saturated fatty acid, dimethyl aspartate hydrochloride, a condensation reagent, a base reagent, and an organic solvent to carry out a condensation reaction to obtain a methyl ester-protected deuterated intermediate. In the present invention, the method for preparing the methyl ester-protected deuterated intermediate using the deuterated saturated fatty acid preferably refers to the method for preparing the methyl ester-protected intermediate using the saturated fatty acid in the above technology, and will not be elaborated here.

[0064] After obtaining the methyl ester-protected deuterated intermediate, the present invention performs a demethyl ester protection reaction on the methyl ester-protected deuterated intermediate to obtain the deuterated amino acid surfactant. In the present invention, the method for preparing the deuterated amino acid surfactant using the methyl ester-protected deuterated intermediate preferably refers to the method for preparing the hydrogenated amino acid surfactant using the methyl ester-protected intermediate in the above technology, and will not be elaborated here.

[0065] The present invention has no special limitation on the preparation method of the salt of the deuterated amino acid surfactant, and the method well-known to those skilled in the art can be adopted. Taking the preparation of the sodium salt or potassium salt of the deuterated amino acid surfactant as an example, it preferably refers to the preparation method of the sodium salt or potassium salt of the hydrogenated amino acid surfactant, and will not be elaborated here.

[0066] In the examples of the present invention, taking the preparation of the sodium salt of the deuterated amino acid surfactant as an example, the reaction formula is as follows:

[0067]

[0068] The present invention provides the application of the amino acid surfactant and / or its salt described in the above technical solution, or the amino acid surfactant and / or its salt prepared by the preparation method described in the above technical solution, in daily chemical products. In the present invention, the daily chemical products preferably include detergents or cosmetics. In the present invention, the concentration of the amino acid surfactant and / or its salt in the detergent is preferably 0.4 to 4 wt%, more preferably 2 to 4 wt%; the present invention has no special limitation on other components in the detergent, and components well-known to those skilled in the art can be used. In the present invention, the concentration of the amino acid surfactant and / or its salt in the cosmetics is preferably 0.4 to 20 wt%, more preferably 5 to 10 wt%; the present invention has no special limitation on other components in the cosmetics, and components well-known to those skilled in the art can be used. The amino acid surfactant provided by the present invention has excellent surface tension. For example, when the amino acid surfactant is added to water to prepare an amino acid surfactant aqueous solution with a concentration of 4 wt%, its surface tension ≤ 40.79 mN / m, and when the concentration of the amino acid surfactant aqueous solution is 0.4 wt%, its surface tension ≤ 42.16 mN / m.

[0069] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0070] Example 1 Synthesis of hydrogenated surfactant (n = 1) and its salt

[0071] Place a magnetic stir bar in a 100 mL round-bottom flask, add 3 g of geraniol, then add 18 mL of methanol and 6 mL of tetrahydrofuran, add 0.15 g of Pd / C catalyst, introduce hydrogen into the system, and maintain stirring reaction at room temperature (25 °C) for 3 days; filter the obtained product system, rotary evaporate the filtrate, and purify the residue by column chromatography (the volume ratio of petroleum ether to ethyl acetate is 30:1) to obtain tetrahydrogeraniol with a yield of 81.2%.

[0072] Add 3.79 g of CrO 3 and 4 mL of H 2The Jones reagent solution prepared from O was added to a mixed solution of 2.5 g of tetrahydrogeraniol in acetone (50 mL) and acetic acid (20 mL) at 0 °C until the reaction mixture turned red. After stirring the mixture at room temperature for 12 h, 20 mL of water was added to the reaction system, and then sodium metabisulfite was added until the reaction mixture turned green. The resulting product system was extracted with ethyl acetate three times, the organic phase was collected, dried over anhydrous sodium sulfate, filtered, the solvent in the filtrate was evaporated, and the residue was purified by column chromatography (the volume ratio of petroleum ether to ethyl acetate was 20:1) to obtain tetrahydrogeranic acid with a yield of 44.1%.

[0073] At room temperature, 1.13 g of L-aspartic acid dimethyl ester hydrochloride and 3.98 g of 1H-benzotriazol-1-yloxytris(pyrrolidino)phosphonium hexafluorophosphate (pyBOP) were added to a mixed solution of 1.2 g of tetrahydrogeranic acid in acetonitrile (35 mL) and DMF (4.9 mL). Then, 3.45 mL of diisopropylethylamine was added, and the mixture was stirred at room temperature for 12 h. The resulting product system was extracted with ethyl acetate three times, and the combined organic phase was extracted with saturated brine, dried over anhydrous sodium sulfate, filtered, the solvent in the filtrate was evaporated, and the residue was purified by column chromatography (the volume ratio of petroleum ether to ethyl acetate was 5:1) to obtain the methyl ester-protected hydrogenated surfactant (n = 1) with a yield of 66.7%.

[0074] 10 mL of a 1 mol / L sodium hydroxide solution was added to a solution of 1.4 g of the methyl ester-protected hydrogenated surfactant (n = 1) in ethanol (24 mL), and the mixture was stirred at room temperature for 4 h. The pH value of the resulting product system was adjusted to 2 with 1 mol / L hydrochloric acid, extracted with ethyl acetate three times, the organic phase was collected, dried over anhydrous sodium sulfate, filtered, the filtrate was concentrated under vacuum, and the residue was washed twice with ether and acetone respectively to obtain the hydrogenated surfactant (n = 1) with a yield of 61.1%.

[0075] The hydrogenated surfactant (n = 1) was dissolved in ethanol, and an equal amount of an ethanol solution of NaOH and an ethanol solution of KOH were added respectively, and precipitates were formed. After centrifugation, the precipitates were washed twice with ether and acetone respectively to obtain the sodium salt and potassium salt of the hydrogenated surfactant (n = 1). The sodium salt is denoted as SGA (the hydrogen spectrum is as Figure 1 shown).

[0076] Example 2 Synthesis of hydrogenated surfactant (n = 2) and its salts

[0077] A magnetic stir bar was placed in a 100 mL round-bottom flask, and 4 g of farnesol was added. Then, 30 mL of methanol and 10 mL of tetrahydrofuran were added, followed by 0.25 g of Pd / C catalyst. Hydrogen was introduced into the system, and the mixture was stirred at room temperature for 3 days. The resulting product system was filtered, and the filtrate was rotary evaporated. The residue was purified by column chromatography (petroleum ether:ethyl acetate = 30:1) to obtain hexahydrofarnesol with a yield of 76.8%.

[0078] A solution of Jones reagent prepared from 3.15 g of CrO 3 and 3.4 mL of H 2 O was added dropwise to a mixture of 3 g of hexahydrofarnesol in acetone (65 mL) and acetic acid (25 mL) at 0 °C until the reaction mixture turned red. The mixture was stirred at room temperature for 12 h, then 20 mL of water was added to the reaction system, followed by sodium metabisulfite until the reaction mixture turned green. The resulting product system was extracted with ethyl acetate three times, and the organic phases were collected, dried over anhydrous sodium sulfate, filtered, and the solvent in the filtrate was evaporated. The residue was purified by column chromatography (petroleum ether:ethyl acetate = 20:1) to obtain hexahydrofarnesoic acid with a yield of 68.9%.

[0079] At room temperature, 1.54 g of L-aspartic acid dimethyl ester hydrochloride and 5.43 g of pyBOP were added to a mixture of 2.3 g of hexahydrofarnesoic acid in acetonitrile (47.5 mL) and DMF (16 mL). Then, 4.7 mL of diisopropylethylamine was added, and the mixture was stirred at room temperature for 12 h. The resulting product system was extracted with ethyl acetate three times, and the combined organic phases were further extracted with saturated brine, dried over anhydrous sodium sulfate, filtered, and the solvent in the filtrate was evaporated. The residue was purified by column chromatography (petroleum ether:ethyl acetate = 5:1) to obtain the methyl ester-protected hydrogen surfactant (n = 2) with a yield of 68.3%.

[0080] 7.8 mL of 1 mol / L sodium hydroxide solution was added to a solution of 2.5 g of the methyl ester-protected hydrogen surfactant (n = 2) in ethanol (32 mL). The mixture was stirred at room temperature for 4 h. The pH was adjusted to 2 with 1 mol / L hydrochloric acid, and the mixture was extracted with ethyl acetate three times. The organic phases were collected, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under vacuum. The residue was washed twice with ether and twice with acetone to obtain the hydrogen surfactant (n = 2) with a yield of 59.4%.

[0081] Dissolve the hydrogen surfactant (n = 2) in ethanol, and add equal amounts of ethanol solutions of NaOH and KOH respectively. Precipitates are formed; centrifuge, and wash the precipitates twice with ether and acetone respectively to obtain the sodium salt and potassium salt of the hydrogen surfactant (n = 2). The sodium salt is denoted as SFA (the hydrogen spectrum is as shown in Figure 2 ).

[0082] Example 3 Synthesis of hydrogen surfactant (n = 3) and its salts

[0083] Place a magnetic stir bar in a 100 mL round-bottom flask, add 4 g of phytol, then add 30 mL of ethanol and 10 mL of tetrahydrofuran, add 0.2 g of Pd / C catalyst, introduce hydrogen into the system, and maintain stirring reaction at room temperature for 3 days; filter the obtained product system, rotary evaporate the filtrate, and purify the residue by column chromatography (the volume ratio of petroleum ether to ethyl acetate is 30:1) to obtain phytanol with a yield of 74.4%.

[0084] Add the Jones reagent solution prepared from 2.4 g of CrO 3 and 3 mL of H 2 O to a mixed solution of 3 g of phytanol in acetone (65 mL) and acetic acid (25 mL) at 0 °C until the reaction mixture turns red. Stir the mixture at room temperature for 12 h, then add 20 mL of water to the reaction system, and then add sodium metabisulfite until the reaction mixture turns green; extract the obtained product system with ethyl acetate three times, collect the organic phase, add anhydrous sodium sulfate for drying, then filter, evaporate the solvent in the filtrate, and purify the residue by column chromatography (the volume ratio of petroleum ether to ethyl acetate is 20:1) to obtain phytanic acid with a yield of 95.5%.

[0085] At room temperature, add 1.63 g of L-aspartic acid dimethyl ester hydrochloride and 2.5 g of pyBOP to a mixed solution of 3 g of phytanic acid in acetonitrile (48 mL) and DMF (16.3 mL), then add 5 mL of diisopropylethylamine, and stir the reaction at room temperature for 12 h; extract the obtained product system with ethyl acetate three times, then extract the combined organic phase with saturated brine, add anhydrous sodium sulfate for drying, then filter, evaporate the solvent in the filtrate, and purify the residue by column chromatography (the volume ratio of petroleum ether to ethyl acetate is 5:1) to obtain the methyl ester-protected hydrogen surfactant (n = 2) with a yield of 67.5%.

[0086] 6 mL of a 1 mol / L sodium hydroxide solution was added to an ethanol (15 mL) solution of 2.95 g of a methyl ester-protected hydrogenated surfactant (n = 3), and the mixture was stirred at room temperature for 4 h; the resulting product system was adjusted to pH 2 with 1 mol / L hydrochloric acid, extracted with ethyl acetate three times, the organic phase was collected, dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under vacuum. The residue was washed twice with ether and twice with acetone respectively to obtain the hydrogenated surfactant (n = 3) with a yield of 63.8%.

[0087] The hydrogenated surfactant (n = 3) was dissolved in ethanol, and an equal amount of an ethanol solution of NaOH and an ethanol solution of KOH were added respectively, and precipitates were formed; after centrifugation, the precipitates were washed twice with ether and twice with acetone respectively to obtain the sodium salt and potassium salt of the hydrogenated surfactant (n = 3). Its sodium salt is denoted as SPA (the hydrogen spectrum is as Figure 3 shown).

[0088] Example 4 Synthesis of deuterated surfactant (n = 1) and its salts

[0089] Tetrahydrocitraconic acid was prepared by referring to the method of Example 1.

[0090] 2 g of tetrahydrocitraconic acid and 0.5 g of 10% Pt / C catalyst were uniformly dispersed in 20 mL of D 2 O, 0.46 g of NaOH was added, and then the mixture was loaded into a high-pressure reaction kettle, and argon was evacuated and replaced three times to ensure that there was no oxygen in the reaction system; the reaction kettle was sealed, and the reaction system was heated to 220 °C, and the first hydrogen-deuterium exchange reaction was carried out with stirring for 4 days; after the reaction was completed, the heating was stopped, and when it was cooled to room temperature, the reaction kettle was opened. After the resulting product system was freeze-dried to remove water, 20 mL of D 2 O was added again, and the second hydrogen-deuterium exchange reaction and the third hydrogen-deuterium exchange reaction were carried out according to the above operation; after the reaction was completed, the resulting product system was transferred to a beaker, and H 2 O was added, and the pH value of the system was adjusted to 2 with concentrated hydrochloric acid (37 wt%), and then extracted with ethyl acetate five times. The extracted organic phases were combined, the Pt / C catalyst was removed by filtration, the filtrate was dried over a desiccant (anhydrous sodium sulfate), and then the desiccant was removed by filtration. The filtrate was concentrated to obtain deuterated tetrahydrocitraconic acid with a yield of 60.6%.

[0091] By referring to the method of Example 1, deuterated surfactant (n = 1) and its sodium salt and potassium salt were prepared using deuterated tetrahydrocitraconic acid. Its sodium salt is denoted as D-SGA, and the deuteration rate is 90.1%.

[0092] Example 5 Synthesis of deuterated surfactant (n = 2) and its salts

[0093] Prepare hexahydrofarnesoic acid according to the method of Example 2.

[0094] Disperse 4 g of hexahydrofarnesoic acid and 1 g of 10% Pt / C catalyst evenly in 50 mL of D 2 O. Add 0.66 g of NaOH, and then put the mixture into a high-pressure reactor. Purge with argon repeatedly for 3 times to ensure that there is no oxygen in the reaction system. Seal the reactor and heat the reaction system to 220 °C. Maintain stirring and carry out the first hydrogen-deuterium exchange reaction for 4 days. After the reaction is completed, stop heating. When it cools to room temperature, open the reactor. After freeze-drying the obtained product system to remove water, add 50 mL of D 2 O again, and carry out the second and third hydrogen-deuterium exchange reactions according to the above operation. After the reaction is completed, transfer the obtained product system to a beaker, add H 2 O, adjust the pH value of the system to 2 with concentrated hydrochloric acid (37 wt%). Then extract with ethyl acetate 5 times. Combine the extracted organic phases, filter, dry and concentrate to obtain deuterated hexahydrofarnesoic acid with a yield of 67.2%.

[0095] According to the method of Example 2, use deuterated hexahydrofarnesoic acid to prepare deuterated surfactants (n = 2) and their sodium and potassium salts. The sodium salt is denoted as D-SFA with a deuteration rate of 90.0%.

[0096] Example 6 Synthesis of Deuterated Surfactants (n = 3) and Their Salts

[0097] Prepare phytanic acid according to the method of Example 3.

[0098] Disperse 1 g of phytanic acid and 0.1 g of 10% Pt / C catalyst evenly in 10 mL of D 2 O. Add 0.13 g of NaOH, and then put the mixture into a high-pressure reactor. Purge with argon repeatedly for 3 times to ensure that there is no oxygen in the reaction system. Seal the reactor and heat the reaction system to 220 °C. Maintain stirring and carry out the first hydrogen-deuterium exchange reaction for 4 days. After the reaction is completed, stop heating. When it cools to room temperature, open the reactor. After freeze-drying the obtained product system to remove water, add 10 mL of D 2 O again, and carry out the second and third hydrogen-deuterium exchange reactions according to the above operation. After the reaction is completed, transfer the obtained product system to a beaker, add H 2 O, adjust the pH value of the system to 2 with concentrated hydrochloric acid (37 wt%). Then extract with ethyl acetate 5 times. Combine the extracted organic phases, filter, dry and concentrate to obtain deuterated phytanic acid with a yield of 70.1%.

[0099] Referring to the method of Example 3, deuterated surfactants (n = 3) and their sodium and potassium salts were prepared using deuterated phytanic acid. The sodium salt is denoted as D-SFA, and the deuteration rate is 91.2%.

[0100] Test Example 1: Measurement of surface tension

[0101] Three kinds of hydrogenated surfactants prepared in the examples of the present invention and lauroyl aspartic acid were respectively prepared into aqueous solutions with concentrations of 200 mg / L, 400 mg / L, and 1000 mg / L, and the pH value was adjusted to 7 - 8 (0.1 mol / L hydrochloric acid solution or 0.1 mol / L NaOH solution can be used to adjust the pH value according to actual needs). According to the hanging plate method in SY / T 5370 - 2018 "Determination Method of Surface and Interfacial Tension", the surface tension was measured, and lauroyl aspartic acid was used as a comparison. The results are shown in Table 1. It can be seen from the data in Table 1 that except for SGA with a shorter chain among the branched amino acid surfactants provided by the present invention, the interfacial tensions of SFA and SPA in the concentration range of 200 - 1000 mg / L are all lower than 34.5 mN / m, which fully shows that the surfactant provided by the present invention can significantly reduce the interfacial tension. The surface tensions of the three kinds of deuterated surfactants prepared in the examples of the present invention are similar to those of the corresponding hydrogenated surfactants.

[0102] Table 1: Test results of surface tension

[0103]

[0104] Test Example 2: Measurement of wettability

[0105] Three kinds of hydrogenated surfactants prepared in the examples of the present invention were prepared into an aqueous solution with a mass concentration of 500 mg / L, and the pH value was adjusted to 7 - 8 (0.1 mol / L hydrochloric acid solution or 0.1 mol / L NaOH solution can be used to adjust the pH value according to actual needs). The contact angle was measured, and the solid interface was selected as the paraffin interface, and lauroyl aspartic acid was used as a comparison. The results are shown in Table 2 and Figures 4 to 6 . Among them Figure 4 is the contact angle diagram of the SGA aqueous solution at 60 s, Figure 5 is the contact angle diagram of the SFA aqueous solution at 60 s, Figure 6 is the contact angle diagram of the SPA aqueous solution at 60 s. It can be seen from Table 2 and Figures 4 to 6 that the branched amino acid surfactants provided by the present invention have good wettability. In particular, SPA can reduce the contact angle to 35.71° within 100 s; while the wetting effect of lauroyl aspartic acid is poor, only reducing to 91.69°. The contact angles of the three kinds of deuterated surfactants prepared in the examples of the present invention are similar to those of the corresponding hydrogenated surfactants.

[0106] Table 2: Test results of contact angle

[0107]

[0108] Test Example 3: Test of foam stability

[0109] Prepare aqueous solutions of 3 kinds of hydrogenated surfactants prepared in the examples of the present invention with a mass concentration of 500 mg / L, adjust the pH value to 7-8 (the pH value can be adjusted with 0.1 mol / L hydrochloric acid solution or 0.1 mol / L NaOH solution according to actual needs). At room temperature, add 5 mL of the prepared test solution to a 25 mL stoppered graduated cylinder respectively, cover the stopcock, shake vigorously up and down 180° for 15 times, observe the foaming property, and record the foam heights H at 0 s and 5 min 0 、H 5min 。

[0110] Figure 7 It is a graph of the foam height of the SPA aqueous solution at T = 0 s (left) and the foam height at T = 5 min (right).

[0111] Calculate the foam stability of the test solution according to the following formula:

[0112] Stability = H 5min / H 0 ×100%.

[0113] The test results of foam stability are shown in Table 3.

[0114] Through Figure 7 and the data in Table 3, it can be seen that the branched amino acid surfactant provided by the present invention has good foam stability. In particular, the foam stability of SPA can reach 97.1%, which is better than that of lauroyl aspartic acid. The foam stabilities of the 3 kinds of deuterated surfactants prepared in the examples of the present invention are similar to those of the corresponding hydrogenated surfactants.

[0115] Table 3 Foam stability results

[0116] Surfactant type <![CDATA[H 0 (mL)]]> <![CDATA[Foam stability H 5min / H 0 > SGA 0.60 33.33％ SFA 13.80 87.70％ SPA 15.30 97.10％ Lauroyl aspartic acid 11.43 75.20％

[0117] This invention is a project funded by the Natural Science Foundation of Shandong Province · ZR2022QB118.

[0118] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An amino acid surfactant or a salt thereof, wherein the amino acid surfactant has a structure shown in Formula I: Formula I; R as described in formula I is or R as described in formula I is and at least one hydrogen in R is replaced by deuterium, and the deuteration rate of R ≥ 80%; n is 2 or 3.

2. The amino acid surfactant or a salt thereof according to claim 1, characterized in that the salt is a sodium salt or a potassium salt of the amino acid surfactant.

3. A method for preparing the amino acid surfactant according to claim 1 or 2, comprising the following steps: When the amino acid surfactant does not contain deuterium, the method for preparing the amino acid surfactant comprises the following steps: Mix a saturated fatty acid, dimethyl aspartate hydrochloride, a condensation reagent, a base reagent and an organic solvent, and carry out a condensation reaction to obtain a methyl ester-protected intermediate; the chemical formula of the saturated fatty acid is RCOOH, and R is defined as in Formula I; Carry out a demethyl ester protection reaction on the methyl ester-protected intermediate to obtain the amino acid surfactant; When the amino acid surfactant contains deuterium, the method for preparing the amino acid surfactant comprises the following steps: Mix the saturated fatty acid, catalyst, sodium hydroxide with D 2 O and conduct a hydrogen-deuterium exchange reaction to obtain deuterated saturated fatty acid; Mix the deuterated saturated fatty acid, dimethyl aspartate hydrochloride, a condensation reagent, a base reagent and an organic solvent, and carry out a condensation reaction to obtain a methyl ester-protected deuterated intermediate; Carry out a demethyl ester protection reaction on the methyl ester-protected deuterated intermediate to obtain the amino acid surfactant.

4. The preparation method according to claim 3, characterized in that the condensation reagent includes benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate; the base reagent includes diisopropylethylamine.

5. The preparation method according to claim 3, characterized in that the catalyst is a platinum-carbon catalyst; the temperature of the hydrogen-deuterium exchange reaction is 200-220 °C.

6. Use of the amino acid surfactant or a salt thereof according to claim 1 or 2 or the amino acid surfactant or a salt thereof prepared by the preparation method according to any one of claims 3-5 in daily chemical products.

7. The use according to claim 6, characterized in that the daily chemical products include detergents or cosmetics; the concentration of the amino acid surfactant or a salt thereof in the detergent is 0.4-4 wt%, and the concentration of the amino acid surfactant or a salt thereof in the cosmetics is 0.4-20 wt%.

Images