A dioctyl ether composition, its preparation and use

Abstract

The present application belongs to the technical field of daily chemical industry. More specifically, it relates to a dioctyl ether composition, a preparation method and application thereof. The specific method of the present application comprises the following steps: S1: carrying out an aldol condensation reaction of furfural and acetone under the action of an alkaline catalyst to obtain a first mixture containing a C8 unsaturated ketone intermediate; S2: carrying out a hydrogenation reaction on the first mixture to convert the C8 unsaturated ketone intermediate into 4-(2-tetrahydrofuryl)-2-butanol, to obtain a second mixture; S3: adding glycerol and 1,3-butanediol to the second mixture, and carrying out a dehydration ring-opening and etherification reaction under the action of an acidic catalyst at 100-180 DEG C, to obtain a third mixture containing a dioctyl ether composition; S4: separating and purifying from the third mixture to obtain a dioctyl ether composition.

Description

Technical Field

[0001] This invention belongs to the field of daily chemical technology. More specifically, it relates to a dioctyl ether composition, its preparation method, and its application. Background Technology

[0002] Dioctyl ether is a high-performance emollient ester substitute with excellent spreadability, low viscosity, and good skin affinity, showing great promise for application in high-end skincare, sunscreen, and personal care products. Currently, cosmetic-grade dioctyl ether is mainly produced by acid-catalyzed dehydration of petrochemical-derived n-octanol. This process suffers from problems such as equipment corrosion, difficulty in waste liquid treatment, and the product's color and residue failing to meet cosmetic-grade purity requirements.

[0003] Meanwhile, developing green chemicals using renewable biomass resources has become an industry trend. Existing technologies, such as US9162949B2, report a route for synthesizing n-octanol from biomass platform molecules (furfural / acetone) through multiple conversion steps. However, this process aims to prepare alcohol monomers, resulting in a complex reaction network. Dioctyl ether is only generated as a byproduct and is not used as a target product for targeted synthesis and purification. Therefore, there is currently a lack of a method for directly and selectively preparing high-purity dioctyl ether compositions that meet cosmetic quality requirements from biomass sources. Summary of the Invention

[0004] The technical problem this invention aims to solve is the difficulty in efficiently preparing dioctyl ether compositions for cosmetics using biomass raw materials, as is present in existing technologies. Based on this challenge, this invention provides a dioctyl ether composition, its preparation method, and its applications.

[0005] The purpose of this invention is to provide a dioctyl ether composition.

[0006] Another object of the present invention is to provide a method for preparing a dioctyl ether composition.

[0007] Another object of the present invention is to provide an application of a dioctyl ether composition.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution: A method for preparing a dioctyl ether composition, the specific preparation steps of which include: S1: Furfural and acetone are subjected to aldol condensation reaction under the action of an alkaline catalyst to obtain a first mixture containing C8 unsaturated ketone intermediates; S2: The first mixture is subjected to a hydrogenation reaction to convert the C8 unsaturated ketone intermediate into 4-(2-tetrahydrofuranyl)-2-butanol to obtain the second mixture; S3: Add glycerol and 1,3-butanediol to the second mixture, and carry out dehydration ring-opening and etherification reactions at 100-180°C under the action of an acidic catalyst to obtain a third mixture containing a dioctyl ether composition; S4: Separate and purify from the third mixture to obtain the dioctyl ether composition.

[0009] The beneficial effects of the above technical solution are as follows: The above technical solution constructs a reaction chain from biomass furfural → C8 platform compound → complex dioctyl ether composition. In stages S1 and S2, furfural is first converted to 4-(2-tetrahydrofuranyl)-2-butanol through condensation and hydrogenation, thus avoiding the technical bottleneck of competing side reactions for acetalization between glycerol / 1,3-butanediol and furfural under acidic conditions. The significance of this stepwise strategy is that when the reaction proceeds to S3, the only substrates in the system that can participate in the acid-catalyzed reaction are 4-(2-tetrahydrofuranyl)-2-butanol, glycerol, and 1,3-butanediol. Under acidic conditions, these three undergo intramolecular dehydration ring-opening and intermolecular dehydration etherification, respectively, forming selective coupling.

[0010] Glycerol and 1,3-butanediol participate in the etherification reaction as co-reactants. Both are inexpensive, bulk chemicals of bio-based origin, widely available and low in cost. The polyhydroxyl feature in their molecular structure enables them to form stable ether bonds with the ring-opening product of 4-(2-tetrahydrofuranyl)-2-butanol.

[0011] Furthermore, the alkaline catalyst is selected from any one of sodium hydroxide, potassium hydroxide, and calcium hydroxide.

[0012] Furthermore, the acidic catalyst is selected from p-toluenesulfonic acid and 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate.

[0013] Furthermore, in S1, the molar ratio of furfural to acetone is 1:6-10.

[0014] Excess acetone as a reactant can effectively improve the equilibrium conversion rate of furfural, and use Le Chatelier's principle to push the condensation equilibrium toward the product. Secondly, excess acetone also acts as a reaction solvent, which allows furfural to be fully dispersed in the homogeneous system, reducing the probability of furfural molecules condensing to form resinous polymers.

[0015] Furthermore, in S2, the hydrogenation reaction includes: catalytically hydrogenating the first mixture under the action of a hydrogenation catalyst and hydrogen gas; The hydrogenation catalyst comprises a noble metal catalyst and a support, wherein the noble metal catalyst is selected from any one of Pd, Ru, Pt or Rh; and the support is selected from any one of activated carbon, alumina or silica.

[0016] Furthermore, the hydrogenation reaction conditions are: temperature of 120-150℃, hydrogen pressure of 0.6-0.9MPa, and reaction time of 6-8h.

[0017] Furthermore, the dehydration ring-opening and etherification reaction conditions are: temperature 120-160℃, reaction time 12-24h, and reaction pressure 0.6-1.0MPa.

[0018] Furthermore, the ratio of the total molar number of glycerol and 1,3-butanediol to the molar number of 4-(2-tetrahydrofuranyl)-2-butanol in the second mixture is 1.05-1.08:1.

[0019] Glycerol and 1,3-butanediol each possess different hydroxyl functionalities and molecular chain lengths. When both undergo etherification with 4-(2-tetrahydrofuranyl)-2-butanol, the specific reaction involves the primary hydroxyl group of the polyol reacting with the primary hydroxyl group formed after ring-opening of 4-(2-tetrahydrofuranyl)-2-butanol, undergoing intermolecular dehydration to form an ether bond. Since each molecule of the 4-(2-tetrahydrofuranyl)-2-butanol ring-opening product molecule provides only one primary hydroxyl group for the reaction, theoretically, one molecule of 4-(2-tetrahydrofuranyl)-2-butanol requires one molecule of polyol to form a single ether structure. However, if the polyol content is exactly 1.0 equivalent, some of the 4-(2-tetrahydrofuranyl)-2-butanol may not react in time due to limited mass transfer, resulting in incomplete conversion. In the above-described scheme of this invention, the total polyol ratio is set to 1.05-1.08:1, i.e., an excess of 5%-8% based on the stoichiometric ratio. The design of this excess ratio is based on the following mechanistic considerations: a slight excess of polyol, on the one hand, utilizes Le Chatelier's principle to shift the equilibrium towards the product, and on the other hand, ensures that 4-(2-tetrahydrofuranyl)-2-butanol molecules have a sufficient probability of collision with the polyol and complete etherification. Simultaneously, this excess is precisely controlled to prevent excessive polyol from triggering competitive self-etherification side reactions between polyol molecules, or from leaving excessive excipients in the product and affecting its purity. Furthermore, the design of blending glycerol and 1,3-butanediol allows two polyols with different chain lengths to participate in the reaction simultaneously. The resulting composite ether product contains both glycerol ether and butanediol ether structural units. The difference in their molecular chain lengths (glycerol is a 3-carbon chain, butanediol is a 4-carbon chain) gives the product composition a richer molecular conformational distribution, improving the product's performance as a skin moisturizer at the molecular level.

[0020] A dioctyl ether composition is prepared by the above-described preparation method, wherein the acid value of the dioctyl ether composition is ≤0.1 mg KOH / g, and the viscosity of the dioctyl ether composition at 25°C is 4-10 cSt.

[0021] Acid value directly reflects the amount of residual acidic substances in the product, including unreacted acidic catalysts, incompletely converted carboxyl-containing intermediates (such as furfural oxidation product furoic acid), or acidic byproducts generated by the oxidative degradation of the product at high temperatures. If these acidic impurities are present in the final product, they will not only affect the product's odor and color stability, but also trigger the hydrolysis of ester raw materials or the corrosion of metal ions in cosmetic formulations, leading to a shortened product shelf life. In the technical solution of this invention, by controlling the amount of acidic catalyst in stage S3 and the separation and purification process in stage S4, the product acid value can be reduced to ≤0.1mg KOH / g, meeting the acid value standard for cosmetic-grade raw materials. Viscosity is chemically a macroscopic manifestation of intermolecular forces and the degree of molecular chain entanglement. The viscosity of the product of this invention at 25℃ is 4-10 cSt, a value within the optimal skin-feel range for commonly used oil-phase raw materials in cosmetics. Viscosity below 4 cSt results in a product that is too thin, spreads too quickly, and lacks moisturizing properties, while viscosity above 10 cSt results in a product that is too viscous, has poor spreadability, and easily produces a greasy feeling. The coexistence of two structural units with different chain lengths, glycerol ether and butanediol ether, ensures that there are appropriate van der Waals forces between the product molecules to maintain a certain cohesive energy, while preventing excessive entanglement due to excessively long molecular chains, thus achieving the ideal viscosity window of 4-10 cSt.

[0022] An application of the above-mentioned dioctyl ether composition in cosmetics, wherein the dioctyl ether composition is used as a moisturizer in skin creams, sunscreens, or serums. Detailed Implementation

[0023] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0024] Unless otherwise specified, all reagents and materials used in the following examples are commercially available. All raw materials used in the examples or comparative examples are cosmetic grade, with furfural purity ≥99%, acetone purity ≥99.5%, glycerin purity ≥99%, and 1,3-butanediol purity ≥99%.

[0025] Example 1 S1: 96.1 g (1.0 mol) of furfural and 348.5 g (6.0 mol) of acetone were added to a 2 L three-necked flask equipped with a mechanical stirrer and a reflux condenser. 4.0 g of 10 wt% sodium hydroxide solution was added dropwise under stirring. The reaction temperature was controlled at 28 °C and the reaction was carried out for 6 h to obtain the first mixture containing the C8 unsaturated ketone intermediate.

[0026] S2: The first mixture obtained in S1 was transferred to a 2 L high-pressure reactor, and 4.8 g of 5 wt% Pd / C catalyst (with a Pd loading of 5 wt%) was added. The catalyst was supported by activated carbon. After sealing, the reactor was purged with nitrogen three times, followed by purging with hydrogen three times. Hydrogen was introduced until the pressure reached 0.8 MPa, the temperature was raised to 135 °C, the stirring speed was 600 r / min, and the reaction was carried out for 7 h to obtain the second mixture. This second mixture contained 4-(2-tetrahydrofuranyl)-2-butanol, i.e., THFA. GC analysis showed that the THFA yield was 95.2%.

[0027] S3: The second mixture obtained in S2 was cooled to 60°C, filtered to remove the Pd / C catalyst, and the filtrate was transferred to a 2 L three-necked flask equipped with a water separator. 19.6 g (0.213 mol) of glycerol, 19.2 g (0.213 mol) of 1,3-butanediol, and 8.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate ([BSO3HMIm][OTf]) were added. The mixture was heated to 150°C and stirred at atmospheric pressure (0.1 MPa) for 18 h. During the reaction, water was promptly separated using a water separator to promote the shift of the reaction equilibrium towards the product. GC-MS analysis showed that the THFA conversion rate was 97.6%.

[0028] S4: Cool the third mixture obtained in S3 to room temperature, wash three times with 200 mL of deionized water, allow to stand and separate, and collect the oil phase. The oil phase is then distilled under reduced pressure at a vacuum of -0.095 MPa, and the fraction is collected at a temperature of 160~180℃ to obtain 182.4 g of a colorless, transparent, oily liquid dioctyl ether composition.

[0029] GC analysis showed that the total molar yield, based on furfural, was 85.6%. The product had an acid value of 0.06 mg KOH / g and a viscosity of 6.8 cSt at 25°C.

[0030] Example 2 S1: 96.1 g (1.0 mol) of furfural and 580.8 g (10.0 mol) of acetone were added to a 2 L three-necked flask equipped with a mechanical stirrer and a reflux condenser. 4.5 g of 10 wt% potassium hydroxide solution was added dropwise under stirring. The reaction temperature was controlled at 25 °C and the reaction was carried out for 5 h to obtain the first mixture containing the C8 unsaturated ketone intermediate.

[0031] S2: The first mixture obtained in S1 was transferred to a 2 L high-pressure reactor, and 5.0 g of 5 wt% Ru / C catalyst (Ru loading 5 wt%) was added. The reactor was sealed and purged three times with nitrogen, followed by three purgings with hydrogen. Hydrogen was introduced until the pressure reached 0.9 MPa, the temperature was raised to 150 °C, the stirring speed was 600 r / min, and the reaction was carried out for 6 h to obtain the second mixture, which contained THFA. GC analysis showed that the THFA yield was 94.8%.

[0032] S3: The second mixture obtained in S2 was cooled to 60°C, filtered to remove the Ru / C catalyst, and the filtrate was transferred to a 2 L three-necked flask equipped with a water separator. 20.9 g (0.227 mol) of glycerol, 20.5 g (0.228 mol) of 1,3-butanediol, and 7.5 g of p-toluenesulfonic acid were added. The mixture was heated to 160°C and stirred at 0.8 MPa for 12 h. During the reaction, the generated water was promptly separated using the water separator to promote the shift of the reaction equilibrium towards the product. GC-MS analysis showed that the THFA conversion rate was 96.9%.

[0033] S4: Cool the third mixture obtained in S3 to room temperature, wash three times with 200 mL of deionized water, allow to stand and separate, and collect the oil phase. The oil phase is then distilled under reduced pressure at a vacuum of -0.095 MPa, and the fraction is collected at a temperature of 160~180℃ to obtain 180.1 g of a colorless, transparent, oily liquid dioctyl ether composition.

[0034] GC analysis showed that the total molar yield, based on furfural, was 84.5%. The product had an acid value of 0.08 mg KOH / g and a viscosity of 7.2 cSt at 25°C.

[0035] Example 3 S1: 96.1 g (1.0 mol) of furfural and 464.6 g (8.0 mol) of acetone were added to a 2 L three-necked flask equipped with a mechanical stirrer and a reflux condenser. 5.0 g of 10 wt% calcium hydroxide solution was added dropwise under stirring. The reaction temperature was controlled at 30 °C and the reaction was carried out for 7 h to obtain the first mixture containing the C8 unsaturated ketone intermediate.

[0036] S2: The first mixture obtained in S1 was transferred to a 2 L high-pressure reactor, and 5.2 g of 5 wt% Pt / C catalyst (Pt loading 5 wt%) was added. The reactor was sealed and purged three times with nitrogen, followed by three purgings with hydrogen. Hydrogen was introduced until the pressure reached 0.6 MPa, the temperature was raised to 120 °C, the stirring speed was 600 r / min, and the reaction was carried out for 8 h to obtain the second mixture, which contained THFA. GC analysis showed that the THFA yield was 93.5%.

[0037] S3: The second mixture obtained in S2 was cooled to 60°C, filtered to remove the Pt / C catalyst, and the filtrate was transferred to a 2 L three-necked flask equipped with a water separator. 18.2 g (0.198 mol) of glycerol, 17.8 g (0.198 mol) of 1,3-butanediol, and 9.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate ([BSO3HMIm][OTf]) were added. The mixture was heated to 120°C and stirred at 1.0 MPa for 24 h. During the reaction, water was promptly separated using a water separator to promote the shift of the reaction equilibrium towards the product. GC-MS analysis showed that the THFA conversion rate was 95.8%.

[0038] S4: Cool the third mixture obtained in S3 to room temperature, wash three times with 200 mL of deionized water, allow to stand and separate, and collect the oil phase. The oil phase is then distilled under reduced pressure at a vacuum of -0.095 MPa, and the fraction is collected at a temperature of 160~180℃ to obtain 175.8 g of a colorless, transparent, oily liquid dioctyl ether composition.

[0039] GC analysis showed that the total molar yield, based on furfural, was 82.5%. The product had an acid value of 0.05 mg KOH / g and a viscosity of 6.2 cSt at 25°C.

[0040] Example 4 Steps S1 to S2 are the same as in Example 1, resulting in a second mixture containing THFA with a THFA yield of 95.2%.

[0041] S3: The second mixture obtained from S2 was cooled to 60°C, filtered to remove the Pd / C catalyst, and the filtrate was transferred to a 2 L three-necked flask equipped with a water separator. 28.9 g (0.314 mol) of glycerol, 9.6 g (0.107 mol) of 1,3-butanediol, and 8.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate ([BSO3HMIm][OTf]) were added. The mixture was heated to 150°C and stirred at atmospheric pressure (0.1 MPa) for 18 h. During the reaction, water was promptly separated using a water separator. GC-MS analysis showed a THFA conversion rate of 96.8%.

[0042] S4: Same as in Example 1, 179.2 g of a colorless, transparent, oily liquid dioctyl ether composition was obtained.

[0043] GC analysis showed that the total molar yield, based on furfural, was 84.1%. The product had an acid value of 0.07 mg KOH / g and a viscosity of 7.8 cSt at 25°C.

[0044] Example 5 Steps S1 to S2 are the same as in Example 1, resulting in a second mixture containing THFA with a THFA yield of 95.2%.

[0045] S3: The second mixture obtained from S2 was cooled to 60°C, filtered to remove the Pd / C catalyst, and the filtrate was transferred to a 2 L three-necked flask equipped with a water separator. 9.8 g (0.106 mol) of glycerol, 28.8 g (0.319 mol) of 1,3-butanediol, and 8.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate ([BSO3HMIm][OTf]) were added. The mixture was heated to 150°C and stirred at atmospheric pressure (0.1 MPa) for 18 h. During the reaction, water was separated promptly using a water separator. GC-MS analysis showed a THFA conversion rate of 97.1%.

[0046] S4: Same as in Example 1, 181.0 g of a colorless, transparent, oily liquid dioctyl ether composition was obtained.

[0047] GC analysis showed that the total molar yield, based on furfural, was 84.9%. The product had an acid value of 0.06 mg KOH / g and a viscosity of 5.4 cSt at 25°C.

[0048] Comparative Example 1 Steps S1 to S2 are the same as in Example 1, resulting in a second mixture containing THFA with a THFA yield of 95.2%.

[0049] S3: Cool the second mixture obtained from S2 to 60°C, filter to remove the Pd / C catalyst, transfer the filtrate to a 2 L three-necked flask equipped with a water separator, without adding glycerol and 1,3-butanediol, only add 8.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate, i.e., [BSO3HMIm][OTf], heat to 150°C, and stir the reaction at atmospheric pressure, i.e., 0.1 MPa, for 18 h.

[0050] S4: Perform post-processing as in Example 1.

[0051] GC analysis revealed an extremely low yield (<5%) of the target product, dioctyl ether. The main products were intramolecular dehydration products of THFA, namely 2-octen-1-ol derivatives and THFA dimer ether compounds. This indicates that in the absence of polyol excipients, THFA primarily undergoes intramolecular dehydration under acidic conditions rather than the target ring-opening etherification reaction.

[0052] Comparative Example 2 Steps S1 to S2 are the same as in Example 1, resulting in a second mixture containing THFA with a THFA yield of 95.2%.

[0053] S3: Cool the second mixture obtained from S2 to 60°C, filter to remove the Pd / C catalyst, transfer the filtrate to a 2 L three-necked flask equipped with a water separator, add 18.4 g (0.200 mol) of glycerol, 18.0 g (0.200 mol) of 1,3-butanediol and 8.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate ([BSO3HMIm][OTf]), so that the ratio of the total molar amount of glycerol and 1,3-butanediol to the molar amount of THFA is 1.00:1, heat to 150°C, and stir the reaction at atmospheric pressure (0.1 MPa) for 18 h.

[0054] S4: Perform post-processing as in Example 1.

[0055] GC analysis showed that the THFA conversion rate was 89.2%, significantly lower than the 97.6% in Example 1. This indicates that due to limited mass transfer and equilibrium constraints during equimolar feeding, some THFA failed to participate in the reaction, resulting in incomplete conversion.

[0056] Comparative Example 3 Steps S1 to S2 are the same as in Example 1, resulting in a second mixture containing THFA with a THFA yield of 95.2%.

[0057] S3: Cool the second mixture obtained from S2 to 60°C, filter to remove the Pd / C catalyst, transfer the filtrate to a 2 L three-necked flask equipped with a water separator, add 21.2 g (0.230 mol) of glycerol, 20.7 g (0.230 mol) of 1,3-butanediol and 8.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate ([BSO3HMIm][OTf]), so that the ratio of the total molar amount of glycerol and 1,3-butanediol to the molar amount of THFA is 1.15:1, heat to 150°C, and stir the reaction at atmospheric pressure (0.1 MPa) for 18 h.

[0058] S4: Perform post-processing as in Example 1.

[0059] GC analysis showed a THFA conversion rate of 97.8%, comparable to 97.6% in Example 1. However, significant polyol self-etherification byproducts, including glycerol diether and butylene glycol diether, were detected in the product, leading to a decrease in the purity of the target product, the dioctyl ether composition. The GC purity was only 91.2%, compared to 97.5% in Example 1. This indicates that while excess polyol can ensure THFA conversion, it can trigger competitive self-etherification side reactions among excipients, affecting product purity. Furthermore, the post-processing requires increased washing cycles to remove residual excess polyol, increasing process complexity and material loss.

[0060] Comparative Example 4 Steps S1 to S2 are the same as in Example 1, resulting in a second mixture containing THFA with a THFA yield of 95.2%.

[0061] S3: Cool the second mixture obtained from S2 to 60°C, filter to remove the Pd / C catalyst, transfer the filtrate to a 2 L three-necked flask equipped with a water separator, add 38.4 g (0.426 mol) of 1,3-butanediol, without adding glycerol, add 8.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate ([BSO3HMIm][OTf]) to make the molar ratio of 1,3-butanediol to THFA 1.06:1, heat to 150°C, and stir the reaction at atmospheric pressure (0.1 MPa) for 18 h.

[0062] S4: Perform post-processing as in Example 1.

[0063] GC analysis showed a THFA conversion rate of 96.2% and a yield of 83.8% for the target product, dioctyl ether composition. The product had an acid value of 0.07 mg KOH / g and a viscosity of 4.2 cSt at 25°C. Compared to 6.8 cSt in Example 1, the product viscosity was lower when only 1,3-butanediol was used, resulting in a thinner texture and insufficient moisturizing effect.

[0064] Comparative Example 5 Steps S1 to S2 are the same as in Example 1, resulting in a second mixture containing THFA with a THFA yield of 95.2%.

[0065] S3: Cool the second mixture obtained from S2 to 60°C, filter to remove the Pd / C catalyst, transfer the filtrate to a 2 L three-necked flask equipped with a water separator, add 39.2 g (0.426 mol) of glycerol, without adding 1,3-butanediol, add 8.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate ([BSO3HMIm][OTf]) to make the molar ratio of glycerol to THFA 1.06:1, heat to 150°C, and stir the reaction at atmospheric pressure (0.1 MPa) for 18 h.

[0066] S4: Perform post-processing as in Example 1.

[0067] GC analysis showed a THFA conversion rate of 96.5% and a yield of 84.2% for the target product, dioctyl ether composition. The product had an acid value of 0.06 mg KOH / g and a viscosity of 8.5 cSt at 25°C. Compared to 6.8 cSt in Example 1, the product viscosity was higher when using only glycerol, resulting in a thicker, more viscous feel and poorer spreadability.

[0068] Comparative Example 6 Steps S1 to S2 are the same as in Example 1, resulting in a second mixture containing THFA with a THFA yield of 95.2%.

[0069] S3: The second mixture obtained from S2 was cooled to 60°C, filtered to remove the Pd / C catalyst, and the filtrate was transferred to a 2 L three-necked flask equipped with a water separator. 19.6 g (0.213 mol) of glycerol, 19.2 g (0.213 mol) of 1,3-butanediol, and 4.0 g of 98 wt% concentrated sulfuric acid were added. The mixture was heated to 150°C and stirred at atmospheric pressure (0.1 MPa) for 18 h. During the reaction, the system color rapidly darkened from light yellow to dark brown, and a distinct charring odor was produced.

[0070] S4: The same post-processing as in Example 1 was performed, but severe emulsification was found during the washing process, making separation difficult and requiring a significant extension of the standing time.

[0071] GC analysis showed a THFA conversion rate of 98.5%, but the yield of the target product, dioctyl ether composition, was only 62.3%, with a GC purity of only 78.6%. A large amount of olefinic byproducts and polyol polymerization products were detected in the product, with an acid value as high as 2.8 mgKOH / g and a viscosity of 15.6 cSt at 25°C. This indicates that using traditional liquid strong acid sulfuric acid, due to its excessive acidity and lack of selectivity, triggered serious side reactions while catalyzing the target reaction, including excessive dehydration to generate olefins, polyol polymerization, and resinification of furfural residues. The resulting product failed to meet cosmetic-grade requirements in terms of yield, purity, and physical properties.

[0072] Comparative Example 7 Steps S1 to S2 are the same as in Example 1, resulting in a second mixture containing THFA with a THFA yield of 95.2%.

[0073] S3: The second mixture obtained in S2 was cooled to 60°C, filtered to remove the Pd / C catalyst, and the filtrate was transferred to a 2 L three-necked flask equipped with a water separator. 19.6 g (0.213 mol) of glycerol, 19.2 g (0.213 mol) of 1,3-butanediol, and 8.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate ([BSO3HMIm][OTf]) were added. The mixture was heated to 200°C and stirred at atmospheric pressure (0.1 MPa) for 18 h. During the reaction, the system rapidly darkened in color, and a large amount of gas was generated.

[0074] S4: Perform post-processing as in Example 1.

[0075] GC analysis showed a THFA conversion rate of 99.1%, but the yield of the target product, dioctyl ether composition, was only 55.8%, with a GC purity of only 72.3%. A large amount of C8-C16 alkanes and olefinic light components were detected in the product, indicating that the excessively high reaction temperature led to deep hydrogenolysis and thermal cracking side reactions. Simultaneously, the product's color was significantly darkened, with a Gardner color number greater than 8, making it unsuitable for cosmetic formulations.

[0076] Comparative Example 8 Steps S1 to S2 are the same as in Example 1, resulting in a second mixture containing THFA with a THFA yield of 95.2%.

[0077] S3: The second mixture obtained in S2 was cooled to 60°C, filtered to remove the Pd / C catalyst, and the filtrate was transferred to a 2 L three-necked flask equipped with a water separator. 19.6 g (0.213 mol) of glycerol, 19.2 g (0.213 mol) of 1,3-butanediol, and 8.0 g of 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate ([BSO3HMIm][OTf]) were added. The mixture was heated to 80°C and stirred at atmospheric pressure (0.1 MPa) for 18 h. During the reaction, almost no water was separated from the water separator.

[0078] S4: Perform post-processing as in Example 1.

[0079] GC analysis showed that the THFA conversion rate was only 34.7%, and the yield of the target product, dioctyl ether composition, was only 18.2%. This indicates that the reaction temperature of 80°C could not overcome the activation energy barrier of the dehydration ring-opening and etherification reactions, and the reaction was basically stagnant. Most of the THFA did not participate in the reaction and was removed by washing with water during the post-treatment process.

[0080] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a dioctyl ether composition, characterized in that, The specific preparation steps include: S1: Furfural and acetone are subjected to aldol condensation reaction under the action of an alkaline catalyst to obtain a first mixture containing a C8 unsaturated ketone intermediate; S2: The first mixture is subjected to a hydrogenation reaction to convert the C8 unsaturated ketone intermediate into 4-(2-tetrahydrofuranyl)-2-butanol to obtain the second mixture; S3: Add glycerol and 1,3-butanediol to the second mixture, and carry out dehydration ring-opening and etherification reactions at 100-180°C under the action of an acidic catalyst to obtain a third mixture containing a dioctyl ether composition; S4: Separate and purify from the third mixture to obtain the dioctyl ether composition.

2. The method for preparing a dioctyl ether composition according to claim 1, characterized in that, The alkaline catalyst is selected from any one of sodium hydroxide, potassium hydroxide, and calcium hydroxide.

3. The method for preparing a dioctyl ether composition according to claim 1, characterized in that, The acidic catalyst is selected from p-toluenesulfonic acid and 1-butylsulfonic acid-3-methylimidazolium trifluoromethanesulfonate.

4. The method for preparing a dioctyl ether composition according to claim 1, characterized in that, In S1, the molar ratio of furfural to acetone is 1:6-10.

5. The method for preparing a dioctyl ether composition according to claim 1, characterized in that, In S2, the hydrogenation reaction includes: catalytically hydrogenating the first mixture under the action of a hydrogenation catalyst and hydrogen gas; The hydrogenation catalyst comprises a noble metal catalyst and a support, wherein the noble metal catalyst is selected from any one of Pd, Ru, Pt or Rh; and the support is selected from any one of activated carbon, alumina or silica.

6. The method for preparing a dioctyl ether composition according to claim 5, characterized in that, The hydrogenation reaction conditions are: temperature 120-150℃, hydrogen pressure 0.6-0.9MPa, and reaction time 6-8h.

7. The method for preparing a dioctyl ether composition according to claim 1, characterized in that, The dehydration, ring-opening, and etherification reaction conditions are: temperature 120-160℃, reaction time 12-24h, and reaction pressure 0.6-1.0MPa.

8. The method for preparing a dioctyl ether composition according to claim 1, characterized in that, The ratio of the total molar amount of glycerol and 1,3-butanediol to the molar amount of 4-(2-tetrahydrofuranyl)-2-butanol in the second mixture is 1.05-1.08:

1.

9. A dioctyl ether composition, characterized in that, The dioctyl ether composition is prepared by the preparation method according to any one of claims 1-8, wherein the acid value of the dioctyl ether composition is ≤0.1 mg KOH / g, and the viscosity of the dioctyl ether composition at 25°C is 4-10 cSt.

10. The use of the dioctyl ether composition as described in claim 9 in cosmetics, characterized in that, The dioctyl ether composition is used as a skin moisturizer in skin creams, sunscreens, or serums.