Method for synthesizing ethylhexylglycerin by using glycerin as raw material

Abstract

The invention relates to the technical field of organic synthesis, and particularly discloses a method for synthesizing ethylhexylglycerin by taking glycerin as a raw material. The method comprises the following steps: reacting glycerol with an acetone substance under the action of an acid catalyst at normal temperature to obtain a glycerol upper protection product; under the protection of inert gas at the temperature of 50-130 DEG C, enabling the protection product on the glycerol to react with isooctanol under the action of a basic catalyst; after the reaction is finished, adding water, stirring and layering, adding an oil phase into a dilute acid aqueous solution, heating to remove a protecting group, and separating a water phase to obtain an ethylhexylglycerin crude product and isooctanol; and performing post-treatment on the product obtained in the step S3 to obtain ethylhexylglycerin. According to the method, glycerin and isooctanol are used as reaction raw materials, all the reaction raw materials can be bio-based, the obtained product is also bio-based, and the synthesis process is simple in step, easy to operate, few in by-product, high in glycerin conversion rate, high in yield of the obtained product and suitable for large-scale industrial production.

Description

Technical Field

[0001] The present application relates to the technical field of organic synthesis, and more specifically, to a method for synthesizing ethylhexylglycerol using glycerol as a raw material. Background Art

[0002] Ethylhexylglycerin, commonly referred to as octoxyglycerin, with the CAS number 70446-33-9, is a colorless, nearly odorless liquid with excellent performance in cosmetic formulations. It is a globally recognized general-purpose and multifunctional additive and a very effective deodorizing active. Specifically, its use as an emollient and humectant in cosmetics improves the skin feel of cosmetic formulations and reliably inhibits the growth and reproduction of odor-causing bacteria without affecting beneficial skin flora. Furthermore, it can enhance the efficacy of traditional preservatives such as phenoxyethanol, methylisothiazolinone, or methylparaben, thereby reducing the amount of preservatives added to cosmetics. It can also be blended with other cosmetic ingredients as an antimicrobial stabilizer.

[0003] At present, the synthesis of ethylhexylglycerol in China mainly adopts the traditional Williamson etherification method, such as Figure 1 As shown, epichlorohydrin and isooctyl alcohol are first used as raw materials to generate 1-chloro-3-isooctyloxy-2-propanol (a chlorinated intermediate). This is then treated with an alkali (such as sodium hydroxide or sodium acetate) to dehydrochlorinate and ring-close to form octyl glycidyl ether. This octyl glycidyl ether is then further hydrolyzed to open the ring and yield the target product, ethylhexylglycerol. However, this method produces a large number of impurities, making product purification difficult. Furthermore, the final hydrolysis step cannot be performed directly, resulting in the formation of oligomers. It requires esterification with an acid before hydrolysis to ensure a high yield, making the process rather cumbersome. Consequently, an increasing number of researchers are seeking improvements to the traditional process.

[0004] Some existing synthesis methods use glycidol as a raw material to react with isooctyl alcohol to produce ethylhexyl glycerol. However, this method is relatively dangerous and difficult to store, making it difficult to achieve industrial production. Other methods, such as the Chinese patent application CN 114380668 A, use isooctyl alcohol and glycerol to directly produce ethylhexyl glycerol. However, this method has been shown to have extremely low glycerol conversion rates, poor yields, and a high concentration of impurities, making purification difficult. The resulting product is of low purity. Summary of the Invention

[0005] In order to solve the above technical problems, the present application provides a method for synthesizing ethylhexylglycerol using glycerol as raw material.

[0006] The present application provides a method for synthesizing ethylhexylglycerol using glycerol as a raw material, which adopts the following technical solution: A method for synthesizing ethylhexylglycerin using glycerol as a raw material comprises the following steps: Step S1: At room temperature, glycerol and acetone react in the presence of an acidic catalyst to obtain a glycerol-protected product. The reaction formula of this process is: ; Step S2: reacting the protected glycerol product with isooctyl alcohol in the presence of an alkaline catalyst at a temperature of 50-130° C. and under the protection of an inert gas; the reaction formula of the process is: ; Step S3: adding water to the product obtained in step S2, stirring, separating and separating the layers, and collecting the oil phase; adding the oil phase to a dilute acid aqueous solution at a temperature of 30-80° C. to remove the protecting group; then separating the aqueous phase, and collecting the oil phase to obtain a crude ethylhexylglycerol product and isooctyl alcohol; the reaction formula of this process is: ; Step S4: post-treating the product of step S3 to obtain ethylhexylglycerol.

[0007] By adopting the above technical scheme, the present application first uses glycerol and acetone-like substances to react under the action of an acidic catalyst to protect the hydroxyl group of glycerol and obtain a glycerol-protected product, and then the glycerol-protected product is reacted with isooctyl alcohol under the action of an alkaline catalyst. After the reaction is completed, water is added to separate the layers, and the oil phase is added to a dilute acid aqueous solution for deprotection, and finally, after post-treatment, ethylhexyl glycerol is obtained. The present application uses bio-based glycerol and bio-based isooctyl alcohol as starting materials. The reaction raw materials are environmentally friendly and easy to obtain. The obtained product is a bio-based product that meets the requirements of natural, organic, and sustainable development. It has been verified that the molar yield is above 75%, that is, the conversion rate of glycerol is above 75%, while the ordinary one is less than 60%. There are fewer by-products and a higher reaction yield. At the same time, there are fewer impurities in the reaction process, which is easy to purify. The steps are simple, and the purity of the final product can reach more than 99.2%, which is suitable for large-scale industrial production.

[0008] Preferably, in step S1, the acetone-based substance is acetone or acetone dimethyl acetal.

[0009] Preferably, in step S1, the acidic catalyst includes one of formic acid, sulfuric acid, p-toluenesulfonic acid and trifluoroacetic acid.

[0010] Through the above technical solution, the present application adopts one of formic acid, sulfuric acid, p-toluenesulfonic acid and trifluoroacetic acid as the acidic catalyst, which can further accelerate the reaction speed, shorten the reaction time, improve production efficiency and reduce production costs.

[0011] Preferably, in step S1, the molar ratio of glycerol to acetone is 1:(8-15).

[0012] By adopting the above technical solution, the present application optimizes the ratio between glycerol and acetone substances, and by using excess acetone to push the reaction equilibrium toward the positive direction, inhibiting the occurrence of side reactions, reducing the generation of by-products, and improving the conversion rate of glycerol, thereby improving the yield and purity of the final product.

[0013] Preferably, in step S1, the amount of the acidic catalyst used is 3-5% of the mass of the glycerol.

[0014] By adopting the above technical solution, the present application optimizes the amount of acidic catalyst used, further increases the reaction rate, shortens the reaction time, improves production efficiency, and reduces production costs.

[0015] Preferably, in step S2, the alkaline catalyst includes one of sodium hydroxide, potassium hydroxide, sodium amide, sodium hydride, potassium hydride and tetrabutylammonium hydroxide.

[0016] By adopting the above technical solution, the present application uses one of sodium hydroxide, potassium hydroxide, sodium amide, sodium hydride, potassium hydride and tetrabutylammonium hydroxide as an alkaline catalyst, which can further accelerate the reaction speed, shorten the reaction time, improve production efficiency and reduce production costs.

[0017] Preferably, in step S2, the molar ratio of the alkaline catalyst to the protected product on glycerol is (0.2-1.5):1.

[0018] By adopting the above technical solution, the present application optimizes the ratio of the alkaline catalyst and the protected product on glycerol, thereby optimizing the dosage of the acidic catalyst, further increasing the reaction rate, shortening the reaction time, improving production efficiency, and reducing production costs.

[0019] Preferably, in step S2, the molar ratio of the protected product on glycerol to isooctyl alcohol is 1:(1-15).

[0020] By adopting the above technical solution, the present application optimizes the ratio between the protected product on glycerol and isooctyl alcohol, promotes the forward progress of the reaction, inhibits the occurrence of side reactions, reduces the generation of by-products, and improves the conversion rate of glycerol, thereby improving the yield and purity of the final product.

[0021] Preferably, in step S3, the acid in the dilute acid aqueous solution includes one of sulfuric acid, hydrochloric acid, trifluoroacetic acid, p-toluenesulfonic acid and formic acid.

[0022] Preferably, in step S4, the post-processing is specifically: recovering isooctyl alcohol under the conditions of a vacuum degree of 5-10 Pa and a temperature of 65-75° C., and then heating to 135-145° C. to collect ethylhexylglycerin.

[0023] In summary, this application has the following beneficial technical effects: 1. The method for synthesizing ethylhexylglycerol in this application uses glycerol as the reaction raw material. The reaction raw material is environmentally friendly and easily available. The product produced is a bio-based product that meets the requirements of being natural, organic, and sustainable. The synthesis process is simple and easy to operate, making it suitable for large-scale industrial production. 2. The method for synthesizing ethylhexylglycerol of the present application has fewer by-products, a higher glycerol conversion rate, a higher yield of the obtained product, and is easy to purify during the synthesis process, so the obtained product has a higher purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a synthetic pathway diagram of traditional ethylhexylglycerin in the background technology of this application; Figure 2 This is the chromatogram and peak table of ethylhexylglycerin prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0025] The present application is further described in detail below with reference to the embodiments.

[0026] The raw materials used in this application are all commercially available products, and the glycerol in this application is bio-based glycerol, and the isooctyl alcohol is bio-based isooctyl alcohol.

[0027] In some embodiments of synthesizing ethylhexylglycerol using glycerol as a raw material, the acetone-like substance is acetone or acetone dimethyl acetal; In some embodiments of synthesizing ethylhexylglycerol using glycerol as a raw material, the acidic catalyst includes one of formic acid, sulfuric acid, p-toluenesulfonic acid, and trifluoroacetic acid; In some embodiments of synthesizing ethylhexylglycerol using glycerol as a raw material, the molar ratio of glycerol to acetone is 1:(8-15); In some embodiments of synthesizing ethylhexylglycerol using glycerol as a raw material, the amount of the acidic catalyst used is 3-5% of the mass of the glycerol; In some embodiments of synthesizing ethylhexylglycerol using glycerol as a raw material, the alkaline catalyst includes one of sodium hydroxide, potassium hydroxide, sodium amide, sodium hydride, potassium hydride, and tetrabutylammonium hydroxide; In some embodiments of synthesizing ethylhexylglycerol using glycerol as a raw material, the molar ratio of the basic catalyst to the protected product on glycerol is (0.2-1.5):1; In some embodiments of synthesizing ethylhexylglycerol using glycerol as a raw material, the molar ratio of the protected product on glycerol to isooctyl alcohol is 1:(1-15); In some embodiments of synthesizing ethylhexylglycerol using glycerol as a raw material, the acid in the dilute aqueous acid solution comprises one of sulfuric acid, hydrochloric acid, trifluoroacetic acid, p-toluenesulfonic acid, and formic acid; In some embodiments of synthesizing ethylhexylglycerol using glycerol as a raw material, the above raw materials and proportions are used by the following method: Step S1: reacting glycerol with an acetone-based substance under the action of an acidic catalyst at room temperature to obtain a glycerol-protected product; Step S2, reacting the protected glycerol product with isooctyl alcohol in the presence of a basic catalyst at a temperature of 50-130° C. and under the protection of an inert gas; Step S3, adding water to the resultant of step S2, stirring, separating the layers and collecting the oil phase, adding the oil phase to a dilute acid aqueous solution at a temperature of 30-80° C. to remove the protecting group, then separating the aqueous phase and collecting the oil phase to obtain a crude ethylhexylglycerol product and isooctyl alcohol; Step S4: Recovering isooctyl alcohol from the product obtained in step S3 under conditions of a vacuum degree of 5-10 Pa and a temperature of 65-75° C., then heating the product to 135-145° C. to collect ethylhexyl glycerol. Testing shows that the purity of the obtained ethylhexyl glycerol is above 99.2%, and the molar yield is above 75%, indicating high yield and purity.

[0028] The applicant uses the following embodiments for illustrative purposes.

[0029] Example 1 A method for synthesizing ethylhexylglycerin using glycerol as a raw material comprises the following steps: Step S1: at room temperature, glycerol and acetone are mixed and formic acid is added to react for 2 hours, followed by post-treatment to remove the acid to obtain a glycerol-protected product, wherein the molar ratio of glycerol to acetone is 1:8, and the amount of formic acid used is 3% of the mass of the glycerol; Step S2, mixing isooctyl alcohol and sodium hydroxide, and adding the glycerol protected product dropwise at a temperature of 50° C. under the protection of nitrogen for 4 hours, wherein the molar ratio of isooctyl alcohol to the glycerol protected product is 10:1, and the molar ratio of sodium hydroxide to the glycerol protected product is 1.5:1; Step S3: After the reaction in step S2 is completed, a small amount of water is added to the reaction system, stirred, and the layers are separated. The oil phase is collected, and the oil phase is added to a 10% by mass aqueous solution of dilute sulfuric acid at a temperature of 30° C. to remove the protecting group. After the reaction is completed, the aqueous phase is separated, and the oil phase is collected to obtain a crude product of ethylhexylglycerol and isooctyl alcohol. Step S4: Recover the isooctyl alcohol from the product of step S3 under vacuum of 5 Pa and a temperature of 65-75° C. for the next reaction, then raise the temperature to 135-145° C. to collect ethylhexylglycerol. The purity of the ethylhexylglycerol is 99.255%, and the molar yield is 75.04%.

[0030] Example 2 A method for synthesizing ethylhexylglycerin using glycerol as a raw material comprises the following steps: Step S1, at room temperature, mixing glycerol and acetone dimethyl acetal and adding sulfuric acid to react for 3 hours, followed by post-treatment to remove the acid, to obtain a glycerol protected product, wherein the molar ratio of glycerol to acetone dimethyl acetal is 1:15, and the amount of sulfuric acid used is 5% of the mass of the glycerol; Step S2, mixing isooctyl alcohol and potassium hydroxide, and adding the glycerol protected product dropwise at a temperature of 130° C. under the protection of nitrogen for 6 hours, wherein the molar ratio of isooctyl alcohol to the glycerol protected product is 15:1, and the molar ratio of potassium hydroxide to the glycerol protected product is 1.1:1; Step S3: After the reaction in step S2 is completed, a small amount of water is added to the reaction system, stirred, and the layers are separated. The oil phase is collected, and the oil phase is added to a 10% by mass concentration dilute hydrochloric acid aqueous solution at a temperature of 80° C. to remove the protecting group. After the reaction is completed, the aqueous phase is separated, and the oil phase is collected to obtain a crude ethylhexylglycerol product and isooctyl alcohol. Step S4: Recover the isooctyl alcohol from the product of step S3 under vacuum of 10 Pa and a temperature of 65-75° C. for the next reaction, then raise the temperature to 135-145° C. to collect ethylhexylglycerol. The purity of the ethylhexylglycerol is 99.312%, and the molar yield is 76.12%.

[0031] Example 3 A method for synthesizing ethylhexylglycerin using glycerol as a raw material comprises the following steps: Step S1, at room temperature, mixing glycerol and acetone and adding p-toluenesulfonic acid, reacting for 1 hour, and then post-treating to remove the acid to obtain a glycerol-protected product, wherein the molar ratio of glycerol to acetone is 1:10, and the amount of p-toluenesulfonic acid is 4% of the mass of the glycerol; Step S2, mixing isooctyl alcohol and sodium amide, and adding the glycerol protected product dropwise at a temperature of 90° C. under the protection of nitrogen for 5 hours, wherein the molar ratio of isooctyl alcohol to the glycerol protected product is 1.2:1, and the molar ratio of sodium amide to the glycerol protected product is 0.5:1; Step S3: After the reaction in step S2 is completed, a small amount of water is added to the reaction system, stirred, and the layers are separated. The oil phase is collected, and the oil phase is added to a 10% by mass concentration dilute trifluoroacetic acid aqueous solution at a temperature of 55° C. to remove the protecting group. After the reaction is completed, the aqueous phase is separated, and the oil phase is collected to obtain a crude ethylhexylglycerol product and isooctyl alcohol. Step S4: Recover the isooctyl alcohol from the product of step S3 under vacuum of 8 Pa and a temperature of 65-75° C. for the next reaction, then raise the temperature to 135-145° C. to collect ethylhexylglycerol. The purity of the ethylhexylglycerol is 99.278%, and the molar yield is 75.83%.

[0032] Example 4 A method for synthesizing ethylhexylglycerin using glycerol as a raw material comprises the following steps: Step S1: at room temperature, glycerol and acetone dimethyl acetal are mixed and trifluoroacetic acid is added to react for 2 hours, followed by post-treatment to remove the acid to obtain a glycerol-protected product, wherein the molar ratio of glycerol to acetone dimethyl acetal is 1:9, and the amount of trifluoroacetic acid used is 3.5% of the mass of the glycerol; Step S2, mixing isooctyl alcohol and sodium hydride, and adding the protected product of glycerol dropwise at a temperature of 65° C. under the protection of nitrogen for 4.5 hours, wherein the molar ratio of isooctyl alcohol to the protected product of glycerol is 1.5:1, and the molar ratio of sodium hydride to the protected product of glycerol is 0.3:1; Step S3: After the reaction in step S2 is completed, a small amount of water is added to the reaction system, stirred, separated, and the oil phase is collected. The oil phase is added to a 10% by mass concentration of dilute p-toluenesulfonic acid aqueous solution at a temperature of 40° C. to remove the protecting group. After the reaction is completed, the aqueous phase is separated and the oil phase is collected to obtain a crude ethylhexylglycerol product and isooctyl alcohol. Step S4: Recover the isooctyl alcohol from the product of step S3 under vacuum of 6 Pa and a temperature of 65-75° C. for the next reaction, then raise the temperature to 135-145° C. to collect ethylhexylglycerol. The purity of the ethylhexylglycerol is 99.262%, and the molar yield is 75.71%.

[0033] Example 5 A method for synthesizing ethylhexylglycerin using glycerol as a raw material comprises the following steps: Step S1: at room temperature, glycerol and acetone are mixed and formic acid is added to react for 3 hours, followed by post-treatment to remove the acid, to obtain a glycerol-protected product, wherein the molar ratio of glycerol to acetone is 1:14, and the amount of trifluoroacetic acid used is 4.5% of the mass of the glycerol; Step S2, mixing isooctyl alcohol and potassium hydride, and adding the protected product on glycerol dropwise at a temperature of 110° C. under the protection of nitrogen for 5.5 hours, wherein the molar ratio of isooctyl alcohol to the protected product on glycerol is 1.4:1, and the molar ratio of potassium hydride to the protected product on glycerol is 0.2:1; Step S3: After the reaction in step S2 is completed, a small amount of water is added to the reaction system, stirred, separated, and the oil phase is collected. The oil phase is added to a 10% by mass concentration of dilute formic acid aqueous solution at a temperature of 70° C. to remove the protecting group. After the reaction is completed, the aqueous phase is separated, and the oil phase is collected to obtain a crude ethylhexylglycerol product and isooctyl alcohol. Step S4: Recover the isooctyl alcohol from the product of step S3 under vacuum of 9 Pa and a temperature of 65-75° C. for the next reaction, then raise the temperature to 135-145° C. to collect ethylhexylglycerol. The purity of the ethylhexylglycerol is 99.305%, and the molar yield is 76.03%.

[0034] Data Analysis According to the data of the above embodiment and combined Figure 2 It can be seen that the present application first adopts glycerol and acetone-like substances to react under the action of an acidic catalyst, plays a protective role on the hydroxyl group of glycerol, obtains a protected product on glycerol, then reacts the protected product on glycerol with isooctyl alcohol under the action of an alkaline catalyst, adds water and delaminates after the reaction is completed, and the oil phase is added to a dilute acid aqueous solution for deprotection, and finally undergoes post-processing, and the ethylhexyl glycerol purity obtained can reach more than 99.2%, and the molar yield can reach more than 75%, that is, the conversion rate of glycerol can reach more than 75%. Compared to traditional synthetic methods, the synthetic method of the present application is simple in steps, easy to operate, and impurities are small in the synthetic process, and the final product purity obtained is higher. Compared to some existing synthetic methods, the present application uses bio-based glycerol and bio-based isooctyl alcohol as reaction raw materials, which not only ensures that the reaction raw materials are environmentally friendly and easy to obtain, the obtained product belongs to a bio-based product, meets the requirements of natural, organic, sustainability, and can significantly improve the conversion rate of glycerol, and make the final product yield and purity both higher, suitable for large-scale industrial production.

[0035] The embodiments of this specific implementation method are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for synthesizing ethylhexylglycerol using glycerol as raw material, characterized in that: The following steps are involved: Step S1: At room temperature, glycerol and acetone react in the presence of an acidic catalyst to obtain a glycerol-protected product. The reaction formula of this process is: ； Step S2: reacting the protected glycerol product with isooctyl alcohol in the presence of an alkaline catalyst at a temperature of 50-130° C. and under the protection of an inert gas; the reaction formula of the process is: ； Step S3: adding water to the product obtained in step S2, stirring, separating and separating the layers, and collecting the oil phase; adding the oil phase to a dilute acid aqueous solution at a temperature of 30-80° C. to remove the protecting group; then separating the aqueous phase, and collecting the oil phase to obtain a crude ethylhexylglycerol product and isooctyl alcohol; the reaction formula of this process is: ； Step S4: post-treating the product of step S3 to obtain ethylhexylglycerol.

2. The method for synthesizing ethylhexylglycerol using glycerol as raw material according to claim 1, wherein: In step S1, the acetone-based substance is acetone or acetone dimethyl acetal.

3. The method for synthesizing ethylhexylglycerol using glycerol as raw material according to claim 1, characterized in that: In step S1, the acidic catalyst includes one of formic acid, sulfuric acid, p-toluenesulfonic acid and trifluoroacetic acid.

4. The method for synthesizing ethylhexylglycerol using glycerol as raw material according to claim 1, characterized in that: In step S1, the molar ratio of glycerol to acetone is 1:(8-15).

5. The method for synthesizing ethylhexylglycerol using glycerol as raw material according to claim 1, characterized in that: In step S1, the amount of the acidic catalyst used is 3-5% of the mass of the glycerol.

6. The method for synthesizing ethylhexylglycerol using glycerol as raw material according to claim 1, characterized in that: In step S2, the alkaline catalyst includes one of sodium hydroxide, potassium hydroxide, sodium amide, sodium hydride, potassium hydride and tetrabutylammonium hydroxide.

7. The method for synthesizing ethylhexylglycerol using glycerol as raw material according to claim 1, characterized in that: In step S2, the molar ratio of the alkaline catalyst to the protected product on glycerol is (0.2-1.5):

1.

8. The method for synthesizing ethylhexylglycerol using glycerol as raw material according to claim 1, characterized in that: In step S2, the molar ratio of the protected product on glycerol to isooctyl alcohol is 1:(1-15).

9. The method for synthesizing ethylhexylglycerol using glycerol as raw material according to claim 1, characterized in that: In step S3, the acid in the dilute acid aqueous solution includes one of sulfuric acid, hydrochloric acid, trifluoroacetic acid, p-toluenesulfonic acid and formic acid.

10. The method for synthesizing ethylhexylglycerol using glycerol as raw material according to claim 1, characterized in that: In step S4, the post-processing is specifically as follows: recovering isooctyl alcohol under the conditions of a vacuum degree of 5-10 Pa and a temperature of 65-75° C., and then heating the mixture to a temperature of 135-145° C. to collect ethylhexylglycerin.

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