A method for preparing ethylhexylglycerol and its application

Abstract

This invention discloses a method for preparing ethylhexylglycerol and its application, comprising the following steps: adding isooctanol and a base to a solvent, stirring and cooling to 0-5 degrees Celsius, then adding a dichloromethane solution of p-toluenesulfonyl chloride dropwise. After the addition is complete, the mixture is brought to room temperature and stirred for a period of time. A sample is taken for gas chromatography analysis until the isooctanol is completely consumed. Water is added to separate the layers, and the dichloromethane layer is collected. The dichloromethane layer is washed twice with water and dried to obtain a dichloromethane solution of isooctyl p-toluenesulfonate, which is then dried and reserved. Glycerol and boric acid are added to a reaction flask for dehydration reaction, and after the reaction is complete, a diglyceride borate intermediate is obtained. The prepared diglyceride borate intermediate is added dropwise to a dichloromethane solution of isooctyl p-toluenesulfonate to obtain isooctyl borate diglyceride ether. Then, the solvent is removed, and the mixture is hydrolyzed with water to obtain the target compound, ethylhexylglycerol. This invention, through the application of the diglyceride borate structure, reduces the generation of by-products, and the overall yield is higher compared with current traditional processes.

Description

Technical Field

[0001] This invention relates to a method for synthesizing ethylhexylglycerol preservatives via a novel synthetic route, and particularly to the use of a diglyceride borate structure to obtain monoethylhexylglycerol ether, i.e., the target compound ethylhexylglycerol, in high yield. Background Technology

[0002] Traditional preservatives used in daily chemical products have a certain degree of toxicity and can easily cause harm to the environment and human health. Ethylhexylglycerin is a new multifunctional cosmetic additive with preservative, moisturizing, and deodorizing effects. Its emergence brings hope, especially when used in daily chemical product systems with its synergistic effect with other traditional preservatives. This can significantly reduce the amount of traditional preservatives required, is non-irritating to the skin, significantly reduces the toxicity of the preservative system, and has a moisturizing effect. Furthermore, it enhances the effectiveness of traditional preservatives, making ethylhexylglycerin play an important role in future green preservative systems.

[0003] Ethylhexylglycerol has a boiling point of around 300℃, making separation and purification difficult during production. It is prone to oxidation and discoloration during the process, and polymerization during synthesis easily produces impurities. High impurity content in ethylhexylglycerol affects its color, imparts an off-odor, and some impurities may even compromise its toxicological safety, making it unsuitable as a daily chemical additive. The production routes for ethylhexylglycerol are relatively mature. Currently, most methods involve etherification to generate glycidyl ether intermediates, followed by ethylhexylglycerol production. Reported processes for producing ethylhexylglycerol are quite common. One method involves the addition reaction of acid anhydrides with glycidyl ether followed by alkaline hydrolysis, but this easily produces self-polymerization byproducts of glycidyl ether. Another method involves the reaction of alcohols with glycidyl ether under acid or alkaline catalysis to prepare ethylhexylglycerol, but this has a long reaction time and produces many impurities. A third method involves catalytically opening the epoxy groups of ethylhexyl glycidyl ether to achieve carbonyl addition, followed by hydrolysis. Although the production routes for ethylhexylglycerol are relatively mature, production costs are constantly being reduced to adapt to market competition.

[0004] Therefore, considering the problems mentioned above, it is necessary to provide a new technical solution. Summary of the Invention

[0005] To at least address one of the technical problems existing in the prior art, and given the important role of ethylhexylglycerin in preservatives and other fields, and to adapt to the broader environment of the cosmetics industry, the applicant's R&D team has continuously innovated and efficiently produced high-specification ethylhexylglycerin preservative products. The specific solution is as follows:

[0006] On one hand, the present invention provides a method for preparing ethylhexylglycerin, comprising the following steps:

[0007] a. Add isooctyl alcohol and alkali to the solvent, stir and cool to 0-5 degrees Celsius, then add a dichloromethane solution of p-toluenesulfonyl chloride dropwise. After the addition is complete, return to room temperature and stir for a period of time. Take a sample and analyze by gas chromatography until the isooctyl alcohol is completely consumed. Add water to separate the layers, collect the dichloromethane layer, wash the dichloromethane layer twice with water and dry it to obtain a dichloromethane solution of p-toluenesulfonyl ester. Dry and keep for later use.

[0008] b. Add glycerol and boric acid to a reaction flask for dehydration reaction. After the reaction is complete, diglyceride borate intermediate is obtained.

[0009] c. Add a dichloromethane solution of isooctyl p-toluenesulfonate prepared in step a to the borate diglyceride intermediate obtained in step b, to obtain isooctyl ether of borate diglyceride, then remove the solvent and hydrolyze with water to obtain the target compound ethylhexylglycerol.

[0010] The preparation reaction process is as follows:

[0011]

[0012] In a preferred embodiment of the method for preparing ethylhexylglycerol according to the present invention, the solvent used in step a is dichloromethane.

[0013] In a preferred embodiment of the method for preparing ethylhexylglycerol according to the present invention, the base used is one of pyridine and DMAP.

[0014] In a preferred embodiment of the method for preparing ethylhexylglycerol according to the present invention, in step a, the molar ratio of isooctyl alcohol to p-toluenesulfonyl chloride is 1:1.

[0015] In a preferred embodiment of the method for preparing ethylhexylglycerol according to the present invention, in step b, glycerol and boric acid are added to a reaction flask, heated to 100°C, and subjected to dehydration reaction under reduced pressure and vacuum.

[0016] In a preferred embodiment of the method for preparing ethylhexylglycerol according to the present invention, in step b, the molar ratio of boric acid to glycerol is 1:2.

[0017] In a preferred embodiment of the method for preparing ethylhexylglycerol according to the present invention, in step c, after the dehydration reaction in step b is completed, the temperature is lowered to room temperature and stirred. Then, a dichloromethane solution of isooctyl p-toluenesulfonate prepared in step a is added dropwise to the diglyceride borate intermediate. After the addition is complete, the temperature is raised to 60°C, and after stirring for a period of time, a sample is taken for GC analysis. The content of isooctyl p-toluenesulfonate is found to be less than 1%, and the solvent is removed.

[0018] In a preferred embodiment of the method for preparing ethylhexylglycerol according to the present invention, in step c, the molar ratio of isooctyl p-toluenesulfonate intermediate to diglyceride borate intermediate is approximately 1.2:1.

[0019] As a preferred embodiment of the method for preparing ethylhexylglycerol according to the present invention, in step c, the hydrolysis by adding water can be carried out by simply adding water and stirring at room temperature to obtain the target compound ethylhexylglycerol.

[0020] On the one hand, the ethylhexylglycerol prepared by the above method provided by the present invention can be used as a preservative.

[0021] Compared with the prior art, the present invention has at least one or more of the following beneficial effects:

[0022] The preparation method of this invention reduces the generation of byproducts by applying the borate diglyceride structure, and the overall yield is higher than that of current traditional processes.

[0023] Although the preparation method of this invention involves three steps, each step is simple and easy to scale up for industrial production.

[0024] This method does not require an acidic or alkaline environment for hydrolysis; it can be performed in water. It does not have high requirements for the acid and alkali resistance of the equipment, thus reducing production costs and ensuring a safe and controllable production process.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Detailed Implementation

[0026] The embodiments of the present invention will be described in detail below, and the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0027] On one hand, the present invention provides a method for preparing ethylhexylglycerin, comprising the following steps:

[0028] a. Add isooctyl alcohol and alkali to the solvent, stir and cool to 0-5 degrees Celsius, then add a dichloromethane solution of p-toluenesulfonyl chloride dropwise. After the addition is complete, return to room temperature and stir for a period of time. Take a sample and analyze by gas chromatography until the isooctyl alcohol is completely consumed. Add water to separate the layers, collect the dichloromethane layer, wash the dichloromethane layer twice with water and dry it to obtain a dichloromethane solution of p-toluenesulfonyl ester. Dry and keep for later use.

[0029] b. Add glycerol and boric acid to a reaction flask for dehydration reaction. After the reaction is complete, diglyceride borate intermediate is obtained.

[0030] c. Add a dichloromethane solution of isooctyl p-toluenesulfonate prepared in step a to the borate diglyceride intermediate obtained in step b, to obtain isooctyl ether of borate diglyceride, then remove the solvent and hydrolyze with water to obtain the target compound ethylhexylglycerol.

[0031] The synthetic route of the above preparation method is as follows:

[0032]

[0033] Preferably, in step a, the solvent used is dichloromethane.

[0034] Preferably, in step a, the molar ratio of isooctyl alcohol to p-toluenesulfonyl chloride is 1:1.

[0035] Preferably, in step a, the base used is either pyridine or DMAP.

[0036] Preferably, in step a, cooling to 0-5 degrees Celsius is achieved using an ice-water bath.

[0037] Preferably, in step b, the molar ratio of boric acid to glycerol is 1:2.

[0038] Preferably, in step b, glycerol and boric acid are added to a reaction flask, heated to 100°C, and subjected to dehydration under reduced pressure and vacuum.

[0039] Preferably, in step c, the molar ratio of isooctyl p-toluenesulfonate intermediate to diglyceride borate intermediate is approximately 1.2:1.

[0040] Preferably, in step c, after the dehydration reaction in step b is completed, the mixture is cooled to room temperature and stirred. Then, a dichloromethane solution of isooctyl p-toluenesulfonate prepared in step a is added dropwise to the diglyceride borate intermediate. After the addition is complete, the temperature is raised to 60°C, and the mixture is stirred for a period of time. A sample is then taken for GC analysis, and the isooctyl p-toluenesulfonate content is found to be less than 1%. The solvent is then removed. More preferably, a second sample is taken for GC analysis. If no other impurities are found in the target compound ethylhexylglycerol, the mixture is extracted and separated into layers. The oil layer is collected to obtain an ethylhexylglycerol solution.

[0041] Preferably, in step c, the hydrolysis by adding water directly and stirring at room temperature yields the target compound, ethylhexylglycerol. No acid or alkaline environment adjustment is required, resulting in mild and environmentally friendly conditions.

[0042] The structure of the isooctyl ether diboronate intermediate of this invention is as follows:

[0043]

[0044] The intermediate structure is highly susceptible to hydrolysis, making subsequent hydrolysis simple and readily available. After repeated deliberation and summarization by the R&D team, it was concluded that it is also crucial to ensure that the water is completely removed in the early stages of steps b and c, as this is key to improving yield.

[0045] On the other hand, the ethylhexylglycerol prepared by the above method provided by the present invention can be used as a desiccant.

[0046] Example 1: Synthesis of Ethylhexylglycerol

[0047] Add 20g (153.8mmol) of isooctanol, 100ml of dichloromethane, and 12.1g (153.8mmol) of pyridine to a 250ml four-necked flask and stir. Cool the mixture to 0-5℃ in an ice-water bath. Separately, prepare a dichloromethane solution with 29.2g (153.8mmol) of p-toluenesulfonyl chloride and place it in a dry constant-pressure dropping funnel. Maintain the internal temperature between 0-5℃ and add the solution dropwise. After the solution is completely added, gradually reduce the temperature to room temperature and stir for 2 hours. Then, take a sample for GC (gas chromatography) analysis. When the isooctanol is completely consumed, add 50ml of water to stop the reaction. Separately, wash the dichloromethane layer twice with 50ml of water each time. Collect the dichloromethane layer, dry it with anhydrous sodium sulfate, filter it, and seal it for later use.

[0048] 13.8 g (150 mmol) of glycerol and 4.65 g (75 mmol) of boric acid were added to a 250 ml three-necked reaction flask. The mixture was heated to 100 °C and dehydrated under reduced pressure for 6 hours. After the dehydration reaction was completed, the mixture was cooled to room temperature and stirred. 39.8 g (39%, 90 mmol) of a dichloromethane solution of p-toluenesulfonate was added dropwise. After the addition was complete, the mixture was heated to 60 °C and stirred for 5 hours. A sample was taken for GC analysis, and the p-toluenesulfonate content was found to be less than 1%. The solvent was removed, and the mixture was cooled to room temperature. 50 ml of water was added and stirred at room temperature for 3 hours. A sample was taken for GC analysis, and the content of the target compound, ethylhexylglycerol, was 92.3%. 100 ml of dichloromethane was added for extraction and separation. The oil layer was washed twice with 50 ml of water. The oil layer was collected and the solvent was evaporated to obtain 15.6 g of ethylhexylglycerol solution.

[0049] Tests showed that the ethylhexylglycerin solution had a GC content of 93.8% and a yield of 79.9%.

[0050] In the example, after the mixture was gradually turned to room temperature and stirred for 2 hours, a sample was taken for GC analysis, which showed that the proportion of isooctanol in the raw material was 0.6% and the proportion of the target compound was 98.7%.

[0051] In the example, the dichloromethane layer was dried with anhydrous sodium sulfate and filtered before quantitative analysis. The content of isooctyl p-toluenesulfonate was found to be 39%, the weight of the dichloromethane solution of isooctyl p-toluenesulfonate was 65 g, and the yield was 96%.

[0052] Example 2: Synthesis of Ethylhexylglycerol

[0053] Add 20 g (153.8 mmol) of isooctanol, 100 ml of dichloromethane, and 18.8 g (153.8 mmol) of DMAP to a 250 ml four-necked flask and stir. Cool the mixture to 0-5 °C in an ice-water bath. Separately, prepare a dichloromethane solution by dissolving 29.2 g (153.8 mmol) of p-toluenesulfonyl chloride in a dry constant-pressure dropping funnel. Add the solution dropwise while maintaining the internal temperature between 0-5 °C. After the solution is completely added, gradually reduce the temperature to room temperature and stir for 2 hours. Take a sample for GC analysis. Once the isooctanol is completely consumed, add 50 ml of water to terminate the reaction. Separately, wash the dichloromethane layer twice with 50 ml of water each time. Collect the dichloromethane layer, dry it with anhydrous sodium sulfate, filter it, and seal it for later use.

[0054] 13.8 g (150 mmol) of glycerol and 4.65 g (75 mmol) of boric acid were added to a 250 ml three-necked reaction flask. The mixture was heated to 100 °C and dehydrated under reduced pressure for 6 hours. After the dehydration reaction was completed, the mixture was cooled to room temperature and stirred. 44.9 g (34.6%, 90 mmol) of a dichloromethane solution of p-toluenesulfonate was added dropwise. After the addition was complete, the mixture was heated to 60 °C and stirred for 5 hours. A sample was taken for GC analysis, and the p-toluenesulfonate content was found to be less than 1%. The solvent was removed, and the mixture was cooled to room temperature. 50 ml of water was added and stirred at room temperature for 3 hours. A sample was taken for GC analysis, and the content of the target compound, ethylhexylglycerol, was 92.7%. 100 ml of dichloromethane was added for extraction and separation. The oil layer was washed twice with 50 ml of water. The solvent in the oil layer was collected and evaporated to obtain 15 g of ethylhexylglycerol solution.

[0055] Tests showed that the ethylhexylglycerin solution had a GC content of 91.4% and a yield of 77%.

[0056] In the example, after the mixture was gradually turned to room temperature and stirred for 2 hours, a sample was taken for GC analysis, which showed that the proportion of isooctanol in the raw material was 0.7% and the proportion of the target compound was 98.2%.

[0057] In the example, the dichloromethane layer was dried with anhydrous sodium sulfate and filtered before quantitative analysis. The content of isooctyl p-toluenesulfonate was found to be 34.6%, and the weight of the dichloromethane solution of isooctyl p-toluenesulfonate was 72.2 g, with a yield of 95%.

[0058] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing ethylhexylglycerin, characterized in that, Includes the following steps: a. Add isooctyl alcohol and alkali to the solvent, stir and cool to 0-5 degrees Celsius, then add a dichloromethane solution of p-toluenesulfonyl chloride dropwise. After the addition is complete, return to room temperature and stir for a period of time. Take a sample and analyze by gas chromatography until the isooctyl alcohol is completely consumed. Add water to separate the layers, collect the dichloromethane layer, wash the dichloromethane layer twice with water and dry it to obtain a dichloromethane solution of p-toluenesulfonyl ester. Dry and keep for later use. b. Add glycerol and boric acid to a reaction flask for dehydration reaction. After the reaction is complete, diglyceride borate intermediate is obtained. c. Add a dichloromethane solution of isooctyl p-toluenesulfonate prepared in step a to the borate diglyceride intermediate obtained in step b, to obtain isooctyl ether of borate diglyceride, then remove the solvent and hydrolyze with water to obtain the target compound ethylhexylglycerol. The preparation reaction process is as follows: 。 2. The method for preparing ethylhexylglycerol according to claim 1, characterized in that, In step a, the solvent used is dichloromethane; and / or The base used is either pyridine or DMAP.

3. The method for preparing ethylhexylglycerol according to claim 1, characterized in that, In step a, the molar ratio of isooctyl alcohol to p-toluenesulfonyl chloride is 1:

1.

4. The method for preparing ethylhexylglycerol according to claim 1, characterized in that, In step b, glycerol and boric acid are added to the reaction flask, heated to 100°C, and dehydrated under reduced pressure.

5. The method for preparing ethylhexylglycerol according to claim 1, characterized in that, In step b, the molar ratio of boric acid to glycerol is 1:

2.

6. The method for preparing ethylhexylglycerol according to claim 1, characterized in that, In step c, after the dehydration reaction in step b is completed, the temperature is lowered to room temperature and stirred. Then, a dichloromethane solution of isooctyl p-toluenesulfonate prepared in step a is added dropwise to the diglyceride borate intermediate. After the addition is complete, the temperature is raised to 60°C, and after stirring for a period of time, a sample is taken for GC analysis. The content of isooctyl p-toluenesulfonate is found to be less than 1%, and the solvent is removed.

7. The method for preparing ethylhexylglycerol according to claim 1, characterized in that, In step c, the molar ratio of isooctyl p-toluenesulfonate intermediate to diglyceride borate intermediate is 1.2:

1.

8. The method for preparing ethylhexylglycerol according to claim 1, characterized in that, In step c, hydrolysis with water is achieved by simply adding water and stirring at room temperature to obtain the target compound, ethylhexylglycerol.

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