A new method for preparing ethylhexylglycerin
Through the new synthesis route, isooctanol, alkaline substances and phase transfer catalysts are used to react with propylene chlorine to form an allyl isooctanyl ether intermediate, and a slow dropping reaction is used with formic acid and hydrogen peroxide under low temperature conditions, followed by ring-opening hydrolysis, which solves the problems of low yield, complex process and high production cost in the existing process, and achieves efficient and low-cost preparation of ethylhexylglycerol.
Patent Information
- Application Number
- CN202411946376.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-04-04
AI Technical Summary
The existing ethylhexylglycerol production process has problems such as low yield, complex process, high production cost, and the use of epoxy raw materials and a large number of catalysts.
Using a new synthesis route, the reaction with propylene chloride at a specific temperature is adopted by isooctanol, alkaline substances and phase transfer catalysts is carried out to form an allyl isooctanyl ether intermediate. Then, the reaction is slow dropwise with formic acid and hydrogen peroxide under low temperature conditions, followed by ring-opening hydrolysis, and the efficient preparation of ethylhexylglycerol is gradually achieved through this step.
It improves the synthesis yield of ethylhexylglycerol, reduces raw material cost and energy consumption, simplifies the process flow, avoids the generation of polyester by-products, and has high product purity, which is suitable for large-scale production.
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for synthesizing an ethylhexylglycerin preservative through a new synthesis route, and particularly relates to the application of low-cost and low-energy consumption raw materials, formic acid and hydrogen peroxide, which improves various deficiencies of the existing process and can prepare an ethylhexylglycerin product with a relatively high yield. Technical Background
[0002] In the 21st century, the cosmetics industry has integrated and absorbed the high-tech achievements of modern multidisciplinary disciplines, improved the safety, functionality, stability and environmental protection of cosmetics, developed new cosmetic raw materials and high-efficiency additives, and adopted green and environmentally friendly surfactants. These are the hot spots in cosmetic research. With the development of the naturalness, safety, scientificity, biochemistry, efficacy, functionality and practicality of cosmetics, the use of safe and reliable additives in the cosmetics industry is becoming more and more important. Ethylhexylglycerin is a multifunctional cosmetic additive with both preservative and moisturizing and deodorizing effects. It has its own unique functions such as good biocompatibility and mild and non-irritating to the skin, so it is widely used in cosmetics.
[0003] However, traditional preservatives used in daily chemical products are toxic and can cause some harm to the environment and human health. In January 2014, the European Union announced a ban on the use of triclosan in cosmetics, and the ban also included some uncommon parabens; media reports included news that infant bathroom products produced by internationally renowned daily chemical companies contained formaldehyde, warning that the use of traditional preservatives would increase risks and cause panic around the world. China's newly implemented "2015 Cosmetic Safety Technical Specifications" (replacing the "2007 Cosmetic Hygiene Specifications") has attracted great attention to the safety of preservatives, so the position of ethylhexylglycerin in the field of preservatives has become increasingly important. Although there are many production processes for ethylhexylglycerin, they all have a series of problems such as relatively low yield, complex process, high production cost, and the use of epoxy raw materials and a large number of catalysts. Therefore, it is a general trend to develop a greener and simpler process route to produce ethylhexylglycerin.
[0004] Ethylhexylglycerin is a new multifunctional cosmetic additive that has both preservative and moisturizing and deodorizing effects. By utilizing its synergistic effect with other traditional preservatives for use in daily chemical product systems, the amount of traditional preservatives added can be greatly reduced. It does not irritate the skin and significantly reduces the toxicity of the preservative system. It has a moisturizing effect and can enhance the ability of traditional preservatives. Therefore, ethylhexylglycerin will play an important role in future green preservative systems.
[0005] The boiling point of ethylhexyl glycerol is about 300℃. It is difficult to separate and purify it in the process. It is easy to oxidize and discolor during the process. It is easy to polymerize and produce impurities during synthesis. Ethylhexyl glycerol with high impurity content will affect the color and have peculiar smell. Some impurities will affect toxicological safety and cannot be used as a daily chemical additive. The route for producing ethylhexyl glycerol is relatively mature. At present, most of them are produced by etherification technology to generate glycidyl ether intermediates, and then produce ethylhexyl glycerol. The more popular process methods for producing ethylhexyl glycerol that have been reported so far are: one is to hydrolyze with alkali after the addition reaction of acid anhydride and glycidyl ether, but it is very easy to produce glycidyl ether self-polymerization by-products; another method is to prepare ethylhexyl glycerol by alcohol and glycidyl ether under acid or alkali catalysis, which has a long reaction time and many impurities; the third method is to open the epoxy group of ethylhexyl glycidyl ether by catalysis for carbonyl addition, and then hydrolyze. Although the process route for preparing ethylhexyl glycerol is relatively mature, in order to adapt to market competition, continuously reduce production costs, continue to innovate, and efficiently produce products with higher specifications will become the direction of people's attention.
[0006] Therefore, based on the above problems and in order to adapt to the general environment of the cosmetics industry, this patent proposes a new method for preparing ethylhexylglycerin. Summary of the invention
[0007] In order to solve at least one of the above problems, and in view of the important position of ethylhexylglycerin in the field of preservatives and the urgent needs of the current market, this patent proposes a new method for preparing ethylhexylglycerin, and the method route is as follows:
[0008]
[0009] The target compound of the present invention comprises the following steps:
[0010] (a), adding isooctyl alcohol, alkaline substance and phase transfer catalyst to a reaction flask, stirring and heating and maintaining the temperature in the range of 30-40°C, adding propylene chloride dropwise, keeping warm and stirring after adding, and detecting and analyzing the isooctyl alcohol content. The reaction is terminated when the isooctyl alcohol content is less than 5%, and then adding water to the reaction flask and stirring until the solution is clear and separated, the water layer is extracted and mixed with the oil layer, the combined organic phase is washed with hydrochloric acid, and then washed with saturated sodium bicarbonate until the pH value is in the range of 6-7, and then washed with saturated brine and collected, and then dried with anhydrous sodium sulfate, the dried filtrate is desolventized to 60°C and then distilled with an oil pump to obtain the target intermediate allyl isooctyl ether;
[0011] (b) In another reaction flask, add formic acid and hydrogen peroxide under the condition of maintaining the temperature below 20° C. and stir, then slowly increase the temperature to maintain the temperature at 40-45° C. and slowly dropwise add the allyl isooctyl ether intermediate prepared in step (a), keep the temperature and stir after the dropwise addition, and detect and analyze the content of the allyl isooctyl ether intermediate until the allyl isooctyl ether intermediate is consumed, then remove a large amount of formic acid under negative pressure and cool to room temperature for retention;
[0012] (c) Add an appropriate amount of alkaline solution to the reaction solution of step (b), maintain the pH value at 11-12, and stir at room temperature to perform ring-opening hydrolysis and stratification. Combine the oil phase extracted from the aqueous layer with the organic oil layer, then wash with hydrochloric acid, then with saturated sodium bicarbonate solution, and then with saturated brine. Collect the organic layer, dry it with anhydrous sodium sulfate, filter it, and pump the filtrate to 80°C with a water pump, then change the oil pump to distill and collect the target product ethylhexylglycerol.
[0013] As a preferred embodiment of the present invention, in step a, the alkaline substance comprises sodium hydroxide. Further preferably, the molar ratio of propylene chloride to solid sodium hydroxide is 1:2.
[0014] As a preferred embodiment of the present invention, in step a, the water layer is extracted twice with ethyl acetate, and the extracted oil phase is mixed with the oil layer of the clear layer.
[0015] As a preferred embodiment of the present invention, in step c, the water layer is extracted twice with ethyl acetate, and the extracted oil phase is mixed with the oil layer of the clear layer.
[0016] As a preferred embodiment of the present invention, in step a, the combined organic phase is washed once with 2 mol / L hydrochloric acid, then washed with saturated sodium bicarbonate until it is nearly neutral, and then washed once with saturated brine.
[0017] As a preferred embodiment of the present invention, in step a, GC analysis shows that the content of the target intermediate allyl isooctyl ether is ≥ 98%.
[0018] As a preferred embodiment of the present invention, in step c, the alkaline solution is a sodium hydroxide solution.
[0019] As a preferred embodiment of the present invention, in step c, the combined organic phase is washed once with 2 mol / L hydrochloric acid, then washed with saturated sodium bicarbonate until it is nearly neutral, and then washed once with saturated brine.
[0020] As a preferred embodiment of the present invention, in step c, the content of the target substance ethylhexylglycerol obtained by GC analysis is >99%.
[0021] As a preferred embodiment of the present invention, in step a, the phase transfer catalyst used is tetrabutylammonium hydroxide, and the amount of the catalyst accounts for 5‰ of the mass of isooctyl alcohol.
[0022] As a preferred embodiment of the present invention, in step a, the molar ratio of isooctyl alcohol to propylene chloride is 1:1.2.
[0023] As a preferred embodiment of the present invention, in step b, the mass concentration of the hydrogen peroxide used is preferably between 35% and 50%.
[0024] As a preferred embodiment of the present invention, in step b, the molar ratio of hydrogen peroxide to formic acid is 1:4.
[0025] As a preferred embodiment of the present invention, in step b, the molar ratio of the intermediate allyl isooctyl ether to hydrogen peroxide is 1:2.5.
[0026] As a preferred embodiment of the present invention, the method specifically comprises the following steps:
[0027] (a) adding isooctyl alcohol, sodium hydroxide and a phase transfer catalyst to a reaction flask, stirring and heating to maintain the temperature at 30-40°C, adding propylene chloride dropwise, and starting sampling and GC analysis after the addition of heat preservation and stirring for 24 hours, until the isooctyl alcohol content is less than 5%, then adding water to the reaction flask and stirring evenly until the clear layer is separated, extracting the water layer with ethyl acetate twice, mixing the extracted oil phase with the clear layer to form an organic phase, washing the combined organic phase with 2 mol / L hydrochloric acid once, then washing with saturated sodium bicarbonate to a pH value in the range of 6 to 7, then washing with saturated brine once, collecting the washed organic phase, drying with anhydrous sodium sulfate after collection, removing the solvent with a water pump at negative pressure to 60°C, and then changing the oil pump for distillation to obtain the target intermediate allyl isooctyl ether, and GC analysis shows that the content of the target intermediate allyl isooctyl ether is ≥ 98%;
[0029] (b) In another reaction flask, add formic acid and hydrogen peroxide while maintaining the temperature below 20° C. and stir, then slowly increase the temperature to maintain the temperature at 40-45° C. and slowly dropwise add the allyl isooctyl ether intermediate prepared in step (a), keep the temperature and stir for 24 hours, start sampling and control in GC until the allyl isooctyl ether intermediate is consumed, then remove a large amount of formic acid under negative pressure and cool to room temperature for retention;
[0030] (c) Add an appropriate amount of 30% aqueous sodium hydroxide solution to the reaction solution of step (b) to maintain the pH at 11-12, then stir at room temperature for 2 h to perform ring-opening hydrolysis and separate the layers. The aqueous layer is extracted twice with ethyl acetate and then combined with the organic oil layer. The layer is then washed once with 2 mol / L hydrochloric acid and then washed with saturated sodium bicarbonate solution until it is nearly neutral. The organic layer is then collected and dried over anhydrous sodium sulfate and filtered. The filtrate is pumped down to 80°C with a water pump and then distilled with an oil pump to collect the target ethylhexylglycerin. GC analysis shows that the content of the target ethylhexylglycerin is >99%.
[0031] Compared with the prior art, the present invention has at least the following beneficial effects:
[0032] 1. The overall yield of the synthesis process of the present invention is higher than that of the current traditional process.
[0033] 2. The cost of raw materials used in the synthesis process is low, the reaction energy consumption is low, and the reaction conditions of the entire route are relatively mild.
[0034] 3. The reaction process is simple and convenient for large-scale production.
[0035] 4. This method first prepares the allyl isooctyl ether intermediate, then epoxidizes the double bond, and then performs ring-opening hydrolysis. Compared with some traditional process routes, the generation of by-products such as polyesters is eliminated from the source. The structure of the allyl isooctyl ether intermediate of the present invention is as follows:
[0036] DETAILED DESCRIPTION
[0037] The present invention will be further described below in conjunction with the embodiments.
[0038] Example 1 Synthesis of Ethylhexylglycerol
[0039] Add 20g (153.8mmol) of isooctyl alcohol, 14.8g (369mmol) of sodium hydroxide and 0.25g (5‰ of isooctyl alcohol) of 40% tetrabutylammonium hydroxide solution into a 250ml four-necked bottle, stir and heat to 30-40°C, maintain the temperature range and slowly add propylene chloride liquid (about 6 drops / min), keep warm for 24h after dropping, take a sample for GC analysis, the isooctyl alcohol content is 4.2%, add 30ml of water and stir until the clear liquid separates, extract the water layer with 30ml×2 ethyl acetate twice, and The organic phase separated from the extracted ethyl acetate and the clear liquid is combined, washed once with 30 ml of 2 mol / L hydrochloric acid, then washed once with 80 ml of saturated sodium bicarbonate solution until the pH value is in the range of 6 to 7, and then washed once with 50 ml of saturated brine. The washed organic phase is dried with 50 g of anhydrous sodium sulfate and then filtered. After the solvent is removed from the filtrate, the oil pump is changed and distilled to obtain 24.6 g of transparent clear liquid of allyl isooctyl ether intermediate. GC analysis shows that the content of allyl isooctyl ether intermediate is 98.7%, and the yield is 93.3%;
[0040] In another 500ml four-necked reaction bottle, 65.3g (1.42mol) of formic acid and 34.5g (355mmol) of 35% hydrogen peroxide were slowly added under 10°C and stirred. After the addition, the temperature was slowly raised to 40-45°C. 24.6g (142mmol) of the prepared allyl isooctyl ether intermediate was added dropwise while maintaining the temperature in this range. The dropping speed was controlled at 15-20s / drop. After the dropping was completed and the temperature was kept warm for 24h, sampling and GC analysis were started. The peak of allyl isooctyl ether intermediate disappeared. After a large amount of formic acid was removed under negative pressure, the temperature was lowered to room temperature and stirred. 30% sodium hydroxide was added dropwise The solution was 100 g, and the pH value was detected to be about 12. The pH was maintained by stirring for 2 h of ring-opening hydrolysis, and then the layers were separated. The aqueous layer was extracted twice with 30 ml of ethyl acetate × 2, and the extract and the organic phase were combined and washed once with 2 mol / L HCl (50 g), and then washed once with a saturated sodium bicarbonate solution (200 g), and then washed once with 100 g of saturated brine. After drying and filtering with 20 g of anhydrous sodium sulfate, the solvent was removed, and the oil pump was changed for distillation to collect 25.6 g of the transparent target ethylhexylglycerol. The content of the target ethylhexylglycerol was 99.3% by GC analysis, and the yield was 88.8%.
[0041] Example 2 Synthesis of Ethylhexylglycerol
[0042] Add 200g (1.53mol) of isooctyl alcohol, 148g (3.69mol) of sodium hydroxide and 2.5g (5‰ of isooctyl alcohol) of 40% tetrabutylammonium hydroxide solution into a 1L four-necked bottle, stir and heat to 30-40°C, maintain the temperature range and slowly add propylene chloride liquid (about 6 drops / min), keep warm for 24h after dropping, take a sample and GC analysis, the isooctyl alcohol content is 3.9%, add 300ml of water and stir until the clear liquid separates, extract the water layer twice with 300ml×2 ethyl acetate, and extract The organic phase separated from the ethyl acetate and the clear liquid was combined, washed once with 300 ml of 2 mol / L hydrochloric acid, then washed once with 500 ml of saturated sodium bicarbonate solution until the pH value was in the range of 6 to 7, and then washed once with 500 ml of saturated brine. The washed organic phase was dried with 50 g of anhydrous sodium sulfate and then filtered. After the solvent was removed from the filtrate, the oil pump was changed and distilled to obtain 243.6 g of transparent clear liquid of allyl isooctyl ether intermediate. The content of allyl isooctyl ether intermediate was 98.3% by GC analysis, and the yield was 92%;
[0043] In another 1L four-necked reaction bottle, add 647.7g (14.1mol) of formic acid and 266g (3.52mol) of 45% hydrogen peroxide slowly under 10°C, and slowly raise the temperature to 40-45°C after the addition. Add 243.6g (1.43mol) of the prepared allyl isooctyl ether intermediate dropwise while maintaining the temperature in this range. The dropping speed is controlled at 15-20s / drop. After the dropping is completed and the temperature is kept warm for 24h, start sampling for GC analysis. The peak of allyl isooctyl ether intermediate disappears. After removing a large amount of formic acid under negative pressure, cool to room temperature and stir, and add 30% sodium hydroxide solution dropwise. 1kg, the detected pH value is about 12, the pH is maintained and stirred for ring-opening hydrolysis for 2h, then the layers are separated, the aqueous layer is extracted twice with ethyl acetate 300ml×2, the extract and the organic phase are combined and washed once with 2mol / L HCl (500g), then washed once with saturated sodium bicarbonate solution (2000g), and then washed once with 1kg saturated brine, 50g of anhydrous sodium sulfate is added for drying and filtration, and the solvent is removed, and the oil pump is changed for distillation to collect 258.2g of the transparent target ethylhexylglycerol, and the content of the target ethylhexylglycerol is 99.1% by GC analysis, and the yield is 88.3%.
Claims
1. A new method for preparing ethylhexylglycerin, characterized in that: The synthesis steps include: (a) adding isooctyl alcohol, alkaline substance and phase transfer catalyst to a reaction flask, stirring and heating and maintaining the temperature in the range of 30°C-40°C, adding propylene chloride dropwise, keeping warm and stirring after adding, and detecting and analyzing the isooctyl alcohol content. The reaction is terminated when the isooctyl alcohol content is less than 5%, and then adding water to the reaction flask and stirring until the solution is clear and separated, extracting the water layer and mixing it with the oil layer, washing the combined organic phase with hydrochloric acid, and then washing with saturated sodium bicarbonate until the pH value is in the range of 6 to 7, and then washing with saturated brine and collecting the washed organic phase, and drying it with anhydrous sodium sulfate after collection. After desolventizing the dried filtrate and heating it to 60°C, the oil pump is changed for distillation to obtain the target intermediate allyl isooctyl ether; (b) adding formic acid and hydrogen peroxide to another reaction flask while maintaining the temperature below 20° C. and stirring, then slowly raising the temperature to maintain the temperature at 40-45° C. and slowly adding the allyl isooctyl ether intermediate prepared in step (a) dropwise, keeping the temperature and stirring after the addition is completed, and detecting and analyzing the content of the allyl isooctyl ether intermediate until the allyl isooctyl ether intermediate is consumed, then removing a large amount of formic acid under negative pressure and cooling to room temperature for later use; (c) adding an appropriate amount of alkaline solution to the reaction solution of step (b) to maintain pH=11-12, and then stirring at room temperature to perform ring-opening hydrolysis and stratification, combining the oil phase extracted from the aqueous layer with the organic oil layer, and then washing with hydrochloric acid, and then washing with a saturated sodium bicarbonate solution until it is nearly neutral, and then washing with saturated brine, collecting the organic layer by stratification, drying it with anhydrous sodium sulfate, filtering, and removing the solvent from the filtrate to 80°C, and then changing the oil pump for distillation to collect the target product ethylhexylglycerol; The synthetic route is as follows:
2. The novel method for preparing ethylhexylglycerol according to claim 1, characterized in that: In step a, the phase transfer catalyst used is tetrabutylammonium hydroxide, and the amount of the catalyst used accounts for 5‰ of the mass of isooctyl alcohol.
3. The novel method for preparing ethylhexylglycerol according to claim 1, characterized in that: In step a, the molar ratio of isooctyl alcohol to propylene chloride is 1:1.
2.
4. The novel method for preparing ethylhexylglycerol according to claim 1, characterized in that: In step a, the alkaline substance is sodium hydroxide; and / or In step c, the alkaline solution is a sodium hydroxide solution.
5. The novel method for preparing ethylhexylglycerol according to claim 4, characterized in that: The molar ratio of propylene chloride to solid sodium hydroxide is 1:
2.
6. The novel method for preparing ethylhexylglycerol according to claim 1, characterized in that: In step b, the mass concentration of the hydrogen peroxide used is between 35% and 50%.
7. The novel method for preparing ethylhexylglycerol according to claim 1, characterized in that: In step b, the molar ratio of hydrogen peroxide to formic acid is 1:
4.
8. The novel method for preparing ethylhexylglycerol according to claim 1, characterized in that: In step b, the molar ratio of the intermediate allyl isooctyl ether to hydrogen peroxide is 1:2.
5.
9. The novel method for preparing ethylhexylglycerol according to claim 1, characterized in that: In step a, the aqueous layer is extracted twice with ethyl acetate, and the extracted oil phase is mixed with the oil layer of the clear layer; and / or In step c, the aqueous layer is extracted twice with ethyl acetate, and the extracted oil phase is mixed with the oil layer of the clear layer.
10. The novel method for preparing ethylhexylglycerol according to claim 1, characterized in that: In step a, the filtrate is dried over anhydrous sodium sulfate and filtered using a water pump under negative pressure to remove the solvent, and after the temperature reaches 60° C., an oil pump is used for distillation to obtain the target intermediate allyl isooctyl ether; and / or In step c, the filtrate is desolventized by a water pump to 80° C. and then an oil pump is used for distillation to collect the target ethylhexylglycerin.