CN103319342A - Method for synthesizing ethyl oleate - Google Patents

Abstract

The invention discloses a synthesis method of ethyl oleate, which is characterized in that the esterification reaction of oleic acid and ethanol is carried out under the _H2SO4 / _SiO2 immobilized catalyst, and then the _reaction liquid is filtered, and the filtrate is passed through Purified by column chromatography or distilled to obtain a colorless or light yellow clear liquid which is ethyl oleate; the molar ratio of the oleic acid to ethanol is 1:1.5~5; the molar ratio of the catalyst to the oleic acid is 1:10~ 50. Compared with the prior art, the present invention has the advantages of simple process, convenient operation, low production cost, high yield, milder reaction conditions, further reduction of raw material consumption, yield can be increased to more than 95%, production cost is significantly reduced, and the catalyst The method can be recycled, does not pollute the environment, and is an environmentally friendly, cost-effective and promising method for synthesizing ethyl oleate.

Description

A kind of synthetic method of ethyl oleate

technical field

The invention relates to the technical field of organic chemical synthesis, in particular to a method for synthesizing ethyl oleate.

Background technique

Ethyl oleate is light yellow oily liquid, mainly used as surfactant, lubricant, penetrating agent, cosolvent, essence, water repellant and resin toughener, and also used as fragrance. The most typical method for the synthesis of ethyl oleate is to use oleic acid and ethanol as raw materials, use sulfuric acid as a catalyst to heat and reflux for 10 hours, neutralize with sodium methoxide to pH 8~9 after cooling, and then wash with water until neutral. Finally, it is obtained by drying with anhydrous calcium chloride and filtering. (Xu Kexun. Handbook of Fine Organic Chemical Raw Materials and Intermediates. Beijing: Chemical Industry Press 1998, 4:1~350). The disadvantage of this method is that the reaction time is too long, and the post-treatment process of the product is longer, and the industrial cost is higher.

Another commonly used method is to use the impregnation method to prepare supported mesoporous phosphotungstic acid carbon as a catalyst (Tan Xiaoyu, Yang Lina, Liu Jing, Xu Junbo, Research on the Catalytic Synthesis of Ethyl Oleate by Supported Phosphotungstic Acid Mesoporous Carbon. Carbon , 2011, 1(145):25~28). In this method, the reaction temperature is 110°C, the loading capacity of phosphotungstic acid is 30%, the reaction time is 4 hours, and the esterification rate of oil is 89.34%. Although the reaction time of this method is shorter than that of the traditional preparation method, the reaction temperature is higher and the reaction time is longer. The preparation cost of the catalyst is higher and cannot be recycled and reused.

In summary, the ethyl oleate prepared by the prior art has a complex synthesis process and great environmental pollution, which seriously restricts its wide application. Therefore, it is necessary to find a method for the synthesis of ethyl oleate with a milder, more economical and green system, which is of great significance for the application of ethyl oleate in production.

Contents of the invention

The purpose of the present invention is to provide a kind of synthetic method of ethyl oleate for the deficiencies in the prior art, extracting oleic acid and ethanol carry out esterification reaction under H ₂ SO ₄ /SiO ₂ solid-supported catalysts, synthetic ethyl oleate The reaction system of the ester is mild, easy to operate, the consumption of raw materials is reduced, the yield can be increased to more than 95%, the production cost is significantly reduced, and the post-treatment of the catalyst is simple and recyclable without polluting the environment. A promising method for the synthesis of ethyl oleate.

The specific technical scheme for realizing the object of the present invention is: a kind of synthetic method of ethyl oleate, it is characterized in that this method carries out esterification reaction with oleic acid and ethanol under H ₂ SO ₄ /SiO ₂ solid-supported catalysts, and then The reaction solution was filtered to remove the catalyst, and the filtrate was purified to obtain a colorless or light yellow clear liquid which was ethyl oleate. The specific synthesis steps were as follows:

a, preparation of solid acid catalyst

Mix _SiO2 solid with anhydrous methyl ether and sulfuric acid with a concentration of 98% in a weight-to-volume ratio of 2g:4ml:1ml, and then dry at 130~140°C for 4~5h to obtain a light brown fine powder called H ₂ SO ₄ /SiO ₂ solid-supported catalyst;

b. Esterification reaction

Mix oleic acid and ethanol at a molar ratio of 1:1.5~5, then carry out esterification reaction for 1~5 hours under the H ₂ SO ₄ /SiO ₂ solid-supported catalyst prepared above, and the reaction temperature is 50~110 °C; the molar ratio of the H ₂ SO ₄ /SiO ₂ solid-supported catalyst to oleic acid is 1:10~50;

c. Purification

The catalyst was filtered out from the above-mentioned esterification reaction solution, and the filtrate was purified by silica gel column chromatography or vacuum distillation to obtain a colorless or light yellow transparent oily liquid as ethyl oleate. the

Compared with the prior art, the present invention has simple process, convenient operation, mild reaction conditions, the yield can be increased to more than 95%, the consumption of raw materials is further reduced, the production cost is significantly reduced, and the catalyst can be recycled without polluting the environment. A green, cost-effective and promising synthetic method of ethyl oleate.

Description of drawings

Fig. 1 is the infrared spectrogram of the present invention.

Detailed ways

The present invention will be further elaborated below by specific embodiment:

Example 1

a, preparation of solid acid catalyst

Weigh 10.0g of SiO ₂ solid and 20.0ml of anhydrous ether, stir and mix, then slowly add 5ml of sulfuric acid with a concentration of 98% dropwise, stirring is required during the dropwise addition, ventilate it after the dropwise addition, let the methyl ether volatilize, and then place it in an oven After drying, the oven temperature was set at 135° C., and the drying time was 4 hours. A light brown fine powder was obtained as a H ₂ SO ₄ /SiO ₂ immobilized catalyst, which was ready for use.

b. Esterification reaction

Stir and mix 1.00ml oleic acid with 0.55ml ethanol and 0.013g of the H ₂ SO ₄ /SiO ₂ solid-supported catalyst prepared above, and carry out esterification reaction under stirring. The reaction temperature is 90°C and the reaction time is 2.5 hours.

c. Purification

The reaction solution of the above-mentioned esterification is filtered, and the catalyst filtered out can be recycled. The filtrate is purified by silica gel column chromatography to obtain 0.981 g of ethyl oleate, a colorless and clear liquid, with a yield of 91.4%. n ²⁰ _D =1.4532.

The NMR test data are as follows: ¹ H-NMR(500MHz,CDCl ₃ ):δ(ppm) 5.34(m, 2H), 4.12(q,J=7.2Hz, 2H), 2.28(t,J=7.5Hz,2H ), 1.62(m, 2H), 1.24-1.31 (m,24H), 0.89(t, J=6.0Hz, 3H).

After detecting and analyzing the above-mentioned obtained product ethyl oleate, it can be confirmed as a pure target product.

Example 2

a, preparation of solid acid catalyst

Weigh 10.0g of SiO ₂ solid and 20.0ml of anhydrous ether, stir and mix, then slowly add 5ml of sulfuric acid with a concentration of 98% dropwise, stirring is required during the dropwise addition, ventilate it after the dropwise addition, let the methyl ether volatilize, and then place it in an oven After drying, the oven temperature is set at 140° C., and the drying time is 3.5 hours. A light brown fine powder is obtained as a H ₂ SO ₄ /SiO ₂ immobilized catalyst, which is ready for use.

b. Esterification reaction

Stir and mix 50.0ml oleic acid, 20.0ml ethanol and 1.9g of the H ₂ SO ₄ /SiO ₂ solid-supported catalyst prepared above, and carry out esterification reaction under stirring. The reaction temperature is 110°C and the reaction time is 1.5 hours.

c. Purification

After the esterification reaction was completed, the reaction system was filtered, and the filtrate was distilled under reduced pressure to obtain 46.7 g of ethyl oleate, a pale yellow clear liquid. (bp: 205～208℃/7mmHg) The theoretical yield of ethyl oleate is 49.0g, so the yield of ethyl oleate in the experiment is 95.3%. The measured refractive index of the sample n ²⁰ _D =1.4538.

Referring to accompanying drawing 1, carry out infrared spectrum detection to the above-mentioned product ethyl oleate, its data are as follows: 3006.67cm ^-1 is the vibrational absorption peak of CH on the C=C double bond of ethyl oleate; 2926cm ^-1 and ^{2854.96cm- 1} is CH stretching vibration absorption peak of methyl group and methylene group; 1738.09cm ^-1 is C=O ester carbonyl stretching vibration absorption peak; 1178.78cm ^-1 and 1036.03cm ^-1 are asymmetric stretching vibration absorption peaks of COC bond; 1462.38cm ^-1 and 1383.78cm ^-1 are the CH bending vibration absorption peaks of methyl and methylene groups; the peaks at 980cm ^-1 ~ 650cm ^-1 are the CH out-of-plane bending vibrations when multiple CH ₂ are in a straight chain absorption peak. Infrared spectrum data measured in the experiment and literature (Ling Guanting, Tang Shuchao, Tao Minqiang. Food Additive Handbook [M]. Third Edition. Beijing: Chemical Industry Press, 2003.411-412) The infrared characteristic absorption of the main group of ethyl oleate Consistent, indicating that the product is ethyl oleate.

The above is only a further description of the present invention, and is not intended to limit this patent. All equivalent implementations of the present invention should be included in the scope of claims of this patent.

Claims (1)

1. the synthetic method of an ethyl oleate, it is characterized in that the method with oleic acid and ethanol at H ₂SO ₄/ SiO ₂Carry out esterification under the solid-carrying type catalyzer, then with reacting liquid filtering, filtrate is through purifying to such an extent that faint yellow clarified liq is ethyl oleate, and concrete synthesis step is as follows:

The preparation of a, solid acid catalyst

With SiO ₂Solid and anhydrous diethyl ether and concentration be 98% sulfuric acid by weight volume ratio be after 2g:4ml:1ml mixes, dry 4 ~ 5h under 130 ~ 140 ℃ of temperature, the fine powder that obtains light brown is H ₂SO ₄/ SiO ₂The solid-carrying type catalyzer;

B, esterification

Oleic acid is mixed for 1:1.5 ~ 5 in molar ratio with ethanol, then at the H of above-mentioned preparation ₂SO ₄/ SiO ₂Carry out 1 ~ 5 hour esterification under the solid-carrying type catalyzer, its reaction oil bath temperature is 50 ~ 110 ℃; Described H ₂SO ₄/ SiO ₂The mol ratio of solid-carrying type catalyzer and oleic acid is 1:10 ~ 50;

C, purification

Leach catalyzer in the reaction solution with above-mentioned esterification, filtrate is purified through silica gel column chromatography or underpressure distillation, and obtaining colourless or light yellow transparent oily liquid is ethyl oleate.

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