SU1525144A1 - Method of obtaining benzoic acid anhydride - Google Patents

Abstract

The invention relates to a method for producing benzoic acid anhydride and can be used in the chemical industry. The goal is to simplify the process. It is carried out by the oxidation of benzoin with molecular oxygen at 95-130 ° C to produce an oxidate containing benzyl, which is oxidized with molecular oxygen in the presence of benzaldehyde at 40-80 ° C in a low polarity solvent. The method makes it possible to use benzyl contained in oxidized benzoin as a starting product without prior isolation.

Description

The invention relates to organic chemistry, namely to a method for producing benzoic acid anhydride, which is an industrial product.

The purpose of the invention is to simplify the process by using as a starting material for the preparation of benzoic acid anhydride (B) benzoyl oxidate containing benzyl, without prior isolation.

Example 1. In a bubble type plant at atmospheric pressure, air is oxidized at 95 C with 400 ml of a solution containing 67.8 g of benzoin in methyl benzoate. Air flow 0.8-1 l / min. After 24 hours of oxidation, the extreme conversion of benzoin to the reaction products is achieved, while the oxidate contains, g: benzyl 45.6; benzoin 1.7; benzoic acid 22.9; benzaldehyde 0.4. Yield,% of theoretical: benzyl 69,6J benzoic acid 30.3 (taking into account the return to the additional oxidation of unreacted benzoin and benzoaldehyde, which has not been oxidized to benzoic acid).

Then the reaction mixture is cooled to 40 ° C, 46.0 g of benzaldehyde is added and oxidized with the same air flow. After 7 hours of oxidation, the reaction mixture contains, g: benzyl 22.6; benzaldehyde 3.8; benzoic acid 66.8, benzoin 1.7; benzoic anhydride 23.5. After removing the remaining components of the reaction mixture by distillation in vacuo, 23.2 g of benzoic anhydride and 66.3 g of benzoic acid are obtained. The yield of benzoic acid anhydride on the reacted benzyl was 93.7%, and the code of benzoic acid on the reacted benzaldehyde was 88.5%.

Example 2. Under the conditions of Example 1, the same benzoin solution is oxidized.

(L

at 115 ° C. After 16 hours of oxidation, the oxide contains, g: benzyl, 41.7; benzoin 0.85; benzoic acid 26.9; benzaldehyde 0.25. Yield,% of theoretical; benzyl 62.1, benzoic acid 34.5.

The reaction mixture is then cooled and continued to oxidize under the conditions of Example 1. After the oxidation, the reaction mixture contains, g: benzyl, 19.3; benzaldehyde 3.0; benzoic acid 73.9; benzoin 0.85; benzoic anhydride 21.2. After removing the remaining components of the reaction mixture by distillation in vacuo, 20.9 g of benzoic anhydride and 73.4 g of benzoic acid are obtained. The yield of benzoic acid anhydride on the reacted benzyl was 86.7%, the yield of benzoic acid on the reacted benzaldehyde was 93.4%.

Example 3. Under the conditions of Example 1, the same solution of benzoin is oxidized at 130 ° C. After 7 hours of oxidation, the oxidate contains, g: benzyl 38.5; benzoin 0.84; benzoic acid 28.0 benzaldehyde 0.1. Yield,% of theory: benzyl 57.3, benzoic acid 35.9.

The reaction mixture is then cooled and continued to oxidize under the conditions of Example 1. After the oxidation, the reaction mixture contains, g: benzyl 20.4; benzaldehyde 2.6; benzoic acid 75.7, benzoin 0.84; benzoic anhydride 18.5. After removing the remaining components of the reaction mixture by distillation in vacuo, 18.2 g of benzoic anhydride and 75.1 g of benzoic acid are obtained. The yield of benzoic acid anhydride on the reacted benzyl was 93.4%, the yield of benzoic acid on the reacted benzaldehyde was 94.1%.

The resulting benzoic anhydride has so pl. 41-42 0.

IR spectrum in CC1 (spectrometer UR-26), 1780, 1721.

The resulting benzoic acid is i.p. 121-122 ° C.

IR spectrum in CC1c. (spectrometer 1688.

-one

UR-20), see Example

p 4. In a bubbling plant at atmospheric pressure, air is oxidized at 95 ° C with 400 ml of a solution containing 67.8 g of benzoin in dimethylformamide. Air flow 0.8-1.0 l / min. After 5 h

0

five

0

five

0

0

five

0

five

oxidation oxidate contains, g: benzyl 48.2; benzoin 0.4 benzaldehyde 4.9; benzoic acid 7,8. Benzyl Vcod 71.8% (from theoretical).

Then the reaction mixture is cooled to 40 ° C, 48.7 g of benzaldehyde are added and oxidized at the same air flow rate. After 7 hours of oxidation, the reaction mixture contains 46.1 g of benzaldehyde and traces of benzoic anhydride.

Example 5. Under the conditions of Example 1, the same solution of benzoin in methyl benzoate is oxidized. After 24 hours of oxidation, the oxidate contains, g: benzyl 45.8; benzoin 1.6, benzoic acid 22.7j benzaldehyde 0.4. Yield,% of theoretical: benzyl 68.2; benzoic acid 29.1.

Then the reaction mixture is cooled to 60 ° C, 46.0 g of benzaldehyde is added and oxidized at the same air flow rate. After 7 hours of oxidation, the reaction mixture contains, g: benzyl 21.4; benzaldehyde 2.8; benzoic acid 75, G; benzoin 1,4; benzoic anhydride 20.9. After removing the remaining components of the reaction mixture by distillation in vacuo, 20.5 g of benzoic anhydride and 72.0 g of benzoic acid are obtained. The yield of benzoic acid anhydride on the reacted benzyl was 78.1%, the yield of benzoic acid on the reacted benzaldehyde was 98.2%.

Example 6. Under the conditions of Example 1, the same solution of benzoin in methyl benzoate is oxidized. After 24 hours of oxidation, the oxidate contains, g: benzyl 46.2 benzoin 0.9; benzoic acid 23.4, benzaldehyde 0.2. Yield,% of theoretical: benzyl

68,8-, benzoic acid 30. I

Then the reaction mixture is cooled to 80 ° C, 46.0 g of benzaldehyde is added and oxidized at the same air flow rate. After 7 hours of oxidation, the reaction mixture contains, g: benzyl, 19.7J, benzaldehyde 3.0; benzoic acid 73.1; benzoin 0.8; benzoic anhydride 21.3. After removing the remaining components of the reaction mixture by distillation in vacuo, 20.9 g of benzoic anhydride and 72.6 g of benzoic acid are obtained. The yield of benzoic acid anhydride on the reacted benzyl was 73.3%, the yield of benzoic acid on the reacted benzaldehyde was 99.0%.

5 15251446

Claims (1)

/ The claims that, in order to simplify the process, A method for the preparation of ben-anhydride oxidation with molecular oxygen of eoic acid, including oxidation, exposes benzoin in methylbenzyl in the presence of benzaldehyde benzoate at 95-130 ° C to obtain benzoyl containing 5 wherein p ,,, oxidizes.