SU498284A1 - Method for producing duric acid - Google Patents

Description

This invention relates to a process for the preparation of aromatic acids, in particular duryl acid, used in the synthesis of plasticizers and polyester resins.

A known method for producing duric acid by oxidizing durol with oxygen in a lower aliphatic acid medium when heated in the presence of transition metal salts and organic acids as a catalyst, followed by isolation of the target product by known methods.

However, the yield of duric acid is negligible.

In order to increase the yield of the target product, the oxidation of durene is proposed; lead in a mixture with lower aliphatic aldehydes, preferably at a molar ratio of durol: lower aliphatic acid: aldehyde, equal to 1: 9-20.0: 0.3-0.6.

The output of duric acid is 73% in terms of the reacted durol with a product purity of 98-99.0%.

Consumption of aliphatic acid 1,8-U mol / mol durol.

Catalyst consumption 0.1 -1%. Reaction temperature 110-150 ° C.

Example 1. iB reaction column load 0,075 mol (10.0 g) of durene (grade h), so pl. 79-80 ° C; 1.50 mol (90.0 g) of acetic acid, so pl. 16-17 ° C, Pts 1.3710;

0.042 mol (3.0 g) of acetic acid., T. Kip. 20-21 ° C, UD 1.3390; and 0.05 g

cobalt acetate monohydrate.

The rate of oxygen supply 10-12 l / h. The reaction temperature is 108-110 ° С, the duration is 6 hours.

At the end of the experiment, the reaction mass was dispersed at 35 ° C / 25-g. and get 74.70 g

Q mixture of acetic acid with durol, "0 ° 1,3776, containing 1.20 g of durol.

The residue is treated with a 20% sodium hydroxide solution while cooling, the undissolved part is colored green.

 filtered off, washed with cold water, dried in air and get 2.90 g of durol, so pl. 77-79 ° C.

The filtrate is treated with concentrated hydrochloric acid, the precipitate is filtered off, washed well with water, dried and obtain 5.70 g of a mixture of duric and di: methylphthalic acids, so pl. 140-190 ° C, neutralization equivalent of 147.5, which is treated with 100 ml of concentrated acetic acid, 0.13 g of dimethylphthalic acid is separated, m.p. 250 ° C, the equivalent of neutralization 98.2, the acetic acid is distilled off from the filtrate and duryl acid is obtained as a residue, which is washed with acetic acid. the water and dried. Yield 5.2 g

(72.9%), t. Pl. 146-149 ° C, the equivalent of neutralization 162.8.

From the effluent gas (B, 0.12 g of carbon dioxide (0,, 27 mol) is recovered, which corresponds to the complete oxidation of 0.145-10 mol of acetic acid.

Example 2. In the reaction column load of 0.15 mol (20,0 C) durene, 1.33 mol (80.0 g of acetic acid, 0, .042 mol (3.0 g) of acetic aldehyde and 0.20 g of tetrahydrate cobalt acetate. The oxygen supply rate is 1 hour, the reaction temperature is 108-110 ° C, the duration is 8 hours.

(After cooling, 4.8 g of precipitate is separated, which is a mixture of duric and dimethylphthalic acids, mp 15.9- 2 ° C (incomplete melting), the filtrate is dispersed and at 35 ° C / 25 mm distills off 62 , 0 g of mixture of ccd

hydrochloric acid and durol, pb 1.3770, containing l, iO g of durol. The solid residue is treated with 20% sodium hydroxide solution, cooled, the durene is filtered off, washed with water and dried. Yield 1.80 g, so pl. 76-78 ° C. The alkaline filtrate is acidified with concentrated hydrochloric acid, the precipitate is filtered off, washed thoroughly with water, and dried. Weight M, 10 g, t. PL. 146-148 ° C, the equivalent of neutralization 164.9.

To separate duric and dimethylphthalic acids, a precipitate is treated with 2 x 100 g of concentrated acetic acid, and 0.55 g of dimethyl phthalic acid is separated with a neutralization equivalent of 98.7, which does not melt to 250 ° C.

After distillation of the acetic acid from the filtrate, 4.10 g of duric acid are obtained. 148-158 ° C, the equivalent of neutralization of 159.1. Yield durilic acid 15.20 g (73.07%).

0.49 g of carbon dioxide (7.45 mol) is separated from the exhaust gases, which corresponds to a total oxidation of 3.72 10 mol of acetic acid.

Claims (2)

1.-A method for producing duric acid by oxidizing durol with oxygen in an environment of lower aliphatic acid at elevated temperatures in the presence of transition metal salts and organic acids in catalyst thirst followed by separation of the target product by known methods, characterized in that, in order to increase the yield of the slit product, oxidation Durol lead ev mixtures with lower aliphatic aldehydes. 2. Method p. 1, characterized in that the oxidation is carried out at a molar ratio of durene: lower aliphatic acid: aldehyde, equal to 1: 9-20.0: 0.3-0.6.