RU2466989C1 - METHOD OF OBTAINING n-CYMENE HYDROPEROXIDE - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to obtaining n-cemene hydroperoxide, which can be used for combined production of cresol and acetone. In accordance with invention claimed is method of obtaining n-cymene hydroperoxide by liquid-phase oxidation of n-cymene with air oxygen at atmospheric pressure, temperature of the process 80-110°C, for 1-3 hours, in presence of N-hydroxyphthalimide as catalyst in amount 1-5 wt %, until content of n-cymene hydroperoxyde is 25-28%.

EFFECT: catalyst excludes application of initiator and alkaline additives, which simplifies the process considerably; high rate of n-cymene oxidation is achieved.

1 cl, 3 ex

Description

The invention relates to the petrochemical industry and can be used in the process of joint production of cresol and acetone (B. D. Kruzhalov, B. I. Golovanenko. Joint production of phenol and acetone. - M.: Gostoptekhizdat, 1963; G. D. Kharlampovich, Yu. . V. Churkin. Phenols. - M.: Chemistry, 1974).

It is known that n-zimol hydroperoxide is produced by oxidation of n-zimol at elevated temperature in the presence of alkaline additives and an oxidation initiator, followed by isolation of the target product.

Closest to the proposed method for producing n-zimole hydroperoxide is the liquid-phase oxidation of n-zimol with atmospheric oxygen, supplied in an amount of 3.5-4 wt.% For raw materials at a temperature of 135-138 ° C in the presence of 0.5% initiator - n- hydroperoxide Tsimola. The total contact time in the oxidation reactors is 4 hours. The content of hydroperoxide in the oxidate is not higher than 13 wt.%. The conversion of the original hydrocarbon is 14-14.7 wt.%. The selectivity of the formation of tertiary hydroperoxide n-zimol - 82 mol.%. The oxidation rate of n-cymol is approximately 4-6% per hour (G.D. Kharlampovich, Yu.V. Churkin. Phenols. - M .: Chemistry, 1974).

The amount of by-products increases significantly during the oxidation of n-cymol in comparison with the oxidation of isopropylbenzene, which is largely associated with the formation of isopropylbenzoic acid, the final product of the oxidation of the methyl group in the n-cymol molecule. The content of this acid in the oxidation products is about 16-18% for the reacted zymol.

To increase the speed of the process, oxidation is carried out at elevated temperature. In some cases, this leads to spontaneous decomposition of hydroperoxides, significant energy consumption and a decrease in the selectivity of the process due to an increase in the formation of by-products, including isopropylbenzoic acid. Therefore, one should strive to reduce the temperature. It is known that the content of carboxylic acids decreases sharply if the content of n-cimol hydroperoxide in the oxidate does not exceed 6-8% (the selectivity of the formation of tertiary hydroperoxide is very noticeably increased), but such a low content of hydroperoxide will complicate the process flowchart and lead to additional costs that is not profitable from an economic point of view.

To increase the selectivity, the process is carried out in the presence of catalysts — metal salts of chromium, nickel, titanium, manganese, etc. But in this case, additional purification of the oxidation products from inorganic spent catalysts is required.

The objective of the invention is to eliminate the above disadvantages, increase the rate of oxidation of n-cymene, while maintaining high selectivity, as a result of using a single-component catalyst.

This technical problem is solved using the method of producing n-zimole hydroperoxide by liquid-phase oxidation of n-zimol with atmospheric pressure and a temperature of 80-110 ° C, in the presence of 1-5 wt.% N-hydroxyphthalimide as a catalyst. Under these conditions, it is possible to achieve a conversion of n-cimol of the order of 25-28% in 1-3 hours of reaction with a selectivity of formation of n-cimol hydroperoxide of 92-95%. Also, under these conditions, the content of isopropylbenzoic acid formed during the oxidation of the methyl group can be reduced to 0-0.2%. A characteristic feature of the used catalyst is the simplicity of its preparation and the possibility of its multiple use. N-hydroxyphthalimide eliminates the use of initiator and alkaline additives.

The present invention is illustrated by the following examples.

Example 1

4 cm ^{3 of} n-cymol and 2.4 wt.% N-hydroxyphthalimide were charged into a 10 cm ³ glass reactor, oxygen was supplied at atmospheric pressure, at a temperature of 90 ° C for 1.5 hours, and continuously stirred.

The content of n-cymene hydroperoxide was 23.2% with a selectivity of its formation of 94.1%. The oxidate was analyzed for the content of hydroperoxide by the iodometric method of analysis. Patentiometric titration showed that the content of isopropylbenzoic acid in the oxidate was 0.14%.

Example 2

4 cm ^{3 of} n-cymol and 2.4 wt.% N-hydroxyphthalimide were charged into a 10 cm ³ glass reactor, oxygen was supplied at atmospheric pressure, at a temperature of 80 ° C for 2.5 hours, and continuously stirred.

The content of n-cymene hydroperoxide was 25.7% with a selectivity of its formation of 95.0%. The oxidate was analyzed for the content of hydroperoxide by the iodometric method of analysis. Patentiometric titration showed that the content of isopropylbenzoic acid in the oxidate was 0.08%.

Example 3

4 cm ^{3 of} n-cymene and 2.4 wt.% N-hydroxyphthalimide were charged into a 10 cm ³ glass reactor, oxygen was supplied at atmospheric pressure, at a temperature of 110 ° C for 1.5 hours, and continuously stirred.

The content of n-cymene hydroperoxide was 27.8% with a selectivity of 92.4%. The oxidate was analyzed for the content of hydroperoxide by the iodometric method of analysis. Patentiometric titration showed that the content of isopropylbenzoic acid in the oxidate was 0-21%.

Claims (1)

A method of producing n-cimole hydroperoxide by liquid-phase oxidation of n-cimole with atmospheric pressure and elevated temperature in the presence of a catalyst, characterized in that the process is carried out at a temperature of 80-110 ° C for 1-3 hours, and N- hydroxyphthalimide in an amount of 1-5 wt.%.