CS267350B1 - Process for producing 4-hydroxybenzene sulfonic acid - Google Patents

Abstract

The solution relates to a method for producing 4-hydroxybenzenesulfonic acid by reacting phenol with sulfuric acid or oleum at a temperature of 70 to 110° C, such that sulfuric acid or oleum is gradually added to the phenol over a period of 1 to 3 hours, with the molar ratio between phenol and sulfuric acid being 1:1 to 1.05, then the reaction mixture is kept for 1 to 2 hours at a temperature of 80 to 110° C and, after cooling to 30 to 70° C, it is diluted with water at a temperature of 10 to 25° C in a weight ratio to the reaction mixture of 1:0.1 to 0.5.

Description

The invention relates to a process for the preparation of 4-hydroxybenzenesulphonic acid by the reaction of phenol with sulfuric acid or an acid containing free sulfur oxide.

4-Hydroxybenzenesulfonic acid has a wide application in the chemical industry. It is used in the production of ferments, polyester fibers, as well as in the production of pharmaceutical intermediates. Recently, 4-hydroxybenzenesulfonic acid, free or in the form of the sodium salt, has found application as a catalyst in the production of the herbicide chloridazon,

To date, several methods for producing 4-hydroxybenzenesulfonic acid are known. One of the most common is the direct eulfonation of phenol. According to DE 141 751 (1897), the same amount of phenol and 98% sulfuric acid are mixed under cooling, then the reaction mixture is heated to 150 DEG C. for 10 hours and, after adding sulfuric acid, the mixture is heated at 110 DEG C. for 6 hours. A further procedure for the preparation of 4-hydroxybenzenesulfonic acid consists in sulfonating phenol with 1.1 parts of sulfuric acid at 110 DEG C. for 36 hours (Kirk Othmsr Encyclopedia of Chemical Technology 10, 374).

FR 893 369 describes the eulfonation of aromatic compounds with sulfuric acid with quantitative azeotropic removal of the water formed by the reaction with an inert solvent. This procedure gave an 80% yield of 4-hydroxybenzenesulfonic acid. Luczyn et al. / Chem. Abstr. 91, 107-106, 1979 (describe the sulfonation of phenol with sulfuric acid at a temperature of 95 to 150 ° C in a glass column under the simultaneous countercurrent action of an inert solvent. By this procedure, a mixture of sulfonic acids was obtained in 80% yield. OP 7015019 discloses the preparation of 4-hydroxybenzenesulfonic acid by sulfonation of phenol with sulfuric acid at 90-100 ° C for 16 hours. Parrod (Comppt. Rend. 230, 450, 1950) describes the sulfonation of phenol and sulfuric acid as a function of temperature. According to the results, the sulfonation of phenol to prepare 4-hydroxybenzenesulfonic acid yields up to 11% of 2-hydroxybenzenesulfonic acid. Another negative feature of the hitherto known processes for the production of 4-hydroxybenzenesulfonic acid by the sulfonation of phenol is the formation of a relatively high proportion (up to 10%) of 2,4-hydroxybenzenedisulfonic acid,

A process for the preparation of 4-hydroxybenzenesulphonic acid has now been found by reacting phenol with sulfuric acid or sulfuric acid containing free sulfur oxide according to the invention. The essence of the invention is that sulfuric acid or sulfuric acid containing free sulfur oxide is gradually added to the phenol melt at a temperature of 70 to 110 ° C over a period of 1 to 3 hours, the molar ratio between phenol and sulfuric acid being 1: 1 to 1 , 05. The reaction mixture is then kept at 80 to 110 ° C for a further 1 to 2 hours. After cooling to 30 to 70 ° C, the reaction mixture is diluted with water at 10 to 25 ° C in a weight ratio of 1: 0.1 to 0.5.

The advantage of the process according to the invention is the fact that a high yield of high purity 4-hydroxybenzenesulfonic acid is obtained in a simple procedure, which can be used without further purification, for example in the production of the herbicide chloridazon.

The following examples illustrate but do not limit the scope of the invention.

Example 1

139.7 g of phenol, which was heated to 90 DEG C., were charged to the flask. Sulfuric acid (148.1 g) was uniformly added to the phenol melt at a concentration of 98.3% with stirring for 2 hours, the temperature of the reaction mixture being maintained at 90-105 ° C. After the addition of eiric acid, the reaction mixture was kept at the indicated temperature for a further hour. After this time, the reaction mixture was cooled to 40 ° C and diluted with 64 g of water while cooling. The reaction mixture thus obtained contained 70.5% of 4-hydroxybenzene sulfonic acid, which represents a yield of 96%.

CS 267 350 Bi

2,4-Hydroxybenzenedisulfonic acid represented less than 0.2% in the reaction mixture.

Example 2

Following the procedure as in Example i and except that 139.2 g of oil containing 20.49% of sulfur dioxide were used, a reaction mixture containing 73.1% of 4-hydroxybenzenesulfonic acid was obtained, which represents a yield of 97.1% of theory.

Claims (2)

CS 267 350 B1 2,4-Hydroxybenzenedisulfonic acid represented less than 0.2% in the reaction mixture. Example 2 Following the procedure described in Example 1, using 139.2 g of oleate containing 20.49% eir oxide, a reaction mixture of 73.1% 4-hydroxybenzenesulphonic acid was obtained, yielding 97.1% of theory. . OBJECT OF THE INVENTION The process for producing 4-hydroxybenzenesulfonic acid by reacting phenol with sulfuric acid is preferably sulfuric acid containing free sulfur trioxide, characterized in that sulfuric acid is gradually added to the phenol melt at 70-110 ° C over 1-3 hours. optionally, sulfuric acid containing a sulfur dioxide, a ratio of 1: 1 to 1.05 between phenol and sulfuric acid, and the reaction mixture is maintained at 80 to 110 ° C for 1 to 2 hours, and after cooling to 30 to 70 ° C, with diluent at a temperature of 10 to 25 ° C in a weight ratio to the reaction mixture of 1: 0.1 to 0.5.