SU525680A1 - Method for preparing 2-amino naphtho (1,2-) thiazole - Google Patents

Description

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The invention relates to methods for the preparation of 2-aminonaphto l, 2- d j thiazole, an intermediate product for the synthesis of azo-rasites.

A known method for producing 2-aminonaphto l, 2-cl thiazole by reacting hydrochloric acid 1-naphtylamine and ammonium rodanide to form N - (naphthyl-1) thiourea and its subsequent cyclization under the action of bromine l or sulfur chloride 2 or sulfuryl chloride 3j.

However, an expensive starting product, 1-naphthylamine, obtained in industry from 1-naphthol, which, in turn, is synthesized from 1-tetralone, has to be used for the process.

In order to increase the efficiency of the process, 2-amino-4,5-dihydronaphto 1,2-d thiazole is proposed to be dehydrated by the action of nitrosylsulfuric acid at 0-20 ° C.

The starting material, 2-amino-4,5-dihydronaphto l, 2- d thiazole, can be obtained by the known method of reacting 1-tetralone with thiourea in the presence of an oxidizing agent, for example, sulfuryl chloride.

An important advantage of the proposed method is the ability to use the obtained 2-amphnonafto | l, 2-d thiazole for the synthesis of azo dyes, without isolating it into a diazo compound directly in the reaction mass by the action of an excess of nitrosyl sulfuric acid.

PRI and MER 1. To a mixture of 14.6 g (0.1 mol of 1-tetralone and 15.2 g (0.2 mOoCH) of thiourea, 15.1 g (0.113 mol) of sulfuryl chloride are added dropwise with stirring The reaction mixture was heated for 10 hours at room temperature, then dissolved in 2OO ml of boiling water, filtered at 50 ° C. The 20% ammonia solution was added to pH 8-9. The product which precipitated upon cooling was filtered and spilled with cold water until neutral and dried, the yield of 2-amino-4,5-dihydronaphtho l, 2-d thiazole 16.0 g (8O%).

The resulting 2-amino-4,5-digpdronaphto l, 2-dj thiazole is added in 30 minutes with a solution of nitrosylsulfuric acid prepared by heating 5.7 g of sodium nitrite in 160 ml of concentrated sulfuric acid, the solution is stirred for 2.5 hours at that the same temperature, then slowly with very vigorous stirring, poured into 1500 g of a mixture of water with ice. After 3 hours, the precipitated 2-aminonaphto l, 2-d thiazole sulfate is filtered off and treated to transfer to the base 16O ml of a 12% ammonia solution, separated, washed with cold water and dried. The yield is 12.35 g (78%), mp.188 .1 89 ° C, after one crystallization from alcohol, mp. 19 ° -191 ° C (according to literary data T.PL. 190-191 ° C).

PRI mme R 2. 16.0 g of 2-amino-4,5-dihydronaphtho 1, 2-d thiazole, prepared as indicated in Example 1, is introduced in 30 minutes at a temperature of about 0 ° C into a nitrosyl sulfur solution acid, prepared by heating 11.4 g of sodium nitrite in 160 ml of concentrated sulfuric acid, and stirring for 2.5 hours at the same temperature,

then poured into 750 g of ice. The resulting suspension, containing 85% of the theoretical amount of naphtho sulfate, 2-dj thiazole-2-diazonium, is used for combination with azo-components in the synthesis of azo dyes.

Claims (2)

Invention Formula A method for preparing l-2-d thiazole 2-aminonaphto, characterized by heme, which, in order to increase the efficiency of the process, 2-amino-4,5-dihydronaphlo l, 2-d thiazole is dehydrated in the presence of nitrosylsulfuric acid at 0-2 ° C . Sources of information taken into account in the examination: 1, J.Cheiti.Soc. 1669, 1936 2. US Patent No. 2003444, Class 260-44, 1936 3, US Patent No. 20556О9, class 260-305, 1937