CS246956B1 - Preparation method of the 2-cyano-4-nitroaniline - Google Patents

Abstract

Process for preparing 2-cyano-4-nitroaniline by pressure amination of 2-chloro-5-nitrobenzonitrile, which lies in being on 2-Chloro-5-nitrobenzonitrile acts aqueous 25 až ammonia solution 45%, at a temperature of 98-110 ° C, and formed 2-cyano-4-nitroaniline which upon cooling at 25 to 35 ° C, the reaction is eliminated The compound produced is used as an active component of disperse dyes.

Description

(54) A process for the preparation of 2-cyano-4-nitroaniline

Process for the preparation of 2-cyano-4-nitroaniline by pressure amination of 2-chloro-5-nitrobenzonitrile, which comprises treating 2-chloro-5-nitrobenzonitrile with an aqueous solution of ammonia at a concentration of 25 to 45%, at a temperature of 98 to 110 DEG C., and the resulting 2-cyano-4-nitroaniline, which precipitates after cooling to 25 DEG-35 DEG C., is separated from the reaction mixture. The compound produced is used as an active component of disperse dyes.

The invention relates to a process for the preparation of 2-cyano-4-nitroaniline by pressure amination of 2-chloro-5-nitrobenzonitrile.

2-Cyano-4-nitroaniline is present as an active component in a large number of the most recent disperse dyes, mainly of red shades (Cl. Disp. Red. 72,73,90,134). Its preparation is generally known. Starting from o-chlorobenzonitrile, the nitration is converted to 2-chloro-5-nitrobenzonitrile by nitration in a large excess of concentrated nitric acid, and then by pressure amination with ethanolic ammonia to 2-cyano-4-nitroaniline.

The 2-cyano-4-nitroaniline thus prepared contains a significant amount of 2-carbamido-4-nitroaniline in addition to the considerable impurities resulting from the Sandmayer reaction in the preparation of O-chlorobenzonitrile. It comes from a partially hydrolyzed nitrile group.

This intermediate then degrades the resulting dyes.

As proven experimentally, 2-carbamido-4-nitroaniline dyes have the same low spreading rate and thus reduce the overall spreading rate of the dispersed azo dyes prepared.

We have now found reaction conditions in which the formation of 2-carbamido-4-nitroaniline in the preparation of 2-cyano-4-nitroaniline is minimized. Thus, in addition to the purity branches of the prepared azo dyes, they also reach their spreading capacity. Contrary to the literature data, we have found that the stated temperature of 150 [deg.] C. at the amination is too high and the reaction time is too long. As the first reaction, pressure amination occurs and immediately thereafter hydrolysis of the nitrile group to the carbamidic group occurs in the reaction medium. By lowering the reaction temperature, shortening the reaction time and increasing the ammonia concentration, it has now been possible to suppress the subsequent amination reaction and its products. Lowering the temperature, reducing the reaction time contributes to the economics of production and leads to better products.

The process for the preparation of 2-cyano-4-nitroaniline by pressurized amine of 2-chloro-5-nitrobenzonitrile consists in treating 2-chloro-5-nitrobenzonitrile with an aqueous ammonia solution at a concentration of 25% to 45% at a temperature of 98 to 110 And the resulting 2-cyano-4-nitroaniline, which precipitates upon cooling to 25-35 ° C, is separated from the reaction mixture by weight.

He did

13.8 parts of o-chlorobenzonitrile (t, solidification 43 to 43.5 ° C, tv, 232 ° C prepared by emoxidation of o-halotoluene) are dissolved in 146 parts of 98% HgSO 4 at 0 to 10 ° C and then at constant temperature. 7.8 parts of 98% HNO 2 were added over 30 minutes at this temperature. After the introduction of HNO 2, the reaction mixture was stirred for 1 hour at 0-10 ° C and then poured slowly onto 500 parts of finely crushed ice. The precipitated 2-chloro-5-nitrobenzonitrile is filtered off with suction and washed with about 500 parts of water until neutral to Congo red. The aspirated and washed product is dried at 60 to 70 ° C for 4 hours. Yield 17.47 parts, i.e. 95.7% of theory of 2-chloro-5-nitrobenzonitrile, m.p. Mp 102-105 ° C.

parts of the 2-chloro-5-nitrobenzonitrile thus prepared are charged to an iron autoclave with 143 parts of 30% aqueous ammonia. The contents of the autoclave are heated with stirring to a reaction temperature of 110 DEG C. (1.078 MPa) and this temperature is maintained throughout the reaction. It is then cooled with stirring to 25 ° C and the precipitated product is filtered off with suction and washed with about 600 parts of water. Yield 38 parts, i.e. 94.5% of theory of crude 2-cyano-4-nitroaailine, m.p. Mp 182-199 ° C. The content determined by polarographic analysis is 98.8%.

Example 2

The iron autoclave was charged with 37 parts of 2-chloro-5-nitrobenzonitrile and 77 parts of 45% aqueous ammonia. The contents of the autoclave are heated with stirring to a reaction temperature of 110 ° C (1.17 MPa) and this temperature is maintained throughout the reaction. It is then cooled with stirring to 25-30 ° C and the precipitated product is filtered off with suction and washed with about 600 parts of water.

The yield of 31 parts, ie, 93.7% of the theory of 2-cyano-4-nitroaniline, m.p. 203 DEG-210 DEG C. containing only traces of 2-emino-5-nitrpbenzamide.

Claims (1)

object of the invention A process for the preparation of 2-cyano-4-nitroaniline by pressure amination of 3-chloro-5-nitrobenzonitrile, characterized in that ee is treated with 2% -45% aqueous ammonia solution at 98-110 ° C. and the resulting 2-cyea-4-nitroanilium, which upon cooling to 25-35 ° C, precipitates from the reaction mixture. Corrections in printed descriptions of inventions