CS242615B1

CS242615B1 - The method of isolating phenylhydrazine hydrochloride

Info

Publication number: CS242615B1
Application number: CS829707A
Authority: CS
Inventors: Stefan Truchlik; Ervin Sohler; Otakar Jancina
Original assignee: Stefan Truchlik; Ervin Sohler; Otakar Jancina
Priority date: 1982-12-27
Filing date: 1982-12-27
Publication date: 1986-05-15
Also published as: CS242650B1; CS970782A1

Abstract

Vynález sa týká spdsobu izolácie fenylhydrazínhydrochloridu z reakčnej zmesi získanej hydrolýzou fenylhydrazíndisulfónanu sodného kyselinou chlorovodíkovou. Reakčná zmes sa po neutralizácii roztokem amoúiaku alebo hydroxidom alkalického kovu protiprúdne extrahuje aromatickým organickým rozpúšťadlom,z ktorého sa zriedenou kyselinou chlorovodíkovou získá roztok fenylhydrazínhydrochloridu. Fenylhydrazírihydrochlorid je ddležitý medziprodukt pri výrobě farmaceutických preparátov, farbív a pesticídov.The invention relates to a method for isolating phenylhydrazine hydrochloride from a reaction mixture obtained by hydrolysis of sodium phenylhydrazine disulfonate with hydrochloric acid. The reaction mixture is neutralized with ammonia solution or alkali metal hydroxide and extracted countercurrently with an aromatic organic solvent, from which a solution of phenylhydrazine hydrochloride is obtained with dilute hydrochloric acid. Phenylhydrazine hydrochloride is an important intermediate in the production of pharmaceuticals, dyes and pesticides.

Description

242 615

The invention relates to a process for the isolation of phenylhydrazine hydrochloride.

Although phenylhydrazine hydrochloride has become an important intermediate for the preparation of pharmaceutical preparations, dyes, pesticides and the like, a conventional manufacturing process, based on the aniazine-based anthiazole, followed by reduction of benzenediazonium chloride and hydrolysis of sodium phenylhydrazin disulfonate, is used on a large scale scale. . Continuous preparation is also known on this principle / Chemistry - Ing. - Techn 402, / 1965 /, Chemie-Ing.Techn. £ 2, 58 (1980).

The disadvantage of these processes is that, after the phenyl hydrazine hydrochloride has been salted out and filtered from the sodium phenylhydrazine disulfonate reaction mixture, about 10% of the resulting phenylhydrazine hydrochloride is left in the mother liquor and the isolated product is not sufficiently pure.

We have now found a method for isolating phenylhydrazine hydrochloride from the reaction mixture obtained by hydrolyzing sodium phenylhydrazine disulfonate with hydrochloric acid according to the invention.

The present invention is based on the fact that the reaction mixture is countercurrently extracted with an aromatic organic solvent from the group consisting of benzene, xylene, toluene, ethylbenzene, from which a solution of phenylhydrazine hydrochloride is diluted with hydrochloric acid by means of ammonia solution or alkaline hydroxide. The advantage of this method is that there is no loss of phenylhydrazine hydrochloride as it is salted out of the crude reaction mixture, followed by filtration and single-stage extraction of technical phenylhydrazine.

A further advantage of the process is that by extracting the phenylhydrazine with hydrochloric acid from a solution of the aromatic solvent, the highly pure phenylhydrazine hydrochloride is obtained without the accompanying purity of phenolic and pitch-like character.

It should also be pointed out that in the process of the invention, the proportion of minerals, the phenolic impurities in the evaporation waters is.

The following examples illustrate, but do not limit, the invention. EXAMPLE 1 155.8 g of 32% strength hydrochloric acid were added to 901 g of a reaction mixture containing 191.8 g of sodium phenylhydrazine disulfonate at 80 DEG to 90 DEG C. for 1 h. with simultaneous cooling, neutralized with a 40% aqueous solution of sodium hydroxide to pH 7 and metered into a laboratory dosing pump at the top of the virgin plate extractor. Counter-flowing 632 gylene was fed to the bottom of the extractor. The xylene solution of phenylhydrazine was shaken with 653 g of 3.4% hydrochloric acid to give 739 g of an 11.9% aqueous solution of pure phenylhydrazine hydrochloride. The yield of phenylhydrazine hydrochloride, calculated on sodium phenylhydrazin disulfonate, is 99% of theory. Example 2

As in Example 1, using only toluene and solvent, 739 g of an 11.8% aqueous solution of pure phenylhydrazine hydrochloride was obtained, representing 98.2% of theory, calculated on sodium phenylhydrazin disulfonate. Example 3 (comparative) 57.8 g of 98.9% aniline was dissolved in 290 g of 18.1% hydrochloric acid and 105.9 g of 40% aqueous water was added to the stirred solution at 2-5 ° C. nitrite solution. The obtained diazonium salt solution was gradually added to 448.6 g of reducing solution (containing 41.4 g of sodium bisulfite and 115.4 g of sulfite) at 30-35 ° C. Then the reaction mixture was heated to 80 ° C for 1 h, the pH was adjusted to 6 to 6.5 with acetic acid and 1 g of zinc dust was added. After stirring for 1 h, the mixture was filtered while hot, 160 g of 3 242 015 32% hydrochloric acid were added to the filtrate with stirring at 80-90 ° C, and stirring was continued for 4 h. Then the reaction mixture was cooled to 15-20 ° C and the precipitated phenylhydrazine hydrochloride was filtered off. 120 g of a filter cake containing 80.6 g of phenylhydrazine hydrochloride were obtained, corresponding to a 90.81% yield calculated on starting aniline.

Claims

P R E D Μ E T V Y | The process for the isolation of phenylhydrazine hydrochloride from a reaction mixture obtained by the hydrolysis of sodium hydrochloride phenylhydrazin disulfonate, characterized in that the reaconase is countercurrently extracted with an aromatic organic solvent from the benzene group after neutralization with ammonia or alkali metal hydroxide solution , toluene, xylene, ethylbenzene, from which a solution of phenylhydrazine hydrochloride is obtained by dilute hydrochloric acid. .