SU72812A1 - Method for producing alpha naphthylamine - Google Patents

Description

Alpha naphthylamine, one of the most important semi-products of the aniline dye industry, is currently obtained when alpha-nitronaphthalene is reduced by sodium disulfide.

This method consists in the fact that the calculated amount of nitronaphthalene is loaded into the reaction apparatus, and then the disulfide is gradually loaded, followed by a bale with a total duration of 19 hours.

As a result of laboratory research, the inventor has experimentally proved the possibility of carrying out a continuous process of reducing nitronaphthalene with disulfide.

The main distinguishing features of the proposed method are: preheating of nitronaphthalene and disulfide to a temperature of 85-90 ° C, perhaps more thorough mixing of the heated reagents before entering them into the reaction apparatus and maintaining a constant excess of disulfide within 20-30%.

Practically, the method can be carried out as follows: nitronaphthalene and a disulfide solution are heated to a temperature of 85-90 ° C in dosers using water circulating in the coil, and fed into a tube filled with rings or other shaped bodies of chemically inert material. The tube mixes these reagents. The mixture is fed to the bottom of the reaction apparatus with a capacity of 1 l, equipped with a reflux condenser, a stirrer, a thermometer and an electric heating device.

During the process, the temperature of the reaction mass is maintained within 102-105 ° C, and the feed rate of the reactants is designed to remain in the reaction apparatus for 8-10 hours, which corresponds to nitronaphthalene 30-36 g (or 25-30 ml) ) and a disulfide solution of about 25 g (or 90 ml.

№ 72812

The reaction mass, containing alpha naphthylamine and thiosulfate solution, as well as other mineral salts, is continuously fed to a separator, from which the alpha naphthylamine is rinsed and then distilled under vacuum.

The solution of mineral salts is subjected to purification, evaporation and crystallization.

The yield of alpha naphthylamine is about 80-90% of theory.

Subject invention

The method of producing alpha naphthylamine by reducing alpha-kitronaphthalene with sodium disulfide, characterized in that for the purpose of carrying out the process in a continuous way, these reagents are preheated to 85-90 ° C, mixed thoroughly with an excess of disulfide within 20-30% and passed through at 102 - 105 ° C through the reaction apparatus with the calculation of the mixture being in it for 8-10 hours.