SU23405A1 - Method of separating alphaaphthylamine from a reduction mass - Google Patents

Description

Both in the technique and in the laboratories, α-naphthylamine is obtained from α-nitronaphthalene by reducing the latter with iron shavings in the presence of hydrochloric acid (Veshan method).

As a result of the reduction process in an apparatus called a reducer, a so-called reduction mass is obtained consisting of a-naphthylamine, ferrous oxide of iron, water and a small amount of tar.

The reduction mass is then loaded into special furnaces and subjected to distillation with water vapor overheated to 300 °. The mixture of water vapor and vapor a - naphthylamine, the passage through the refrigerators condenses and flows into the receiver, while α-naphthylamine, as the liquid more heavily, drops down and water flows down the top of the receiver; Flowing water with a temperature of 50–60 ° contains a significant amount of both dissolved and emulsified α-naphtylamine, in view of which a number of settling tanks pass. The a-naphthylamine obtained by distillation with superheated steam is contaminated with resins and has a dark brown resinous color. The product is subjected to vacuum distillation for purification.

The disadvantages of this method are low productivity of steam distillation furnaces and significant tarification of the product during distillation, as a result of which there is also a reduced yield.

The proposed method, which has in mind to eliminate these drawbacks, is as follows: after being reduced from the reducer, the reducing mass is lowered into the boiler with heating directly by furnace gases or superheated steam (the boiler is equipped with a stirrer) and then a small amount of kerosene is poured in and heated. First, the water is distilled into the mixture of kerosene. The distillation of water is carried out to a temperature of 125-130 °, after which kerosene is added to the boiler at the rate of Via

from the naphthylamine present in the reduction mass and heat the mixture yes

boil. Pairs of a-naphthylamine and kerosene entering the refrigerator (the temperature of the water in the refrigerator should not be lower than 45-50), condense, drain into the receivers, where the solution is cooled and naphthylamine drops out into white shiny needles. Receivers are better equipped with mechanical agitators. Distillation is carried out until taken; the last sample of the distillate, when hydrochloric acid is added, will not produce a cheesy white precipitate of salt a - naphtylamine. The crystallized naphthylamine kerosene is filtered off.

hell cetrofuch. and / can be considered ready | h |) abrikatom. Non-corrosive kerosene impurities — did not have a noticeable adverse effect during trial paintwork; however, if desired, kerosene can be: removed either completely by washing in gasoline, or its amount can be reduced to an insignificant amount by washing with a soap solution in the cold, washing with light kerosene in a careful separation in the center-fuge. Naphthylamine yields 90% to 93% of theoretical nitrogaphthylamine. Filtered from a-naphthylamine, the kerosene is again distilled. Co, holding naphthylamine in the pursuit depends on the fraction of kerosene taken, but it is not recommended to take only the high fraction, since the supersaturation of the solution may arrive before the aftilamine solidifies, and then it drops to the bottom in the liquid state and upon cooling freezes solid mass. - It is better to take the kerosene fraction FROM 225 to 300 °; then the whole product precipitates in a crystalline state, and the amount of the precipitated product ranges from 9 to 12%. The solution is kept at an ordinary temperature of up to 4%, but if the solution is cooled to 5, then no more than 1-2% will remain in the solution.

The distillation technique can be organized in another form, for which an individual boiler is needed to evaporate kerosene and a boiler into which the reduction mass is mixed in with the high boiling kerosene fraction. The vaporized kerosene vapors are fed through a layer of reduction mass. Sun distillation takes place under vacuum within the temperature range of 155-210 °, without vacuum-220-280 °.

The subject matter of the invention.

A method of separating α-naphthylamine from a reduction mass, characterized by

in that a-naphthylamine is distilled off with kerosene vapor.