SU1366513A1 - Method of obtaining monosulfoacids of aromatic amines or salts thereof - Google Patents

Abstract

The invention relates to sulfonic acid derivatives, in particular to the preparation of sulfonic acids of aromatic amines (SC) or their salts used in the synthesis of dyes. In order to simplify and intensify the process of sulfonation of the corresponding amines in the solvent medium with SO, another solvent, dichloroethane, and a temperature of 20-30 ° C is used. Target SCs are isolated in free form or as a salt. The method allows to create waste-free production, and mild conditions and one-step process greatly simplify the process. 1 tab. sh (l

Description

00

a ate

This invention relates to an improved process for the preparation of monosulfoxyl aromatic amines or their salts, which are used in the synthesis of dyes.

The purpose of the invention is to simplify and intensify the process, which is achieved by carrying out the sulfonation of amines with sulfuric anhydride in dichloroethane (DCE) at 20-30 ° C.

The invention is illustrated by examples.

Example. Ba-salt of sulfanilic acid. 16.5 ml (0.181 g-mol) of aniline is dissolved in 160 ml of dichloroethane. To a solution of aniline in dichloroethane, a solution of 43.04 g (0.538 g-mol) of sulfuric anhydride in 40 ml of dichloroethane is gradually added with good stirring at such a rate that the temperature in the reaction mass does not exceed 30 ° C. When the reagents are mixed, a white precipitate is formed. The reaction mass is held for 0.5 h at, after which the dichloroethane is drained. Pre-dichloroethane is checked for the content of the starting amine by TLC; dichloroethane aniline does not contain.

The colorless solid sulfonation product is dissolved in I00 ml of water. The solution is neutralized with an aqueous suspension of barium carbonate at 60 ° C, the aniline liberated after neutralization is distilled off with sharp para. After distilling off the aniline, the aqueous solution is practically evaporated under vacuum of a water jet pump. Ba salt is recovered with a yield of 50% of theoretical.

Found: C 30.33; H 2.72; N 5.93; S 13.63.

Calculated,%: C 29.92; H 2.49; N 5.81; S 13.31.

the UV spectrum of Ba-salt is 248 nm (. 1848), the solvent is water.

IR spectrum of BA salt in liquid paraffin: 3225 cm (V.,.) Ate; 1600cm

(U, „) ate .; and 1500 cm (sway, arom.koltsa) with., in the region of 1250 -1100 cm (Iso., shsim wide 1178 cm cf., 1128 cm-cf.,

- (i;) s.

S-o

cm

1178 cm 036- (i ,,, J s., 693

Sulfanilic acid.

Sulfanilic acid is obtained in a similar way by making the following changes in the procedure of the isolation step.

At the end of the reaction, DCE is drained, the solid product of sulfonation of the solution

ryt in 100 ml of water. The aqueous solution is neutralized with concentrated ammonia. After neutralization, the liberated aniline is distilled off with steam. A neutral solution of the ammonium salt is evaporated twice in volume. Sulfanilic acid is made into acid, one stripped off with a solution of 30 ml of concentrated sulfuric acid under ice-cooling. The precipitated white precipitate is filtered, washed with cold water, and dried. 17.2 g of sulfanilic acid is obtained, which constitutes 48-49% of the theoretical yield and 96-98% for the aniline reacted (taking into account the return).

Found,%: C 34.49; H 5.27; N 6.78; S 15.42.

Calculated,%: C 34.44; H 5.30; N 6.70; S 15.35.

M.p. S-benzylthiuronic salt 183-185 ° C (t.pl.lit.).

UV spectrum of sulfanilic acid:

0

25 L max

nm (15020), solution

the water is water.

IR spectrum of sulfanilic acid in liquid paraffin: 3220. (fj-c); 1635 cm. Wed, 1600 cm ate., 1578., 1550 cm Wed. (fluctuated

Wed

arom.koltsa); in the area of 1200-1100 (50g “sim) 1171., 1121cm 1036 (and sim.), 686 cm-s (Jy.

Similarly receive other proiz-. water (see table).

In comparison with the known method, the proposed method has the following advantages with TV amy.

The process proceeds in one chemical stage. The impregnation of solutions of sulfuric anhydride in DCE allows wire-. to put the reaction practically at room temperature (20-30 ° C) and at atmospheric pressure against; shorten i the reaction time to 1 h, against 3 h.

It is possible to create waste-free production, since the fusion solvent containing unreacted sulfuric anhydride and an unreacted (or filtered starting amine, returns to the cycle. The process is simple and standard equipment.

The method differs from the known ones in that it is based on the reaction of direct sulfonation of aromatic amines in an inert medium, while the known methods of basic

five

J - 1

They are formed on the rearrangement reaction of the predominantly formed amine acid sulfate (or chlorosulfonate).

Claims (1)

Invention Formula The method of obtaining monosulfonic acid aromatic amines or their salts by sulfonation of the corresponding amines with sulfuric anhydride in an inert op 66513 solvent, followed by the separation of the target products by known methods, using a dichloroethane method to simplify and intensify the process, the process is carried out at 20–30 ° C and the target Q products are in free form or in salt form. oh and 2 H) yo Hfm S 8 S