DD292247A5 - PROCESS FOR PREPARING DIAMINOTHIOXANILIDES - Google Patents

Abstract

The invention relates to a process for the preparation of diaminothiooxanilides which are suitable as intermediates for dyes. The synthesis is carried out by reduction of Nitroaminothiooxaniliden in waeszriger suspension with sodium sulfide at temperatures of 80 to 100 C. {Thiocarbonsaeureamide; Thiooxanilide; Nitro compounds; Reduction; Diaminothiooxanilide}

Description

Unlike other reducing agents by sodium sulfide is not attacked. Dia reduction products are considerably legible in the alkaline medium produced by the reducing agent and the reaction. They can be separated by neutralization and isolated.

embodiments

General procedure for the reduction of nitroaminooxanilides of the formula II:

3.16 g of compound of formula II are suspended in 25 ml of water at 95 ° C. For this purpose, a freshly prepared solution of 2.50 g of sodium sulfide in 20 ml of water is added with thorough mixing. The mixture is heated to boiling and the temperature is about 15 minutes between 95 and 100 ⁰ C. It forms m.-sist a clear yellow solution. Allow to cool slightly, filtered if necessary and neutralized the cooled to room temperature solution with acetic acid. The crystalline precipitate is filtered off with suction and washed first with water and then with methanol.

example 1

Using 4-Nitrothioanilids of 4-Aminooxanilthiosäure according to the above general rule and receives 1.81 g (63% of theory) of 4,4'-Diaminothiooxalsäureanilid. After recrystallization from propanol, the compound melts at 210

Example 2

If the procedure according to the general procedure, but the 3-nitrothioanilide of 4-Aminooxanilthiosäure used, we obtain 2.22 g (77% of theory) of 3-aminothioanilide of 4-Aminooxanilthiosäure. After recrystallization from chlorobenzene, the melting range is 195 to 199 ⁰ C.

Example 3

Using the 3-Nitrothioanilids of 3-Aminooxanilthiosäure obtained according to the general procedure 1.21 g (42% of theory) of 3,3'-Diaminothiooxalsäureanilid of melting point 184 to 186 ⁰ C after recrystallization from propanol.

Claims (1)

Process for the preparation of diaminothiooxanilides of the formula (D, <C0 ^> -NH-G-C-NH- <^ Q characterized in that nitroaminothiooxanilides of the formula 0> -MH-OO-NH- ^ ₀ N ^N - (, I) be reduced with sodium sulfide in aqueous suspension at 80 to 100 ⁰ C. Field of application of the invention The invention relates to a process for the preparation of diaminothiooxanilides of the formula -NH-CS-OO-NH- ^ ₀ \ H ₂ N ^m 2 which are suitable as intermediates for the synthesis of organic dyes. Characteristic of the known state of the art Thiooxanilides can according to J. ehem. Soc. 1959, 2669 or according to J. prakt. Chem. 331 (1989) 243. However, the direct synthesis of Diaminothiooxaniliden of formula I is hardly possible by these methods. In principle, this is the reduction of thiooxanilidane containing nitro groups. Due to the lability of the thiocarbonyl group and the very low solubility of these compounds in common solvents, the majority of the methods used to reduce nitro groups have proven unsuitable. Thus, the reduction with zinc or iron in acidic solution leads to desulfurization or to the formation of indefinable product mixtures. For the same reason fails the catalytic hydrogenation, and also the reduction with sodium dithionite in an acidic or alkaline medium does not lead to the goal. Object of the invention The aim of the invention is a process for the preparation of diaminothiooxanilides of the formula Explanation of the essence of the invention The invention was based on the object, a production process for Diaminothiooxanilide starting from Nitroaminooxaniliden the formula to develop. According to the invention, the compounds of formula II are reacted in aqueous suspension with sodium sulfide between 80 and 100 ⁰ C. It is surprising that despite the extremely low solubility of the starting materials, the reaction proceeds to complete reduction of the nitro group and the thiocarbonyl group in