METHOD FOR PRODUCTION OF TETRAETHYL-4(OR 5)-RHODAMINEISOTHIOCYANATES Russian patent published in 2022 - IPC C07D311/82 

FIELD: organic chemistry.

SUBSTANCE: invention relates to the field of organic chemistry, specifically to a method for the production of tetraethyl-4-(or 5)-rhodamineisothiocyanates. According to the proposed method for the production of tetraethyl-4-(or 5)-rhodamineisothiocyanates, interaction of tetraethyl-4(or 5)-aminorhodamines with a sulfur-containing compound is performed with subsequent isolation of a target product. The method is characterized in that, as the sulfur-containing compound, disulfide is used, and source tetraethyl aminorhodamine is first subjected to ammonia treatment with an aqueous ammonia solution saturated with gaseous ammonia at a molar content of ammonia, equal to 0.040-0.050 mol per 0.040 mol of tetraethyl aminorhodamine, carried out at a temperature of 0-4°C until pH reaches 9-10 value. After that, reaction mass is treated with disulfide based on a molar ratio of tetraethyl aminorhodamine to disulfide, equal to 0.040:0.063-0.076, then, the resulting reaction mass is kept at a temperature of 0-4°C for 1.5-2.5 h, and it is introduced into a one-molar aqueous solution of salt of heavy metal selected from a group of iron, copper, lead. The resulting precipitate of corresponding heavy metal salt is acidified with concentrated hydrochloric acid until pH of 1, after which it is filtered, dried, extracted with acetone and then chloroform, passed through a layer of silica gel, and evaporated.

EFFECT: proposed method provides high yield and required purity of a final product, which does not contain impurities preventing its use in the manufacture of luminescent serums.

5 cl, 5 ex