Syntheses of Cyanine Dyes. III

Improved Method for the Synthesis of Thioacetanilide from Acetanilide

Abstract

It has been assumed that the synthesis of thioacetanilide by the reaction of K₂S and P₂S₅ on acetanilide was essentially the reaction of acetanilide and K-thiophosphate formed. Conditions for the formation of maximum yield in this reaction was checked and thereby the formation rate of thioacetanilide as against acetanilide was increased to 80% of the calculated amount. The solubility of thioacetanilide in alkaline aqueous solution becomes zero when its concentration increases to over 25% and has a maximum solubility at 9% concentration.