Synthesis of 5-Amino-1,2,3-Thiadiazoles

5-Amino-1,2,3-thiadiazoles can be composed through a series of reactions of diethyl carboxylate, hydrazine hydrate and chloroacetaldehyde. The synthetic conditions of each step are optimalized—the 4 step method of intermediate 5-chloro-1,2,3-thiadiazole is shortened to a 3 step method, and steam distillation is improved. The purity reached 99% (by GC). The product 5-amino-1,2,3-thiadiazoles can be obtained from chloroform∶ethyl alcohol (V/V)= 4∶1, mp:138~139℃, the overyield is about 40%.