Example 16: Synthesis of 4-methyl-2-hydrazinylbenzothiazole
4-Methyl-2-aminobenzothiazole (8.21 g, 0.05 mol), hydrazine monohydrochloride (1.14 g, 0.017 mol), 85% hydrazine hydrate (1.96 g, 0.033 mol) and ethylene glycol (41 ml) were mixed under nitrogen protection. The reaction mixture was heated to 140°C and kept at this temperature for 15 hours. Upon completion of the reaction, the mixture was allowed to cool slowly to room temperature and allowed to stand overnight under nitrogen atmosphere. The following morning, water (45 mL) was added to the reaction mixture to promote crystallization. Subsequently, the mixture was filtered and the target product 4-methyl-2-hydrazinylbenzothiazole was isolated. The product was dried under vacuum at 60°C overnight to give a final 8.00 g in 89% yield with a melting point of 143°-151°C. The purity of the product was 85.8% as determined by non-aqueous titration.
