Patent ID: 8178692

Claim:
A method for producing 1,2,4-triazol-3-one comprising (i) combining semicarbazide hydrochloride and formic acid to form an initial composition, (ii) heating the initial composition to a temperature of at least 70° C. and maintaining the temperature for at least 1 hour to form a product composition, (iii) distilling the product composition to remove a portion of unreacted formic acid and form a concentrated product slurry, (iv) slurrying the concentrated product slurry in ethanol to form an ethanol slurry, and heating the ethanol slurry to at least 40° C. over a period of at least 10 minutes, (v) collecting crude 1,2,4-triazol-3-one from the ethanol slurry, (vi) combining the crude 1,2,4-triazol-3-one with water and heating to dissolve crude 1,2,4-triazol-3-one to form a product solution, (vii) cooling the product solution to lower than 10° C., and (viii) collecting recrystallized 1,2,4-triazol-3-one from the product solution.