Structural Elucidation of an Unknown Impurity in 4-Nitro-o-cresol, an Intermediate of Acetamizuril

OBJECTIVE To identify the structure of an unknown impurity in 4-nitro-o-cresol, an intermediate of acetamizuril. METHODS The impurity was prepared through diazotization hydrolysis and steam distillation. The structure was confirmed by MS, HMR and IR analysis. RESULTS The impurity was identified as 4,6-dinitro-o-cresol. CONCLUSION It is very important for the structure identification of the impurity to control the quality and synthesis process improvement of acetamizuril.