Etodolac Impurity B

Etodolac Impurity B is a synthetic byproduct arising from the incomplete alkylation step during Etodolac production, characterized by a 4-hydroxy-2-methylindene core fused to a pyrazolone ring, with a truncated acyl side chain lacking the terminal carboxylic acid moiety present in the parent compound. The structure incorporates an enolic hydroxyl group and an amide linkage, distinguishing it from Etodolac's 4-chloro substitution. This impurity serves as a critical HPLC reference standard for quantifying process-related impurities in Etodolac active pharmaceutical ingredient batches.