4-Hydroxy methyl butonoate

4-Hydroxy methyl butonoate is a substituted ester derivative featuring a four-carbon aliphatic chain with a terminal methyl ester group and a hydroxyl moiety positioned at the β-carbon relative to the ester functionality. The compound exhibits structural similarity to butyric acid derivatives, with the hydroxyl group introducing potential for hydrogen bonding and stereoelectronic interactions. As an API impurity, it likely arises via partial hydrolysis or oxidation pathways during parent drug synthesis. This compound serves as a critical HPLC reference standard for quantifying process-related impurities in parent drug formulations.