Didesmethylcitalopram

Didesmethylcitalopram is a structurally related impurity of citalopram, characterized by a dibenzofuran core linked to a piperazine ring via an amide bond, with two methyl groups removed from the piperazine nitrogen atoms. The molecule retains a fluoro-substituted benzene ring and a methoxyphenyl group, conferring steric and electronic differences compared to the parent drug. This compound arises as a synthetic byproduct during citalopram alkylation steps, due to incomplete methylation of the piperazine moiety. It serves as an HPLC reference standard for quantifying process-related impurities in citalopram active pharmaceutical ingredients.