Pipemidic acid hydrochloride

Abstract

The title compound exists as a C 14 H 18 N 5 O + 3 cation and a Cl - anion. The apical N atom of the piperazine ring shows quaternary character due to proton transfer from HCl. The fused pyridine and pyrimidine rings are nearly coplanar and the piperazine ring adopts a chair conformation. The carboxyl and carbonyl O atoms are involved in an O-H…O intramolecular hydrogen bond and the Cl - anion is involved in an N-H…Cl intermolecular hydrogen bond with the quaternary N atom.