Crystal structure of {[2-hydroxy-2-(3-methoxyphenyl)cyclohexyl]methyl}dimethylammonium benzoate

Abstract

The title compound, C16H26NO2+·C7H5O2−, is a benzoate salt of the painkiller Tramadol. The six-membered cyclohexane ring of the cation adopts a slightly distorted chair conformation and carries OH and 3-methoxyphenyl substituents at the 2-position and a protonated methylazaniumylmethyl group at the 3-position. In addition, a weak intramolecular C—H...O hydrogen bond is observed in the cation. In the crystal, weak O—H...O, N—H...O and C—H...O hydrogen bonds link the components into chains along [010]. A C—H...π contact is also observed.