title: Crystal structure of {[2-hy-droxy-2-(3-meth-oxy-phen-yl)cyclo-hex-yl]meth-yl}di-methyl-ammonium benzoate.
abstract: The title compound, C16H26NO2 (+)·C7H5O2 (-), is a benzoate salt of the painkiller Tramadol. The six-membered cyclo-hexane ring of the cation adopts a slightly distorted chair conformation and carries OH and 3-meth-oxy-phenyl substituents at the 2-position and a protonated methyl-aza-niumylmethyl group at the 3-position. In addition, a weak intra-molecular 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.
authors.affiliation: Department of Chemistry, GSSS Institute of Engineering Technology for Women, Mysuru 570 016, India.
authors.forename: S N
authors.initials: SN
authors.lastname: Sheshadri
authors.affiliation: Department of Chemistry, BET Academy of Higher Education, Bharathi College, Bharthi Nagara, Mandya 571 422, India.
authors.forename: P
authors.initials: P
authors.lastname: Nagendra
authors.affiliation: Department of Engineering Chemistry, Cauvery Institute of Technology, Mandya 571 402, India.
authors.forename: B P
authors.initials: BP
authors.lastname: Siddaraju
authors.affiliation: Department of Chemistry, Cambridge institute of Technology, Bengaluru 560 036, India.
authors.forename: K H
authors.initials: KH
authors.lastname: Hemakumar
authors.affiliation: Department of Materials Science, Mangalagangotri, Mangalore University, Mangaluru 574 199, India.
authors.forename: K
authors.initials: K
authors.lastname: Byrappa
authors.affiliation: Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore, 570 006, India.
authors.forename: N K
authors.initials: NK
authors.lastname: Lokanath
authors.affiliation: PURSE Lab, Mangalagangotri, Mangalore University, Mangaluru 574 199, India.
authors.forename: S
authors.initials: S
authors.lastname: Madan Kumar
keywords: Tramadol; crystal structure; inter­molecular hydrogen bonds