Skeletal formula of (S)-(+)-ketamine hydrochloride, [C₁₃H₁₇ClNO⁺][Cl⁻].

Based on the conformation in the crystal structure reported in P. Hakey et al., Acta Cryst. E 2008, 64, o1487.

Note: The direction of optical rotation in ketamine depends not only on its absolute configuration but also on its conformation, which differs between salts and the free base. This image is based on the crystal structure of the hydrochloride salt form, i.e. (S)-(+)-ketamine, which has an axial phenyl group. In contrast, the free base form of each enantiomer of ketamine exhibits optical rotation in the opposite direction to the corresponding hydrochloride salt and has an equatorial phenyl group. The free bases are thus (R)-(+)-ketamine and (S)-(−)-ketamine.