File:Ketamine-free-base-enantiomers'-conformations-2D-skeletal.png

Skeletal formulae showing the conformations of the (R)- and (S)-enantiomers of the ketamine molecule, C₁₃H₁₆ClNO, as found in the crystal structures of the free base reported in B. Chankvetadze et al., J. Sep. Sci. 2002, 25, 1155-1166, doi:10.1002/1615-9314(20021101)25:15/17<1155::AID-JSSC1155>3.0.CO;2-M

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 from the crystal structures of the free base forms, (R)-(+)-ketamine and (S)-(−)-ketamine, which have equatorial phenyl groups. In contrast, the hydrochloride salt of each enantiomer exhibits optical rotation in the opposite direction to the corresponding free base form and has an axial phenyl group. The hydrochlorides are thus (R)-(−)-ketamine and (S)-(+)-ketamine hydrochloride.