2'-hydroxy-5,9-dimethyl-2-(3-methyl-2-butenyl)-6,7-benzomorphan (pentazocine) hydrochloride hydrate

The title compound [1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(3-methyl-2-butenyl)-2,6-methano- 3- benzazocin-8-ol hydrochloride hydrate, C19H28NO+.-Cl-.1/8H2O, (I)] crystallizes with two molecules per asymmetric unit. A comparison of the bond lengths and torsion angles shows a side-chain orientation similar to that of cyclazocine but unlike that of naloxone. The two molecules are linked through a hydrogen-bond network to the interlayer Cl ions, forming a linear chain extending along the ac diagonal of the unit cell.