Stable polymorph of morphineCAS number: 57–27–2.

In the stable polymorph of the title compound, C17H19NO3 [systematic name: (5α,6α)-7,8-didehydro-4,5-epoxy-17-methylmorphinan-3,6-diol], the molecular conformation is in agreement with the characteristics of previously reported morphine forms. The molecule displays the typical T-shape and its piperidine ring adopts a slightly distorted chair conformation. Intermolecular O—H...O hydrogen bonds link the molecules into helical chains parallel to the b axis. Intramolecular O—H...O hydrogen bonds are also observed.