The molecule is the conjugate acid of morphinone arising from protonation of the tertiary amino group; major species at pH 7.3. It is a conjugate acid of a morphinone.
(4R,4aR,7aR,12bS)-9-hydroxy-3-methyl-2,3,4,4a,7a,13-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-3-ium-7-one