Mephentermine hemisulfate monohydrate: an adrenergic agent.

The title molecule, a hydrated hemisulfate salt of ethyl(2-methyl-1-phenyl-2-propyl)ammonium, C11H18N+.0.5SO4(2-).H2O, consists of a phenethylamine skeleton in which the N atom is protonated. There are two molecules in the asymmetric unit, with the S atom of the SO4(2-) ion lying on a pseudo-twofold axis. The ethylamine side chain is in an extended conformation in both the symmetry-independent molecules. The distance of the N atom from the centre of the benzene ring is 5.1 A for molecule 1 and 5.3 A for molecule 2. The packing is stabilized by N-H...O and O-H...O hydrogen bonds.