Crystallographic characterization of several erythromycin A solvates: the environment of the solvent molecules in the crystal lattice.

Four solvates of erythromycin have been crystallographically characterized. The solvates of THF and dioxane are very similar but differ in notable ways. The isopropanol solvate exhibits uncommon modes of hydrogen bonding, which have previously been seen only in the erythomycin B hydrate. The methanol solvate is strikingly similar to the methanol solvate of 6-O-methyl erythromycin.