Two polymorphs of chlorpropamide: the δ-form and the high-temperature ∊-form

The epsilon-form of chlorpropamide [systematic name: 4-chloro-N-(propylaminocarbonyl)benzenesulfonamide], C(10)H(13)ClN(2)O(3)S, has been obtained as single crystals from solution (and not as a polycrystalline sample by heating the alpha-, gamma- or delta-forms). The results of anisotropic structure refinements for the epsilon- and delta-forms are reported. The density of the delta-polymorph is the highest, and that of the epsilon-polymorph the lowest, among the five known chlorpropamide polymorphs. The main intermolecular hydrogen-bonding pattern in polymorphs delta and epsilon is the same as in polymorphs alpha, beta and gamma, but the conformations differ. The densities of the polymorphs were found to depend on the molecular conformations.