Study of Polymorphic Behaviour of 2,2'-Dichloro benzil Using Dynamic Thermal and X-Ray Diffraction Technique

2,2’-Dichloro benzil (1) was synthesized and its two polymorphic forms were obtained by recrystallization from the solvents acetone/ chloroform and ethanol. The polymorphism present in the compound was confirmed by combined results of differential scanning calorimetry and single crystal X-ray crystallography. Each molecule crystallizes with one molecule in the asymmetric unit and the molecular conformations are quite different for both. The polymorph 1a crystallizes as monoclinic c2/c space group in the solvent ethanol and the polymorph 1b crystallizes as monoclinic P21/c space group in the solvent THF. X-ray crystal structures of conformational polymorphs were analyzed to understand the interplay of molecular conformation and intermolecular lattice energy in the crystallization and stability of polymorphs.