Benztropine mesylate: crystal structure and kinetics of dehydration

The crystal structure of benztropine mesylate has been determined. It is or thorhombic, Pbca, with a = 12. 885(8)Angstrom, b = 32.012(9)Angstrom, and c = 10.027(3) Angstrom. It exhibits similar packing to that seen in the prev iously reported crystal structure of benztropine mesylate monhydrate. Xray powder diffraction patterns have been used to identify the anhydrous and mo nohydrate forms. The dehydration of the monohydrate follows a first-order r eaction mechanism with activation energy of 92(8) kJ mol(-1).