Patent ID: 8269003

Claim:
A process for the preparation of the alpha crystal form of the compound of Formula II: wherein the process comprises: (a) suspending or dissolving the compound of the Formula I in a solvent; (b) adding methane sulfonic acid at a temperature of 25° C. to 30° C. to the suspension or solution formed in step (a); (c) heating the mixture formed in step (b) to at least 70° C. for 1 to 2 hours; and (d) cooling the mixture to ambient temperature and isolating the alpha crystal form of the compound of Formula II wherein the alpha crystal form of the compound of Formula II is a stable crystal form and wherein the alpha crystal form of the compound of Formula II is characterised by an X-ray diffraction pattern having peaks at 2-theta 4.87°, 10.40°, 18.56° and 24.82° and absence of peaks at 5.87°, 9.72° and 20.0°.