The present invention provides an improved process for preparing modafinil, whereby it may be isolated in high purity by a single crystallization. The process produces modafinil free of sulphone products of over-oxidation and other byproducts. The invention further provides new crystalline Forms II VI of modafinil and processes for preparing them. Each of the new forms is differentiated by a unique powder X-ray diffraction pattern. The invention further provides pharmaceutical compositions containing novel modafinil Forms II IV and VI.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a divisional of U.S. patent application Ser. No. 09/916,885 filed Jul. 27, 2001 now U.S. Pat. No. 6,849,120, which claims the benefit of U.S. provisional applications No. 60/221,110, filed Jul. 27, 2000; No. 60/226,491, filed Aug. 18, 2000; No. 60/229,160, filed Aug. 30, 2000; No. 60/230,088, filed Sep. 5, 2000 and 60/593, 332, filed Jan. 2, 2001 which are incorporated herein by reference.
