Original Publication Date: 1979-Mar-01
Included in the Prior Art Database: 2005-Feb-20
A sample of 2-phenylimidazole containing a mutagen impurity was successfully purified by employing a crystal-growing technique as follows: The sample was placed into a sublimation apparatus, evacuated, then backfilled with dry nitrogen gas to a partial pressure of 10 cm. The stopcock was then CLOSED and the container placed into an oil bath (bottom of cold finger coincident with oil bath level) at 175 degrees C. Needlelike crystals which were colorless grew rapidly onto the cold finger (65 degrees C), and the brown impurity remained behind. The nutrient was, of course, liquidus but thermally stable under these conditions. By accelerating the procedure through further elevation of the oil bath temperature, the sample could be "distilled.