Patent ID: 7645904

Claim:
A method of purifying a compound represented by the following Structural Formula: wherein: Y is a covalent bond or an optionally substituted straight chained hydrocarbyl group, or, Y, taken together with both >C═Z groups to which it is bonded, is an optionally substituted aromatic group; R 1 -R 4 are independently —H, an optionally substituted aliphatic group, an optionally substituted aryl group, or R 1 and R 3 taken together with the carbon and nitrogen atoms to which they are bonded, and/or R 2 and R 4 taken together with the carbon and nitrogen atoms to which they are bonded, form a non-aromatic heterocyclic ring optionally fused to an aromatic ring; R 7 -R 8 are independently —H, an optionally substituted aliphatic group, or an optionally substituted aryl group; and Z is O or S; comprising dissolving the compound in a solvent selected from the group consisting of THF-acetone, THF-CH 3 CN, THF, acectone, CH 3 CN, THF-EtOH, or acetone-EtOH, and precipitating the compound with water.