Patent ID: 6844471

Claim:
A method of converting (Z)-1-(3,5-disubstituted phenyl)-2-(4-substituted phenyl)ethene of general formula (II) to (E)-1-(3,5-disubstituted phenyl)-2-(4-substituted phenyl)ethene of general formula (I) wherein R 1 , R 2 , and R 3 are the same or different and independently represent aryl(C 1 -C 4 ) alkyl group or substituted aryl(C 1 -C 4 )alkyl group, the method comprising the steps of: (a) treating an isomeric mixture of (Z)-1-(3,5-disubstituted phenyl)-2-(4-substituted phenyl)ethene of the general formula (II) and (E)-1-(3,5-disubstituted phenyl)-2-(4-substituted phenyl)ethene of the general formula (I) or (Z)-1-(3,5-disubstituted phenyl)-2-(4-substituted phenyl)ethene of the general formula (II) with a halogen in catalytic amounts, in an organic solvent for a period of 15 min to 16 hrs, at a temperature ranging from −10° C. to +110° C.; (b) quenching the resulting solution of step (a) in water and reducing the halogen using a reducing agent; and (c) isolating the product formed in step (b) to produce (E)1-(3,5-disubstituted phenyl)-2-(4-substituted phenyl)ethene of general formula (I).