Patent ID: 6734324
Filing Date: 2004-05-11
Classification: C07C

Abstract:
A process for the preparation of a compound of the formula: in whichR1 and R2 are at each occurrence independently hydroxyl, C1-6-alkyl, C1-6-alkoxy, halogen, phenyl or phenoxy; R2 is hydroxyl, C1-6-alkyl, C1-6-alkoxy, halogen, phenyl or phenoxy; R3 is hydrogen or C1-6-alkyl; m is an integer from 0 to 4; and n is an integer from 0 to 5, comprising reacting diketene with an N-phenyl-p-phenylenediamine of the formula: in which R1, R2, R3, m and n have the meanings indicated above, in the presence of 3 to 40 percent strength acetic acid at a temperature of from 20 to 100Â° C.