Reusable transition metal complex catalyst useful for the preparation of high pure quality 3,3′-diaminobenzidine and its analogues and a process thereof

摘要

The present invention provides a reusable transition metal complex catalyst useful for the preparation of high pure quality 3,3′-diaminobenzidine and its analogues. The present invention also provides to a process for the preparation of a reusable transition metal complex catalyst. The present invention further provides a process for the preparation of 3,3′-diaminobenzidine (DAB) or 3,3′,4,4′ Tetraminobiphenyl (TAB) using reusable transition metal complex catalyst. The high quality 3,3′-diaminobenzedine (DAB) and its analogues are prepared by coupling 4-halo-2-nitroaniline to 3,3′-dinitrobenzidine (DNB) using transition metals as catalysts followed by reduction of 3,3′-dinitrobenzidine to the corresponding substituted 3,3′-diaminobenzidine of formula 1 in high yields.