PRODUCTION OF SULFONIC ACID GROUP-CONTAINING DIAMINOTRIPHENYLMETHANE DYE

摘要

1. A process for the preparation of a water-soluble diaminotriphenylmethane dye containing from 2 to 4 sulfo groups by anodic oxidation of the leuco compound in an electrolysis cell which is divided into two compartments, wherein the leuco compound is subjected to anodic oxidation at an oxygen overvoltage of 400 mV at a pH of = 4, in the presence or absence of mineral acid anions carrying oxygen atoms.