(a) in the Chloroacetic acid or methyl bromide in sulfate Janson 3H-indol-3-one,2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro- (namely VAT dye C.I. 73025) [FIAT 764 and 1313], or in the cold sulfuric acid in?3H-indol-3-one,2-(1,3-dihydro-3-oxo-2H-indol-2-ylidene)-1,2-dihydro- (GP 23496 l); (b) 3-Bromo-6-(carboxymethylamino)-2-chlorobenzoic acid?and Sodium methanolate reaction, product with Potassium hydroxide treatment, and air oxidation (USP 957683). Note: C.I. 73025 chemical structure as above.