Abstract: A process for producing a purified 3,4-toluenediamine product and a mixture of 4- and 5-methylbenzotriazoles from a mixture of ortho-toluenediamine isomers, the process having the steps of(a) dissolving a mixture of ortho-toluenediamine isomers in water to form an aqueous solution;(b) cooling the aqueous solution to a temperature whereby crystals of a purified 3,4-toluenediamine product are formed in an aqueous mother liquor;(c) separating the purified 3,4-toluenediamine product crystals from the aqueous mother liquor;(d) reacting the aqueous mother liquor with a diazotization agent selected from sodium nitrite, potassium nitrite, nitrous acid and nitrous anhydride in the presence of acetic acid to form a reaction mixture containing a mixture of 4- and 5-methylbenzotriazoles; and(e) recovering the mixture of 4- and 5-methylbenzotriazoles from the reaction mixture.