Selective Oxidation Of The Leuco Compound Of C.I. Acid Blue 9

Oxidation of leuco compound of C.I. acid blue 9 by high valence metallic oxide is the primary way in the production of C.I. acid blue 9. Due to the heavy metal pollution and solid waste caused by metallic oxide, much attention has been paied to searching an green technology for this oxidation process. Here, selective oxidation of leuco compound of C.I. acid blue 9 with hydrogen peroxide catalyzed by heteropoly compound and oxidation by iodobenzene diacetate oxidation was investgated.Commercial Keggin phosphotungstic acid was used to catalyze the hydrogen peroxide to oxidize the leuco compound of C.I. acid blue 9. The effect of temperature, pH, the amount of catalyst and way of adding hydrogen peroxide on the reaction were studied through orthogonal test, and the results showed that the conversion of the substrate reached up to 80% through the conditions:the reaction time is 24 hours, pH is 5.0, the amount of catalyst is 5 mol% of substrate, the way of adding hydrogen peroxide is 2 mL/2 h, and the volume of hydrogen peroxide (30%) is 24 milliliter relative to 25 millimole substrate. And the selectivity was just 10%.At the foundation of research that the oxidation of leuco compound of C.I. acid blue 9 with hydrongen peroxide catalyzed by Keggin phosphotungstic acid, conversion of substrate could be achieved 80% when Keggin sodium phosphotungstate, Keggin phosphomolybdic acid and synthetic Keggin phosphorus vanadium molybdenum acid were used as catalyst in the same conditions. And the C.I. acid blue 9 selectivity was 15.0% when using Keggin sodium phosphotungstate as catalyst, and the Keggin phosphomolybdic acid lead to the selectivity going up to 32.5%, and the Keggin phosphorus vanadium molybdenum acid increased the selectivity to 43.7%. Increasing the ratio of vanadium in the Keggin phosphorus vanadium molybdenum acid was useless to improve the the selectivity.The effect of temperature, amount of oxidant and solvent on the reaction were investigated in the selevtive oxidation of the leuco compound of C.I. acid blue 9 by stoichiometric iodobenzene diacetate, and the result that 100% of conversion substrate and 90% of dye selectivity could be attained from this condition:reaction temperature is 25℃, the molar ratio between C.I. acid blue leuco compound and oxidant is 1:1.8, acetic acid aqueous solution is used as solvent and the mass fraction of water is 7.5%. Besides, the factors including the reaction time and the way of adding iodobenzene diacetate had been discussed, and the results suggested that the reaction time and the way of adding iodobenzene diacetate had no effect on the reaction.