Applications of 2,5-Diaminotoluene sulfate

Chemical Properties

2,5-Diaminotoluene sulfate (C7H12N2O4S, CAS registry No. 615-50-9) is also called 2-methylbenzene-1,4-diamine; sulfuric acid, which is a light tan to light purple powder. Its melting point is 300 oC. The solubility of 2,5-diaminotoluene sulfate is as follows: in water 5.03 g/L (20 °C), in acetone/water 1:1: < 1 g/L, in DMSO: 5 < S < 15 g/L, in ethanol 1 < S < 10 g/L. The pH of saturated aqueous solution is 2.47 at 20 °C. When heated to decomposition it emits very toxic fumes of /nitrogen oxides and sulfur oxides.

Effective Inhibitor

2,5-Diaminotoluene sulfate is the sulfate salt of toluene-2,5-diamine. In a study of eosin-sensitized photo-oxidation reactions, toluene-2,5-diamine was an inhibitor, competing efficiently with oxygen and with trypsin for reactions with the triplet state of eosin. Triplet eosin was reduced to the ground state and/or a semi-reduced eosin radical and an oxidized form of toluene-2,5-diamine. Toluene-2,5-diamine also competed effectively with trypsin for oxidation by semi-oxidized eosin.

Applications

Toluene-2,5-diamine and its sulfate are used as ingredients in the formulation of permanent hair dyes, colors, and tints[1]. According to information supplied to the US Food and Drug Administration (FDA) by industry as part of the Voluntary Cosmetic Ingredient Reporting Program (VCRP), toluene-2,5-diamine and the sulfate salt are used in a total of 79 and 168 products, respectively. All uses reported for these ingredients are in hair coloring products. According to a survey of current use concentrations conducted by the Cosmetic, Toiletry, and Fragrance Association (CTFA), toluene-2,5-diamine is used at concentrations of 0.2% to 3.0% in hair dyes and colors and toluene-2,5-diamine sulfate is used at concentrations of 0.1% to 4.0% in hair dyes and colors and at 3% in hair bleaches. They are used in hair-dye formulations to produce black, drab and warm-brown, blond and grey shades on the hair.

Toluene-2,5-diamine and the sulfate salt can also be used as intermediates in the production of dyes used for textiles, furs, leathers, biological stains and indicators, spirit varnishes and wood stains, and pigments[1]. Toluene-2,5-diamine is used as an intermediate in the production of 2 dyes: Cl Basic Red 2 and Cl Acid Brown 103. Cl Basic Red 2 is used to dye fabrics and paper and is used in spirit inks, biological stains, and solvent dyes. Both dyes are used to color leather. 2,5-Diaminotoluene sulfate is also used in bleach-toner formulations for silver (at levels of 0.1%), smoke (0.04%) and platinum-blond (0.08%) shades.

References

[1]. Burnett, C. L.; Bergfeld, W. F.; Belsito, D. V.; Klaassen, C. D.; Marks, J. G., Jr.; Shank, R. C.; Slaga, T. J.; Snyder, P. W.; Alan Andersen, F., Final amended report of the safety assessment of toluene-2,5-diamine, toluene-2,5-diamine sulfate, and toluene-3,4-diamine as used in cosmetics. International journal of toxicology 2010, 29 (3 Suppl), 61S-83S.

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