OXIDATION PRODUCTS IN HAIR DYES 413 i ii iii fr Bands Figure 1. TLC pattern--Insoluble oxidation products of p-phenylenediamine. I, faint yellow, Rf 0.68 II, bright yellow, Rf 0.55 III, red, Rf 0.35 IV, intense dark blue, Rf 0.20 V, brown, origin. fr: solvent front. st: starting line. Bands: bands which appear on plate after exposure to air elute it showed it to be present in only very minute amounts, and no further attempt was made to characterize this material. In order to obtain sufficient material for analysis, the TLC separation was scaled-up by the use of "chromatosticks" (7). In this manner, sufficient amounts of bands II, III, and IV were obtained for further analysis. IDENTITY OF TLC BANDS Band I This is always weak and may be absent if the precipitate is well washed with H20. By extracting the tiltrate (after removal of the in- soluble oxidation products) with ether, a yellow material was isolated which had R/and visible spectrum identical with those obtained from band I. This material was identified from its melting point and infrared spectrum as p-nitroaniline. The p-nitroaniline formed varies from a very minor amount at low peroxide concentrations to an important com- ponent at high peroxide concentration. However, most of this material remains in solution. Band II This material gave the following analysis' C, 68.05% H, 5.85% N, 26.14% mol. wt., 212, corresponding to C•2H•2N4. It was found to be

414 0.0 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS .iol •.20 •.30 •.50 .60 .70 1.0 Figure oe. 3 4 5 6 7 8 9 10 11 12 13 14 15 WAVELENGTH (MICRONS) Infrared spectrum of 2-(4'-aminoanilino)-5-hydroxy-l,4-quinonediimine, crystal- lized acetone-H•O, KBr disc Figure 3. Visible spectrum of 2-(4'-aminoanilino)-5-hydroxy-l,4-quinonediimine (1 q- 1) EtOH-H20. ---- pH •-• 9 (ammoniacal) approximately 20 rag/liter - - - pH • 7 approxi- mately 23 rag/liter