372 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Methoxyl Value of Methylated Pigment For determination of phenolic groups, the pigment was methylated by means of diazomethane. The pigment (1.6 g) dissolved in carbitol (80 ml) was treated with a large excess of an ether solution of diazomethane (180 ml, 0.3 N), and the mixture was stirred at room temperature for 48 hours. The ether was evaporated with air, and the solution poured into water. The methylated pigment was recovered by filtration, washing, and drying recovery, 97%. The methoxyl value was determined by the micro-Zeisel method and expressed as per cent methoxyl (CH30) in the methylated pigment. Alkaline Hydrolysis of the Pigment The pigment (1.0 g) was treated with 10% sodium hydroxide (20 ml) at the boil for 24 hours. Extraction with methylene chloride then gave a recovery of 0.30 g PPD, identified by melting point, 139- 140øC, and infrared spectrum. Since the pigment was half PPD in composition (elementary analysis), then, correcting for water (12.8ø-/o) and ash (2.0%) in the pigment sample, the recovery of PPD was 70%. A blank experiment in which 0.50 g PPD itself was subjected to the same treatment gave 72% recovery of PPD, m.p. 135-140øC. The recovery from the pigment, then, represented 97% recovery versus blank. RESULTS AND DISCUSSION Bandrowski' s Base In common with other investigations, it was found that Bandrowski's base (BB) was formed when p-phenylenediamine (PPD) alone, in the absence of other dye intermediates, was oxidized under hair dyeing conditions, i.e., in 3% peroxide at pH 9.5 and room temperature for one hour. The procedure was to sample the entire oxidation mixture, rather than the precipitate alone, and examine it by spectral and chroma- tographic methods, against a standard of pure BB. By either method it was found that other products were formed along with BB. The absorption maximum, measured in citrate buffer at pH 2.3, was displaced from 400 m• for pure BB, to 380 m• for the oxidation mixture (Fig. 3). It is likely that the other products were similar to BB in structure, and, if they had the same absorbance, there was obtained a 40% yield of BB and BB-like products from PPD in one hour. The presence of various products, including BB, was clearly

REACTIONS OF OXIDATION DYE INTERMEDIATES 373 shown by the chromatographic method which could detect BB at a level of 0. l ,. Of greater interest were the oxidation mixtures of PPD with a second dye component (resorcinol, m-aminophenol, etc.) (Table I). The chromatogram showed a large number of products indeed. No BB was found when the second component was used in amount equal to PPD. In that case, the spectrum showed no absorption near 400 m/• attribut- able to BB (Fig. 3), and the chromatogram was lacking its BB spot. When PPD was used in large excess, BB again appeared. This absence of BB was characteristic of several diverse compounds reacting with PPD, including meta and para difunctional aromatic amines and phenols. This indicates that, in hair dyeing mixtures, the self-coupling of PPD (to give Bandrowski's base) is the slowest reaction which occurs the PPD reacts faster with the other dye intermediates available. This also means that most hair color formulations on the market, in which PPD is not in excess, are not likely to form BB, and BB does not account for any of the coloring effects obtained with permanent hair color for- mulations currently in use. Quinonediimine QDI is readily prepared and isolated if one works in anhydrous media (4). It is so reactive in water, however, that for its detection under hair dyeing conditions it was necessary to resort to an indirect method, namely, hydrolysis of the QDI, and measurement of the am- monia evolved. Pure QDI gave 17% of the theoretical amount of ammonia by hydrolysis at 38øC and pH 9.6 for one hour (Table II). (The unhydrolyzed QDI, or 83%, apparently underwent polymerization to products which were not themselves hydrolyzable.) Other common nitrogen-containing compounds, namely BB and PPD, in the absence of peroxide, did not give ammonia (Table III). It was, therefore, assumed that any significant evolution of ammonia in an oxidation mixture would indicate the presence of free QDI. What is more important, the absence of ammonia would indicate that free QDI was not present, at least for the time necessary to achieve hydrolysis. Oxidation dye intermediates were then treated, singly and in combination, with peroxide under hair dyeing conditions, and the ammonia evolved was measured. PPD yielded significant amounts of ammonia, about 5% of the theoretical in one hour, indicating that some QDI was formed. This is, of course, much less ammonia than is obtained by the direct hydrolysis of QDI. This is probably so because only a portion of the PPD is converted to QDI the