REACTIONS OF OXIDATION DYE INTERMEDIATES 369 Quinonediimine Reaction Solutions i i •50 X (m•) Figure 5. QDI aqueous reaction solutions. Ether extracts from reactions in 0.05 M Na2COa- borax buffer, pH 9.6 -- QDI, 0.0251 g/100 ml buffer, 3 min. - - - QDI: resorcinol, molar ratio 3.05 0.0295 g QDI/100 ml buffer, 1 min. ß ß ß QDI: resorcinol, molar ratio 0.47 0.0272 g QDI/100 ml buffer, 1 min.

37O JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS A mixture of 648 g (6.00 moles) PPD, 600 g (6.00 moles) resorcinol, 9 1. water, 3 1.20% Na.2C0a, and 1.2 1. 35% H202 (13.6 moles) was stirred together in a stainless steel kettle for 26 hours without tempera- ture control pH 9.5. This mixture contained 4.4% by weight of PPD, 4.5% resoreinol, 4.1% Na2C0a, and 3.2% HsOs. The temperature rose to 90 øC in the first half hour and thereafter fell to room temperature. At the end of the time period, the clear brown solution was adjusted to pH 7.8 with HC1. The precipitate was filtered off, washed with 5 1. water, and milled with water for 16 hours. The pigment was recovered by filtration and dried under vacuum at 70 øC to constant weight. The yield was 467 g when corrected for water and ash content, it was 398 g, equivalent to 31% of theory for C•sHsN202. Properties of Pigment Water Uontent.--Karl Fischer method gave low results because of the insolubility of the pigment in the methanolic medium. Found by vacuum drying at 150 øC, 11.2% water still present gave a Karl Fischer value of 1.6% total water found, 12.8%. Elementary Analysis.--Calcd. for C1•HsN20•'2H•0: C, 58.1 H, 4.84 N, 11.3 O, 25.8. Found: C, 58.7 H, 4.96 N, 11.1 0, 25.4 ash (inorganic), 2.0%. Solubility.--The pigment was insoluble in water at neutrality but soluble in strong acid or alkali insoluble in most organic solvents slightly soluble in glacial acetic acid, pyridine, or dimethyl formamide soluble (about 10%) in carbitol or dimethyl sulfoxide (DMS0). Chromatography.--On thin layer of silica gel (developed with most solvents, eg, chloroform-methanol, 9:1), the pigment showed mostly residue at origin with about 12 minor bands moving freely. Develop- ment with chloroform-DMS0 (3: 1) showed six major yellow-brown bands of same shade close to origin and poorly resolved plus minor bands moving freely. Acetyl Value of A cetylated Pigment For determination of total acetylatable groups (NH2 NH, and OH), the following method was used (10): The pigment (1 g) was allowed to stand in 25 ml of a pyridine-acetic anhydride reagent (3:1) for three days at room temperature. (Alterna- tively, the mixture was heated on the steam bath for four hours.) A 25-ml blank reagent was carried along at the same time. Both solutions were then treated with 25 ml of water, and the excess acetic acid was