GB802554A - Improvements in or relating to the dyeing of animal fibres - Google Patents

Abstract

In Example (1) 6-nitro-2:4-diaminophenol is prepared by nitrating 2:4-diaminophenol. Similarly in Example (3) 2-amino-4-(N-methyl)-amino-6-nitrophenol is prepared by nitrating 4 - N - methylamino - 2 - aminophenol. In Example (2) 2:4:6-triaminophenol is prepared by reduction of picramic acid. Similarly in Example (4) 4-N-methylamino-2:6-diaminophenol is prepared by reduction of the compound of Example (3), and in Example (5) 2-N-methylamino-4:6-diaminophenol is prepared by reduction of N-methyl-picramic acid. In Example (6) 2-(N-b -hydroxyethyl) amino-4:6-diaminophenol is prepared by refluxing calcium picramate with glycol monochlorohydrin, followed by reduction of the product. Similarly in Example (7) 4-di-(b -hydroxyethyl)-amino-2:6-diaminophenol is prepared by condensing isopicramic acid with glycol bromohydrin followed by reduction. In Example (8) 1:2 - dihydroxy - 3:5 - diaminobenzene is prepared by simultaneously reducing and deacetylating dinitropyrocatechol diacetate. In Example (9) 1-bromo-2-hydroxy-3:5-diamino-benzene is prepared by brominating 2:4-dinitroaniline, refluxing the product with potassium hydroxide, acidifying and reducing. In Examples (10), (11) and (12) 6-methoxy-2:4-diaminophenol, 3:5-diamino salicylic acid and 2-methylamino-4-aminophenol are prepared by reduction of the corresponding nitro compounds. In Example (13) 4-b -hydroxyethylamino-2-aminophenol is prepared by condensing potassium 2-nitro-4-aminophenate with glycol chlorohydrin followed by reduction. In Example (14) 6 - methyl - 2:4 - diaminophenol is prepared by heating 4-nitro-o-toluidine with potassium hydroxide, the product then being nitrated and finally reduced.ALSO:Animal fibre, e.g. hair, is dyed with oxidation dyes by applying an aqueous solution of a compound of the formula <FORM:0802554/IV (c)/1> wherein R1 and R2 each represent a hydrogen atom, a lower alkyl or lower hydroxyalkyl group, R3 represents a hydrogen atom or a lower hydroxy alkyl group and X represents a halogen atom or an amino, hydroxyl, carboxyl, lower alkyl or lower alkoxy group or, when at least two of the radicals R1, R2 and R3 each represent a hydrogen atom, a nitro group or, when at least one of the radicals R1, R2 and R3 is other than a hydrogen atom, a hydrogen atom, allowing the compound to oxidize on the fibre and finally rinsing. Oxidation may be accelerated by the use of a peroxide, e.g. hydrogen peroxide. The compound may be employed in the form of a salt and the pH of the solution is preferably adjusted to 5-8 by the addition of an alkali or an acid. Examples are given.