GB1295789A - - Google Patents

Abstract

1295789 Indamine dyestuffs L'OREAL 19 April 1971 [10 April 1970] 26659/71. Heading C4P Indamine dyes and their inorganic or organic addition salts have the general formula wherein each of R 1 , R 2 , R 3 and B 4 independently represent H, halogen, C 1 -C 6 alkyl or alkoxy and R 5 and R 6 either both represent hydrogen or both represent the same or different optionally substituted alkyl radicals. Suitable salts include the tartrates, acetates, arylsulphonates, hydrochlorides, persulphates, perchlorates and the zinc chloride double salts. The compounds may be prepared by condensing 2,6-diaminopyridine with a para-phenylene diamine of formula in an aqueous, aqueous alcoholic or aqueous acetone medium in the presence of an oxidizing agent and optionally converting the resulting indamine or indamine salt into a desired salt. The oxidizing agent is suitably H 2 O 2 or an inorganic per-salt. Compounds where at least 2 of R 1 , R 2 , R 3 and R 4 are not hydrogen may be obtained by condensing 2,6-diaminopyridine with a quinone diimine of formula in an aqueous medium or in an inert solvent, in the presence of an acid corresponding to the desired salt. Compounds where R 5 and R 6 are both alkyl groups may also be prepared by condensing 2,6-diaminopyridine with a pnitroso-N,N-dialkylanidine of formula in an aqueous or alcoholic medium at 30-60‹ C. The compounds of Formula I are used for dyeing keratinaceous fibres, e.g. hair, either alone or in compositions containing other dyes and other ingredients conventionally employed in hair dyes. They can also be employed in the form of wave-setting lotions.