GB417875A - The manufacture of dyestuffs of the gallocyanine series - Google Patents

Abstract

Gallocyanine dyes are prepared by condensing according to known methods gallic acid or derivatives thereof with a nitroso compound of a secondary or tertiary aromatic amine of the general formula <FORM:0417875/IV/1> wherein "aryl" indicates a residue of the benzene series and R is hydrogen, alkyl, substituted alkyl, aralkyl, or substituted aralkyl. These dyes can be transformed into other derivatives which still contain the grouping <FORM:0417875/IV/2> according to the usual methods known in this series of dyestuffs; thus the carboxylic acid group can be split off, the dyes may be reduced to the leuco form, or condensed with aromatic mono- or diamines or sulphonic acid derivatives thereof, or with aldehydes, phenols, naphthols or naphtholsulphonic acids, or they may be sulphonated. The products are clear, fast dyes having a good solubility in water. In examples, (1) gallic acid is condensed with nitrosomethylphenyltaurine in methanol (or ethanol or glacial acetic acid); when printed as chrome-lake good blue shades are obtained, and chromed wool is similarly dyed blue; by heating the dye in weak alkaline solution the carboxy group is split off; using nitroso-di-(sulphoethyl)-aniline for the condensation a similar dye is obtained; (2) pyrogallic acid is condensed with nitrosomethylphenyltaurine to give a blue dye; (3) gallamide is condensed with nitrosoethylphenyltaurine to give a greenish-blue dye; this may be transformed to its leuco compound by means of zinc dust and hydrochloric acid and this can be printed as chrome lake in solution or after isolation; or the anilido compound is obtained by heating with aniline, and this can be used for printing purposes directly or after sulphonation; or the dye may be condensed in hydrochloric acid solution with formaldehyde, or with resorcinol to give a phenocyanine from which the carboxylic radicle may be split off by boiling with aqueous soda; (4) gallamide is condensed with nitroso-o-tolyltaurine and with nitrosophenylbenzyltaurine to give blue dyes; using nitrosmethylphenyltaurine for the condensation and further condensing the product with p-aminodiethylaniline an arylidogallocyanine derivative is obtained. The nitroso compounds employed as intermediates are prepared by introducing the nitroso group into tertiary alkylaryltaurines by means of sodium nitrite and hydrochloric acid or by similar treatment of secondary aryltaurines to give nitroamines which are converted into the p-nitroso compounds by introducing into concentrated hydrochloric acid.