GB469443A - Process for the manufacture of acid aminotriarylmethane dyestuffs - Google Patents

Abstract

Triarylmethane dyes are made by (a) condensing an aromatic amine, at least one amino group of which is substituted by at least one arylated ethylsulphonic acid residue, with an aromatic aldehyde and oxidizing the leucocompound thus obtained; (b) condensing a hydrol of the diarylmethane series with an aromatic amine as defined above and oxidizing the leuco compound; (c) condensing one mol. of formaldehyde with two mols. of an amine as defined above and condensing the product thus obtained with an aromatic amine by oxidation. The aryl residues may be substituted by further amino groups or by alkylamino, arylamino, halogen, hydroxy or methoxy groups; sulpho groups and an alkyl or sulpho-alkyl group may be introduced into the amino group substituted by one arylated ethyl sulphonic acid residue. In examples, tetramethyldiaminobenzhydrol is heated with (1) (N-ethyl-phenyl)-a -amino-b -sulpho-ethylbenzene sulphonic acid [obtained by sulphonating (N-ethyl-phenyl)-a -amino-b -sulpho-ethylbenzene], and (2) (N-m-tolyl-N-b -sulpho-ethyl)-a -amino-b -sulpho-ethylbenzene [obtainable by condensing (N-m-tolyl)-a -amino-b -sulpho-ethylbenzene with b -chlorethane sulphonic acid] in aqueous, weakly acid solution, the products being oxidized in the usual manner, e.g. by lead or manganese dioxides (violet-blue shades on wool); (N-o-tolyl)-a -amino-b -sulpho-ethylbenzene is heated with (3) p-diethylaminobenzaldehyde (reddish-violet), and (4) o-chlorobenzaldehyde (green - blue); (5) (N - ethylphenyl) - a - amino - b - sulpho - ethylbenzene is heated with formaldehyde and the product condensed with diethylaniline in presence of dichromate (blue-violet). Aromatic amines having the amino group substituted by at least one arylated ethylsulphonic acid residue are made by condensing aromatic amines with the addition products of aryl ethylenes, such as styrene and chlorsulphonic acid.