Patent GB-824280-A (GB)
Title: New monoazo-dyestuffs of the benzene-azo-benzene series and process for their manufacture
IPC: C09B43/11
Filed: 1956-01-31
Abstract: The invention comprises dyestuffs, free from groups imparting solubility in water, of formula R1-N=N-R2, where R1 is a benzene residue containing as the sole substituent a tertiary amino group pto the azo link and R2 is a benzene residue containing two amino groups in m-position relative to each other, the two N atoms of which together have at least one and at most three aliphatic substituents including not more than one benzene residue.  They may be made by coupling, advantageously in an acidic medium, diazotized 4-tertiary-amino-anilines with appropriate 1,3-diamino benzenes. Some of the dyestuffs may also be made by eliminating the acyl group from dyestuffs of formula R1-N=N-R3 and R1-N=N-R4, where R1 is as above, R3 is a benzene residue containing oto the azo link an Acyl NH-, <FORM:0824280/IV(c)/1> or <FORM:0824280/IV(c)/2> group and an alkylated amino group pto the azo link, and R4 is a benzene residue containing oto the azo link an <FORM:0824280/IV(c)/3> or <FORM:0824280/IV(c)/4> group and an NH2 group pto the azo link.  In the above formul  the aryl groups represent benzene residues. Preferred diazo-components are of formula <FORM:0824280/IV(c)/5> where X and Y are lower alkyl residues which may contain OH, MeO or CN groups.  Preferably X and Y contain at most 2 carbon atoms each. Specified diazo components are 1-amino-4-dimethyl- or -diethyl-, -ethyl-b -oxy- and -cyano-ethyl-, -methyl-b -cyanoethyl- and -di-(b -cyanoethyl)-aminobenzenes.  The N atoms of the 1,3-diaminobenzenes may contain a phenyl substituent and/or aliphatic residues, e.g. cyano- and oxy-alkyl and especially alkyl groups, which preferably contain one or two carbon atoms.  Advantageously the coupling components contain no substituents other than those in the 1,3-positions although substituents such as a methyl group may be present.  Specified coupling components are 1-methyl-, dimethyl-, diethyl-, di-(b -oxyethyl)- and -phenylamino - 3 - aminobenzenes, 1,3 - dimethylaminobenzene, 1-dimethylamino-3-methyl- and -(b -cyanoethyl)-anilines, 1-dimethylamino-3-amino-6 - methylbenzene and 1 - amino - 3 - dimethylamino-4-methylbenzene.  Desirably the reactants, particularly the coupling components, are in a pure state. The dyestuffs are particularly used in the dyeing of polyacrylonitrile fibres especially by fixing the dyestuff on the fibres in the form of one of its salts.  Salts of many acids are specified, representative being hydrochloric, sulphuric and phosphoric acids, and methane-, benzene-, naphthalene- and cymene-sulphonic, formic, chloracetic, oxalic, tartaric, gluconic, ethylene-diaminotetracetic, benzoic, salicylic and phthalic acids. The fibres may be dyed by treatment with salts of the dyestuffs or mixtures of acids and dyestuffs which lead to their formation, by treatment with the dyestuffs followed by an acid treatment or by an acid treatment followed by dyeing with the dyestuff base. An excess of acid is preferred in each of the three methods. Organic acids are advantageously used in the third method.  The dyeing may be effected in an aqueous medium optionally with the addition of dispersing agents such as soap, sulphite cellulose waste liquor, fatty alcohol sulphonates, higher alkyl sulphonic acids, benzimidazole sulphonic acids containing a m  high alkyl substituent and ethylene oxide-alcohol condensation products. Generally treatment at raised temperature with an aldehyde or an agent yielding aldehyde is necessary to improve fastness. Formaldehyde and condensates and precondensates thereof are preferred.  The aldehyde treatment may take place after or together with the dyeing process and mixtures of the dyestuff and aldehyde used in the latter treatment may contain hydrotropic agents such as urea.  The dyestuff may react with the aldehyde to yield a condensate which may be used to dye the fibres. Blue tints are obtained which are not changed on chroming.  Examples are provided illustrating the preparation of the dyestuffs and their use in dyeing polyacrylonitrile fibres from certain of the above specified reactants, the acylated components used being 1-dimethyl-amino-3-acetyl-aminobenzene and 1 - N - methyl - N - acetylamino - -3-aminobenzene.