Patent GB-885046-A (GB)
Title: New cationic azo dyestuffs derived from imidazole and methods for their production and their use
Inventor: BAUMANN HANS
IPC: C09B39/00
Filed: 1959-06-25
Abstract: The invention comprises dyes having cations of formula <FORM:0885046/IV (c)/1> where R1 and R2 are H, alkyl, cycloalkyl, aralkyl or aryl or members of a non-aromatic ring, R3 and R4 are alkyl, cycloalkyl or aralkyl, Ar is o- or p-phenylene or o- or p-naphthylene or the divalent residue of 4,41-azo-benzene and X is Hlg, alkoxy, alkylthiol, sulphonic acid, alkyl- or aryl-sulphonic acid ester or R5-N-R6 where R5 is H, free or substituted alkyl, cycloalkyl or aralkyl, R6 is free or substituted alkyl or aryl or R5 and R6 form a heterocyclic ring and of formula <FORM:0885046/IV (c)/2> where R1, R2, R3 and R4 are as above Ar1 is the divalent residue of a diphenyl compound, preferably of diphenyl, stilbene, diphenyl ether, diphenyl, sulphide or diphenylamine, and X is <FORM:0885046/IV (c)/3> where R1, R2, R3 and R4 are as above.  The dyes may be made by coupling appropriate diazo or tetrazo compounds with the required imidazole with subsequent quaternisation or by coupling a diazo compound of an amine of formula H2N-Ar-Y, where Y is a substituent which may be split off as an anion, e.g. halogen, alkoxy, sulphonic acid or sulphonic acid ester group, with an appropriate imidazole with subsequent quaternisation and, if desired, treatment with an amine of formula R5NHR6, or with an N-substituted carboxylic acid amine, e.g. dialkylformamides, to replace Y.  During salt formation other conversions such as hydrolysis, reduction, esterification and etherification may be effected.  The dyes may also be made by coupling a diazo compound of an amine of formula H2N-Ar-H with the required imidazole, quaternising and treating the salt with appropriate amines in the presence of oxidising agents.  The dyes may be isolated by salting out from acid solution.  Indicated as substituents for the dyes are halogen, alkyl, aralkyl, hydroxy, alkoxy, nitro, cyano, amino, acylamino, alkyl- and aryl-sulphone, carboxylic acid and ester, carboxylic acid amide which may be substituted, sulphonic acid amide and arylazo groups.  Representative of diazo components specified are 2,5-dichloro- and dimethoxy-anilines, 2-nitro-4-methoxy-aniline, 4 - dimethylaminoaniline, 4 - N - bis - (21 - cyanoethyl) - aniline and 4 - (21 - methoxy) - phenylamino-aniline and of specified imidazoles are imidazole and its 4-methyl, 4,5-diphenyl, 4,5 - pentamethylene, 4 - (41 - dimethylamino) - phenyl and 4 - (41 - dimethylamino) - phenyl derivatives.  Usual alkylating agents are employed.  Representativ of specified amines used in the last of the above processes are monoethylamine, methyl - 2 - hydroxyethylamine, ethyl - 2 - cyanoethylamine, N,N - dimethyl - 1,3 - diaminopropane, pyrrolidine, hexamethylene imine, piperazine and benzylamine.  Conventional oxidising agents are used.  The anions may be organic or inorganic, amongst those listed being halogen, sulphate, perchlorate, methosulphate and alkylbenzene sulphonate, and double salts may also be formed, e.g. with zinc chloride.  By reaction with acids or acid dyes they may be converted into lacquer or pigment dyes.  When soluble in water they colour materials of mordanted cotton, natural or synthetic polyamides, e.g. wool, silk, leather, polyhexamethylene diamine adipate or polycaprolactam, cellulose esters or ethers, polyurethanes, polyesters and especially polyacrylonitriles. Numerous examples are provided of the preparation of the dyes and their use in colouring processes to give various shades of red, blue and yellow. Diazo dyes are obtained from monoazo dyes such as 4-amino-41-dimethylamino-azobenzene, and from 3,31-dimethoxy - 4,41 - diaminodiphenyl and 4,41-diamino-diphenyl and -diphenyl sulphide. Specifications 787,891, 791,932 and 837,472 are referred to.