Patent GB-561302-A (GB)
Title: Improvements relating to the manufacture of insoluble azo dyestuffs
IPC: C09B39/00
Filed: 1942-10-30
Abstract: Azo dyes are obtained in substance or formed on textile materials by coupling a diazotised aromatic amine or aminoazo compound, free from water-solubilizing groups, with a coupling compound of the general formula HO-Ar1-C(R1, R11)-Ar11-OH or HO-Ar1-C(R1, R11(OH)-C(R1, R11 -Ar111-OH, wherein Ar1, Ar11 and Ar111 represent substituted benzene residues free from additional water-solubilising groups, of which one or more has or have at least one free coupling position, and R1, R11 represent H or hydrocarbon residues.  The products give readily dischargeable yellow, orange and brown dyeings, fast to light and washing, and the shades may be modified and their fastness to light improved by after-treatment with salts of metals such as copper, cobalt or nickel.  Specified coupling components are 4 : 41-dihydroxy-3 : 31-dimethyldiphenylmethane and its a  : a -dimethyl derivative, 2 : 21 - dihydroxy - 5 : 51 - dimethyl- or dichloro - diphenylmethane, 2 : 21 - dihydroxy-4 : 41 : 6 : 61-tetramethyl-diphenylmethane and its 5 : 51-dichloro derivative, 4 : 41-dihydroxy-2 : 21 - dimethyl - 5 : 51 - diisopropyl - diphenylmethane and o : o1-bis-(2-hydroxy-5-methylbenzyl)-p-cresol. In examples, (1) a viscose fabric is impregnated with an aqueous solution containing sodium hydroxide and 2 : 21-dihydroxy - 5 : 51 - dimethyl - diphenylmethane, dried, passed through an aqueous solution of diazotised 4 - nitro - 21 - methyl - 41 - amino - 51 - methoxy-azobenzene, rinsed and dried to obtain a readily dischargeable dark brown dyeing; (2) a cotton fabric is impregnated as in (1), dried, passed through an aqueous solution of diazotised 4 - benzoylamino - 2 - methoxy - 5 - chloroaniline, rinsed and dried to obtain a readily dischargeable orange dyeing; (3) a cotton fabric is impregnated as in (1) printed with a paste containing diazotised 4 - nitro - 21 - methyl - 41-amino - 51 - methoxy - azobenzene and a thickener, dried, washed and dried to obtain a dark brown print; (4) dyes are similarly produced on textile materials (a) from 2 : 21-dihydroxy - 5 : 51 - dimethyl - diphenylmethane and diazotised 2 : 5-dichloroaniline, (b) from 4 : 41 - dihydroxy - 3 : 31 - dimethyl - diphenylmethane and diazotised 2 : 5-dichloroaniline or 6-chloro-2-aminotoluene, (c) from 4 : 41-dihydroxy - 2 : 21 - dimethyl - 5 : 51 - diisopropyl-diphenylmethane and diazotised 4 - benzoylamino - 2 - methoxy - 5 - chloroaniline, (d) from 2 : 21 - dihydroxy - 5 : 51 - dimethyl - diphenylmethane and tetrazotised 4 : 41 - diaminodiphenylamine, (e) from 2 : 21 - dihydroxy-4 : 41 : 6 : 61 - tetramethyl - diphenylmethane and diazotised 4-nitro-21-methyl-4-1-amino-51-methoxy -azobenzene, (f) from o : o1-bis-(2-hydroxy-5-methyl-benzyl)-p-cresol and tetrazotised 4 : 41 - diaminodiphenylamine; (5) a cotton fabric is printed with a preparation containing 2 : 21 - dihydroxy - 5 : 51 - dimethyl - diphenylmethane, the diazoimino compound from tetrazotised dianisidine and diethanolamine, sodium hydroxide and methylated spirit and thickening, and the print is dried, steamed in presence of vapour of acetic or formic acid, washed and dried; (6) the dyestuff, 4-nitro-21-methyl-41-amino-51-methoxy-azobenzene --> 2 : 21 - dihydroxy - 5 : 51 - dimethyl - diphenylmethane is prepared in substance.  2 : 21 - Dihydroxy - 5 : 51 - dimethyl - diphenylmethane is prepared by heating for 7 hours p-cresol with aqueous formaldehyde and hydrochloric acid in petroleum ether at 40 DEG  C., separating the precipitated o ; o1-bis-(2-hydroxy-5-methyl-benzyl)-p-cresol, and fractionating the filtrate.  The corresponding 4 : 41 : 6 : 61-tetramethyl, 5 : 51-dichloro and 4 : 41 : 6 : 61-tetramethyl-5 : 51-dichloro derivatives of 2 : 21-dihydroxydiphenylmethane are similarly obtained with replacement of the p-cresol by 3 : 5-dimethylphenol, p-chlorophenol and 3 : 5-dimethyl-4-chlorophenol respectively.  4 : 41 - Dihydroxy - 2 : 21 - dimethyl-5 : 51-diisopropyl-diphenylmethane is similarly obtained from thymol.