Verfahren zur Diazotierung aromatischer Amine

摘要

Aromatic primary amines which are slightly soluble in water and whose salts are readily hydrolysed by water are diazotized by treating the amine when it has a particle size of less than 30 microns with nitrous acid at a pH between 1.5 and 5. The amines may be mixed with a dispersing, wetting or emulsifying agent and are dried and ground to a particle size of preferably below 10 microns. The powder is then suspended in water and diazotized at room temperature or slightly above, e.g. with a mixture of acetic acid and sodium nitrite. The dispersing, wetting and emulsifying agents mentioned are a condensate of formaldehyde and naphthalene sulphonic acid, alkyl-naphthalene sulphonates, olein-polyglycol ether, diglycol, dextrin and abietic acid polyglycol ether and one or more of these is used in the following examples: (i) 21-nitro - 2:4 - dimethyl - 5 - methoxy - 4 aminoazobenzene is diazotized at pH 3.0-3.5; (ii), (vi), (vii) 41-nitro-2:5-dimethoxy-4-aminobenzene is diazotized at pH 2.9-3.5; (iii) 2-aminodiphenyl sulphone is diazotized at pH 1.7-2.2; (iv) 2-nitro-1-aminobenzene is diazotized at pH 2.9; (v) 1-amino-anthraquinone is diazotized at pH 1.8.