Colour-constitution relationships in 2-acylamino-4- N,N-diethylaminoazobenzene disperse dyes

Abstract

Nitration of N,N-diethylaniline in concentrated sulphuric acid afforded a readily separable mixture of the 3- and 4-nitro derivatives, the former being the major product. Reduction and subsequent reaction of 3-amino- N,N-diethylaniline with acid chlorides, chloroformates, isocyanates and sulphonylchlorides gave a range of coupling components suitable for the synthesis of blue azo disperse, using 2-bromo-4-nitro-6-cyanoaniline as diazo component. The colour of the dyes is discussed with respect to electronic and steric effects in the acylamino (and analogous) substituents; depending on the acylamino substituent, positive or negative solvatochromic effects were apparent in ethanol with respect to benzene and/or cyclohexane.