Novel azo dyes derived from phthalimide. Part 1: Synthesis and spectroscopic properties

Abstract

A series of azo dyes has been synthesised based on N‐alkylphthalimide diazo components featuring one of three different alkyl groups. An analogous set of dyes was prepared in which the N‐alkylphthalimidylazo systems bore an o,o‐dibromo‐substitution pattern. In these cases, cyanodebromination was performed to give the corresponding dicyano analogues. All the synthesised intermediates and dyes were characterised by mass spectrometry, proton nuclear magnetic resonance spectroscopy and elemental analysis. The absorption maxima of the dyes in dimethylformamide (N,N‐dimethyl ∼) were observed to be in the range 435–608 nm and found to be consistent with results seen in previous studies of conventional monoazo disperse dyes. Replacement of both halogens in the dibromo‐substituted dyes with cyano groups led to large bathochromic shifts (128–141 nm) in absorption maxima. Bathochromism was also observed when acetylamino groups were present on the coupler ring ortho to the azo link. However, variation of the N‐alkyl function on the imido ring from n‐butyl to sec‐butyl and iso‐propyl had little effect on absorption maxima, values being similar to that reported for the parent N‐unsubstituted analogue.

Synthesis and application of N-butyl substituted phthalimide disperse dyes

“…Phthalimide disperse dyes (Dye-1, Dye-2 and Dye-3) were synthesized according to Scheme 1, 9 and characterized using infrared (IR) analysis, MS, elemental and 1 H-NMR spectrophotometry.…”

“…8 More recently, phthalimide-based alkali-clearable dyes have been reported. [9][10][11][12] Phthalimide-based azo disperse dyes undergo ring opening and are converted to water-soluble phthalate groups under relatively mild alkaline conditions without the breaking of azo bonds. The hydrolyzed dye tends to be soluble during washing after dyeing and domestic laundering, lowering the degree of staining on fabrics.…”

Computational modelling of the influence of substituent effects on phthalimidylazo disperse dye hydrolysis and interaction energy

“…Unlike conventional disperse dyes, which tend to migrate to the fibre surface at high temperatures or in the presence of nonionic solvents, the phthalimide-type disperse dyes have a low tendency for thermo-migration, and therefore feature improved fastness to washing [3]. The Huntsman Corporation [5] and Choi et al [6][7][8] have introduced phthalimide as a diazo component in disperse dyes (DR2-DR4 in Figure 1). The Huntsman Corporation [5] and Choi et al [6][7][8] have introduced phthalimide as a diazo component in disperse dyes (DR2-DR4 in Figure 1).…”