Synthesis and spectroscopic properties of novel phthalimide‐derived monoazo disperse dyes containing ester groups

Abstract

The synthesis and spectroscopic properties of monoazo dye series, whose members consist of N‐alkylphthalimide diazo components combined with a coupling component containing two ester groups, are reported. Such colourants are potentially alkali‐clearable as a consequence not only of the presence of diester functionality on the coupler, but also through use of the base‐sensitive phthalimide system. Shortening the N‐alkyl group by removing one or two methylene units from a butyl chain made little difference to absorption properties, as would be expected given the relatively minor differences in inductive character produced. Shifts in the absorption maximum of the dyes associated with dibromination of the phthalimidylazo motif and its subsequent cyanodehalogenation were in agreement with theory and literature data for related series. Diester substitution on the coupling component brought about hypsochromism and hypochromism.

Synthesis of quenchers to control the fluorescence of Rhodamine B and improve the contrast ratio of blue filters for LCDs

“…The terminal amino function of quencher 4 bears electron‐donating ethyl groups, whereas the corresponding substituents in quencher 5 are isopropyl ethanoate groups that have an electron‐withdrawing character. Consequently, in line with theory and previous studies on phthalimidylazo derivatives , the absorption maximum of quencher 4 is shifted bathochromically relative to that of quencher 5 . In addition, the terminal amino nitrogen of quencher 5 is more crowded, as it bears bulky branched groups, leading to lower planarity and a reduced extinction coefficient .…”

Investigation of alkaline hydrolysis of phthalimide‐based azo dye and its application to after‐treatment optimisation for high‐fastness dyeing of polyesters

“…It is proposed that azo disperse dyes incorporating a phthalimide moiety undergo a ring opening and convert to a water‐soluble product without breaking the azo bonds under relatively mild alkaline conditions (Scheme ). Phthalimidylazo disperse dyes first appeared as the subject of patents in the 1970s , and they also formed the basis for claims of good fastness and dyeability with polyester in the 2000s . Although their chemistry has been commercially exploited by industry , few studies address the alkaline hydrolysis kinetics of phthalimide‐based dyes .…”

Synthesis of temporarily solubilised azo disperse dyes containing a β‐sulphatoethylsulphonyl group and dispersant‐free dyeing of polyethylene terephthalate fabric

“…Dyes 4 to 6 were prepared by coupling of the diazotised compound with N , N ‐diethylaniline, 3‐(diethylamino)acetoanilide, or 3‐(diethylamino)‐4‐methoxyacetoanilide. Then, the dibromo azo dyes 4 , 5 , and 6 were converted to corresponding dicyano dyes 7 , 8 , and 9 , respectively, using cyanodebromination . Substitution of dibromo into dicyano group was proven by the fact that IR spectra of dyes 7 to 9 showed a new vibrational peak at 2235 cm −1 for a cyano group, while those of dyes 4 to 6 did not contain it.…”