The Hydrolysis of Reactive Dyeings

Abstract

Twelve reactive dyes were synthesised containing the same chromophore but different reactive systems and different bridge members. These dyes were applied to mercerised cotton at approximately standard depth and the effects on the dyeings of alkaline and acid hydrolysis were studied. Increasing reactivity of dichloro‐ and trichloro‐pyrimidyl dyes is accompanied by a growing tendency to acid and, more particularly, alkaline hydrolysis. The position at which saponification occurs depends on the nature of the bridge member. In a second series of dyes, various reactive systems were combined with the same chromophore through an imino group; no general relation between reactivity and tendency to hydrolysis could be established for these dyes.

Further Studies of the Acid‐catalysed Hydrolysis of Type 3 Dye‐Fibre Bonds between Cellulose and Triazinyl Reactive Dyes

“…Since this will be affected by buffer-anion affinity, the use of buffers may lead to confusing results. Reference has been made t o anomalous results in acidhydrolysis studies [8] and the probable cause is now shown.…”

A greener approach to cotton dyeings with excellent wash fastness

“…It is suggested that, in the case of conventionally dyed cotton, a small amount of dyefibre bond cleavage occurs as a result of the wash-off stages and, particularly, the five-wash fastness tests. It is known that the dye-fibre bond formed using vinylsulfone reactive dyes on cotton is more alkali-sensitive than that derived from monohalotriazine dyes, 8 and this would explain the Remazol RR dyeings having slightly inferior wash fastness to the Procion H-EXL and Cibacron F dyeings. The cotton adjacent picks up the small amount of loose colour that is generated, the stain becoming quite noticeable after five washes; in addition, the colour strength of the dyeing is reduced.…”

Modification of jute with sericin for improvement in dyeing

“…[4], [1] In order to improve the exhaustion and consequent fixation of reactive dye on cellulosic and ligno cellulosic substrates, several attempts including introduction of two identical or different reactive groups per chromophore have been reported in the literature with little or marginal improvement in the exhaustion of such dyes into textile substrates. [3] Reactive dye however when applied on proteineous fibres such as wool and silk, more than 90% exhaustion of dye is achieved even without necessitating use of any salt for promotion of exhaustion. [5] Incorporation of amino compounds into cotton and jute prior to dyeing is reported to be prospective with respect to improvement of exhaustion of reactive dye into such modified fibers even in absence of salt.…”