Historical developments:- Explained Completely
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Historical developments:-
Reactive dyes for cellulosic fibers
Cellulosic fibers are significantly dominated by cotton. Other cellulose-based fibed fibers include viscose rayon, linen, cupraammonium rayon, jute and lyocell, and these can be dyed with dyes used on cotton [1]. Cellulose is ionized under alkaline conditioins and can behave as a nucleophile towards compounds containing electron-deficient carbon atoms (e.g. reactive dyes).
A variety of attempts have been made to brdingt about the formation of a covalent bond between a dye and a fiber. In this respect, there are two general approaches: producing a dye within the fiber, and producing a dye that is reactive towards the fiber. A covalent dye cellulose combination was achieved in 1895 by Cross and Bevan. These workers showed that cellulose (Cell -OH) treated with strongf alkal was changed into "soda cellulose" which could be treated with benzoyl chloride to form benzoyl cellulose. The resultant benzoyl cellulose was nitrated, the nitro group was reduced, and the amino group was diazotized.The diazo group was coupled with N,N-dimethylaniline to give "dyed" fibers. The reaction used to produce this red cellulose are shown in Fig.1.
The first commercial reactive dyes for cellulose were developed by Rattee and Stephen and marketed by ICI in 1956 under the trade name Procian M [19-24]. These dyes were introduced for the production of fast bright shades on cellulosic fibers using continuous dyeing methods. Procian Brilliant Red 2B in (1) is one of the early members of this family. Procion M dyes contained the highly reactive dichlrotriazine group, and reacted with cellulose under alkaline conditions at room temperature.
