Synthesis and application of reactive dyes with heterocyclic reactive systems

Abstract

Synthetic methods are described for the preparation of the reactive dyes of the general formula 4. The dyestuffs have been used f or dyeing cotton according to a uniform dyeing process. Parameters such as the most favourable dyeing temperatures, exhaust and fixing values have been determined. Investigations have been carried out for estimation of the stabilities of bonding between dyestuff and fibre under both acidic and alkaline conditions. Among the triazine dyes, the highest average relative fixation values (70%) are exhibited by the 2-aryl and 2-heteroaryl derivatives. Among the reactive dyes based on pyrimidine, the 5-cyano-2,4-dichloro derivatives show a higher level with 73% while the 2,4-diβuoropyrimidines show the highest level with 84%. The 2,4-diβuoropyrimidine dyes also show the best overall picture with respect to hydrolysis fastness properties, permitting the conclusion that the dye-fibre bonds are stable under both acid and alkaline conditions. The other pyrimidine dyes can be generally regarded as moderate, while the reactive dyes based on triazine showed poor results.