Abstract
Aim and Objective: Reactive dye molecules are commonly employed to dye or modify colour characteristics
of wool fibres. Yellowness of wool fibres poses a challenge and here, we report synthesis of a reactive
fluorescent molecule and its application to wool fibres to reduce yellowness of the wool fibre and improve
its colour features.
Material and Methods: The new molecule was based upon 7-amino-4-methylcoumarin (AMC) and 2,4,6-
trichloro-1,3,5-triazine (TZT). The synthesis involved a two-step chemical reaction, initiated by the nucleophilic
substitution of a chloro group on the triazine ring with the hydroxyl group of 4-hydroxybenzenesulfonic
acid. The substitution of 2nd chloro group at triazine ring with the amino group of 7-amino-4-methylcoumarin
resulted in a novel molecule with a monofunctional reactive chloro group (AMC-MCT molecule).
Results: The new molecule was applied to the wool fibres using exhaust dyeing method. This exhibited a high
exhaustion value; however low fixation and total efficiency values were observed for the new molecule. The
resultant wool fibres exhibited fluorescence which shows that aminocoumarin fluorophore retained its fluorescence
when incorporated in the new molecule. An assessment of the molecule for yellowness index in a controlled
exposure to UV radiation suggested an improvement in whiteness of wool fibre.
Conclusion: A novel aminocoumarin based fluorescent whitening molecule 2 has been synthesised and applied
to the wool fibres. The new molecule continued to exhibit fluorescence after its application to the wool fibres.
These results will encourage researchers to explore further possibilities for reactive whitening agent for wool
fibres.
Keywords:
Fluorescent whitening molecule, Keratin fibre, 7-amino-4-methylcoumarin, 2, 4, 6-trichloro-1, 3, 5-triazine 4-hydroxybenzenesulfonic
acid, nucleophilic substitution.
Graphical Abstract
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