Links the chromophore to the reactive system. ⚗️ The Reaction Mechanism
Common in dyes. The chlorine atom on the dye molecule is displaced by the hydroxyl ( OHcap O cap H ) group of the cellulose or the amino ( NH2cap N cap H sub 2 ) group of protein fibres. Result: A stable carbon-oxygen or carbon-nitrogen bond. 2. Nucleophilic Addition The Chemistry of Synthetic Dyes. Reactive Dyes
Known for incredibly vivid and brilliant shades. Links the chromophore to the reactive system
The dye attaches to the fibre through a chemical reaction triggered by alkaline conditions (high pH). There are two main types of reaction mechanisms: 1. Nucleophilic Substitution Result: A stable carbon-oxygen or carbon-nitrogen bond
Generally requires salt to drive the dye into the fibre and alkali to fix it. 🌍 Environmental Impact
The part that provides color (usually azo, anthraquinone, or phthalocyanine groups). Solubilising Group: Often sulfonic acid salts ( SO3Nacap S cap O sub 3 cap N a ) that make the dye water-soluble.
While reactive dyes are safer than many older synthetics (like those using heavy metals), they require large amounts of salt and water for the fixation and rinsing processes. Modern research focuses on "low-salt" dyes and increasing the to reduce chemical waste.