Sodium dodecyl benzene sulphonate mediated tautomerism of Eriochrome Black-T: Effect of charge transfer interaction

► SDBS molecules can interact with quinone-hydrazone tautomer of anionic EBT molecule and stabilizes it, whereas SDS cannot. ► The nature of interaction between SDBS and EBT is charge transfer type. ► Electron rich SDBS acts as electron donor and electron deficient quinone-hydrazone tautomer of EBT acts as acceptor. ► The interaction between SDBS and EBT shifts tautomerisation of EBT to less stable quinone-hydrazone form at pH 7.0. In the absence of SDBS, this tautomerisation happens at pH 9.45.