A partition experimental evidence of molecular complex formation of some quinones with sodium dodecyl sulphate anion in aqueous phase by spectrophotometric method

In an experiment involving partition of four different quinones between their saturated solutions in CCl4 and aqueous solution of sodium dodecyl sulphate (SDS), done spectrophotometrically, it was observed that below the critical micellisation concentration (c.m.c.) of SDS, the solubility of each quinone in aqueous phase increased linearly with [SDS], just above c.m.c. it dropped sharply and then again increased, becoming nearly constant at very high [SDS]. The absorption λmax of each quinone (excepting o-chloranil) in aqueous SDS showed a red shift relative to that in CCl4 and the red-shifted λmax is independent of [SDS]. These observations were rationalised by considering complexation and phase equilibria.