Model system for mechanistic study of catalytic bleaching of cotton

Abstract

We have dcveloped a homogeneous model system to study the mechanism of hydrogen peroxide bleaching using [Mn2O3(N,N'N ''-trimethyl-1-1,4,7-triazacyclononane)(2)](PF6)(2) (MnTMTACN) as catalyst. Thee primary model pigment exarnined is morin (3,5,7,2',4'-pentahydroxyflavone) owing to its presence in native cotton 1-iber. Additionally, a series of model compounds with systematic structural diffierences are examined in order to facilitate the development ofa mechanistic understanding of the bleaching system. The pigment oxidative degradation reaction is monitored by UV-Vis spectrophotornetry. The influence of pH is examined in both hornooeneous and heterogenous model systems. The use of MnTMTACN catalyst enables low-temperature hydrogen peroxide bleaching of cotton fabric at slightly lower pH values.