Model System for Mechanistic Study of Catalytic Bleaching of Cotton

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