MECHANISTIC INVESTIGATIONS INTO THE BRIGHTNESS STABILIZATION EFFECTS OF HEXADIENOL

The total amounts of 3,4,5-trimethoxyacetophenane and 2,6-dimethoxyphe nol formed via the photocleavage of ethoxy-alpha-(2',6'-dimethoxypheno xy)-acetophenone (1) in benzene and 3:2 ethanol/benzene, have been qua ntified in the presence and absence of 2,4-hexadienol, a potential pho tostabilizing agent for mechanical pulps. Photodegradation of 1 in eth anol/benzene solutions was shown to be reduced by the addition of hexa dienol. Photolysis of bleached chemithermomechanical pulp (BCTMP) trea ted with trans,trans-2,4-hexadienol was shown to yield all four possib le geometric isomers of the hexadienol. These results suggest that a p otential mode of stabilization of mechanical pulps by the hexadienol i s triplet quenching of the excited state of lignin chromophores such a s the alpha-carbonyl groups of phenacyl aryl ethers.