SINGLET OXYGEN QUENCHING BY TERTIARY ALKYL ETHERS

The efficiency of singlet oxygen O2(lDELTA(g)) (O-1(2)) quenching by methyl tert-butyl ether and methyl tert-amyl ether bas been quantified by steady state and time-resolved O-1(2) luminescence measurements. These ethers are very poor O-1(2) quenchers with bimolecular quenching rate constants lower than 7 x 10(3) l mol-1 s-1. Moreover, we have shown that the presence of variable amounts of olefinic impurities (olefins being used for the synthesis of acyclic ethers) affects the O-1(2) lifetimes in these solvents, even at concentrations lower than 1%, olefins being relatively efficient O-1(2) quenchers. Discrepancies between O-1(2) lifetimes measured by different groups, as well as between experimental values and those calculated in using additivity factors, may also be explained by the presence of impurities in the solvents used.