The rate constants for reaction of${\rm O}^{-}$ with a number of substituted benzenes and toluenes have been measured. While the values for abstraction from the methyl group of the toluenes$(k\sim 10^{9}\ M^{-1}\ {\rm sec}^{-1})$ are considerably greater than for addition to the ring$(k<10^{8}\ M^{-1}\ {\rm sec}^{-1})$ they are not strongly influenced by additional substitution. The dependence of rate constants on the substituents indicates that${\rm O}^{-}$ is less electrophilic than is OH. The reaction of${\rm O}^{-}$ with phenols and anilines is also quite rapid$(k\sim 10^{9}\ M^{-1}\ {\rm sec}^{-1})$, indicating that in these cases reaction takes place via electron transfer and not addition.

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