Reactions of organometallic compounds containing silicon. Part IV.1a Reactions of dimethylphenyl-, methyldiphenyl- and triphenylsilyl-lithium with 9-methylfluorene

Abstract

The rapid reactions of dimethylphenyl-, methyldiphenyl- and triphenylsilyl-lithium with 9-methylfluorene have been studied using a stop-flow technique. The thermodynamic parameters of activation for the reactions have been determined and compared with those for fluorene. Contrary to normal behaviour the introduction of a methyl group at the 9-position increases the reactivity of the 9-hydrogen atom. This agrees with the results which other workers have obtained for pK values at the 9-position. We have related this to the effect which the 9-methyl group has on the λ_max. value of the corresponding fluorenyl-lithium compound, and discussed these results in terms of delocalisation of the negative charge on the 9-methylfluorenyl anion.