Rate correlations involving the linear combination of substituent parameters. Part IV. Base-catalysed hydrolysis of triethylphenoxysilanes

Abstract

The base-catalysed hydrolysis of meta- and para-substituted triethylphenoxysilanes in 60% aqueous dioxan at 30·2° has been followed spectrophotometrically. The rate constant for spontaneous hydrolysis, k_sp, and the catalytic rate constants k_B and k_OH have been evaluated. k_B and k_sp are shown to correlate better with a four-parameter equation involving σ and σ^– than with the standard Hammett equation. The precision of the k_OH values obtained was much less than either of the other rate constants and only an approximately linear dependence of k_OH on σ could be discerned.