Substituent effects on the formation constants of substituted acetophenone–iodine complexes

Abstract

The formation constants of complexes of iodine with 11 meta- and para-substituted acetophenones are reported for heptane solutions at 25° and correlated by various linear free energy relationships. Neither σ, σ⁺, or a combination of σ⁰(or σⁿ) and σ⁺ satisfactorily correlate the data. Dual substituent parameter equations furnish better results and show that the effects of meta-substituents are not of the σ⁰ type whilst those of para-substituents are of the σ_R⁺ type. The Thirot equation gives the best empirical fit to the data.