Determination of constants of anionic substituents based on nitrile infrared frequencies and intensities

Abstract

A new approach, based on dual-parameter correlation equations, for the determination of σ⁺ and other substituent constants is described; it consists of the simultaneous use of data for a given substituent, obtained from at least two different series. Constants of 14 negatively charged substituents have been calculated on the basis of Yukawa–Tsuno-type correlations of nitrile i.r. frequencies and intensities, measured in polar aprotic solvents. The reliability of the constants of anionic substituents, thus obtained, is exemplified in series of carbonyl frequencies of ketones and esters.