Quantitative Prediction of Leaving Group Orders fronı Aliphatic Carbon in Sjy2 Reactions

Two quantitative conelations of leaving groups effects from aliphatic car¬bon in bimolecular nucleophilic substitution reactions were given by using Ed- wards equation; k GH3Y + X" -> CH3 X + Y- logk/ko = a Ex + p Hx in which k and k0 are the reaction rate constants of the substrate with a nucleo- phile, X and water, respectively, at 25.0°C. Ex is the oxidative dimerization po- tential and Hxis the basicity of the nucleophile, relative to water. Leaving group reactivity order is a function of oxidation and basicity of the leaving group. In a serie of alkyl substrates, CH3Y, the substrate constant a depends linearly to the Ey_ and the substrate constant, log fi depends linearly to the Hy_. a - 1.11 EY_ + 0.87 log/? - 0.13 Hy_ — 1.36 Using these equations, new substrate constants and then the rate constants of bimolecular nucleophilic substitution reactions on CH3Y compounds in water, at 25.0°C can be estimated.