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In physical organic chemistry, the Swain-Lupton equation is a linear free energy relationship (LFER) that is used in the study of reaction mechanisms and in the development of quantitative structure activity relationships for organic compounds. It was developed by C. Gardner Swain and Elmer C. Lupton Jr. in 1968 as a refinement of the Hammett equation to include both field effects and resonance effects. ==Background== In organic chemistry, the Hammett Plot provides a means to assess substituent effects on a reaction equilibrium or rate using the Hammett equation (1): (1) Hammett developed this equation from equilibrium constants from the dissociation of benzoic acid and derivatives (Fig. 1): Hammett defined the equation based on two parameters: the reaction constant (ρ) and the substituent parameter (σ). When other reactions were studied using these parameters, a correlation was not always found due to the specific derivation of these parameters from the dissociation equilibrium of substituted benzoic acids and the original negligence of resonance effects. Therefore, the effects of substituents on an array of compounds must be studied on an individual reaction basis using the equation Hammett derived either for field or resonance effects, but not both. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Swain–Lupton equation」の詳細全文を読む スポンサード リンク
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