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In physical organic chemistry, the Grunwald–Winstein equation is a linear free energy relationship between relative rate constants and the ionizing power of various solvent systems, describing the effect of solvent as nucleophile on different substrates. The equation, which was developed by Ernest Grunwald and Saul Winstein in 1948, could be written〔Eric Anslyn, E.; Dougherty, D. A. ''Modern Physical Organic Chemistry''; University Science Books, 2006, p 456.〕 : where the and are the solvolysis rate constants for a certain compound in different solvent systems and in the reference solvent, 80% aqueous ethanol, respectively. The parameter ''m'' is a parameter measuring the sensitivity of the solvolysis rate with respect to Y, the measure of ionizing power of the solvent. ==Background== The Hammett equation (Equation 1) provides the relationship between the substituent on the benzene ring and the ionizing rate constant of the reaction. Hammett used the ionization of benzoic acid as the standard reaction to define a set of substituent parameters σX, and then to generate the ρ values, which represent ionizing abilities of different substrates. This relationship can be visualized through a Hammett Plot. : (1) However, if the solvent of the reaction is changed, but not the structure of the substrate, the rate constant may change too. Following this idea, Grunwald and Winstein plotted the relative rate constant vs. the change of solvent system, and formulated this behavior in the Grunwald-Winstein equation. Since the equation has the same pattern as the Hammett equation but captures the change of the solvent system, it is considered as an extension of the Hammett equation. 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「Grunwald–Winstein equation」の詳細全文を読む スポンサード リンク
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