37898-11-6Relevant academic research and scientific papers
Solvent Effects on the Rates and the Activation Parameters for the Methoxymercuration of p-Substituted Styrenes
Lewis, Adolphus
, p. 4682 - 4687 (1984)
The second-order rate constants and the activation parameters for the methoxymercuration of a series of para-substituted styrenes have been determined in four methanol/p-dioxane mixtures - XMeOH varied from 1.00 to 0.791.For each styrene log k is a linear function of XMeOH.The average value of the slopes of the correlation lines is 8.25 +/- 0.32 which suggests the involvement of eight-nine MeOH molecules in the rate-determining transition state.For each solvent identical linear plots of log k vs. ? and ?+ are obtained.At 25 deg C, the value of ρ (av -3.26 +/- 0.05) and ρ+ (av -2.86 +/- 0.05) are independent of the solvent's composition.For each styrene ΔG* increases as the methanol concentration decreases; however, δΔG* is constant.While δΔG* varies linearly with ? and ?+, in no case is δΔH* linearly related to δΔS*.In anhydrous methanol this reaction series is isoenthalpic; however, this is not the case for either of the methanol/p-dioxane mixtures.On the basis of the ΔS* values, the reaction series approaches an isoentropic state as the methanol concentration decreases.
Electrophilic Additions to Olefins. A New Approach to Unifying the Mechanisms of Bromination and Oxymercuration
Fukuzumi, S.,Kochi, J. K.
, p. 2783 - 2791 (2007/10/02)
Bromination and oxymercuration of carbon-carbon double bonds represent classical examples of electrophilic addition, but they nonetheless show quite divergent patterns of reactivities for various olefins.However, the olefin reactivities are identical when
Substituent Effects on the Activation Parameters for the Methoxymercuration of p-Substituted Styrenes
Lewis, Adolphus,Azoro, Jerome
, p. 1764 - 1769 (2007/10/02)
The activation parameters for the methoxymercuration of a series of p-substituted styrenes in anhydrous methanol have been determined.The values of ΔH(excit.) and ΔS(excit.) are consistent with the formation of bridged activated complexes in the rate-determining step of these reactions.Analysis of the substituent effects on the values of δ ΔG(excit.) for these reactions using the Yukawa-Tsuno equation required the use of small values for the r parameter.This finding is also consistent with the formation of bridged activated complexes in the rate-determining step.Variations of the substituents have small effects on ΔH(excit.) but large effects on ΔS(excit.). δ ΔH(excit.) is not linearly related to either δ ΔS(excit.) or δ ΔG(excit.).However, δ ΔG(excit.) - as expected for a reaction series in which the values of δ ΔH(excit.) are small and/or constant - is a linear function of δ ΔS(excit.).Product studies on styrene and its p-MeO and p-NO2 derivatives show that these reactions are clean and that they occur regiospecifically, giving the expected Markovnikov addition product in each case.
