A simple linear regression (Q equation) is devised to position solvolyses within the established SN2‐SN1 spectrum of solvolysis mechanisms. Using 2‐adamantyl tosylate as the SN1 model and methyl tosylate as the SN2 model, the equation is applied to solvolyses of ethyl, allyl, secondary alkyl and a range of substituted benzyl and benzoyl tosylates. Using 1‐adamantyl chloride as the SN1 model and methyl tosylate as the SN2 model, the equation is applied to solvolyses of substituted benzoyl chlorides in weakly nucleophilic media. In some instances, direct correlations with methyl tosylate were employed. Grunwald–Winstein l values and kinetic solvent isotope effects are also used to locate solvolyses within the spectrum of mechanisms. Product selectivities (S) for solvolyses at 50 °C of p‐nitrobenzyl tosylate in binary mixtures of alcohol–water and of alcohol–ethanol for five alcohols (methanol, ethanol, 1‐propanol and 2‐propanol and t‐butanol) are reported and show the expected order of solvent nucleophilicity (RCH2OH > R2CHOH > R3COH). The data support the original assignments establishing the NOTs scale of solvent nucleophilicity. Copyright © 2016 John Wiley & Sons, Ltd.

For solvolyses of various benzyl substrates in ethanol–water (EW) and methanol–water (MW) mixtures, product selectivities (S) are reported for chlorides at 75 °C defined as follows using molar concentrations: S = ([ether product]/[alcohol product]) × ([water]/[alcohol solvent]). The results support earlier evidence that solvolyses of 4‐nitrobenzyl substrates are SN2 processes, which are not susceptible to mechanistic changes over the whole range of solvents from water to alcohol. S values at 25 and/or 45 °C in EW and MW, and additional kinetic data including kinetic solvent isotope effects (KSIE) are reported for solvolyses of 4‐nitrobenzyl mesylate and tosylate. A kinetic model, explaining both rates and product, is proposed; a general medium effect due to solvent polarity is combined in one parameter with solvent effects on the nucleophilicity of the water and alcohol molecules acting as nucleophiles in SN2 reactions. According to this model, as alcohol is added to water the rate of reaction decreases due to a decrease in solvent polarity, but the nucleophilicity of water increases relative to alcohol. The availability of experimental rate and product data over the whole range of solvent compositions from alcohol to water, reveals limitations of alternative approaches using activities. Copyright © 2008 John Wiley & Sons, Ltd.

The rates of solvolysis of 4-morpholinecarbonyl chloride (MPC) have measured at 35.0 o C in water, D2O, CH3OD, and in aqueous binary mixtures of acetone, ethanol, methanol, and 2,2,2-trifluoroethanol. An extended (two-term) Grunwald-Winstein equation correlation gave sensitivities towards changes in solvent nucleophilicity and solvent ionizing power as expected for a dissociative SN2 and/or SN1(ionization) pathway. For nine solvents specific rates were determined at two additional temperatures and higher enthalpies and smaller negative entropies of activation were observed, consistent with the typical dissociative SN2 or SN1(ionization) pathway. The solvent deuterium isotope effect values for the hydrolysis of MPC of kH 2O /kD 2O = 1.27 and for the methanolysis of MPC of kMeOH/kMeOD = 1.22 are typical magnitudes of the SN1 or ionization mechanism.

Rate constants for solvolysis of 2‐methylfuran‐3‐carbonyl chloride (1) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, acetone, 2,2,2‐trifluoroethanol, and 1,1,1,3,3,3‐hexafluoro‐2‐propanol are reported. The 34 solvents give an extended Grunwald–Winstein correlation with l = 0.26 ± 0.05, m = 0.71 ± 0.04, and correlation coefficient R2 = 0.963. Activation parameters calculated from the rate constants measured at three different temperatures in five different solvents are presented. In the deuterated methanol, a solvent kinetic isotope effect of 1.15 was observed at 0°C. The kinetic features observed indicate that the reaction proceeds through an SN1 mechanism with a little SN2 character. The reactivity–selectivity principle is also followed in alcohol‐water mixtures.

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