Ethyl trichloroacetate hydrolysis. III. Solvent isotope effects and thermodynamic activation parameters for the water-catalyzed hydrolysis

A study was carried out on the solvolysis of 1-adamantyl chlorothioformate (1-AdSCOCl, 1) in hydroxylic solvents. The rate constants of the solvolysis of 1 were well correlated using the Grunwald–Winstein equation in all of the 20 solvents (R = 0.985). The solvolyses of 1 were analyzed as the following two competing reactions: the solvolysis ionization pathway through the intermediate (1-AdSCO)+ (carboxylium ion) stabilized by the loss of chloride ions due to nucleophilic solvation and the solvolysis–decomposition pathway through the intermediate 1-Ad+Cl− ion pairs (carbocation) with the loss of carbonyl sulfide. In addition, the rate constants (kexp) for the solvolysis of 1 were separated into k1-Ad+Cl− and k1-AdSCO+Cl− through a product study and applied to the Grunwald–Winstein equation to obtain the sensitivity (m-value) to change in solvent ionizing power. For binary hydroxylic solvents, the selectivities (S) for the formation of solvolysis products were very similar to those of the 1-adamantyl derivatives discussed previously. The kinetic solvent isotope effects (KSIEs), salt effects and activation parameters for the solvolyses of 1 were also determined. These observations are compared with those previously reported for the solvolyses of 1-adamantyl chloroformate (1-AdOCOCl, 2). The reasons for change in reaction channels are discussed in terms of the gas-phase stabilities of acylium ions calculated using Gaussian 03.

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Kinetic solvent isotope effects [k(H2O)/k(D2O)] for benzyl nitrate, 4-chlorobutan-l-ol and piperidylsulphamoyl chloride. The significance of activation parameters to the mechanism of the reaction

Journal of the Chemical Society Faraday Transactions 1 Physical Chemistry in Condensed Phases ◽

10.1039/f19848002287 ◽

1984 ◽

Vol 80 (8) ◽

pp. 2287 ◽

Cited By ~ 3

Author(s):

Michael J. Blandamer ◽

John Burgess ◽

Ross E. Robertson ◽

Kalavelil M. Koshy ◽

Edward C. F. Ko ◽

...

Keyword(s):

Isotope Effects ◽

Activation Parameters ◽

Solvent Isotope ◽

Solvent Isotope Effects ◽

Mechanism Of The Reaction

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Rate and Product Studies in the Solvolyses of Two Arenesulfonic Anhydrides

Journal of Chemical Research ◽

10.3184/030823407x218084 ◽

2007 ◽

Vol 2007 (6) ◽

pp. 365-369 ◽

Cited By ~ 5

Author(s):

Dennis N. Kevill ◽

Zoon Ha Ryu

Keyword(s):

Binary Mixtures ◽

Isotope Effects ◽

Activation Parameters ◽

Product Selectivity ◽

Displacement Reactions ◽

Solvent Isotope ◽

Solvent Isotope Effects

The specific rates of solvolysis of benzenesulfonic anhydride (1) and p-toluenesulfonic anhydride (2) have been measured conductometrically at −10°C in 34 solvents for 1 and 33 solvents for 2. Studies at higher temperatures have allowed extrapolated values in additional solvents to be calculated. All of the values, for 35 solvents for 1 and for 37 solvents for 2, have been used in an extended Grunwald–Winstein equation treatment using NT and YOTs values. Activation parameters in several solvents and kinetic solvent isotope effects (MeOH/MeOD) have been determined for both substrates. Product selectivity values ( S) have been determined for binary mixtures of water with ethanol, methanol, or 2, 2, 2-trifluoroethanol. The results from the kinetic and product studies are compared to those previously reported for methanesulfonic anhydride (3). An SN2 mechanism is proposed for the solvolytic displacement reactions of the three substrates in all of the solvents used in the investigation.

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