Kinetics and mechanism of the pyridinolysis of aryl furan-2-carbodithioates in acetonitrile.

doi:10.1021/JO0264269

Paper

Kinetics and mechanism of the pyridinolysis of aryl furan-2-carbodithioates in acetonitrile.

Published Dec 13, 2002 · H. Oh, Myoung Hwa Ku, H. Lee

The Journal of organic chemistry

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60

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Abstract

Kinetic studies on the pyridinolysis of aryl furan-2-carbodithioates 1 are carried out at 60.0 degrees C in acetonitrile. The biphasic rate dependence on the pyridine basicity with a breakpoint at pK(a) degrees = 5.2 is interpreted to indicate a change of the rate-limiting step from breakdown (beta(X) = 0.7-0.8) to formation (beta(X) = 0.2) of the tetrahedral intermediate, T(+/-), at the breakpoint as the basicity of the pyridine nucleophile is increased. Observation of the breakpoint is possible with pyridines since the expulsion rate of the pyridine (k(-)(a)) from T(+/-) is sufficiently low, with the low k(-)(a)/k(b) ratio leading to a low breakpoint, pK(a) degrees. The clear-cut change in the cross-interaction constants, rho(XZ), from a positive (rho(XZ) = +0.86) to a small negative (rho(XZ) = -0.11) value at the breakpoint supports the mechanistic change proposed. The magnitudes of rho(Z) and activation parameters are also consistent with the proposed mechanism.

Study Snapshot

The pyridinolysis of aryl furan-2-carbodithioates in acetonitrile involves a change in the rate-limiting step from breakdown to formation of the tetrahedral intermediate, T(+/-), as pyridine nucleophile basicity increases

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

Paper

Kinetics and mechanism of the pyridinolysis of aryl furan-2-carbodithioates in acetonitrile.

References

Citations

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