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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 23, Number 5
BKCSDE 23(5)
May 20, 2002 

Kinetics and Mechanism of the Pyridinolysis of Aryl Cyclobutanecarboxylates in Acetonitrile
Han Joong Koh, Kwang Lae Han, Hai Whang Lee, Ikchoon Lee
Aryl cyclobutanecarboxylates, Stepwise mechanism, Zwitterionic tetrahedral intermediate, Cross-interaction constant.
Kinetic studies of the reaction of Z-aryl cyclobutanecarboxylates with X-pyridines in acetonitrile at 55.0℃ have been carried out. The reaction proceeds by a stepwise mechanism in which the rate-determining step is the breakdown of the zwitterionic tetrahedral intermediate, T ± . These mechanistic conclusions are drawn based on (i) the large magnitude of ρX and ρZ, (ⅱ) the positive sign of ρXZ and the larger magnitude of ρXZ than normal SN2 processes, (ⅲ) a small positive enthalpy of activation, ΔH , and a large negative, ΔS , and lastly (iv) adherence to the reactivity-selectivity principle (RSP) in all cases.
715 - 720
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