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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 34, Number 12
BKCSDE 34(12)
December 20, 2013 

 
Title
Dual Substituent Effects on Anilinolysis of Bis(aryl) Chlorothiophosphates
Author
Hasi Rani Barai, Hai Whang Lee*
Keywords
Dual substituent effect, Anilinolysis, Bis(aryl) chlorothiophosphate, Deuterium kinetic isotope effect, Cross-interaction constant
Abstract
The reactions of bis(Y-aryl) chlorothiophosphates (1) with substituted anilines and deuterated anilines are investigated kinetically in acetonitrile at 55.0 oC. The Hammett plots for substituent Y variations in the substrates show biphasic concave upwards with a break point at Y = H. The cross-interaction constants (ρXY) are positive for both electron-donating and electron-withdrawing Y substituents. The kinetic results of 1 are compared with those of Y-aryl phenyl chlorothiophosphates (2). The cross-interaction between Y and Y, due to additional substituent Y, is significant enough to result in the change of the sign of ρXY from negative with 2 to positive with 1. The effect of the cross-interaction between Y and Y on the rate changes from negative role with electron-donating Y substituents to positive role with electron-withdrawing Y substituents, resulting in biphasic concave upward free energy correlation with Y. A stepwise mechanism with a rate-limiting leaving group departure from the intermediate involving a predominant frontside attack hydrogen bonded, four-centertype transition state is proposed based on the positive sign of ρXY and primary normal deuterium kinetic isotope effects.
Page
3597 - 3601
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