Dual Substituent Effects on Pyridinolysis of Bis(aryl) Chlorothiophosphates in Acetonitrile

作者：Barai Hasi Rani; Lee Hai Whang^*

来源：BULLETIN OF THE KOREAN CHEMICAL SOCIETY, 2014, 35(6): 1754-1758.

DOI：10.5012/bkcs.2014.35.6.1754

• Dual substituent effects
• Cross-interaction constant
• Pyridinolysis
• Bis(Y-aryl) chlorothiophosphates
• Thiophosphoryl transfer reaction

The nucleophilic substitution reactions of bis(Y-aryl) chlorothiophosphates (1) with X-pyridines are investigated kinetically in acetonitrile at 35.0 degrees C. The free energy relationships with both X and Y are biphasic concave upwards with a break point at X = 3-Ph and Y = H, respectively. The sign of cross-interaction constants (CICs; rho xy) is positive with all X and Y. Proposed mechanism is a stepwise process with a rate-limiting leaving group departure from the intermediate with all X and Y. The kinetic results of 1 are compared with those of Y-aryl phenyl chlorothiophosphates (2). In the case of Y = electron-withdrawing groups, the cross-interaction between Y and Y, due to additional substituent Y, is significant enough to change the sign of rho xy from negative with 2 to positive with 1, indicative of the change of mechanism from a rate-limiting bond formation to bond breaking.

• 出版日期2014-6-20