Kinetics and Mechanism of the Reaction of para-Chlorophenyl Aryl Chlorophosphates with Pyridines in Acetonitrile

초록

Bilkis Jahan Lumbiny, Chan Kyung Kim, Bon-Su Lee amd Hai Whang Lee Department of Chemistry. Inha University, South Korea The Kinetics and mechanism of the pyridinoysis of p-chlorophenyl arly chlorophosphates (p-CIC6H4OP(=O)(CI)OC6H4Y) have been carried out actonitrile at 5℃. A series of works for P=O system have repoted from this laboratory. Lee and coworkers have reported exprimentally the nucleophilic substitution reaction of p-chlorophenyl aryl chlorophosphates with anilines (Lee et al ; Int. J. Chem. kinet,. 2002, 34, 632-637). All the results (pX, pY, βX, pXY, kinetic isotope effects and activation parameters) are consistent with a concerted nucleophilic substitution at substrate, Y = H and Y = p-CH3O were observerd for this reaction. The rates are found faster for the pyridinolysis than those for the aminolysis. βx values are smaller in this work (1.14~1.19) than its aminolysis (1.43~1.49). It indicates the degree of bond formation in case of pyridines in TS is smaller than anilines. px values are found (-5.62 ~ -5.87). Negative px indicates + ve charge development in reaction center which is consistent with that of aminolysis, px (-4.04 ~ -4.24). Our interest is centered on the pyridinolysis of the same substrates as aminolysis for comparative mechanistic investigation changing nucleophile from primary to tertiary amine.