Kinetics and Mechanism of the Reaction od the para-Chlorophenyl Aryl Chlorophospoats with Pyridines in MecN

초록

The kinetics and mechanism of the nucleophilic substitution reactions of p-chlorophenyl aryl chlorophsphates have been carried out in acetonitrile. The minolysis of the same substrates was reported (Lee et al ; Int. J. Chem. Kinet., 2002, 34, 632-637), following a concerted nuclophilic substitution mechanism. The second-order rate constant for substituent at MeCN, X=H (pKa = 5.21) and substituent at substrate, Y=H (sY=0) in acetonitrile, k2 = 897.0 " 10-4 M-1s-1 at 55.00C which is 2 fold faster than corresponding value for the pyridynolysis, k2=505 " 10-4 M-1s-1at 35.00C and 75 fold faster than corresponding value for aminolysis (k2 = 12.0 " 10-4M-1s-1) under the same reaction condition. Our interest is contered on the pytidynolysis of the same substrates for comparative mechanistic inverstigation changing nucleophili from primary to tertiary amine.