Amazing Substituent Effects on the Pyridinolysis of Aryl Ethyl Chlorophosphates in Acetonitrile

초록

The reactions of Y-aryl phenyl chlorophosphates with X-pyridines have been studied kinetically in t\acetonitrile at 35oC, where X = (4-OMe, 4-Me, 3-Me, H, 3-PH, 3-Cl, 3-CN, 4-CN, 4-Ac) and Y=(4-MeO, 4-Me, 3-Me, H, 3-MeO). The two strong pi-acceptor substutients, X=4-Ac and 4-CN in the X-pyridine, exhibit great positive deviation from the Hammett plots while small positive deviation from the Bronsted plots. The Hammett plots (Fig. 1) for substituent Y variations in the substrates are beautiful: changing from biphasic concave downwards with the strongly basic pyridines, via linear with X=H, to biphasic concave upwards with the weakly basic pyridines.