Fragmentation of 2-(dialkylamino)ethyl phosphate derivatives. Mechanism change as a function of substituents at phosphorus
The products and the first-order rate constants for the fragmentation of six phosphonic diesters (2) and two phosphonic monester chlorides (3), all containing the 2-(dialkylaminoethyl) group as one of the ester functions, have been determined. On the basis of different reaction products, different rates of decomposition, and different activation parameters, a new mechanism for the fragmentation of ester chlorides (3) is proposed: fragmentation involving release of the chloride ion and the formation of the 1,1-dialkylaziridinium ion and metaphosphonate as the reactive intermediates. Keywords: fragmentation of phosphates and phosphorochloridates, "metaphosphate" mechanism of phosphates, activation entropy in mechanistic change, 2-(dialkylamino)ethylphosphates.