KINETIC-STUDY OF PROTON NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY OF THE REACTION BETWEEN ETHYL PYRUVATE AND DIETHYL PHOSPHITE YIELDING 2-DIETHOXYPHOSPHONYL-2-HYDROXYPROPIONIC ACID ETHYL-ESTER

A kinetic study of the reaction of ethyl pyruvate (A) with diethyl pho sphite (B) yielding 2-diethoxyphosphonyl-2-hydroxypropionic acid ethyl ester (C), an intermediate product for the preparation of 2-dihydroxy phosphonyl-2-hydroxypropionic acid, which can be used as a corrosion a nd scale inhibitor, was carried out in the present work by using the t echnique of proton nuclear magnetic resonance (H-1-NMR) spectroscopy. The H-1-NMR spectra of the reaction mixture show that the singlet at 2 .07delta assigned to CH3COCOOEt (reactant A) was reduced, while that a t 5.48delta assigned to the hydroxyl proton of the reaction product C was increased with the progress of the chemical reaction, making possi ble a kinetic study of the reaction mentioned. The reaction of A with an equimolar amount of B yielding C was found to be of second order (f irst order with respect to A and first order with respect to B). On th e other hand the reaction between A and B when the reagent B is in exc ess (molar ratio n(A)/n(B) = 1:3) was found to be of pseudo-first orde r with respect to A, although we believe that the apparent and not the intrinsic order of the reaction is changed by using a 1:3 ratio of re agents. Arrhenius activation parameters (E(a), In A, DELTAH(not-equal) and DELTAS(not-equal)) were computed in both cases.