Kinetics and Mechanism of the Reaction between Barbituric Acid and Glycidol, Part III: Methylene Group Reaction with Glycidol at High Concentration

Abstract

The reaction of barbituric acid and glycidol leads to formation of oligoetherols upon addition of glycidol both to the methylene group and imide groups of barbituric acid. The mechanism of reaction was established by kinetic studies on the reaction between 1,3‐dimethylbarbituric acid and glycidol used at high concentration. The obtained rate law and mechanism have been derived from kinetic studies and the results obtained before, where 1,3‐dimethylbarbituric acid and glycidol were used in comparable concentrations. The completed kinetic characteristics of the system is described. It has been found that glycidol reacted with methylene groups of 3‐dimethylbarbituric according to the equation: V=k1/2′·c AH 1/2·cB1/2. The rate‐determining step was transformation of enolate into carbanion. Activation energy of the reaction was 61.3 kJ mol−1 · K−1. Proton transfer from methylene group of 1,3‐dimethylbarbituric into glycidol oxirane oxygen was observed by the 1H‐NMR spectroscopy.

The Kinetics and Mechanism of the Reaction between Barbituric Acid and Glycidol, Part I: The Products Analysis

“…The protocols for hydroxyalkylation reactions of cyclic monoimides were reported before , although no mechanistic or kinetics details were studied except those from our laboratory . However, the various mechanisms of reaction between oxiranes with alcohols , phenols , thiols , carboxylic acids , and amines were described depending on substrate and product acidity and kind of a catalyst used .…”