Theoretical study of the mechanism of thermal decomposition of carbonate esters in the gas phase

Abstract

Theoretical studies on the thermolysis in the gas phase of ethyl methyl and diethyl carbonates were carried out using ab initio theoretical methods at the MP2/6-31G(d) and MP2/6-311þþG(2d,p) levels of theory. Two possible pathways were studied, one of them via a six-membered cyclic transition state and the other one in two steps, via a six-and a four-membered cyclic transition state, respectively, with the formation of an alcohol, ethylene and carbon dioxide. The nucleophilic substitution to give ethers was also studied. The results indicate that the reactions occur via a mechanism in two steps. The progress of the reactions was followed by means of the Wiberg bond indices. The kinetic parameters calculated for the studied reactions agree well with the available experimental results.

An experimental and modeling study of diethyl carbonate oxidation

“…Subsequently, EFA undergoes rapid molecular elimination forming ethanol and CO 2 (R2) [21]. The activation energy for R2 was taken from the barrier height computed by Notario et al [24] and the pre-exponential factor was derived from their computed rate constant at 600 K. These two reactions (R1 and R2) lead to the net reaction of DEC to form ethylene, ethanol and CO 2 which is the main consumption path of DEC under all conditions investigated in this study.…”

Understanding the mechanism of the decomposition reaction of nitroethyl benzoate through the Molecular Electron Density Theory

“…The thermal decomposition of alkyl esters to produce alkenes and carboxylic acids is a well-established process experimentally investigated a great number of times [1][2][3][4][5]. Detailed reviews that report on many studies involving the kinetics and mechanism of the decomposition of esters are available [4,5].…”

DFT Study of substituent effects of 2‐substituted alkyl ethyl methylcarbonates in homogeneous, unimolecular gas phase elimination kinetics

“…While this work was in progress, regretfully the authors of recent publication on the theoretical study of the mechanism of elimination of ethyl methyl and diethylcarbonates [16] were unaware of the abovementioned investigation [13], where the kinetic parameters on ethyl methyl carbonate pyrolysis were shown to be nearly similar to that of Taylor's results (Table I).…”

“…For the reported theoretical calculation [16] on the kinetic parameters of ethyl methyl carbonate using the MP2/6-31G(d) and MP2/6-311++G(2d,p) levels of theory for the ethyl methyl carbonate elimination process, the following parameters were obtained: Ea = 202.1 kJ/mol, log A = 13.9,…”