Thermal decomposition of FC(O)OCH3 and FC(O)OCH2CH3

ARGÜELLO, GUSTAVO A.; BURGOS PACI, MAXI ALBERTO; BERASATEGUI, MATIAS

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2018 vol. 20 p. 12817 - 12826

1463-9076

The thermal decomposition of methyl and ethyl formates has been extensively studied due to their importancein the oxidation of several fuels, pesticidal properties and their presence in interstellar space. We hithertopresent the study of the thermal decomposition of methyl and ethyl fluoroformates, which could help in theelucidation of the reaction mechanisms. The reaction mechanisms were studied using FTIR spectroscopy in thetemperature range of 453?733 K in the presence of different pressures of N2 as bath gas. For FC(O)OCH3 twodifferent channels were observed; the unimolecular decomposition which is favored at higher temperaturesand has a rate constant kFC(O)OCH3 = (5.3 Æ 0.5) Â 1015 exp[À(246 Æ 10 kJ molÀ1/RT)] (in units of sÀ1) and abimolecular channel with a rate constant kFC(O)OCH3 = (1.6 Æ 0.5) Â 1011 exp[À(148 Æ 10 kJ molÀ1/RT)](in units of sÀ1 (mol L)À1). However for ethyl formate, only direct elimination of CO2, HF and ethyleneReceived 27th December 2017, operates. The rate constants of the homogeneous first-order process fit the Arrhenius equationAccepted 28th March 2018 kFC(O)OCH2CH3 = (2.06 Æ 0.09) Â 1013 exp[À(169 Æ 6 kJ molÀ1/RT)] (in units of sÀ1). The difference betweenDOI: 10.1039/c7cp08656c the mechanisms of the two fluoroformates relies on the stabilization of a six-centered transition statethat only exists for ethyl formate. First principles calculations for the different channels were carried outto understand the dynamics of the decomposition.