0000000000451260
AUTHOR
Montserrat Ochando-pardo
Enthalpies of formation of isoprene’s major oxidation byproducts
Abstract The theoretical enthalpies of formation ( Δ f H 298 . 15 ∘ ) of methyl vinyl ketone (MVK, CH 2 CHC(O)CH 3 ), methacrolein (MACR, CH 2 C(CH 3 )CHO), and the radical products formed in their corresponding OH radical oxidations have been calculated with DFT (MPW1K/6-31+G(d,p)) and multilevel (MCCM-UT-CCSD(T)//MPW1K/6-31+G(d,p)) methods. The bond dissociation energies ( BDE , DH 298 . 15 0 ) of the H-atoms that can be abstracted from the MVK and MACR molecules, and the C–O forming bonds of the OH addition products are also calculated. The regioselectivity of the global reaction is discussed in terms of bond strength.
Spanish Secondary School Students' Notions on the Causes and Consequences of Climate Change
This paper is part of an extensive study of secondary school students' preconceived ideas about climate change. Here, we undertake a survey in the province of Valencia (Spain) to ascertain secondary school students' notions of the causes and consequences of climate change. Results show, among other things, that students clearly relate the misuse of motor vehicles and factory emissions to the problem. However, the obvious correlation with household energy use is not observed. The usual confusion with other environmental problems, such as the hole in the ozone layer, as described in previous studies, is also detected. Students know almost no greenhouse gases other than CO2, while the socio‐ec…
Methyl vinyl ketone+OH and methacrolein+OH oxidation reactions: a master equation analysis of the pressure- and temperature-dependent rate constants.
High-level electronic structure calculations and master equation analyses were carried out to obtain the pressure- and temperature-dependent rate constants of the methyl vinyl ketone+OH and methacrolein+OH reactions. The balance between the OH addition reactions at the high-pressure limit, the OH addition reactions in the fall-off region, and the pressure-independent hydrogen abstractions involved in these multiwell and multichannel systems, has been shown to be crucial to understand the pressure and temperature dependence of each global reaction. In particular, the fall-off region of the OH addition reactions contributes to the inverse temperature dependence of the rate constants in the Ar…
Pressure dependence in the methyl vinyl ketone + OH and methacrolein + OH oxidation reactions: an electronic structure study.
High-level electronic structure calculations were carried out for the study of the reaction pathways in the OH-initiated oxidations of methyl vinyl ketone (MVK) and methacrolein (MACR). For the two conformers of MVK (called synperiplanar and antiperiplanar), the addition channels of OH to the terminal and central carbon atom of the double bond dominate the overall rate constant, whereas the abstraction of the methyl hydrogen atoms has no significant kinetic role. In the case of MACR, only the antiperiplanar conformer is important in its reactivity. In addition, the lower Gibbs free energy barrier for MACR corresponds to the aldehydic hydrogen abstraction reaction, which will be somewhat mor…