Honors Project On-Campus Access Only
Carbonyl oxides, which are formed from alkenes through ozonolysis, play an important role in atmospheric chemistry. This study examined their rearrangement into carboxylic acids with the aid of another molecule that acts as a catalyst. Because carbonyl oxides are very unstable, computation is useful in studying this reaction. The bimolecular pathways for the reaction of formaldehyde oxide with CO2, SO2, NO2 and NO were studied. The geometries of all structures involved and their energies were calculated using several computational methods: BB1K/6-31+G(d,p), B3LYP/6-31+G(d,p), CBS-QB3, G3 and CBS-APNO. In each pathway, the carbonyl oxide and catalyst molecule formed a cyclic adduct, which then broke apart into a carboxylic acid and the catalyst. Depending on the catalyst used, the adduct could form and break apart in one or more steps or other pathways forming different products were possible. These reactions were also studied with a methyl group on the carbonyl oxide. The relative energies for the reaction were similar to the non-methylated pathways, although the placement of the methyl group on either the syn or anti position affected the reaction mechanism and energy. Transition state theory was used to determine the rate of the first step in each reaction and indicated that the SO2 reaction should occur at the highest relative rate. RRKM theory was used to determine branching ratios for the reactions.
Guinn, Emily J., "A Computational Analysis of Bimolecular Processes Involving Carbonyl Oxides in the Atmosphere" (2008). Chemistry Honors Projects. Paper 3.
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