A joint computational modeling and FT-IR analysis on propene

Abstract

Propene, commonly known as propylene, of empirical formula C3H6, is one of the simplest alkenes. Despite its simplicity, propene has recently gained interest both in the astrochemical and environmental fields. Propene has been observed in space toward the dark cloud TMC-1 and on Titan’s atmosphere through rotational spectroscopy, and it has been taken into consideration as a possible precursor of chiral molecules, such as propylene oxide, interesting from an astrobiological point of view. Aside from the natural sources, propene is mainly produced from biomass burning, thermal cracking of hydrocarbons, and incomplete combustion of fossil fuels. Propene and its fluoride derivatives represent a valid alternative to chlorofluorocarbons (CFCs), extremely pollutant refrigerant gases, because of their low global warming potential and their low toxicity for human life. An extensive computational survey on propene has not been done to date, therefore during the internship we focused on a wide density functional theory (DFT) benchmark study, which could be helpful also for future theoretical investigations of propene’s higher homologues. The best functionals, obtained from the benchmark, were then used to calculate fundamental frequencies and ground-state rotational constants of propene with different approaches based on the vibrational second-order perturbation theory (VPT2). These results were fundamental for the assignment of the vibrational bands of propene’s infrared spectra, that has been done at different pressures and resolutions, as well as with several types of cells. Finally, the kinetic of the addition reaction of hydroxyl radical to propene has been also addressed, together with the evaluation of the global warming potential (GWP), to assess the impact of propene, as alternative refrigerant gas, on the environment.