Skip to main content
Login | Suomeksi | På svenska | In English

Kinetics and Thermochemistry of the Reactions of Propargyl-Type Radicals with Molecular Oxygen

Show full item record

Title: Kinetics and Thermochemistry of the Reactions of Propargyl-Type Radicals with Molecular Oxygen
Author(s): Pekkanen, Timo Theodor
Contributor: University of Helsinki, Faculty of Science, Department of Chemistry
Discipline: Physical Chemistry
Language: English
Acceptance year: 2016
The oxygen reactions of hydrocarbon radicals are important both in combustion and atmospheric chemistry. In this thesis I have studied the oxygen reactions of propagyl-type radicals (propargyl, 1-methylpropargyl, 3-methylpropargyl and 3-ethylpropargyl). Propargyl radical (2-propyn-1-yl) is an alkyl radical with the structure H3C≡C–CH2● . Because these radicals are resonance stabilised, their oxygen reactions are relatively slow. This means that in a combustion environment they might reach an high enough concentration for their self-reactions to become important. The self-reactions of unsaturated radicals are the first step in the formation of polyaromatic hydrocarbons. I measured the rate coefficients and equilibrium constants for the oxygen reactions of 3-methylpropargly and 3-ethylpropargly at low pressures (0.2 – 3 Torr) using a tubular flow reactor coupled to a resonance-gas-discharge-lamp photoionisation mass spectrometer (PIMS). Laser photolysis was used to generate the radicals. I have compared my experimental results to previous studies done for the propargyl + O2 and 1-methylpropargyl + O2 reactions. I reanalysed the equilibrium data from these previous studies with an improved kinetic mechanism. At temperatures below 500 K the reactions were found to be dependent on bath gas pressure and they also had negative temperature dependence. The reactivity order was found to be 3-ethylpropargyl > 3-methylpropargyl ≈ 1-methylpropargyl > propargyl. Standard reaction enthalpies and entropies are reported for all four reactions. The experimental results were combined with quantum chemical computations.

Files in this item

Files Size Format View
GraduTimoPekkanen.pdf 3.362Mb PDF

This item appears in the following Collection(s)

Show full item record