Document Type

Dissertation

Date of Award

Fall 2017

Degree Name

Doctor of Philosophy in Chemistry - (Ph.D.)

Department

Chemistry and Environmental Science

First Advisor

Joseph W. Bozzelli

Second Advisor

Tamara M. Gund

Third Advisor

Alexei Khalizov

Fourth Advisor

Mengyan Li

Fifth Advisor

Gennady Gor

Abstract

Fundamental thermochemical properties including enthalpies (ΔH°f 298), entropies (S°(T)), heat capacities (Cp(T)), and bond dissociation energies (BDEs) for several common and complex hydrocarbon fuel species are determined using computational chemical methods. ΔH°f 298 values are calculated using isodesmic reactions with the CBS-APNO, CBS-4M, CBS-QB3, G2, G3, G4, Weizmann-1 (W1U) and M06-2X, ωB97X, B3-LYP with basis set 6-31G+ (d,p) and 6-31G++(d,p) calculation methods. Structures, moments of inertia, vibrational frequencies, and internal rotor potentials are calculated for contributions to entropies and heat capacities. Kinetic rate parameters are calculated for hydrogen abstraction and chemical activation reactions.

The recommended ideal gas phase ΔH°f298 (kcal mole-1) values calculated for several normal hydrocarbons and fluorinated species including corresponding radicals from loss of hydrogen atoms show strong comparison to available literature values.

Ethers C—H BDEs in the primary position in comparison to the secondary position increase by 3-8 kcal mole-1 for aliphatic chains. Cyclic ethers posses Entropies (S*298 in cal/mole K) are estimated using B3-LYP methodology with basis sets 6-31+G(d,p) and 6-31++G(d,p) computed frequencies and geometries. Rotational barriers are determined and hindered internal rotational contributions for S*298K and Cp(T) are calculated using the rigid rotor harmonic oscillator approximation, with direct integration over energy levels of intramolecular rotation potential energy curve.

Thermochemical properties for the fluorinated carbon groups CO/C/F, C/CO/F3, C/CO/F/H2, C/C/CO/F/H, C/C/CO/F2, and C/C/CO/F/H are investigated. Previously published enthalpies for fluoroacetaldehyde, fluoroacetaldehyde fluoride, difluoroacetaldehyde, difluoroacetaldehyde fluoride, trifluoroacetaldehyde and trifluoroacetaldehyde fluoride that were previously determined via isodesmic reactions schemes are revised using updated reference species values.

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Chemistry Commons

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