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I. Thermochemistry and reaction kinetics of disolvated protons by ion cyclotron resonance spectroscopy. II. Thermochemical studies of small fluorocarbons by photoionization mass spectrometry

Citation

Berman, D. Wayne (1981) I. Thermochemistry and reaction kinetics of disolvated protons by ion cyclotron resonance spectroscopy. II. Thermochemical studies of small fluorocarbons by photoionization mass spectrometry. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:06042015-131748215

Abstract

The disolvated proton, H(OH2)2+ is employed as a chemical reagent in low pressure (˂ 10-5 torr) investigations by ion cyclotron resonance spectroscopy. Since termolecular reactions are absent at low pressure, disolvated protons are not generally observed. However H(OH2)2+ is produced in a sequence of bimolecular reactions in mixtures containing H2O and one of a small number of organohalide precursors. Then a series of hydrated Lewis bases is produced by H3O+ transfer from H(OH2)2+. In Chapter II, the relative stability of hydrated bases containing heteroatoms of both first and second row elements is determined from the preferred direction of H3O+ transfer between BH(OH2)+ complexes. S and P containing bases are shown to bind H3O+ more weakly than O and N bases with comparable proton affinities. A simple model of hydrogen bonding is proposed to account for these observations.

H+ transfer from H(OH2)2+ to several Lewis bases also occurs at low pressure. In Chapter III the relative importance of H3O+ transfer and H+ transfer from H(OH2)2+ to a series of bases is observed to be a function of base strength. Beginning with CH3COOH, the weakest base for which H+ transfer is observed, the importance of H+ transfer increases with increasing proton affinity of the acceptor base. The nature of neutral products formed from H(OH2)2+ by loss of H+ is also considered.

Chapters IV and V deal with thermochemistry of small fluorocarbons determined by photoionization mass spectrometry. The enthalpy of formation of CF2 is considered in Chapter IV. Photoionization of perfluoropropylene, perfluorocyclopropane, and trifluoromethyl benzene yield onsets for ions formed by loss of a CF2 neutral fragment. Earlier determinations of ΔH°f298 (CF2) are reinterpreted using updated thermochemical values and compared with results of this study. The heat of formation of neutral perfluorocyclopropane is also derived. Finally, the energetics of interconversion of perfluoropropylene and perfluorocyclopropane are considered for both the neutrals and their molecular ions.

In Chapter V the heats of formation of CF3+ and CF3I+are derived from photoionization of CF3I. These are considered with respect to ion-molecule reactions observed in CF3I monitored by the techniques of ion cyclotron resonance spectroscopy. Results obtained in previous experiments are also compared.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Restricted to Caltech community only
Research Advisor(s):
  • Beauchamp, Jesse L.
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 December 1980
Record Number:CaltechTHESIS:06042015-131748215
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:06042015-131748215
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8984
Collection:CaltechTHESIS
Deposited By: Leslie Granillo
Deposited On:04 Jun 2015 22:48
Last Modified:04 Jun 2015 22:49

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