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Title: Tert-butyl ion heat of formation and the isobutene proton affinity

Abstract

A new value of the tert-butyl ion heat of formation has been measured by dissociative ionization of tert-butyl iodide using the photoelectron photoion coincidence technique. The derived [Delta]H[sub f][degrees][sub 0](t-C[sub 4]H)[sup +] of 734 kJ/mol and [Delta]H[sub f][degrees][sub 298](t-C[sub 4]H[sub 9][sup +]) of 711 kJ/mol is 20 kJ/Mol higher than previous experimental measurements, but agrees within 1 kJ/mol with a recent theoretical ab initio calculation. The derived proton affinity for isobutene is thus 802 kJ/mol at 298 K. With these values established, we predict a tert-butyl radical ionization potential of 6.85 eV, which is close to Houle and Beauchamp's vertical IP from PES (6.92 eV) and Lossing's reported onset of 6.92 eV. However, it is considerably higher than the reported adiabatic IP of 6.7 eV. 24 refs., 1 fig., 1 tab.

Authors:
; ;  [1]
  1. Univ. of North Carolina, Chapel Hill, NC (United States)
Publication Date:
OSTI Identifier:
5065455
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society; (United States)
Additional Journal Information:
Journal Volume: 115:26; Journal ID: ISSN 0002-7863
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BUTENES; AFFINITY; BUTYL RADICALS; IONIZATION; IODIDES; DISSOCIATION; IONS; FORMATION HEAT; PROTONS; ALKENES; ALKYL RADICALS; BARYONS; CHARGED PARTICLES; ELEMENTARY PARTICLES; ENTHALPY; FERMIONS; HADRONS; HALIDES; HALOGEN COMPOUNDS; HYDROCARBONS; IODINE COMPOUNDS; NUCLEONS; ORGANIC COMPOUNDS; PHYSICAL PROPERTIES; RADICALS; REACTION HEAT; THERMODYNAMIC PROPERTIES; 400201* - Chemical & Physicochemical Properties; 661300 - Other Aspects of Physical Science- (1992-)

Citation Formats

Keister, J W, Riley, J S, and Baer, T. Tert-butyl ion heat of formation and the isobutene proton affinity. United States: N. p., 1993. Web. doi:10.1021/ja00079a062.
Keister, J W, Riley, J S, & Baer, T. Tert-butyl ion heat of formation and the isobutene proton affinity. United States. https://doi.org/10.1021/ja00079a062
Keister, J W, Riley, J S, and Baer, T. 1993. "Tert-butyl ion heat of formation and the isobutene proton affinity". United States. https://doi.org/10.1021/ja00079a062.
@article{osti_5065455,
title = {Tert-butyl ion heat of formation and the isobutene proton affinity},
author = {Keister, J W and Riley, J S and Baer, T},
abstractNote = {A new value of the tert-butyl ion heat of formation has been measured by dissociative ionization of tert-butyl iodide using the photoelectron photoion coincidence technique. The derived [Delta]H[sub f][degrees][sub 0](t-C[sub 4]H)[sup +] of 734 kJ/mol and [Delta]H[sub f][degrees][sub 298](t-C[sub 4]H[sub 9][sup +]) of 711 kJ/mol is 20 kJ/Mol higher than previous experimental measurements, but agrees within 1 kJ/mol with a recent theoretical ab initio calculation. The derived proton affinity for isobutene is thus 802 kJ/mol at 298 K. With these values established, we predict a tert-butyl radical ionization potential of 6.85 eV, which is close to Houle and Beauchamp's vertical IP from PES (6.92 eV) and Lossing's reported onset of 6.92 eV. However, it is considerably higher than the reported adiabatic IP of 6.7 eV. 24 refs., 1 fig., 1 tab.},
doi = {10.1021/ja00079a062},
url = {https://www.osti.gov/biblio/5065455}, journal = {Journal of the American Chemical Society; (United States)},
issn = {0002-7863},
number = ,
volume = 115:26,
place = {United States},
year = {Wed Dec 29 00:00:00 EST 1993},
month = {Wed Dec 29 00:00:00 EST 1993}
}