The Effect of Substitution on the Ionization Potentials of Free Radicals and Molecules. II. Theoretical Interpretation of δKValues for Alkyl Radicals and Amines

1963 ◽  
Vol 85 (11) ◽  
pp. 1576-1580 ◽  
Author(s):  
Joyce J. Kaufman
Keyword(s):  
Free Radicals ◽  
Ionization Potentials ◽  
Theoretical Interpretation ◽  
Alkyl Radicals

Free radicals by mass spectrometry. XLIL Ionization potentials and ionic heats of formation for C1—C4 alkyl radicals

1970 ◽  
Vol 48 (6) ◽  
pp. 955-965 ◽  
Author(s):  
F. P. Lossing ◽  
G. P. Semeluk
Keyword(s):  
Free Radicals ◽  
Excited States ◽  
Kinetic Data ◽  
Ionization Potentials ◽  
Heats Of Formation ◽  
Alkyl Radicals ◽  
Fragment Ions ◽  
Vibrational Levels ◽  
Upward Curvature ◽  
Linear Sections

Ionization potentials for C1—C4 alkyl free radicals have been re-measured by electron impact, using an energy-resolved electron beam from a double-hemispherical electrostatic monochromator. From these values and kinetic data for heats of formation of the radicals, ionic heats of formation for C1—C4 alkyl ions have been calculated. New values for the four isomeric butyl ions are given. The ionization efficiency curves for the simpler radicals show linear sections corresponding to excitation of vibrational levels; for larger radicals these segments are not resolved and only a smooth upward curvature is seen. In disagreement with earlier results, no evidence for formation of low-lying excited states of the ions could be found, either for parent or fragment ions.

Free radicals by mass spectrometry, XLVII. lonization potentials and ionic heats of formation of C5–C7 alkyl radicals

1976 ◽  
Vol 54 (6) ◽  
pp. 990-992 ◽  
Author(s):  
F. P. Lossing ◽  
Allan Maccoll
Keyword(s):  
Mass Spectrometry ◽  
Electron Beam ◽  
Free Radicals ◽  
Ionization Potentials ◽  
Heats Of Formation ◽  
Alkyl Radicals ◽  
Hydride Ion

Using an energy-resolved electron beam, ionization potentials have been measured for a number of C5–C7 isomeric alkyl radicals, produced by pyrolysis of nitrite intermediates. Values for primary radicals, which could not be produced in sufficient yield, are estimated by extrapolation from lower members of the series. Ionic heats of formation and hydride ion affinities are reported.

FREE RADICALS BY MASS SPECTROMETRY: X. THE IONIZATION POTENTIALS OF METHYL SUBSTITUTED ALLYL RADICALS

1956 ◽  
Vol 34 (3) ◽  
pp. 345-353 ◽  
Author(s):  
C. A. McDowell ◽  
F. P. Lossing ◽  
I. H. S. Henderson ◽  
J. B. Farmer
Keyword(s):  
Mass Spectrometry ◽  
Free Radicals ◽  
Electron Impact ◽  
Heat Of Formation ◽  
Ionization Potentials ◽  
Bond Dissociation Energies ◽  
Allyl Radical ◽  
Dissociation Energies ◽  
Allyl Halides ◽  
Vertical Ionization Potentials

The vertical ionization potentials of the β- and γ-methyl substituted allyl radicals as measured by electron impact are 8.03 ± 0.05 v. and 7.71 ± 0.05 v, respectively. From appearance potential data the following bond dissociation energies can be derived, assuming the dissociation processes to be free from complications:[Formula: see text]With assumptions about the structure of the ions produced by electron impact from the corresponding butenes the dissociation energies of the C4H7—H bonds in these latter compounds can be estimated, and the heats of formation of the corresponding radicals derived, namely:[Formula: see text]From data on the allyl halides we evaluate the heat of formation of the allyl radical to be:[Formula: see text]

IONIZATION POTENTIALS OF ALKYL FREE RADICALS AND n-ALKANES THROUGH C17H36 BY ENERGY-CALIBRATED MOLECULAR ORBITAL METHODS

1966 ◽  
Vol 44 (12) ◽  
pp. 1455-1462 ◽  
Author(s):  
Charles E. Melton ◽  
Hubert W. Joy
Keyword(s):  
Experimental Data ◽  
Free Radicals ◽  
Molecular Orbital ◽  
Ionization Potentials ◽  
Recent Experimental Data ◽  
Normal Alkanes ◽  
Atomic Orbitals ◽  
Large Molecules ◽  
Good Agreement ◽  
Expansion Scheme

Ionization potentials are calculated by simple energy-calibrated molecular orbital techniques for the normal alkanes through C17H36 and for some normal and branched alkyl free radicals. A model is formulated which allows the computations to be extended to extremely large molecules by using "radical" orbitals as well as atomic orbitals in the expansion scheme. Auto-ionization levels as well as ionization potentials are calculated for the radicals. Computed and observed values are in good agreement where recent experimental data are available.

FREE RADICALS BY MASS SPECTROMETRY: VII. THE IONIZATION POTENTIALS OF ETHYL, ISOPROPYL, AND PROPARGYL RADICALS AND THE APPEARANCE POTENTIALS OF THE RADICAL IONS IN SOME DERIVATIVES

1955 ◽  
Vol 33 (5) ◽  
pp. 861-869 ◽  
Author(s):  
J. B. Farmer ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Free Radicals ◽  
Kinetic Energy ◽  
Electron Impact ◽  
Ionization Potentials ◽  
Bond Dissociation Energies ◽  
Radical Ions ◽  
Dissociation Energies ◽  
Propargyl Radicals

The ionization potentials of ethyl, isopropyl, and propargyl radicals have been measured by electron impact on radicals produced by thermal decomposition of appropriate compounds. The values are:ethyl 8.78±0.05 ev., isopropyl 7.90±0.05 ev., and propargyl 8.25±0.08 ev. From the appearance potentials of these ions in various compounds, the following values of bond dissociation energies were obtained:[Formula: see text][Formula: see text] assuming no kinetic energy of the products.

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