ELECTRON SPIN RESONANCE SPECTRA OF ALKYL RADICALS IN $gamma$-IRRADIATED ALKYL HALIDES

Journal Article · Wed Aug 01 04:00:00 EDT 1962 · Transactions of the Faraday Society (England) Superseded by J. Chem. Soc., Faraday Trans., I and II

DOI:https://doi.org/10.1039/tf9625801477· OSTI ID:4756857

Ayscough, P B; Thomson, C

A study of the electron spin resonance spectra of radicals trapped in gamma -irradiated polycrystalline alkyl halides at -196 deg C established that in almost all cases the main species observed in the 1st hours after irradiation is the parent alkyl radical, though isomerization reactions such as isobutyl yields tert-butyl occur at this temperature. Hyperfine splitting constants for the interaction of the alpha - and BETA -protons with the unpaired electron were determined for radicals with the formulas (CH/sub 3/),CH/sub 3-n/(n = 0 to 3)RCH/ sub 2/CH/sub 2/,RR'CHCH/sub 2/, RR'CH (including cycloalkyl) and RR'R''C. It was found that alpha -protons and those in freely rotating methyl groups interact to give isotopic hyperfine splitting of 80-75 Mc/sec, while the magnitude of the interaction of the BETA -protons may vary from <12 to >130 Mc/sec, depending on the configuration of the radical. In panticular, the 2 BETA -protons in RCH/sub 2/CH/sub 2/ are not equivalent, impiying an unsymmetrical equilibrium configuration. Interpretation of the spectra of organic radicals trapped in polycrystalline matrices involves the consideration not only of the number of interacting protons and their relative orientation, but also of the effect of more distant groups which may affect the electron distribution and also the configuration of those groups which give observable hyperfine interaction. Simple alkyl radicals, with the single exception of the isobutyl radical, give spectra consisting of an even number of lines. Since differences in line separation are small, the interpretation must rely heavily on relative intensities which are readily altered by the superposition of similar spectra, or by incipient saturation. (H.H.D.)

• Research Organization: Univ. of Leeds, Eng.
• NSA Number: NSA-17-003053
• OSTI ID: 4756857
• Journal Information: Transactions of the Faraday Society (England) Superseded by J. Chem. Soc., Faraday Trans., I and II, Journal Name: Transactions of the Faraday Society (England) Superseded by J. Chem. Soc., Faraday Trans., I and II Vol. Vol: 58; ISSN TFSOA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ALKYL RADICALS
CHEMISTRY
ELECTRONS
GAMMA SOURCES
HYPERFINE STRUCTURE
INTERACTIONS
IRRADIATION
ISOMERS
LOW TEMPERATURE
PROTONS
QUANTITATIVE ANALYSIS
RESONANCE
SPECTRA
SPIN