Promotion by SF6 of a Radiolytically Induced Chain Reaction for the Geometrical Isomerization of cis or trans-Butene-2 in Dilute Gaseous Mixtures
FOR several years SF6 has been used in radiolytic studies because of its high cross-section for capture of low-energy electrons and consequent effect on observable products resulting from positive-ion neutralization reactions. A reduced yield of H2 from irradiated propane has been reported1 and attributed to electron scavenging by the small proportions of SF6 present. On the other hand, SF6 does not affect the H2 yield from irradiated liquid unsaturates such as trans-butene-2 (ref. 2), indicating that ionic species may not be important with respect to H2 formation from these olefines.
Hydrogen Formation in the Radiolyses of Liquid Butene−1 and trans‐Butene−2
The effect of temperature and various electron or positive‐ion scavengers on hydrogen formation in the radiolyses of liquid butene−1 and trans‐butene−2 have been examined. The hydrogen formation is not appreciably affected by temperature and these additives, which indicates that thermal free radicals and ionic species may not play an important role in hydrogen formation from these olefins. The liquid‐phase radiolyses of C4H8−1—C4D8−1 and trans‐C4H8−2‐trans‐C4D8−2 mixtures have also been investigated. The data indicate that hydrogen for the most part may be formed by bimolecular processes. The results have led to the conclusion that the mechanism of the hydrogen formation may be interpreted in terms of the hydrogen‐atom abstraction reaction of hot hydrogen atoms or the equivalent formed by the direct excitation which may involve ``superexcitation.''
Identification of Dihydroxy Aromatic Compounds in a Low-Temperature Pyrolysis Coal Tar by Gas Chromatography−Mass Spectrometry (GC−MS) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS)
Dihydroxy aromatics in coal tar undergo rapid coupling reactions with each other and with some coal-derived species during coal pyrolysis and liquefaction. However, only limited information on the structure of dihydroxy aromatics is known. In this study, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and gas chromatography−mass spectrometry (GC−MS) were used to characterize the dihydroxy aromatics in a low-temperature pyrolyzed coal tar and its distillate and residue fractions. Negative-ion electrospray ionization (ESI) FT-ICR MS spectra of coal-tar-derived samples had low molecular masses and narrow mass ranges. Negative-ion ESI is extremely selective for the dihydroxy aromatics present in coal tar. The O2 class species had the highest ion intensity among the species in the negative-ion FT-ICR mass spectrum for each sample. Dihydroxy compounds with an aromatic core structure of benzene, indan, biphenyl (and/or acenaphthene), and naphthalene were identified in the distillate fract...