Reactions of the benzyne radical anion in the gas phase, the acidity of the phenyl radical, and the heat of formation of o-benzyne
作者:Yili Guo、Joseph J. Grabowski
DOI:10.1021/ja00016a001
日期:1991.7
The thermally equilibrated ion-molecule reactions of the o-benzyne radical anion have been examined in the gas phase with the flowing afterglow technique. By using the bracketing technique between o-C6H4.- and Bronsted acids of known acidity, we have established the gas-phase acidity of the phenyl radical as DELTA-G-degrees acid[C6H5.] = 371(-3)+6 kcal mol-1. Combination of our experimental acidity of the phenyl radical with appropriate thermochemical data from the literature yields a variety of substantially improved thermochemical values of C6H4 and C6H5. species, most notably, DELTA-H(f)-degrees [o-C6H4] = 105 kcal mol-1. In addition to behaving as a Bronsted base, o-benzyne radical anion is found to undergo a number of other reactions, including electron transfer, H/D exchange, H2+ transfer, and direct addition. The reaction between o-C6H4.- and the simple aliphatic alcohols is shown to be a competition between proton transfer and H2+ transfer while that between o-C6H4.- and dioxygen or 1,3-butadiene is found to be exclusively an associative detachment process. One unanticipated, novel observation from these studies is the facile formation of an addition complex between the o-benzyne radical anion and carbon dioxide, leading to a distonic radical anion (benzoate-type anion, phenyl-type radical) that offers a unique opportunity for examining radical chemistry in ion-molecule encounter complexes.
Negative-ion mass spectra of polyatomic molecules
作者:K. A. G. MacNeil、J. C. J. Thynne
DOI:10.1039/tf9686402112
日期:——
Reaction pathways in the gas phase negative ion chemistry of chlorinated ethenes
作者:Richard A. Kennedy、Chris A. Mayhew、Robert Peverall、Peter Watts
DOI:10.1039/b002866p
日期:——
The reaction rate coefficients and ion products for the gas-phase reactions of O2−, O−, OH−, CF3−, and F− with trichloroethene (CCl2CHCl), 1,1-dichloroethene (CH2CCl2), and Z (cis) and E (trans)-1,2-dichloroethene (CHClCHCl) are presented. With the exception of CCl2CHCl, the O2− bimolecular reaction rate coefficients are substantially below the collisional values. All the other anions react with the