3355-34-8Relevant academic research and scientific papers
1,4-didehydronaphthalene
Roth, Wolfgang R.,Hopf, Henning,Wasser, Thorsten,Zimmermann, Heiko,Werner, Christian
, p. 1691 - 1695 (2007/10/03)
The energy profile of the Bergman equilibrium o-diethinylbenzene (1) ? 1,4-didehydronaphthalene (2) has been established from the temperature and NO dependence of the trapping rate of the diradicals 2 which leads to a heat of formation for 2 of ΔHf0 = 152.9 ± 1.4 kcal·mol-1. Activation parameters for the hydrogen abstraction of 2 and 1,4-didehydrobenzene (5) have been derived from the rate of the naphthalene and benzene formation, when 1 and cis-3-hexene-1,5-diyne (4) are heated in the presence of methanol, toluene, and 1,4-cyclohexadiene. VCH Verlagsgesellschaft mbH, 1996.
The Energy Well of Diradicals, V. - 1,3,5-Cyclohexatriene-1,4-diyl and 2,4-Cyclohexadiene-1,4-diyl
Roth, Wolfgang R.,Hopf, Henning,Horn, Carina
, p. 1765 - 1780 (2007/10/02)
The energy profile of the Bergman rearrangement of (Z)-3-hexene-1,5-diyne (4) has been established from the NO and oxygen dependance of the trapping rate of the intermediate diradical 1 which leads to a heat of formation for 1,4-didehydrobenzene (1) of ΔH0f = 138.0 +/- 1.0 kcal * mol-1.By the same technique the heat of formation of 1,2,4-cyclohexatriene (2), generated by thermolysis of (Z)-1,3-hexadien-5-yne (10), gives ΔH0f = 105.1 +/- 1.0 kcal * mol-1 which indicates a high diradical character for 2. - Key Words: Diradicals / NO and O2 trapping / Heat of formation / Energy well / Rearrangements / Bergman cyclisation
Reactions of the Benzyne Radical Anion in the Gas Phase, the Acidity of the Phenyl Radical, and the Heat of Formation of o-Benzyne
Guo, Yili,Grabowski, Joseph J.
, p. 5923 - 5931 (2007/10/02)
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 Broensted acids of known acidity, we have established the gas-phase acidity of the phenyl radical as ΔG degacid.> = 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, ΔHfdeg = 105 kcal mol-1.In addition to behaving as a Broensted 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.
Determination of the Singlet-Triplet Splitting and Electron Affinity of o-Benzyne by Negative Ion Photoelectron Spectroscopy
Leopold, Doreen,Miller, Amy E. S.,Lineberger, W. C.
, p. 1379 - 1384 (2007/10/02)
The photoelectron spectrum of the o-benzyne negative ion displays transitions to both the X/1A1 and a/3B2 states of the neutral molecule.Results yield adiabatic electron affinities of 0.560(10) and 0.551(10) eV for C6H4 and C6D4, respectively.These values are consistent with extrapolations from studies of larger strained cycloalkynes and imply that the lowest unoccupied MO of o-benzyne is primarly an antibonding acetylenic orbital.The o-benzyne singlet-triplet splitting is determined to be 37.7(6) kcal/mol.Several new vibrational frequencies for the neutral and anionic species are reported.
