Biradical thermochemistry from collision-induced dissociation threshold energy measurements. Absolute heats of formation of ortho-, meta-, and para-benzyne
- Purdue Univ., West Lafayette, IN (United States)
The absolute heats of formation of 1,2-, 1,3-, and 1,4-dehydrobenzene (ortho, meta-, and para-benzyne) have been determined from measurements of the threshold energies for collision-induced dissociation (CID) of ortho, meta-, and para-chlorophenyl anions in a flowing afterglow-triple quadrupole apparatus. The 298 K heats of formation for ortho-, meta-, and para-benzyne derived in this manner are 106.6 [+-] 3.0, 122.0 [+-] 3.1, and 137.3 [+-] 3.3 kcal/mol, respectively. The values for meta- and para-benzyne are higher than those reported previously but are in excellent agreement with recently reported MCSCF and CI calculations. Several control experiments are described which demonstrate that the earlier results for meta- and para-benzyne suffered from an acid-catalyzed isomerization of the reactant chlorophenyl anions in the flowing afterglow prior to CID threshold analysis. 70 refs., 5 figs., 4 tabs.
- OSTI ID:
- 7015404
- Journal Information:
- Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 116:14; ISSN JACSAT; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
400800 -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKYNES
ANIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
COMPILED DATA
CYCLOALKYNES
DATA
DISSOCIATION
ENTHALPY
FORMATION HEAT
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
IONS
ISOMERIZATION
MULTIPOLES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
PHYSICAL PROPERTIES
QUADRUPOLES
RADICALS
REACTION HEAT
SILANES
SILICON COMPOUNDS
THERMOCHEMICAL PROCESSES
THERMODYNAMIC PROPERTIES