Radical pathways of coal dissolution in hydrogen donor media. 2. beta. scission and 1,2 aryl migration reactions of radicals derived from methylindans and tetralin at 327 to 627/sup 0/C
The 1,2 aryl migration and fragmentation reactions of 1-indanylmethyl (1), 2-tetralyl (2), 2-indanylmethyl (3), 1-tetralyl (4), 2-methyl-1-indanyl (5), and 1-methyl-2-indanyl (6) radicals were studied by flash vacuum pyrolysis of the tert-butyl perester precursors at 327 to 627/sup 0/C and 10/sup -2/ torr. Radicals 1 and 2 are interconverted via a 1,2 aryl migration which is readily reversible at all temperatures. This equilibrium is depleted by ..beta.. scission of 1 and recyclization to 4 and by ..beta.. scission of 2 followed by recyclization to 2 or to 3 in modest yields. The reverse neophyl-like rearrangement of 2 to 1 occurs with a lower activation barrier than ..beta.. scission of 1 to form a 2-(o-vinylphenyl)ethyl radical. Enthalpies, entropies, and free energies of reaction were calculated for the above reactions from group additivity parameters, and activation energies were estimated from values reported for simple alkyl radicals. It is shown that the ..beta.. scission of 4 and recyclization to 1 is important only at very high temperatures (> 500/sup 0/C) as a mechanism for the isomerization of tetralin and related hydroaromatic structures to alkylindans and that the reverse neophyl-like rearrangement of 2 to 1 is the favored pathway for isomerizations observed during dissolution of coal in hydroaromatic media at elevated temperatures.
- Research Organization:
- Pacific Northwest Lab., Richland, WA
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 6555622
- Journal Information:
- J. Org. Chem.; (United States), Journal Name: J. Org. Chem.; (United States) Vol. 45:26; ISSN JOCEA
- Country of Publication:
- United States
- Language:
- English
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010405 -- Coal
Lignite
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
AROMATICS
ARYL RADICALS
CARBONACEOUS MATERIALS
CHEMICAL REACTIONS
COAL
DATA
DISSOLUTION
ENERGY SOURCES
EXPERIMENTAL DATA
FOSSIL FUELS
FUELS
HYDROCARBONS
HYDROGEN TRANSFER
INFORMATION
ISOMERIZATION
MATERIALS
NUMERICAL DATA
ORGANIC COMPOUNDS
RADICALS
SOLVENT PROPERTIES
TETRALIN