A theoretical and experimental study of unimolecular and biomolecular radical hydrogen transfer reactions
We have examined the intramolecular radical hydrogen transfer (RHT) reaction of the 2-(2-phenylethyl)cyclohexadienyl radical. Intramolecular hydrogen shift from the cyclohexadienyl ring to the ipso position of the phenyl ring, followed by {beta}-scission would have given benzene and ethylbenzene as products. Competing with this reaction is {beta}-scission to give benzyl radical and isotoluene, or hydrogen loss to give bibenzyl. Studies to date suggest a barrier for thermoneutral hydrogen transfer in the RHT reaction between aromatic systems of ca. 18 kcal/mole. None of the studies of RHT or equivalent mechanisms have attempted to directly observe H{sub 2}, and direct determination of Arrhenius parameters and a detailed examination of the pathway of the hydrogen transfer process remains to be carried out. To better understand the structural and energetic aspects of RHT, we have carried out a semiempirical molecular orbital study of bimolecular and intramolecular RHT reactions for a variety of aromatic systems. We also examined in detail the energetics of hydrogen transfer between ethyl radical and ethylene via RHT, an addition/metathesis/scission pathway, and a hybrid concerted'' pathway. 11 refs., 1 fig., 4 tabs.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (USA)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 5747688
- Report Number(s):
- PNL-SA-19111; CONF-910402-17; ON: DE91012607
- Resource Relation:
- Conference: 201. American Chemical Society (ACS) national meeting, Atlanta, GA (USA), 14-19 Apr 1991
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
COAL LIQUEFACTION
OPTIMIZATION
HYDROGEN TRANSFER
ACTIVATION ENERGY
ARRHENIUS EQUATION
EXPERIMENTAL DATA
MOLECULAR ORBITAL METHOD
RADICALS
DATA
ENERGY
EQUATIONS
INFORMATION
LIQUEFACTION
NUMERICAL DATA
THERMOCHEMICAL PROCESSES
010405* - Coal
Lignite
& Peat- Hydrogenation & Liquefaction
400201 - Chemical & Physicochemical Properties