Carbon-13 magnetic resonance of hydroaromatics. 3. Conformation of 1,2,3,4-tetrahydrophenanthrene and 9,10-dihydrophenanthrene and their methyl derivatives
/sup 13/C chemical shift data have been obtained for 27 methylated 1,2,3,4-tetrahydro- and 9,10-dihydrophenanthrenes. It has been found that methyl-substituent parameters previously determined for the saturated ring of tetralin and 1,2,3,4-tetrahydroanthracene show a remarkable ability to predict the chemical shifts in spite of the significant structural differences in the basic structure of the hydrophenanthrenes, exemplified by the proximity of the C-4 and C-5 positions. Analogous to the tetralins, 1-methyltetrahydrophenanthrene was determined to prefer slightly the conformer with a pseudoaxial methyl, while, in contrast to the tetralins, the C-4 methyl derivatives were forced to exist entirely with the C-4 methyl pseudoaxial. The conformation of the cis-2,4 compound is ambiguous. Variable-temperature /sup 13/C and /sup 1/H NMR has provided ..delta..H and ..delta..S of 10.3 kcal mol/sup -1/ and -3.3 cal K/sup -1/ mol/sup -1/, respectively, for the conformational inversion of cis-9,10-dimethyl-9,10-dihydrophenanthrene. 43 references, 4 figures, 2 tables.
- Research Organization:
- Univ. of Utah, Salt Lake City
- DOE Contract Number:
- AC02-78ER05006
- OSTI ID:
- 5159694
- Journal Information:
- J. Org. Chem.; (United States), Journal Name: J. Org. Chem.; (United States) Vol. 50:18; ISSN JOCEA
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
AROMATICS
CARBON 13
CARBON ISOTOPES
CHEMICAL REACTIONS
CHEMICAL SHIFT
CONDENSED AROMATICS
CONFORMATIONAL CHANGES
DATA
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
METHYLATION
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ORGANIC COMPOUNDS
PHENANTHRENE
RESONANCE
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS