E. Clar, B. Mcandrew, M. Zander
1967
Citations
1
Influential Citations
30
Citations
Journal
Tetrahedron
Abstract
Abstract 1,6-Dimethylpyrene (V), 2,8-dimethylchrysene (IX) methylcoronene (X) and ethylcoronene have been synthesized. The NMR spectra of 1-methylphenanthrene (III), 2-methylphenanthrene (II) and 9-methylphenanthrene (I) are reported. Whilst the Me-group in the first two hydrocarbons produces sharp singlets as usual in aromatics, 9-methylphenanthrene gives rise to a Me-doublet as in methyl olefins, thus indicating the double bond character of the 9:10-position. An analogous observation can be made in the pyrene series: 3-methylpyrene (VII), 1,2-dimethylpyrene (VIII) and 4,9-dimethylpyrene (VI) give Me-singlets, whilst 1-methylpyrene (IV) and 1,6-dimethylpyrene (V) give Me-doublets. 2,8-Dimethylchrysene (IX) shows a Me-singlet, because the inherent sextets are not fixed as in phenanthrene. Methylcoronene (X) produces a Me-doublet. It must be therefore formulated with three sextets and three double bonds of the double bond type to be found in the middle ring of phenanthrene.