THE NEAR-ULTRAVIOLET SPECTRA OF SOME 9-ALKYLPHENANTHRENES

The ultraviolet spectra are reported of a series of 9-alkylphenanthrenes. The bathochromic shifts relative to phenanthrene of the longest-wavelength (α) band are not explicable in terms of hyperconjugation. It is suggested that the band envelope is influenced by the rotameric forms of the alkyl substituents.