Addition of Osmium Tetroxide to Dinaphthylethylenes

Abstract

IT has been claimed by Pullman¹ that the extent of conjugation of a given substituent with an aromatic ring system is determined by the electron density (index of free valence) at the position of substitution. Using the customary resonance terminology, this conclusion may be illustrated by the fact that for 1-substituted naphthalenes there are seven possible structures in which the substituent is linked to the ring by a double bond, but that for 2-substituted naphthalenes there are only six such structures. If X is a substituent, the C—X bond in 1-substituted naphthalenes should therefore have greater double-bond character than the corresponding bond in 2-substituted naphthalenes, and examination of the dipole moments of the halogenated naphthalenes confirms that this is the case². Furthermore, examination of the ultra-violet absorption spectra of suitable substituted compounds shows that there is a correlation between the magnitude of the bathochromic shift, the extent of conjugation, and the index of free valency at the position of substitution³. The experimental evidence supporting Pullman's generalization is not, however, extensive, and the present work was undertaken to provide further information of interest.