Recent advances in the chemistry of large-ring conjugated systems
One of the classical problems of organic chemistry concerns the question whether monocyclic hydrocarbons formally made up of alternating ~.;ingle and double bonds will show so-called " aromatic " behaviour. The bestknown example of this type of compound of course is benzene, which exhi.bits typical aromatic properties. Among these may be mentioned the fact that benzerre does not consist of distinct single and double bonds (as in formula I), but all the bonds are equivalent (as in formula II).