vinylogy

Vinylogy is the transmission of electronic effects through a  conjugated organic bonding system. The concept was introduced in 1926 by Ludwig Claisen to explain the acidic properties of formylacetone and related ketoaldehydes. Its adjectival form, vinylogous, is used to describe functional groups in which the standard moieties of the group are separated only by a conjugated bonded system. For example, a carbon-carbon double bond (>C=C<, a "vinyl" moiety) between a carbonyl group and a hydroxyl group is referred to as a vinylogous carboxylic acid, analogous electronically to a carboxylic acid, RCOOH.