The Big Review VI: Carbonyl Compounds

Abstract

The carbonyl or C=O bond consists of a carbon atom with a large partial charge on it, and an oxygen atom with a large par­tial negative charge. The resulting large dipole moment means that du/dx for the carbonyl stretching vibration is large, giving rise to an intense peak in the 1900 to 1600 region. Ketones contain two alpha carbons attached to the carbonyl group, and their diagnostic peak pattern consists of an in­tense C=O stretch and a C-C-C stretch, both of which are sensitive as to whether the ketone is saturated or aromatic. Car­boxylic acids contain a carbonyl bond with an alpha carbon and OH group attached.