Question #3e390

1 Answer
Feb 13, 2016

A conjugated carbonyl group has a #"C=C"# double bond adjacent to it; an unconjugated carbonyl group has no adjacent double bond.


Examples of unconjugated carbonyl compounds are propanal and propanone.

Typical conjugated (or α,β-unsaturated) carbonyl compounds are propenal



In addition to a normal #"C=O"# resonance contributor, an α,β-unsaturated carbonyl compound has another contributor with a positive charge on the β-carbon.

It can be attacked by nucleophiles at either the β-carbon or the carbonyl carbon.

Note that the product of 1,4-addition is an enol that will tautomerize to the more stable carbonyl compound.