Ketones and aldehydes have carbon atom double-bonded to oxygen atom {carbonyl}. Aldehydes and ketones are colorless, have sweet odor, are polar, are not acidic or basic, are oxidizable to carboxylic acids, and are reducible to alcohols. Carbonyls are reactive. Aldehydes are more reactive than ketones. Aldehydes and ketones are liquids unless they have more than twenty carbons. Small aldehydes and ketones dissolve in water.
Aldehydes and ketones can be substituents {oxy-}.
In aldehyde or ketone carbonyl groups, carbon has slight positive charge and oxygen has slight negative charge. Aldehyde or ketone can hybridize to have positive carbon atom and negative oxygen atom {enolate ion}, with single bond between carbon and oxygen.
If aldehyde or ketone carbonyl carbon attaches to another carbon, the double bond can move between the carbons, and hydrogen atom from second carbon can move to oxygen {keto-enol isomerism}.
Carbonyl can be at carbon-chain end {aldehyde}|: -C=O.
The smallest aldehyde {methanal} {formaldehyde, carbonyl} has one carbon atom.
Aldehydes {ethanal} {acetylaldehyde} can have two carbon atoms.
Other aldehydes {benzaldehyde} or ketones are in camphor, citral, vanillin, cinnamon, and almonds.
Carbonyl can be in carbon-chain middle {ketone}|: =C=O.
The smallest ketone {propanone} {methyl methyl ketone} {acetone} has three carbons.
Ketones {lactone} can have rings with five carbon atoms and one oxygen atom. One carbon atom double-bonds to an oxygen atom outside ring.
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Date Modified: 2022.0225