Re: What is a carbonyl group?

A carbonyl group is a carbon-oxygen double bond. Oxygen can have only two bonds, so nothing else can be bonded to oxygen, but carbon forms four bonds, so there are two "spaces" left over in which other atoms can be bonded to the carbon. A carbonyl group looks like the picture at the left.

Examples of compounds with carbonyl groups are shown below, and include:

• Benzaldehyde, which gives almonds their odor;
• Methyl Ethyl Ketone, a strong, sweet-smelling compound that is sometimes used in paints;
• Acetic Acid, the active ingredient in vinegar; and
• Ethyl Acetate, another sweet-smelling compound which can be used as a flavoring. It is produced in small amounts by the yeast which makes bread rise.

For more information about organic compounds and their structure, try Dave Woodcock's organic nomenclature tutorial. DJB