In organic chemistry, a ketone  is an organic compound with the structure , where R and R can be a variety of carbon-containing substituents. Ketones contain a carbonyl group  (which contains a carbon–oxygen double bond C=O). The simplest ketone is acetone (where R and R is methyl), with the formula . Many ketones are of great importance in biology and in industry. Examples include many sugars (ketoses), many steroids (e.g., testosterone), and the solvent acetone.