Definition of a Ketone
A ketone is an organic compound that contains a carbonyl functional group (C=O) where the carbon atom is bonded to two other carbon atoms. This structural arrangement distinguishes ketones from aldehydes, where the carbonyl carbon is bonded to at least one hydrogen atom. Ketones are key building blocks and intermediates in numerous chemical reactions.
The Ketone Functional Group
The defining feature of a ketone is the carbonyl group, which consists of a carbon atom double-bonded to an oxygen atom (C=O). In ketones, this carbonyl carbon is situated within a carbon chain, meaning it is not at the end of the molecule. The polarity of the carbon-oxygen double bond significantly influences the chemical and physical properties of ketones, including their boiling points and solubility.
Common Examples of Ketones
The simplest and most well-known ketone is acetone, also chemically known as propanone, commonly found in nail polish remover and as an industrial solvent. Another common example is butanone (methyl ethyl ketone, MEK), widely used in industry as a solvent. Cyclohexanone is another important ketone, serving as a precursor in the manufacture of nylon.
Importance and Applications
Ketones are essential in various applications. They serve as excellent industrial solvents due to their ability to dissolve a wide range of organic and inorganic compounds. In biology, specific ketones are produced by the body (known as 'ketone bodies') during fat metabolism, particularly during fasting or low-carbohydrate diets, providing an alternative energy source for the brain and other tissues.