ketoncsoport

A ketoncsoport, often referred to as a carbonyl group within the context of ketones, is a functional group in organic chemistry. It consists of a carbon atom double-bonded to an oxygen atom. This C=O unit is the defining characteristic of ketones and aldehydes. In a ketone, the carbonyl carbon is bonded to two other carbon atoms, forming an R-CO-R' structure where R and R' are alkyl or aryl groups. This contrasts with aldehydes, where the carbonyl carbon is bonded to at least one hydrogen atom.

The presence of the polar carbonyl group significantly influences the chemical and physical properties of ketones. The electronegative oxygen atom pulls electron density away from the carbon atom, making the carbon partially positive and susceptible to nucleophilic attack. This property is central to many of the characteristic reactions of ketones. Ketones are generally less reactive towards nucleophilic addition than aldehydes due to the steric hindrance and electron-donating effects of the two alkyl or aryl groups attached to the carbonyl carbon.

Ketones are found in various natural and synthetic compounds. Acetone, the simplest ketone, is a common solvent. Other ketones, like cyclohexanone, are important industrial intermediates. Many biologically relevant molecules also contain ketone functionalities, such as certain carbohydrates and steroids. The nomenclature for ketones typically involves replacing the final "-e" of the parent alkane with "-one," with numbering to indicate the position of the carbonyl group.