Nomenclature and Structure of Carbonyl Group They are used in many food products and pharmaceuticals to add flavours. Some of these families are manufactured for use as solvents (i.e., acetone) and for preparing materials like adhesives, paints, resins, perfumes, plastics, fabrics, etc. The common names of ketones are derived by naming two alkyl or aryl groups bonded to the carbonyl group. The locations of substituents are indicated by Greek letters, a a¢ , b b¢ and so on beginning with the carbon atoms next to the carbonyl group, indicated as aa¢ .
Some ketones have historical common names, the simplest dimethyl ketone is called acetone. Alkyl phenyl ketones are usually named by adding the name of acyl group as prefix to the word phenone. For example (b) IUPAC names The IUPAC names of open chain aliphatic aldehydes and ketones are derived from the names of the corresponding alkanes by replacing the ending – e with – al and – one respectively. In case of aldehydes the longest carbon chain is numbered starting from the carbon of the aldehyde group while in case of ketones the numbering begins from the end nearer to the carbonyl group.
The substituents are prefixed in alphabetical order along with numerals indicating their positions in the carbon chain. The same applies to cyclic ketones, where the carbonyl carbon is numbered one. When the aldehyde group is attached to a ring, the suffix carbaldehyde is added after the full name of the cycloalkane. The numbering of the ring carbon atoms start from the carbon atom attached to the aldehyde group.
The name of the simplest aromatic aldehyde carrying the aldehyde group on a benzene ring is benzenecarbaldehyde. However, the common name benzaldehyde is also accepted by IUPAC. Other aromatic aldehydes are hence named as substituted benzaldehydes. HCHO Formaldehyde Methanal CH CHO Acetaldehyde Ethanal (CH ) CHCHO Isobutyraldehyde -Methylpropanal g - Methylcyclohexanecarbaldehyde -Methylcyclohexanecarbaldehyde CH CH(OCH )CHO a -Methoxypropionaldehyde -Methoxypropanal CH CH CH CH CHO Valeraldehyde Pentanal CH =CHCHO Acrolein Prop- -enal Phthaldehyde Benzene- , -dicarbaldehyde m -Bromobenzaldehyde -Bromobenzaldehyde Ketones