Aldehydes An aldehyde’s name ends in –al It always has the C=O bond on the first carbon of the chain so it does not need an extra number. It is by default number one on the chain Ethanal. The prefix oxo- should be used for compounds that contain a ketone group in addition to a carboxylic acid or aldehyde.Ketones end in -one When ketones have 5C’s or more in a chain then it needs a number to show the position of the double bond. E.g. pentan-2-one. If two ketone groups then di is put before –one and an an e is added to the stem. Carbonyls: Aldehydes and Ketones . Carbonyls are compounds with a C=O bond. They can be either aldehydes or ketones If the C=O is on the end of the chain with an H attached it is an aldehyde. The name will end in –al CH3CHO ethanal CH3COCH3 If the C=O is in the middle of the chain it is a ketone The name will end in -one propanone Solubility in water The smaller carbonyls are soluble in water because they can form hydrogen bonds with water. C CH3 CH3 O H O H Intermolecular forces in Carbonyls Pure carbonyls cannot hydrogen bond, but bond instead by permanent dipole forces. Reactions of carbonyls In comparison to the C=C bond in alkenes, the C=O is stronger and does not undergo addition reactions easily. The C=O bond is polarised because O is more electronegative than carbon. The positive carbon atom attracts nucleophiles. This is in contrast to the electrophiles that are attracted to the C=C .
Introduction and nomenclature (not explicitly mentioned but necessary for subsequent topics)