Aldehydes are named by replacing the -e ending of the corresponding alkane with -al . It is not necessary to specify the position of the aldehyde group, since it occupies the end of the chain (locant 1).
When the string contains two aldehyde functions, the suffix -dial is used.

aldehydes ketones nomenclature 01

[1] 4,4-Dimethylpentanal

[2] Pent-4-enal

[3] Hexanodial

The -CHO group attached to a ring is called -carbaldehyde . The numbering of the cycle is carried out by giving locant 1 to the carbon of the cycle that contains the aldehyde group.

aldehydes ketones nomenclature 02

[4] Cyclohexanecarbaldehyde

[5] 3-Bromocyclopentanecarbaldehyde

Some common names for aldehydes accepted by IUPAC are:

aldehydes ketones nomenclature 03

[6] Methanal (formaldehyde)

[7] Benzaldehyde

[8] Ethanal (acetaldehyde)

Ketones are named by replacing the -e ending of the alkane with the same chain length with -one . The longest chain that contains the carbonyl group is taken as the main chain and is numbered so that it takes the lowest locant.

aldehydes ketones nomenclature 04

[9] Butanone

[10] 4-Methylpentan-2-one

[11] 3-Methylcyclohexanone

There is a second type of nomenclature for ketones, which consists of naming the chains as substituents, arranging them alphabetically, and ending the name with the word ketone .

aldehydes ketones nomenclature 05

[12] Ethyl methyl ketone

[13] Cyclohexyl methyl ketone

[14] Benzyl methyl ketone

When the ketone acts as a substituent, it is named with the prefix -oxo. Priority groups to the ketone are carboxylic acids and their derivatives, as well as aldehydes.

aldehydes ketones nomenclature 06

[15] 3-Oxobutanal

[16] 2-Bromo-5-oxohexanoic acid