The base name is determined by the longest continuous carbon chain that contains the carbonyl group. The suffix -al denotes an aldehyde; the suffix -one denotes a ketone. Numbering always begins at the chain end nearest the carbonyl.
1.Alkyl, aryl, and halogen sidechains are names in alphabetical order with their proper locant numbers.
2.The multipliers di-, tri-, etc. are added as necessary but do not affect alphabetical order. Only the prefix iso-, as in isopropyl, affects alphabetical order.
3.When there are multiple carbonyl groups, multipliers, di-, tri-, etc., are used with appropriate locant numbers for each carbonly group.
4.When the formyl group, -CHO, is attached directly to a ring, the ring name is followed by the suffix -carbaldehyde.
5.When the formyl group, -CHO, is attached directly to a benzene ring, the compound is commonly names as a benzaldehyde but can also be named as a benzenecarbaldehyde. (This problem does not use the latter.)
6.Unsaturated compounds are named as aldehydes or ketones. The multiple bond is signified by a suffix, -ene or -yne, with a locant number. ie3-methyl-2-pentenal \/\=/=O\
7.The hydroxy and alkoxy groups of are named using prefixes (hydroxy for -OH and alkoxy for -OR) with locant numbers.
8.Stereo prefixes, E and Z or cis and trans, are used to designate double bond configuration. In the second example only the E/Z designation is unambiguous.
9. When the carbonyl group is part of a ring, the base name is derived from the corresponding cycloalkane and numbering starts at the carbonyl carbon.