Carboxylic acids and acid chlorides:
Carboxylic acids and acid chlorides are recognized through adding the suffix -anoic acid and -anoyl chloride correspondingly. Both of these functional groups (Carboxylic acids and acid chlorides) are all the time at the end of the main chain and do not require to be numbered.
Figure: (a) 2-Methylbutanoic acid; (b) 2, 3-dimethylpentanoyl chloride.