Carboxylic acids are named with the suffix -oic acid, added to the stem for the longest carbon chain. The carbon of the COOH group is counted in the chain and is always carbon 1, so no position number is needed for the COOH group.• HCOOH methanoic acid
• CH3COOH ethanoic acid
• CH3CH2COOH propanoic acid
• CH3CH2CH2COOH butanoic acidSubstituents are numbered from the COOH carbon:
• (CH3)2CHCOOH is 2-methylpropanoic acid
• CH3CH(OH)COOH is 2-hydroxypropanoic acid
• CH3CHClCOOH is 2-chloropropanoic acidDicarboxylic acids have a COOH group at each end. The -e of the alkane stays and the suffix is -dioic acid: HOOCCOOH is ethanedioic acid and HOOCCH2COOH is propanedioic acid.When the COOH group is attached to a benzene ring, C6H5COOH, the compound is benzoic acid.Worked example: name CH3CH(CH3)CH2COOH. Start numbering at the COOH carbon (C1). The CH2 is C2, the CH bearing the methyl group is C3, and the end CH3 is C4. The longest chain has four carbons (butanoic acid) with a methyl group on carbon 3, so the name is 3-methylbutanoic acid.
• CH3COOH ethanoic acid
• CH3CH2COOH propanoic acid
• CH3CH2CH2COOH butanoic acidSubstituents are numbered from the COOH carbon:
• (CH3)2CHCOOH is 2-methylpropanoic acid
• CH3CH(OH)COOH is 2-hydroxypropanoic acid
• CH3CHClCOOH is 2-chloropropanoic acidDicarboxylic acids have a COOH group at each end. The -e of the alkane stays and the suffix is -dioic acid: HOOCCOOH is ethanedioic acid and HOOCCH2COOH is propanedioic acid.When the COOH group is attached to a benzene ring, C6H5COOH, the compound is benzoic acid.Worked example: name CH3CH(CH3)CH2COOH. Start numbering at the COOH carbon (C1). The CH2 is C2, the CH bearing the methyl group is C3, and the end CH3 is C4. The longest chain has four carbons (butanoic acid) with a methyl group on carbon 3, so the name is 3-methylbutanoic acid.