Amides are named from the parent carboxylic acid. The stem counts all the carbon atoms in the chain including the C=O carbon, and the ending -oic acid is replaced by -amide.• HCONH2 is methanamide
• CH3CONH2 is ethanamide
• CH3CH2CONH2 is propanamideFor a secondary amide, the group attached to the nitrogen is named as a prefix with the locant N-, to show that it is bonded to nitrogen rather than to a carbon of the chain:• CH3CONHCH3 is N-methylethanamide
• CH3CH2CONHCH2CH3 is N-ethylpropanamideIf two groups are attached to the nitrogen, both are given: CH3CON(CH3)2 is N,N-dimethylethanamide.The benzene ring can appear on either side. C6H5CONH2 is benzamide, and CH3CONHC6H5 is N-phenylethanamide.Worked example: name CH3CH2CH2CONHCH3.
Step 1: the acyl part has 4 carbons, CH3CH2CH2CO−, so the stem is butan-, giving butanamide.
Step 2: a methyl group is on the nitrogen, so add N-methyl.
Name: N-methylbutanamide.Always check which carbons belong to the acyl chain and which are on the nitrogen: splitting the formula at the C−N bond makes this clear.
• CH3CONH2 is ethanamide
• CH3CH2CONH2 is propanamideFor a secondary amide, the group attached to the nitrogen is named as a prefix with the locant N-, to show that it is bonded to nitrogen rather than to a carbon of the chain:• CH3CONHCH3 is N-methylethanamide
• CH3CH2CONHCH2CH3 is N-ethylpropanamideIf two groups are attached to the nitrogen, both are given: CH3CON(CH3)2 is N,N-dimethylethanamide.The benzene ring can appear on either side. C6H5CONH2 is benzamide, and CH3CONHC6H5 is N-phenylethanamide.Worked example: name CH3CH2CH2CONHCH3.
Step 1: the acyl part has 4 carbons, CH3CH2CH2CO−, so the stem is butan-, giving butanamide.
Step 2: a methyl group is on the nitrogen, so add N-methyl.
Name: N-methylbutanamide.Always check which carbons belong to the acyl chain and which are on the nitrogen: splitting the formula at the C−N bond makes this clear.