Which of the following molecules contains an amide functional group?

• A. ${\mathrm{CH}}_3\mathrm{CH}{2}_{}\mathrm{OH}$
• B. ${\mathrm{CH}}_3\mathrm{NH}{2}_{}$
• C. ${\mathrm{CH}}_3\mathrm{COOH}$
• D. ${\mathrm{CH}}_3\mathrm{CONH}{2}_{}$

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the structure of an amide functional group. An amide consists of a carbonyl group (C=O) directly bonded to a nitrogen atom (N). The general structure is \(\mathrm{R{-}C(=O){-}NR'_2}\), where R and R' can be hydrogen or hydrocarbon groups.
2. Step 2: Analyze each given molecule to identify the presence or absence of the amide group. Look for the carbonyl group (C=O) attached to a nitrogen atom (N).
3. Step 3: For \(\mathrm{CH_3CH_2OH}\) (ethanol), note that it contains a hydroxyl group (-OH) but no carbonyl group bonded to nitrogen, so it is not an amide.
4. Step 4: For \(\mathrm{CH_3NH_2}\) (methylamine), observe that it contains an amine group (-NH2) but lacks a carbonyl group, so it is not an amide.
5. Step 5: For \(\mathrm{CH_3CONH_2}\) (acetamide), identify the carbonyl group (C=O) bonded directly to the nitrogen atom (NH2), confirming the presence of the amide functional group.