Which of the following compounds is an ester?

• A. $\mathrm{CH}{3}_{}\mathrm{COOH}$ (propanoic acid)
• B. $\mathrm{CH}{3}_{}\mathrm{CONH}{2}_{}$ (propanamide)
• C. $\mathrm{CH}{3}_{}\mathrm{COOCH}{3}_{}$ (methyl propanoate)
• D. $\mathrm{CH}{3}_{}\mathrm{CH}{2}_{}\mathrm{OH}$ (propanol)

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the functional groups present in each compound. An ester has the general structure \(\mathrm{R-COO-R'}\), where a carbonyl group (\(\mathrm{C=O}\)) is directly bonded to an oxygen atom that is also bonded to another carbon chain.
2. Step 2: Analyze propanoic acid (\(\mathrm{CH_3COOH}\)). It contains a carboxylic acid group, characterized by the \(\mathrm{-COOH}\) functional group, not an ester.
3. Step 3: Analyze propanamide (\(\mathrm{CH_3CONH_2}\)). It contains an amide group, where the carbonyl carbon is bonded to a nitrogen atom (\(\mathrm{-CONH_2}\)), so it is not an ester.
4. Step 4: Analyze methyl propanoate (\(\mathrm{CH_3COOCH_3}\)). This compound has a carbonyl group bonded to an oxygen atom which is bonded to a methyl group, fitting the ester functional group pattern.
5. Step 5: Analyze propanol (\(\mathrm{CH_3CH_2OH}\)). It contains an alcohol group (\(\mathrm{-OH}\)) attached to an alkyl chain, so it is not an ester.