Which of the following structures represents an amine functional group?

• A. $R-{\mathrm{NH}}_2$
• B. $R-{\mathrm{CO}}_{2}H$
• C. $R-{\mathrm{OH}}_1$
• D. $R-{\mathrm{CO}}_1\mathrm{R\text{'}}$

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the functional groups given in the options. Each structure is represented as R attached to a specific group.
2. Step 2: Recall that an amine functional group consists of a nitrogen atom bonded to one or more alkyl or aryl groups, typically represented as \(\mathrm{R-NH_2}\) for a primary amine.
3. Step 3: Identify the groups in the options: \(\mathrm{R-NH_2}\) (amine), \(\mathrm{R-CO_2H}\) (carboxylic acid), \(\mathrm{R-OH}\) (alcohol), and \(\mathrm{R-CO-R'}\) (ketone or carbonyl group).
4. Step 4: Compare each group to the definition of an amine. The group with \(\mathrm{NH_2}\) attached to R matches the amine functional group.
5. Step 5: Conclude that the structure \(\mathrm{R-NH_2}\) represents the amine functional group, while the others correspond to different functional groups.