Question

4. Examine the IR below and classify the compound. - re -- 335) CICE --P'ELLE 4000 3500 3000 2500 2000 1500 1000 Alcohol Aldehyde Amine Ketone Carboxylic Acid

Answer 1

The above stated IR spectrum is of carboxylic acid. Therefore, the correct option is (E).

In carboxylic acids, there are two groups for which peaks can be recognized in the IR spectrum. These two groups are -C=O and OH group. In the spectrum of carboxylic acid, the broad peak at value around 3000 cm^-1 confirms the presence of -OH group. The peak with value 1704.3 cm^-1 is for the -C=O bond. Therefore, the functional group that satisfies the given IR spectrum is carboxylic acid.

In case of ethanol, there is only one peak for -OH group thus option (A) is incorrect.

In case of aldehyde and ketone, there is only one distinct peak for -C=O bond thus option (B) and (D) are incorrect.

In case of amine, there is one distinct sharp peak with value between 3100 cm^-1 to 3500cm^-1. But in the given spectrum there is a broad which does not account for the N-H bond. Thus option (D) is incorrect.