Question

So far, you have seen a number of reducing agents used in reactions. Functional groups react differently with each of these reagents. With this in mind, complete the following reaction, which is the last step in a synthesis of fexofenadine, a nonsedating antihistamine sold under the trade name Allegra.

Short answer

Answer: The steps involved in the final synthesis of fexofenadine (Allegra) are: 1. Identifying the functional groups present in fexofenadine. 2. Identifying the target functional group for reduction in the synthesis (carboxylic acid). 3. Determining the appropriate reducing agent for the target functional group (lithium aluminum hydride, LiAlH4). 4. Writing the balanced equation for the final step in the synthesis: Carboxylic acid precursor + LiAlH4 -> Fexofenadine + LiAlO2.

Step-by-step solution

Determine the functional groups present in fexofenadine.

In the compound structure of fexofenadine, there are alcohol, amine, and carboxylic acid functional groups. The last step in the synthesis is likely a reduction reaction that will involve one of these functional groups.

Identify the target functional group for reduction in the synthesis.

We will focus on the carboxylic acid functional group as the target for reduction, as reducing it will provide the necessary change in the molecule to obtain fexofenadine.

Determine the appropriate reducing agent for the target functional group.

In order to reduce the carboxylic acid functional group to an alcohol, we will use a reducing agent such as lithium aluminum hydride (LiAlH_4).

Write the balanced equation for the final step in the synthesis of fexofenadine.

Reacting the carboxylic acid functional group with LiAlH_4 will lead to the formation of fexofenadine and a byproduct, lithium aluminum oxide (LiAlO_2). The balanced reaction equation is as follows: Carboxylic acid precursor + LiAlH_4 -> Fexofenadine + LiAlO_2 This completes the final step in the synthesis of fexofenadine (Allegra), as we have identified the target functional group, found the appropriate reducing agent and provided the balanced equation for the reaction.