Phenylephrine, an organic substance with molecular formula C9H13NO2, is used as a nasal decongenstant in over-thecounter medications. The molecular structure of phenylephrine is shown below using the usual shortcut organic structure. (a) Would you expect a solution of phenylephrine to be acidic, neutral, or basic?

Verified step by step guidance

1. Identify the functional groups present in the molecular structure of phenylephrine. Look for groups that can donate or accept protons (H+).
2. Notice the presence of an amine group (NH2) in the structure. Amines are known to be basic because they can accept a proton.
3. Consider the presence of any other functional groups that might influence the acidity or basicity of the molecule. In this case, the structure does not contain any strongly acidic groups like carboxylic acids.
4. Evaluate the overall structure to determine if there are any other factors that might affect the pH of the solution. The presence of the aromatic ring does not significantly affect the basicity of the amine group.
5. Conclude that the solution of phenylephrine is expected to be basic due to the presence of the amine group, which can accept protons and increase the pH of the solution.

Key Concepts

Acid-Base Chemistry

Acid-base chemistry involves the study of substances that can donate protons (acids) or accept protons (bases). The pH scale measures the acidity or basicity of a solution, with values below 7 indicating acidity, 7 being neutral, and above 7 indicating basicity. Understanding the nature of a compound's functional groups is crucial in predicting its behavior in solution.

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. In phenylephrine, the presence of an amine group (-NH2) and a hydroxyl group (-OH) suggests potential for both basic and acidic behavior, influencing the overall acidity or basicity of the compound in solution.

Ionization of Phenylephrine

The ionization of phenylephrine in solution is determined by its ability to donate or accept protons. The amine group can accept protons, making the compound more basic, while the hydroxyl group can donate protons, contributing to acidity. The balance between these interactions will dictate whether the solution is acidic, neutral, or basic.