Why are benzophenone, malonic acid and biphenyl soluble with methyl alcohol?
The Correct Answer and Explanation is:
Correct Answer:
Benzophenone, malonic acid, and biphenyl are soluble in methyl alcohol (methanol) due to favorable intermolecular interactions, particularly hydrogen bonding and polarity compatibility, between these organic compounds and methanol.
Solubility depends on the principle of “like dissolves like”, meaning that polar solutes tend to dissolve in polar solvents, and non-polar solutes dissolve in non-polar solvents. Methyl alcohol (methanol) is a polar solvent with the ability to form hydrogen bonds, due to the presence of both a hydroxyl group (-OH) and a relatively small, polar structure.
Let’s explore why each compound is soluble in methanol:
- Benzophenone is a polar organic compound with a carbonyl group (C=O) attached to two phenyl rings. While the phenyl groups are non-polar, the carbonyl group is highly polar and capable of accepting hydrogen bonds from methanol’s hydroxyl group. This interaction increases benzophenone’s solubility in methanol, despite its overall moderate polarity.
- Malonic acid contains two carboxylic acid groups (-COOH), which are strongly polar and capable of both donating and accepting hydrogen bonds. This makes malonic acid highly soluble in polar protic solvents like methanol, which can engage in hydrogen bonding with both the carbonyl oxygen and the hydroxyl hydrogen of the acid.
- Biphenyl consists of two connected benzene rings, making it largely non-polar. However, biphenyl is partially soluble in methanol due to induced dipole interactions and limited hydrophobic-hydrophilic compatibility. Though not as polar as the other two compounds, the small size of methanol allows it to interact weakly with biphenyl, especially at elevated temperatures or concentrations.
In summary, the solubility of benzophenone, malonic acid, and biphenyl in methyl alcohol is largely due to the ability of methanol to form hydrogen bonds and interact with polar functional groups, as well as its small molecular size that enhances solvation capability.
