Give reasons for the following.

• Benzaldehyde reduces tollen’s but not the Fehling’s or benedict’s solution.

Benzaldehyde is an aromatic aldehyde that exhibits specific reactivity with certain chemical reagents. Here are the reasons why it reduces Tollen's reagent but does not reduce Fehling's or Benedict's solutions:

Reactivity with Tollen's Reagent

Tollen's reagent contains silver ions in an ammonia solution, which can be reduced by aldehydes. Benzaldehyde, being an aldehyde, can easily donate electrons to the silver ions, leading to the formation of metallic silver. This reaction is indicative of the presence of aldehydes.

Inactivity with Fehling's and Benedict's Solutions

Fehling's and Benedict's solutions contain copper(II) ions, which require a stronger reducing agent to be reduced to copper(I) oxide. Benzaldehyde, due to its aromatic structure, does not have the necessary reactivity to reduce these copper ions. The stability of the aromatic ring makes it less likely to participate in such reactions.

Summary of Key Points

• Tollen's reagent: Benzaldehyde reduces it due to its ability to donate electrons.
• Fehling's and Benedict's solutions: Benzaldehyde does not reduce them because it lacks the reactivity needed to reduce copper ions.

In essence, the chemical structure and properties of benzaldehyde dictate its selective reactivity with these reagents.