Question

Nitrobenzene on electrolytic reduction in strongly acidic medium gives (a) aniline (b) m-nitroaniline (c) nitrosobenzene (d) p-aminophenol

Short answer

Nitrobenzene is reduced to aniline in strongly acidic medium.

Step-by-step solution

Identify the Problem

The problem involves understanding what compound nitrobenzene will be converted into upon electrolytic reduction in a strongly acidic medium.

Choose Reaction Conditions

Recognize that the reaction occurs under electrolytic conditions in a strongly acidic medium, which influences the type of reduction process nitrobenzene undergoes.

Recall the Reaction Mechanism

Consider that in strongly acidic conditions, nitrobenzene undergoes a reduction to form aniline due to the more favorable pathway that encourages amine formation.

Match Reaction Outcome with Options

Cross-reference the reaction outcome with the given options: aniline (a), m-nitroaniline (b), nitrosobenzene (c), and p-aminophenol (d). In this setting, nitrobenzene is reduced to aniline.

Key concepts

Nitrobenzene

Nitrobenzene is a chemical compound that forms the starting material in the described problem. It consists of a benzene ring attached to a nitro group (-NO2). The nitro group is a significant functional group, influencing the chemical behavior of nitrobenzene.
This compound is yellowish in appearance and possesses a distinct almond-like odor.
This functional group is electron-withdrawing, making nitrobenzene a deactivated benzene, meaning it doesn't readily undergo typical benzene reactions.

• Nitrobenzene extbf{is not} very reactive towards substitution reactions on the ring due to the nature of the nitro group.
• The nitro group can, however, undergo reduction, which is central to this exercise, leading to the formation of various derivatives depending on the reaction conditions.

Strongly Acidic Medium

In chemical reactions, the medium can greatly influence the pathways and products. A strongly acidic medium is one where the concentration of hydrogen ions (H+) is high, creating an environment conducive to certain types of reactions, such as reductions and hydrolyses.

• In this context, the strongly acidic environment helps favor the complete reduction of nitro groups to amino groups, leading to the formation of aniline.
• Acidic conditions can provide the necessary protons that facilitate reactions where electron-rich intermediates, such as radicals, are required.

For nitrobenzene, the presence of excess acid helps stabilize intermediate species that form during reduction, making the reduction more efficient.
It effectively shifts the reaction course away from partial reductions, ensuring complete conversion to an amine.

Aniline Formation

Aniline is the primary product of nitrobenzene reduction in this strongly acidic environment. Aniline consists of a benzene ring bonded to an amino group (-NH2). This chemical transformation is crucial in various industrial applications, especially in dyes and polymer production.
The process of converting nitrobenzene to aniline through electrolytic reduction involves several steps:

• The nitro group (-NO2) is sequentially reduced as it gains electrons and protons, first converting possibly to a nitroso (-NO) group, then a hydroxylamine (-NHOH) group, and finally to the amino group (-NH2).
• Electrolytic reduction leverages external electrical energy to speed up these electron transfer reactions, particularly in a setup that involves an electrode apparatus in an acidic solution.

What sets electrolytic reduction apart is its ability to be controlled precisely, making it especially useful in producing high-purity aniline.
Thus, strong acidic conditions coupled with electrolytic reduction efficiently push nitrobenzene towards forming aniline, which is not only useful as a large scale industrial feedstock but also as a fundamental compound for synthesis.