Question

Electrolytic reduction of nitrobenzene in strongly acidic medium gives (a) azoxybenzene (b) aniline (c) p-aminophenol (d) phenylhydroxyl amine

Short answer

The product is aniline (b).

Step-by-step solution

Understanding the Exercise

The problem involves the electrolytic reduction of nitrobenzene in a strongly acidic medium. We need to identify the product formed from this reaction among the options given.

Identify the Reaction Type

The given scenario describes an electrolytic reduction process. In this process, nitrobenzene undergoes electrochemical reduction. This type of reduction generally involves stepwise gain of electrons which reduces the nitro group.

Predict the Product

In a strongly acidic medium, nitrobenzene is typically reduced to aniline (option b). This is a well-known outcome of the electrochemical reduction of nitrobenzene under acidic conditions as the nitro group gets directly converted to the amine group, -NH2.

Eliminate Incorrect Options

Azoxybenzene, p-aminophenol, and phenylhydroxyl amine do not arise directly from the electrolytic reduction of nitrobenzene in strong acid. Particularly, p-aminophenol requires additional specific conditions for its formation. Aniline is the direct and expected product here.

Key concepts

Nitrobenzene

Nitrobenzene is an organic compound that falls into the category of aromatic nitro compounds. It is structurally composed of a benzene ring bonded to a nitro group (-NO2). The presence of the nitro group imparts distinct chemical properties to nitrobenzene. It is often used as a precursor in chemical reactions, serving as a starting material for the synthesis of various compounds. Nitrobenzene appears as a pale yellow liquid and is characterized by its distinct odor reminiscent of almonds. Its primary applications are found in the production of aniline and as a solvent in industrial processes.

When involved in chemical transformations, nitrobenzene can undergo reduction reactions. During this process, the nitro group can be converted into an amino group (-NH2), leading to the formation of different products depending on the reaction conditions. Understanding the behavior of nitrobenzene in different environments, such as strong acidic mediums, is crucial for predicting the outcomes of reduction reactions.

Aniline

Aniline is a key product obtained from the reduction of nitrobenzene. It is an aromatic amine and consists of an amino group (-NH2) attached to a benzene ring. Aniline is recognized for its significance in the chemical industry for manufacturing dyes, drugs, and plastics.

The conversion of nitrobenzene to aniline is a classic example of a reduction process, where the nitro group is transformed into an amino group. This reaction is particularly facilitated in strong acidic mediums, where specific conditions favor the complete reduction to aniline. The presence of acids helps stabilize the transition state and improve electron transfer, aiding the reduction process. This conversion is efficient and widely exploited in industrial processes to produce high-purity aniline.

Electrochemical Reduction

Electrochemical reduction is a process where chemical reactions are driven by an electric current. In the reduction of nitrobenzene, this involves the stepwise addition of electrons to the nitro group. This form of reduction is achieved in an electrolytic cell, where nitrobenzene is dissolved in a solution and subjected to an electric current.

This reduction technique allows for precise control over the reaction conditions. By adjusting the voltage and current, chemists can direct the flow of electrons to preferentially target the nitro group, reducing it to an amine. Electrochemical reduction is an efficient method for converting nitrobenzene to aniline, especially in industrial settings where scalability and control are important. The process is eco-friendly since it can be carried out with minimal chemical waste and uses electricity as a clean energy source.

Strong Acidic Medium

A strong acidic medium refers to the environment in which the electrochemical reduction of nitrobenzene occurs. In this context, a strong acid, such as hydrochloric acid or sulfuric acid, is used to create a conducive environment for the reduction reaction.

Strong acids facilitate the reduction process by providing a high concentration of protons (H+ ions), which play a crucial role in stabilizing intermediates formed during the reduction of nitrobenzene. The acidic conditions help to avoid unwanted side reactions and direct the reduction towards the formation of aniline.

In the laboratory or industrial applications, the choice of acid and its concentration is critical. It impacts not only the rate of reaction but also the quality and yield of the final product. Using strong acids ensures that the nitro group is effectively reduced to the amino group, resulting in the successful production of aniline.