Problem 156 - Arihant Objective Approach to Organic Chemistry for IIT JEE and NEET all Medical Entrances Part 4

Question

After the reaction of sodium benzene sulphonate with \(\mathrm{NaOH}\), it is hydrolysed by acid, the compound produced is: |MHCET 2001| (a) disodium benzaldehyde (b) benzene (c) benxoic acid (d) phenol

Step-by-Step Solution

Answer

The compound produced is phenol (d).

Step 1: Reaction Setup

Understand the initial reaction where sodium benzene sulphonate reacts with sodium hydroxide (NaOH). This is a typical reaction involving the conversion of benzene sulphonate to a phenoxide ion.

Step 2: Hydrolysis of Phenoxide

The phenoxide ion formed in the previous step is then hydrolysed during the acidic hydrolysis process. This converts the phenoxide ion into phenol.

Step 3: Identify the Product

Recognize that the phenol is the final product of this reaction sequence. There is no further transformation after hydrolysis that would convert phenol into any other compound among the given choices.

Step 4: Conclusion

Based on the provided options, phenol corresponds to option (d). The reactions do not lead to the formation of benzene, benzoic acid, or disodium benzaldehyde in this context.

Key Concepts

Sodium Benzene Sulphonate

Sodium benzene sulphonate is a key player in many organic chemistry reactions. It is a compound where a sulfonate group (\( ext{-SO}_3 ext{Na} \)) is attached to a benzene ring. This gives the compound the ability to undergo different reactions based on conditions. Sodium benzene sulphonate is often used as an intermediate for synthesizing other organic compounds.

In the context of the given reaction, sodium benzene sulphonate reacts with sodium hydroxide (\( ext{NaOH} \)) to form a phenoxide ion. This step sets the stage for subsequent reactions. This reaction is significant because it transforms a sulfonate group into an oxygen-bearing phenoxide ion.

The properties of sodium benzene sulphonate make it a useful reagent in synthetic procedures, shown by its ability to react under alkaline conditions to produce various organic derivatives. Understanding this compound's role helps demystify how complex organic molecules can be manipulated.

Acidic Hydrolysis

Acidic hydrolysis is a chemical process where water is used to break down a compound in the presence of an acid. In this case, the phenoxide ion formed from sodium benzene sulphonate is subjected to acidic hydrolysis.

During acidic hydrolysis, the phenoxide ion reacts with an acid, typically contributing a proton (H+), facilitating the transformation of the phenoxide into phenol. This occurs as the added protons help break the bond between oxygen and sodium of the phenoxide ion. Thus, the oxygen is then bonded to hydrogen, forming phenol. This process highlights the role of proton donors in organic transformations, showing how they can change functional groups within molecules.

• Phenoxide ions are basic and readily accept protons during hydrolysis.
• This reaction is crucial for converting more reactive, unstable ions into stable compound forms, like phenol.

Acidic hydrolysis is an essential mechanism in organic synthesis, enabling the conversion of intermediates or temporary states into valuable and usable chemical compounds.

Organic Chemistry Reactions

Organic chemistry reactions cover a vast array of transformations that molecules undergo due to structural changes and chemical processes. In this exercise, we explore the reaction sequence starting from sodium benzene sulphonate and ending with phenol formation.

Understanding organic reactions involves grasping how each functional group interplays with others in the presence of reagents and catalysts. In our example, the interplay of sulfonate, hydroxide ions, and subsequent acidic conditions illuminate basic principles of functional group transformation.

• Reaction conditions (like presence of \( ext{NaOH} \) and acids) dictate the chemical pathway.
• Sodium benzene sulphonate serves as a starting material, highlighting manipulation of the benzene ring for synthesis.
• Hydrolysis often serves to stabilize organic intermediates into more stable products like phenol.
• Chemists harness these reactions to build larger, more complex molecular structures for various applications.

These reactions underline the importance of understanding functional group behavior, pH impacts, and polymerization, contributing to advances in chemical synthesis and industrial applications.