Question

Which acid derivative on hydrolysis gives only carboxylic acids? (A) Acid chloride (B) Acid amide (C) Acid anhydride (D) Ester

Short answer

The hydrolysis of acid anhydride (option C) produces two carboxylic acids, while the other acid derivatives produce a carboxylic acid along with HCl, NH3, or an alcohol. Therefore, the correct answer is (C) Acid anhydride.

Step-by-step solution

Hydrolysis of Acid Chloride

When an acid chloride is hydrolyzed, it reacts with water to form a carboxylic acid and hydrochloric acid (HCl). The general reaction of acid chloride hydrolysis can be given as follows: \( RCOCl + H_2O \longrightarrow RCOOH + HCl \)

Hydrolysis of Acid Amide

When an acid amide is hydrolyzed, it reacts with water to form a carboxylic acid and ammonia (NH3). The general reaction of acid amide hydrolysis can be given as follows: \( RCONH_2 + H_2O \longrightarrow RCOOH + NH_3 \)

Hydrolysis of Acid Anhydride

Acid anhydrides are derived from carboxylic acids by loss of a water molecule. When an acid anhydride is hydrolyzed, it reacts with water to form two carboxylic acids. The general reaction of acid anhydride hydrolysis can be given as follows: \( (RCO)_2O + H_2O \longrightarrow RCOOH + RCOOH \)

Hydrolysis of Ester

When an ester is hydrolyzed, it reacts with water to form a carboxylic acid and an alcohol. The general reaction of ester hydrolysis can be given as follows: \( RCOOR' + H_2O \longrightarrow RCOOH + R'OH \)

Comparing the Hydrolysis Reactions

Now that we've gone through the hydrolysis reactions of the given acid derivatives, we can compare them to determine which one yields only carboxylic acids. It can be seen that the hydrolysis of acid anhydride (option C) produces two carboxylic acids, while the other acid derivatives produce a carboxylic acid along with HCl, NH3, or an alcohol. Therefore, the correct answer is: (C) Acid anhydride

Key concepts

Carboxylic Acids

Carboxylic acids are a class of organic compounds that are characterized by the presence of a carboxyl group (\( -COOH \)). This functional group comprises a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (\( -OH \)), making it highly reactive.

These organic acids occur widely in nature and are also synthetically produced for various applications. They have distinct sour tastes and are found in substances like vinegar (acetic acid) and citrus fruits (citric acid). In an academic setting like the JEE (Joint Entrance Examination), which tests understanding of organic chemistry, grasping the properties and reactions of carboxylic acids is fundamental.

When studying or solving problems involving carboxylic acids, remember that their acidity is a result of the resonance stabilization of their carboxylate anion, and this property is notably influenced by substituents attached to the carboxyl group.

Hydrolysis Reaction

Understanding Hydrolysis

Hydrolysis reactions are a cornerstone in the study of organic chemistry, often featured in exams like the JEE. These reactions involve the breaking of bonds in molecules through the addition of water. In the context of acid derivatives, hydrolysis typically results in the conversion of these derivatives back to carboxylic acids, alongside other byproducts.

The process is catalyzed by acids or bases and can involve various derivatives, including esters, amides, and anhydrides. The predictability of hydrolysis products is key to understanding chemical reactivity and is essential for students preparing for competitive exams. The hydrolysis of different acid derivatives demonstrates how water can act as a nucleophile, attacking electrophilic carbon atoms of the carboxylic acid derivatives.

Organic Chemistry for JEE

Importance in JEE

Organic chemistry is a significant portion of the JEE syllabus, often daunting for many students. The JEE, a gateway for admissions into prestigious engineering colleges in India, assesses candidates' proficiency across several topics, including acid derivatives and their reactions.

A strong understanding of these concepts not only aids in tackling direct questions but also helps in solving complex synthesis problems. To excel in organic chemistry for JEE, focus on building a solid foundation in the basic concepts, such as functional groups, reaction mechanisms, and stereochemistry.

Strategy for Exam Preparation

Developing a strategy, such as identifying reaction patterns and practicing conversion problems, can be helpful. Remember, grasping the underlying principles behind reactions, like hydrolysis, and being able to interlink them with related topics is far more valuable than merely memorizing processes.