Problem 145 - A Complete Resource Book in Chemistry for JEE Main

Question

The end product (c) in this reaction, $$ \begin{aligned} &\mathrm{CH}_{3} \mathrm{COOH} \stackrel{\mathrm{CaCO}_{3}}{\longrightarrow \mathrm{A}} \stackrel{\text { Heat }}{\longrightarrow \mathrm{B}} \\ &\mathrm{NH}_{2} \mathrm{OH} \\ &\longrightarrow \mathrm{C}, \text { is } \end{aligned} $$ (a) Acetaldehyde oxime (b) Aceto oxime (c) Acetamide (d) Ethane nitrile

Step-by-Step Solution

Answer

C is aceto oxime.

Step 1: Reaction with Calcium Carbonate

The reaction begins with acetic acid (CH₃COOH) reacting with calcium carbonate (CaCO₃). The purpose of this step is to neutralize the acetic acid and produce calcium acetate. The balanced chemical equation is: \[ \text{2 CH}_3\text{COOH} + \text{CaCO}_3 \rightarrow (\text{CH}_3\text{COO})_2\text{Ca} + \text{CO}_2 + \text{H}_2\text{O} \] In this step, compound \(A\) is calcium acetate \((\text{CH}_3\text{COO})_2\text{Ca})\).

Step 2: Heating of Calcium Acetate

Next, calcium acetate is heated to yield acetone (CH₃COCH₃) and calcium carbonate as per the following reaction: \[ (\text{CH}_3\text{COO})_2\text{Ca} \rightarrow \text{CH}_3\text{COCH}_3 + \text{CaCO}_3 \] Here, compound \(B\) formed in this reaction is acetone \((\text{CH}_3\text{COCH}_3)\).

Step 3: Reaction with Hydroxylamine

In the final step, acetone reacts with hydroxylamine (NH₂OH) to produce acetone oxime. This reaction converts the carbonyl group of the ketone into an oxime group. The chemical reaction is: \[ \text{CH}_3\text{COCH}_3 + \text{NH}_2\text{OH} \rightarrow \text{CH}_3\text{C}(NOH)\text{CH}_3 \] Here, the product \(C\) is acetone oxime \((\text{CH}_3\text{C}(\text{NOH})\text{CH}_3\)). This compound is also referred to as aceto oxime.

Key Concepts

Calcium Acetate

Calcium acetate is an important chemical compound that emerges from the reaction of acetic acid with calcium carbonate. In the equation \[ \text{2 CH}_3\text{COOH} + \text{CaCO}_3 \rightarrow (\text{CH}_3\text{COO})_2\text{Ca} + \text{CO}_2 + \text{H}_2\text{O} \], acetic acid (\( \mathrm{CH}_{3} \mathrm{COOH} \)) reacts with calcium carbonate (\( \mathrm{CaCO}_{3} \)) to form calcium acetate, carbon dioxide \((\mathrm{CO}_{2}) \), and water \((\mathrm{H}_{2}\mathrm{O})\).

This compound takes the form of a crystalline substance and is known for its use in various industrial applications. When acetic acid and calcium carbonate interact, they undergo a neutralization process, resulting in the formation of calcium acetate.

The compound is noteworthy for its applications in chemistry due to its ability to decompose at elevated temperatures, ultimately leading to the formation of other useful chemical products such as acetone.

Acetone Formation

The formation of acetone is a key result of heating calcium acetate, a process significant in industrial and chemical contexts. The breakdown of calcium acetate occurs when the compound is subjected to high temperatures, following the reaction: \[ (\text{CH}_3\text{COO})_2\text{Ca} \rightarrow \text{CH}_3\text{COCH}_3 + \text{CaCO}_3 \].

In this decomposition process, the doubled acetate moieties rearrange to produce acetone \((\text{CH}_3\text{COCH}_3)\), while simultaneously regenerating calcium carbonate. This ensures a cycle of regenerations and transformation whereby each molecule's output serves as a precursor for another.

Acetone, a simple ketone, gains significance as a powerful solvent used in multiple applications, including varnishes and chemical synthesis. Its production from calcium acetate justifies the relevance of the heating process in the chemical industry.

Oximation Reaction

Oximation is a fascinating chemical reaction, particularly known for transforming carbonyl groups into oxime groups. This transformation is crucial in the final step of the question's chemical process: \[ \text{CH}_3\text{COCH}_3 + \text{NH}_2\text{OH} \rightarrow \text{CH}_3\text{C}(NOH)\text{CH}_3 \].

Here, acetone reacts with hydroxylamine \((\text{NH}_2\text{OH})\) to yield acetone oxime, also often called aceto oxime.

In the oximation reaction, the carbonyl group within the acetone molecule undergoes a transformation. The oxygen in the carbonyl group interacts with hydroxylamine, forming a more complex structure known as an oxime group. This process effectively replaces the carbonyl group with \( -\text{C}(\text{NOH})- \), creating a stable compound with diverse functionalities in synthesis and chemical modifications.

Understanding the concept of oximation is crucial as this reaction expands the usefulness of simple ketones and aldehydes, further enhancing their presence in chemical reactions and syntheses.