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

Question

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

Step-by-Step Solution

Answer

The final product \(\text{C}\) is aceto oxime (option b).

Step 1: Understand the Reaction Pathway

The reaction involves multiple steps: starting with acetic acid (\(\text{CH}_3\text{COOH}\)), which reacts with calcium carbonate (\(\text{CaCO}_3\)) to form an intermediate \(\text{A}\). When intermediate \(\text{A}\) is heated, it transforms into another intermediate \(\text{B}\). Lastly, \(\text{B}\) reacts with hydroxylamine (NH2OH) to yield the final product \(\text{C}\). Our task is to identify what \(\text{C}\) is.

Step 2: First Stage Reaction: Formation of A

When acetic acid (\(\text{CH}_3\text{COOH}\)) reacts with calcium carbonate (\(\text{CaCO}_3\)), it forms calcium acetate (\(\text{Ca}\left(\text{CH}_3\text{COO}\right)_2\)) and releases carbon dioxide (\(\text{CO}_2\)) and water. This product \(\text{A}\) is calcium acetate.

Step 3: Second Stage Reaction: Formation of B

Upon heating, calcium acetate (\(\text{A}\)) decomposes to give acetone (\(\text{CH}_3\text{COCH}_3\)) and calcium carbonate is regenerated. Therefore, \(\text{B}\) is acetone.

Step 4: Final Stage Reaction: Formation of C

When acetone (\(\text{B}\)) reacts with hydroxylamine (\(\text{NH}_2\text{OH}\)), it forms acetoxime. Acetoxime is the compound formed when hydroxylamine adds to the carbonyl group of acetone, creating \(\text{C}\).

Key Concepts

Calcium Acetate

Calcium acetate is an important compound in the world of organic chemistry reactions. It is formed when acetic acid, with the formula \( \text{CH}_3\text{COOH} \), reacts with calcium carbonate \( \text{CaCO}_3 \). This reaction not only produces calcium acetate but also releases carbon dioxide \( \text{CO}_2 \) and water \( \text{H}_2\text{O} \) as byproducts.
Understanding calcium acetate's chemical structure is key. It consists of two acetate ions (\( \text{CH}_3\text{COO}^- \)) bound to a calcium ion (\( \text{Ca}^{2+} \)). This structure imparts certain distinct properties to calcium acetate, such as its ability to decompose easily upon heating which is crucial in many organic processes.
Calcium acetate is used extensively in reactions where acetone formation is needed, as it serves as a precursor. Its application isn't limited to chemical reactions; it plays a role in various industries, including food as a stabilizer and in medicine for phosphate binding in formulations.

• Formed by reacting acetic acid with calcium carbonate.
• Structure: Contains acetate ions and calcium ion.
• Applications: Used in food, medicine, and as a precursor for acetone.

Acetone Formation

Acetone, a simple ketone with the formula \( \text{CH}_3\text{COCH}_3 \), forms through the decomposition of calcium acetate. This process occurs when calcium acetate is heated, resulting in the breakdown of its structure to release acetone and regenerate calcium carbonate.
Acetone has a carbonyl group (\( \text{C}=\text{O} \)) between two methyl groups, which gives it reactive properties that make it valuable in various organic chemistry processes. It acts as a solvent and a reagent in different chemical reactions.
The production of acetone from heating calcium acetate is a classic transformation in organic synthesis. This reaction was historically significant as one of the first methods to prepare acetone before synthetic routes became more prevalent.

• Product of heated calcium acetate decomposition.
• Structure: Contains a carbonyl group flanked by methyl groups.
• Uses: Solvent, reagent, and historical synthesis pathway.

Hydroxylamine Reaction

Hydroxylamine, with the formula \( \text{NH}_2\text{OH} \), is a reactive compound used to create valuable derivatives from carbonyl-containing molecules like acetone. When acetone forms from calcium acetate and then reacts with hydroxylamine, a chemical transformation occurs, producing acetoxime.
This reaction is characterized by hydroxylamine adding to the carbonyl group in acetone. The resulting compound, acetoxime, \( \text{CH}_3\text{C}(\text{NOH})\text{CH}_3 \), represents a class of compounds known as oximes.
Oximes like acetoxime are crucial in various applications. They are used in the identification and purification of ketones and aldehydes, serving as intermediates in the synthesis of amines. The reaction highlights the versatility of hydroxylamine in converting simple ketones into more complex functional groups.

• Involves hydroxylamine adding to acetone's carbonyl group.
• Product: Acetoxime, classed as an oxime.
• Applications: Used in synthesis and purification processes.