In the following sequence of reaction, the end product is :
`CaC_(2)overset(H_(2)O)rarr(A)overset(Hg^(2+)//H_(2)SO_(4))rarr(B)overset([o])rarr(C)overset(Ca(OH_(2)))rarr(D)overset("Heat")rarr(E)`

Options

A. acetaldehyde
B. formaldehyde
C. acetic acid
D. acetone

Answer

To solve the given sequence of reactions step by step, let's break down each transformation:

1. **Starting Material (Calcium Carbide)**:
The reaction begins with calcium carbide (CaC₂). When calcium carbide reacts with water (H₂O), it produces acetylene (ethyne, C₂H₂) and calcium hydroxide (Ca(OH)₂).
\[ \text{CaC}_2 + 2 \text{H}_2\text{O} \rightarrow \text{C}_2\text{H}_2 + \text{Ca(OH)}_2 \]
- **Hint**: Remember that calcium carbide reacts with water to produce acetylene gas.

2. **Formation of Aldehyde (B)**:
The acetylene (C₂H₂) is then treated with mercuric ion (Hg²⁺) in the presence of sulfuric acid (H₂SO₄). This reaction leads to the formation of an aldehyde, specifically acetaldehyde (ethanal, CH₃CHO).
\[ \text{C}_2\text{H}_2 + \text{Hg}^{2+} + \text{H}_2\text{SO}_4 \rightarrow \text{CH}_3\text{CHO} \quad (\text{Acetaldehyde}) \]
- **Hint**: The addition of Hg²⁺ and H₂SO₄ to acetylene results in the formation of an aldehyde.

3. **Oxidation to Carboxylic Acid (C)**:
The acetaldehyde (CH₃CHO) undergoes oxidation to form acetic acid (ethanoic acid, CH₃COOH).
\[ \text{CH}_3\text{CHO} + [O] \rightarrow \text{CH}_3\text{COOH} \]
- **Hint**: Aldehydes can be oxidized to carboxylic acids using an oxidizing agent.

4. **Reaction with Calcium Hydroxide (D)**:
The acetic acid (CH₃COOH) reacts with calcium hydroxide (Ca(OH)₂) to form calcium acetate (Ca(CH₃COO)₂).
\[ 2 \text{CH}_3\text{COOH} + \text{Ca(OH)}_2 \rightarrow \text{Ca(CH}_3\text{COO)}_2 + 2 \text{H}_2\text{O} \]
- **Hint**: Mixing a carboxylic acid with a base like calcium hydroxide results in the formation of a salt.

5. **Heating to Form Ketone (E)**:
Upon heating the calcium acetate (Ca(CH₃COO)₂), it undergoes decarboxylation to yield acetone (dimethyl ketone, CH₃COCH₃).
\[ \text{Ca(CH}_3\text{COO)}_2 \xrightarrow{\text{Heat}} \text{CH}_3\text{COCH}_3 + \text{CaCO}_3 \]
- **Hint**: Heating calcium acetate leads to the formation of acetone and calcium carbonate.

**Final Answer**: The end product (E) of the sequence of reactions is acetone (dimethyl ketone, CH₃COCH₃).

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