`A overset(Cl_(2))(rarr) B overset("AgCN")(rarr) C overset([H])(rarr) (CH_(3))_(2)` NH Reactant [ A ] is :

Options

A. Methane
B. Ethane
C. Ethene
D. Propane

Answer

To solve the question, we need to identify the reactant A that leads to the final product of a secondary amine through the given reactions. Let's break down the steps:

### Step 1: Identify the Final Product
The final product is a secondary amine, which is represented as (CH₃)₂NH. This indicates that the amine has two methyl groups attached to the nitrogen atom.

### Step 2: Determine the Preceding Reaction
The reaction preceding the formation of the secondary amine involves a compound that undergoes chlorination with Cl₂. Chlorination typically replaces a hydrogen atom with a chlorine atom.

### Step 3: Consider Possible Reactants
To produce a secondary amine, we need to consider what reactant could yield (CH₃)₂NH after chlorination and subsequent reactions. The simplest compound that can yield this product is dimethylamine itself.

### Step 4: Analyze the Chlorination Reaction
If we start with a compound like methane (CH₄) and chlorinate it, we would get CH₃Cl (methyl chloride). However, this would not lead us to a secondary amine.

If we start with ethane (C₂H₆), chlorination would yield CH₃CH₂Cl (ethyl chloride), which also does not lead to a secondary amine.

### Step 5: Identify the Correct Reactant
The correct reactant A that can lead to the formation of (CH₃)₂NH through the chlorination reaction is **dimethylamine (CH₃)₂NH**. This compound can react with Cl₂ to produce a chlorinated product, which can then react with AgCN to form an isocyanide, and finally undergo reduction to yield the secondary amine.

### Conclusion
Thus, the reactant A is **dimethylamine (CH₃)₂NH**.

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