`CH_(3)Br overset("KCN")(rarr)A underset(LiAlH_4)overset(4[H])(rarr)CH_(3)CH_(2)NH_(2)`
IUPAC name of A is

Options

A. Methyl cyanide
B. Methyl isonitrile
C. Acetonitrile
D. Ethane nitrile

Answer

To solve the question, we need to identify the compound A formed from the reaction of CH₃Br with KCN and then determine its IUPAC name.

### Step 1: Identify the reaction between CH₃Br and KCN
- The starting compound is CH₃Br (bromomethane).
- When CH₃Br reacts with KCN (potassium cyanide), the bromine atom is replaced by the cyanide group (CN⁻).
- This reaction is a nucleophilic substitution reaction where the bromine is a leaving group and the cyanide ion acts as the nucleophile.

**Reaction:**
\[ \text{CH}_3\text{Br} + \text{KCN} \rightarrow \text{CH}_3\text{CN} + \text{KBr} \]

### Step 2: Identify the product A
- The product formed from the above reaction is CH₃CN.
- CH₃CN is known as acetonitrile or ethane nitrile.

### Step 3: Determine the IUPAC name of A
- The IUPAC name for CH₃CN is ethane nitrile.
- In IUPAC nomenclature, the longest carbon chain is identified, and the functional group (nitrile in this case) is named accordingly.

### Step 4: Confirm the subsequent reaction with LiAlH₄
- The next part of the question involves the reduction of A (CH₃CN) using LiAlH₄ (lithium aluminium hydride).
- LiAlH₄ is a strong reducing agent that can reduce nitriles to primary amines.
- The reduction of CH₃CN will yield CH₃CH₂NH₂ (ethylamine).

**Reaction:**
\[ \text{CH}_3\text{CN} + 4[H] \xrightarrow{\text{LiAlH}_4} \text{CH}_3\text{CH}_2\text{NH}_2 \]

### Final Answer
Thus, the IUPAC name of compound A (CH₃CN) is **ethane nitrile**.

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