What is the end product in the following sequence of reactions ?
`C_6H_5COOH overset(PCl_5)(rarr)Poverset(2NH_3)(rarr)Qoverset("Reduction")(rarr)R`

Options

A. Aniline
B. Benzylamine
C. Cyanobenzene
D. Benzenediazonium chloride

Answer

To determine the end product R in the given sequence of reactions starting from benzoic acid (C₆H₅COOH), we will analyze each step carefully.

### Step 1: Reaction of Benzoic Acid with PCl₅
- **Starting Material**: C₆H₅COOH (benzoic acid)
- **Reagent**: PCl₅ (phosphorus pentachloride)
- **Reaction**: When benzoic acid reacts with PCl₅, it undergoes acyl chloride formation.
- **Product**: The product of this reaction is benzoyl chloride (C₆H₅COCl). We will denote this product as P.

### Step 2: Reaction of Benzoyl Chloride with Ammonia
- **Starting Material**: P (C₆H₅COCl)
- **Reagent**: NH₃ (ammonia)
- **Reaction**: Benzoyl chloride reacts with ammonia to form an amide.
- **Product**: The product of this reaction is benzamide (C₆H₅CONH₂). We will denote this product as Q.

### Step 3: Reduction of Benzamide
- **Starting Material**: Q (C₆H₅CONH₂)
- **Reagent**: A reducing agent (commonly lithium aluminum hydride, LiAlH₄)
- **Reaction**: Benzamide can be reduced to form benzylamine.
- **Product**: The product of this reduction is benzylamine (C₆H₅CH₂NH₂). We will denote this product as R.

### Final Product
- The end product R after the entire sequence of reactions is **benzylamine (C₆H₅CH₂NH₂)**.

### Summary of the Reaction Sequence
1. C₆H₅COOH + PCl₅ → C₆H₅COCl (P - benzoyl chloride)
2. C₆H₅COCl + NH₃ → C₆H₅CONH₂ (Q - benzamide)
3. C₆H₅CONH₂ + reducing agent → C₆H₅CH₂NH₂ (R - benzylamine)

### Final Answer
The end product R is **benzylamine (C₆H₅CH₂NH₂)**.

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