Which of the following reaction are correct?

Options

A.
B.
C.
D.

Explanation

To determine which of the given reactions are correct, we will analyze each option step by step.

### Step 1: Analyze Option A
- **Reaction**: Ethyl chloride (C2H5Cl) reacts with ammonia (NH3).
- **Mechanism**: This reaction proceeds via an SN2 mechanism, where the nucleophile (NH3) attacks the electrophilic carbon attached to the chlorine (Cl) atom.
- **Product**: The chlorine atom is replaced by an amino group (NH2), resulting in the formation of ethylamine (C2H5NH2) and ammonium chloride (NH4Cl) as a byproduct.
- **Conclusion**: This reaction is correct.

### Step 2: Analyze Option B
- **Reaction**: A tertiary alcohol reacts with aqueous KOH.
- **Mechanism**: Aqueous KOH typically favors nucleophilic substitution (SN) rather than elimination. In this case, the chlorine (Cl) would be replaced by a hydroxyl group (OH) rather than undergoing elimination.
- **Expected Product**: The expected product should be a tertiary alcohol (with OH replacing Cl), not a double bond.
- **Conclusion**: This reaction is incorrect.

### Step 3: Analyze Option C
- **Reaction**: Chlorocyclohexane reacts with alcoholic KOH.
- **Mechanism**: Alcoholic KOH promotes elimination reactions (dehydrohalogenation). In this case, both H and Cl are removed, leading to the formation of a double bond in cyclohexene.
- **Product**: The product is cyclohexene, which is formed by the elimination of HCl.
- **Conclusion**: This reaction is correct.

### Step 4: Analyze Option D
- **Reaction**: A primary amine reacts with nitrous acid (HNO2).
- **Mechanism**: When a primary amine reacts with HNO2, it forms a diazonium salt (R-N2^+Cl^-) which is unstable in the aliphatic case. It will eventually convert to an alcohol (R-OH) upon hydrolysis.
- **Expected Product**: The product should be a primary alcohol, not a tertiary alcohol.
- **Conclusion**: This reaction is incorrect.

### Final Conclusion
The correct reactions are:
- **Option A**: Correct
- **Option B**: Incorrect
- **Option C**: Correct
- **Option D**: Incorrect

Thus, the correct reactions are A and C.

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