KCN reacts readily to give a cyanide with

Options

A. Ethyl alcohol
B. Ethyl bromide
C. Bromobenzene
D. Chlorobenzene

Explanation

To solve the question "KCN reacts readily to give a cyanide with", we need to analyze the reactivity of KCN (potassium cyanide) with different types of compounds. Here’s a step-by-step breakdown of the solution:

### Step 1: Understanding the Components
KCN dissociates in solution to form K⁺ and CN⁻ ions. The CN⁻ ion is a strong nucleophile, which means it can attack electrophilic centers in organic compounds.

**Hint:** Identify the components of KCN and their roles in the reaction.

### Step 2: Identifying Reactants
We need to determine which type of organic compound KCN can react with to form a cyanide. Typically, KCN reacts with alkyl halides, especially primary alkyl halides, through an SN2 mechanism.

**Hint:** Consider the types of organic compounds that can undergo nucleophilic substitution.

### Step 3: Analyzing the Options
1. **S.L.L. Alcohol (C2H5OH)**: Alcohols do not react with KCN to form cyanides because they are not good electrophiles for nucleophilic substitution.

2. **S.L. Bromide (CH3CH2Br)**: This is a primary alkyl halide. When KCN reacts with CH3CH2Br, the CN⁻ ion will attack the carbon bonded to the bromine, leading to the formation of ethyl cyanide (CH3CH2CN) and potassium bromide (KBr).

3. **Bromobenzene**: This is an aromatic compound and does not undergo SN2 reactions with KCN due to the stability of the aromatic ring.

4. **Chlorobenzene**: Similar to bromobenzene, chlorobenzene is also not reactive towards KCN due to the aromatic nature.

5. **Ethylbenzene**: This is not a halide and thus cannot react with KCN to form cyanides.

**Hint:** Evaluate each option based on the type of reaction (SN2) and the structure of the compound.

### Step 4: Conclusion
The only viable option that allows KCN to react and form a cyanide is the primary alkyl halide, which is S.L. Bromide (CH3CH2Br). The reaction will yield ethyl cyanide (CH3CH2CN).

**Final Answer:** KCN reacts readily to give a cyanide with S.L. Bromide (CH3CH2Br).

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