Isobutene is the exclusive product of dehydrohalogenation ( by a strong base ) of

Options

A. isobutyl chloride
B. tert - butyl bromide
C. both (a) and (b)
D. neither (a) nor (b)

Explanation

To determine which compound will yield isobutene as the exclusive product of dehydrohalogenation by a strong base, we need to analyze the provided options. Isobutene (or 2-methylpropene) has the formula C4H8 and can be represented as:

\[ \text{CH}_2=C(CH_3)_2 \]

### Step-by-Step Solution:

1. **Identify the Structure of Isobutene**:
- Isobutene is a branched alkene with the structure CH2=C(CH3)2. This indicates that it has a double bond between the first and second carbon atoms.

2. **Understand Dehydrohalogenation**:
- Dehydrohalogenation is a reaction where a hydrogen halide (HX) is eliminated from an alkyl halide in the presence of a strong base, leading to the formation of an alkene.

3. **Analyze the Options**:
- Let's consider the options provided (A, B, C, D) for possible alkyl halides that can undergo dehydrohalogenation to yield isobutene.

4. **Option A: Isobutyl Chloride (C4H9Cl)**:
- Structure: CH3-CH(CH3)-CH2-Cl
- Upon treatment with a strong base, the base will abstract a β-hydrogen (the hydrogen on the carbon adjacent to the carbon bearing the halide), leading to the formation of isobutene.
- Reaction:
\[ \text{CH}_3-\text{C}(\text{Cl})(\text{CH}_3)-\text{CH}_2-\text{H} \xrightarrow{\text{Strong Base}} \text{CH}_2=\text{C}(\text{CH}_3)_2 + \text{HCl} \]

5. **Option B: Tertiary Butyl Bromide (C4H9Br)**:
- Structure: (CH3)3C-Br
- Similar to option A, the strong base will abstract a β-hydrogen from the tertiary butyl bromide, leading to the formation of isobutene.
- Reaction:
\[ \text{(CH}_3)_3\text{C-Br} \xrightarrow{\text{Strong Base}} \text{CH}_2=\text{C}(\text{CH}_3)_2 + \text{HBr} \]

6. **Conclusion**:
- Both isobutyl chloride and tertiary butyl bromide can yield isobutene as the exclusive product upon dehydrohalogenation with a strong base. Therefore, both options A and B are correct.

### Final Answer:
Isobutene is the exclusive product of dehydrohalogenation of:
- A) Isobutyl Chloride
- B) Tertiary Butyl Bromide