In which of the following reaction the single product formed is not the saytzeff's product

Options

A.
B.
C.
D.

Answer

To determine which reaction produces a single product that is not a Saytzeff product, we need to analyze the reactions and their products based on the stability of the alkenes formed. The Saytzeff rule states that in elimination reactions, the more substituted alkene (the more stable one) is favored as the major product.

### Step-by-Step Solution:

1. **Identify the Reactions**: We have four reactions to analyze, which include dehydration and dehydrohalogenation reactions.

2. **Analyze Each Reaction**:
- **Reaction 1**: Dehydration of an alcohol (e.g., CH3-CH(OH)-CH2-CH3 with sulfuric acid).
- Possible products: Two alkenes can be formed. The more substituted alkene (Saytzeff product) will be the major product, while the less substituted alkene will be the minor product.
- Conclusion: This reaction produces a Saytzeff product.

- **Reaction 2**: Dehydration of cyclopentanol (with sulfuric acid).
- Possible products: The more substituted alkene will be favored (Saytzeff product), but if a less substituted alkene is formed as the only product, it would be the non-Saytzeff product.
- Conclusion: This reaction can produce a non-Saytzeff product depending on the structure.

- **Reaction 3**: Dehydrohalogenation of an alkyl halide (e.g., CH3-CH2-CHBr-CH3 with alcoholic KOH).
- Possible products: The elimination can lead to the formation of a more substituted alkene (Saytzeff product).
- Conclusion: This reaction produces a Saytzeff product.

- **Reaction 4**: Dehydrohalogenation of a tertiary alkyl halide (e.g., (CH3)3CBr with alcoholic KOH).
- Possible products: The elimination will favor the formation of the most substituted alkene (Saytzeff product).
- Conclusion: This reaction produces a Saytzeff product.

3. **Identify the Non-Saytzeff Product**: From the analysis, the second reaction (dehydration of cyclopentanol) is the only one that can yield a product that is not a Saytzeff product, as it can produce a less substituted alkene as the only product.

### Final Answer:
The reaction in which the single product formed is not the Saytzeff product is **Option 2** (dehydration of cyclopentanol).