Which of the following compounds will exhibit geometrical isomerism?

Options

A. 1-phenyl-1-butene
B. 3-phenyl-1-butene
C. 2-phenyl-1-butene
D. 1,1-diphenyl-1-propene

Explanation

To determine which of the given compounds will exhibit geometrical isomerism, we need to analyze the structures of each compound and identify if they have a double bond with different groups attached to the carbon atoms involved in the double bond. Geometrical isomerism occurs when there are different substituents on each carbon of a double bond, allowing for different spatial arrangements (cis and trans forms).

### Step-by-Step Solution:

1. **Identify the Compounds**: The question mentions four compounds:
- 1-phenyl-1-butene
- 3-phenyl-1-butene
- 2-phenyl-1-butene
- 1,1-diphenylpropene

2. **Analyze 1-phenyl-1-butene**:
- Structure: C=C with one phenyl group and one butyl group on one carbon, and hydrogen on the other.
- Since there are different groups (phenyl and butyl) attached to one carbon and hydrogen on the other, this compound can exhibit geometrical isomerism (cis/trans).

3. **Analyze 3-phenyl-1-butene**:
- Structure: C=C with a phenyl group on the third carbon and hydrogen on both sides of the double bond.
- Here, both carbons of the double bond have hydrogen atoms, which are the same. Therefore, this compound does not exhibit geometrical isomerism.

4. **Analyze 2-phenyl-1-butene**:
- Structure: C=C with a phenyl group on the second carbon and hydrogen on both sides of the double bond.
- Similar to the previous compound, both carbons have hydrogen atoms, so this compound does not exhibit geometrical isomerism.

5. **Analyze 1,1-diphenylpropene**:
- Structure: C=C with two phenyl groups attached to one carbon and a methyl group and hydrogen on the other carbon.
- Since both substituents on one carbon are the same (phenyl groups), this compound does not exhibit geometrical isomerism.

6. **Conclusion**: The only compound that exhibits geometrical isomerism is **1-phenyl-1-butene**.

### Final Answer:
**1-phenyl-1-butene** is the compound that exhibits geometrical isomerism.

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