`Ph-CH=CH-Ph underset(C Cl_(4))overset(Cl_(2))rarr X overset(2NaNH_(2))rarrYoverset(H_(2),Pd-CaCO_(3))rarrZ`
Identify product (Z) of the reaction.

Options

A.
B.
C. `Ph-underset(Ph)underset(|)(C)=CH_(2)`
D. `Ph-C-=C-Ph`

Answer

To solve the problem step by step, we will analyze the reaction sequence given in the question:

1. **Starting Material**: The starting material is Ph-CH=CH-Ph, which is a styrene derivative (a phenyl group attached to a vinyl group).

2. **First Reaction (Addition of Cl2 in CCl4)**:
- The first reagent is Cl2 in the presence of CCl4. This is a halogenation reaction.
- When Cl2 is added to the alkene (Ph-CH=CH-Ph), it undergoes an electrophilic addition to form a dihaloalkane. The addition of Cl2 across the double bond occurs in a trans manner, resulting in the formation of 1,2-dichloro-1,2-diphenylethane.
- The product X can be represented as:
\[ \text{Ph-CH(Cl)-CH(Cl)-Ph} \]

3. **Second Reaction (Dehydrohalogenation with 2NaNH2)**:
- The next step involves the treatment of the product X with 2 moles of NaNH2. This reagent is a strong base and will induce dehydrohalogenation, which means it will remove the halogen atoms and a hydrogen atom from adjacent carbon atoms to form a triple bond.
- This reaction will convert the dihaloalkane into an alkyne (specifically, phenylacetylene).
- The product Y can be represented as:
\[ \text{Ph-C≡C-Ph} \]

4. **Third Reaction (Catalytic Hydrogenation with H2 and Pd-CaCO3)**:
- The final step involves the catalytic hydrogenation of the alkyne (Y) using H2 in the presence of palladium on calcium carbonate (Pd-CaCO3), which is known as Lindlar's catalyst.
- This catalyst allows for the partial hydrogenation of alkynes to form cis-alkenes. Therefore, the alkyne will be converted to a cis-alkene.
- The product Z can be represented as:
\[ \text{cis-Ph-CH=CH-Ph} \]

5. **Final Product**: The final product Z is cis-stilbene (cis-1,2-diphenylethylene).

### Summary of Products:
- **X**: 1,2-Dichloro-1,2-diphenylethane (Ph-CH(Cl)-CH(Cl)-Ph)
- **Y**: Phenylacetylene (Ph-C≡C-Ph)
- **Z**: cis-Stilbene (cis-Ph-CH=CH-Ph)