Question

In the following reaction sequence X and Y respectively are

• A. \( V_2O_5 \), 

  

• B. \( Cr_2O_3 \), 

  

• C. \( AlCl_3 \), 

  

• D. \( Cu \), 

  

Hint:

For Friedel-Crafts alkylation reactions, aluminum chloride (\( AlCl_3 \)) is a common catalyst, and the reactant is typically an alkyl halide or alkene. The radical or carbocation intermediate undergoes electrophilic aromatic substitution with the aromatic ring.

Answer 1

The Correct Option is B

In the given reaction, we can identify the type of reaction occurring. The reaction follows the mechanism of an electrophilic aromatic substitution reaction, where the alkyl group reacts with the benzene ring. The presence of \( Br_2 \) and \( AlCl_3 \) suggests that a Friedel-Crafts alkylation is taking place, where the alkyl group is added to the aromatic ring.
- The compound \( X \) is likely an alkene, which will undergo the reaction with bromine (\( Br_2 \)) to form a more reactive species in the presence of aluminum chloride (\( AlCl_3 \)).
- The presence of chromium trioxide (\( Cr_2O_3 \)) is typically involved in such transformations when reacting with an alkene to form a product that undergoes Friedel-Crafts alkylation.
Thus, the correct sequence of reactions involves chromium trioxide (\( Cr_2O_3 \)) to form the alkylated product.