Question

Write the reaction involved in Friedel-Crafts acylation of anisole.

Hint:

Para-substituted products are almost always the major products in electrophilic substitution of bulky or activated rings due to steric reasons.

Answer 1

Step 1: Understanding the Concept:
Friedel-Crafts acylation introduces an acyl group (\( RCO- \)) into the benzene ring using an acid chloride and a Lewis acid catalyst.
Step 2: Detailed Explanation:
Anisole (\( C_6H_5OCH_3 \)) is an activated aromatic ether. The methoxy group is ortho-para directing.
Reaction with acetyl chloride (\( CH_3COCl \)) in the presence of anhydrous \( AlCl_3 \) yields a mixture of ortho and para products.
The para-isomer (4-Methoxyacetophenone) is the major product due to less steric hindrance.
Chemical Equation:
\[ C_6H_5OCH_3 + CH_3COCl \xrightarrow{\text{anh. } AlCl_3} \text{p-}CH_3OC_6H_4COCH_3 + HCl \]
Step 3: Final Answer:
The major product is 4-Methoxyacetophenone.