Predict the major product of the reaction of ${\text{C}}_6{\text{H}}_5\text{CH}({\text{CH}}_3){\text{NH}}_2$ with excess ${\text{CH}}_3\text{I}$ followed by ${\text{Ag}}_2\text{O}/{\text{H}}_2\text{O}$ and heat.

Solution

1. Exhaustive methylation converts the primary amine into a quaternary ammonium iodide.
2. Treatment with ${\text{Ag}}_2\text{O}/{\text{H}}_2\text{O}$ replaces the iodide with a hydroxide ion.
3. Heating the quaternary ammonium hydroxide induces an E2 elimination reaction.
4. The elimination follows the Hofmann rule, yielding the less substituted alkene, which is styrene.
5. Hence the answer is (A).