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Identify A and predict the type of reaction:
Explanation
The more stable carbanion (ortho to $OCH_3$) directs $NH_2$ to the original C–Br carbon.
Detailed Solution
$NH_2^-$ removes the H ortho to Br (between Br and $OCH_3$), and loss of $Br^-$ gives a benzyne intermediate.
Attack of $NH_2^-$ at position b gives the carbanion ortho to $-OCH_3$, which is more stable as the negative charge is close to the electron-withdrawing group; attack at a gives the less stable carbanion.
Protonation by $NH_3$ gives 3-methoxyaniline.
$\because$ The incoming nucleophile ends on the same carbon on which Br (leaving group) was present, it is NOT cine substitution; it is a substitution reaction.
Attack of $NH_2^-$ at position b gives the carbanion ortho to $-OCH_3$, which is more stable as the negative charge is close to the electron-withdrawing group; attack at a gives the less stable carbanion.
Protonation by $NH_3$ gives 3-methoxyaniline.
$\because$ The incoming nucleophile ends on the same carbon on which Br (leaving group) was present, it is NOT cine substitution; it is a substitution reaction.