The Gabriel synthesis is a reliable method for preparing pure primary amines from primary alkyl halides. It avoids the over-alkylation that can be a problem in the direct reaction of alkyl halides with ammonia.
This reaction sequence is the Gabriel phthalimide synthesis, which is a classic method for preparing primary amines.
Step (i): The first reactant is potassium phthalimide. The phthalimide ion is a strong nucleophile. It reacts with benzyl bromide (C$_6$H$_5$CH$_2$Br). The reaction is a nucleophilic substitution (S$_N$2), where the phthalimide anion displaces the bromide ion.
The product of this step is N-benzylphthalimide.
Step (ii): The second step is the hydrolysis of N-benzylphthalimide. The reagent is hydroxide ion (OH$^-$) in water, which indicates basic hydrolysis. This step cleaves the two amide bonds in the N-benzylphthalimide.
The hydrolysis breaks the C-N bonds, releasing the primary amine and phthalic acid (or its salt under basic conditions, sodium phthalate).
The primary amine formed is benzylamine, which has the structure C$_6$H$_5$CH$_2$NH$_2$.
Looking at the options:
(A) is phthalimide.
(B) is benzylamine.
(C) is N,N-dibenzylbenzamide. Incorrect.
(D) is benzyl alcohol. Incorrect.
The major product "A" is benzylamine.
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