Describe the Gabriel phthalimide synthesis and the Hoffmann bromamide degradation with equations. State one special feature or limitation of each.

1. 1 · Gabriel, step 1. Phthalimide + ethanolic KOH → potassium phthalimide + H₂O (the N-H is acidic).
2. 2 · Gabriel, step 2. Potassium phthalimide + R-X, heat → N-alkylphthalimide + KX.
3. 3 · Gabriel, step 3. N-Alkylphthalimide + 2NaOH(aq), heat → R-NH₂ + sodium phthalate (hydrolysis).
4. 4 · Gabriel limitation. Gives only primary aliphatic amines; aryl halides do not react, so aniline cannot be made.
5. 5 · Hoffmann equation. RCONH₂ + Br₂ + 4NaOH → RNH₂ + Na₂CO₃ + 2NaBr + 2H₂O.
6. 6 · Hoffmann feature. The R group moves to N and the carbonyl carbon leaves as carbonate: the amine has one carbon fewer.
7. 7 · Close in one line. So both give pure primary amines: Gabriel keeps the carbon count, Hoffmann lowers it by one.

Scoring tip: Write all three Gabriel steps with the reagent on each arrow; examiners give a mark for each step.