Amines Flashcards
(31 cards)
Q: What’s the general formula of a nitro compound, and how do you make nitrobenzene?
A: R–NO₂ ; Nitration of benzene with conc. HNO₃ + conc. H₂SO₄ at 50–60 °C.
C≡N
Nitrile ; Cyano group (–CN)
CONH₂
Amide
R–N₂⁺
Diazonium salt ; Diazonium ion
R–NH₂
Amine (Primary) (Plain 1° Amine)
NH₃
Ammonia (Simple Ammonia gas)
NH₂NH₂
Hydrazine (Hydrazine gas/liquid)
NO₂
Nitro group (called nitro group always)
R₂C=NH
Imine Schiff base (sometimes)
N₃⁻
Azide (Used in Schmidt reaction)
R–CONH–R’
Secondary amide (Still just amide)
Ar–NH₂
Aromatic amine (like aniline for benzene–NH₂)
RN(NO)OH
Nitrolic acid (advanced rarely used)
Azo compound
(comes from diazonium coupling)
Q: Name two methods to prepare a primary amine from a nitrile.
1)Catalytic hydrogenation: H₂ + Ni/Pt at high T & P
2)Chemical reduction: LiAlH₄ in dry ether, then H₂O quench.
Q: What’s the condition & reagent for Gabriel phthalimide synthesis of primary amines?
A: Phthalimide + KOH → potassium phthalimide; then RX (alkyl halide) in ethanol; finally hydrazine (NH₂NH₂) to liberate R–NH₂.
Q: Give the reagents & conditions for Hofmann degradation of an amide to a primary amine (Hofmann rearrangement).
A:
Reagents: R–CONH₂ + Br₂ + 4 KOH (aq)
Conditions: Heat
Products:
R–NH₂ + CO₂ + HBr
Q: How do you convert a nitro compound to an amine? List three reagent options.
Sn + conc. HCl, then NaOH
Fe + HCl, then NaOH
H₂ + Pd–C, room temp/pressure.
Q: Compare basicity in aqueous solution: 1° vs. 2° vs. 3° amines. Why?
A: 2° > 1° > 3° (Steric hindrance on 3° reduces H-bonding with water).
Q: Alkylation of amines suffers from over-alkylation. What trick helps get pure 1° amine?
A: Gabriel synthesis or use protecting groups (e.g., Boc protection).
Q: What reagent/condition for amide → amine using LiAlH₄? Any caveats?
A: LiAlH₄ in dry ether, under inert atm; quench carefully with H₂O/acid.
Q: Why is methylamine more basic than ammonia?
A: +I effect of CH₃ pushes electron density onto N, making it better at grabbing H⁺.
Q: Draw/write the mechanism highlight for nucleophilic substitution of R–X + NH₃ → R–NH₂. Tip?
A: SN2 attack of NH₃ on R–X → R–NH₃⁺ + X⁻; use excess NH₃ to favor 1° amine over higher amines.
sealed tube 100C
Q3: Reaction to prepare azo dyes?
A: Diazotization (Reagent: HNO₂ at 0–5°C; Product: Ar-N₂⁺ → Coupling with phenol/aniline).
