Amines — Advanced Notes & 50 MCQs

1. Which reagent is used for diazotization of primary aromatic amines?

1. NaBH4
2. NaNO2 + HCl at 0–5°C ✅
3. SOCl2
4. H2/Pd

2. Which test distinguishes primary from secondary and tertiary amines?

1. Tollens' test
2. Hinsberg test (benzenesulfonyl chloride) ✅
3. Bromine water
4. Lucas test

3. Gabriel synthesis uses which starting material to prepare primary amines?

1. Alkyl halide directly
2. Phthalimide (followed by alkylation and hydrolysis) ✅
3. Aniline directly
4. Nitrobenzene only

4. Which amine gives a stable diazonium salt?

1. Aliphatic primary amines
2. Aromatic primary amines (e.g., aniline derivatives) ✅
3. Secondary aliphatic amines
4. Tertiary aliphatic amines

5. Which product forms when aniline is treated with Br2 water?

1. Bromobenzene only
2. 2,4,6-tribromoaniline (due to activation) ✅
3. No reaction
4. Only mono-brominated product

6. Which reagent converts nitrobenzene to aniline?

1. KMnO4
2. Sn/HCl or Fe/HCl (reduction) ✅
3. NaNO2/HCl
4. H2O2

7. Which of the following is most basic in aqueous solution?

1. Aniline
2. Aliphatic primary amine (e.g., methylamine) ✅
3. Ammonia
4. Tertiary aromatic amine

8. Which amine reacts with nitrous acid to form N-nitroso compounds (stable)?

1. Primary aromatic amines (form diazonium)
2. Primary aliphatic amines
3. Secondary amines (give N-nitrosamines) ✅
4. Tertiary amines

9. Hofmann degradation of amides yields:

1. Tertiary amines primarily
2. Primary amines with one fewer carbon (via Hofmann rearrangement) ✅
3. Secondary alcohols
4. Nitro compounds

10. Hinsberg reagent is:

1. SOCl2
2. Benzenesulfonyl chloride (used in Hinsberg test) ✅
3. NaNO2
4. H2SO4

11. Which amine gives positive Tollens' test?

1. All amines
2. Primary aromatic amines only
3. None (amines don't give Tollens' test which is for aldehydes) ✅
4. Tertiary amines only

12. Which reaction converts aniline to diazonium salt?

1. Reduction with Sn/HCl
2. Treatment with NaNO2 and HCl at 0–5°C (diazotization) ✅
3. Nitration
4. Friedel–Crafts

13. Which reagent converts alkyl halide to amine by substitution (Gabriel alternative)?

1. NaBH4
2. NH3 in excess under pressure (nucleophilic substitution) ✅
3. PCC
4. SOCl2

14. Which product forms when primary aromatic amine is diazotized and then treated with CuCN?

1. Phenol
2. Aryl cyanide (Ar–CN) via Sandmeyer reaction ✅
3. Benzene
4. Amide

15. Which amine will be most nucleophilic in polar protic solvent?

1. Aniline (aromatic)
2. Tertiary aliphatic amine (e.g., triethylamine) often more nucleophilic due to alkyl groups donating electrons ✅
3. Ammonia
4. Phenylamine (less nucleophilic)

16. Which reagent converts secondary amine to N-nitrosamine?

1. NaNO2 + HCl
2. NaNO2 + HCl (nitrous acid) ✅
3. SOCl2
4. LiAlH4

17. Which reagent converts amide to amine with one less carbon atom?

1. LiAlH4 reduction
2. Hofmann rearrangement (Br2/NaOH) ✅
3. PCC oxidation
4. NaNO2/HCl

18. Which of the following reduces nitro group to amine selectively under catalytic hydrogenation?

1. Pd/C with H2 ✅
2. KMnO4
3. NaNO2/HCl
4. TsCl

19. Why is aniline less basic than aliphatic amines?

1. Because nitrogen in aniline is sp hybridized
2. Because lone pair is delocalized into benzene ring by resonance (less available for protonation) ✅
3. Because aniline is sterically hindered
4. Because aniline is positively charged

20. Which reagent will acylate an amine to give amide?

1. SOCl2 only
2. Acid chloride (RCOCl) or acid anhydride in presence of base ✅
3. NaNO2
4. H2/Pd

21. Which amine cannot be distinguished by Hinsberg test (remains insoluble)?

1. Primary amine
2. Tertiary amine (insoluble, no reaction) ✅
3. Secondary amine (soluble then insoluble after base)
4. Primary amine (soluble after base)

22. Which reagent converts aryl diazonium salt to phenol?

1. CuCl
2. Warm water (hydrolysis) or Cu2O/H2O (via Sandmeyer variant) ✅
3. NaCN
4. H2/Pd

23. Which is true about basicity in gas phase vs aqueous phase for amines?

1. Orders are always identical
2. Gas phase basicity depends mainly on intrinsic electron density; aqueous basicity influenced strongly by solvation ✅
3. Only steric hindrance matters
4. Only resonance matters

24. Which product forms when aniline reacts with acetic anhydride?

1. Nitroaniline
2. Acetanilide (anilide formation via acetylation) ✅
3. Benzene
4. Aniline dimer

25. Which reagent converts primary aliphatic amine to diazonium salt (stable)?

1. NaNO2/HCl (gives unstable aliphatic diazonium that decomposes) — so none give stable diazonium ✅
2. SOCl2
3. PCC
4. H2/Pd

26. Which of the following yields aniline from nitrobenzene under catalytic hydrogenation without reducing other groups?

1. Strong oxidant
2. H2 with Pd/C (or Sn/HCl) under controlled conditions ✅
3. NaNO2/HCl
4. TsCl

27. Which reaction of diazonium salts leads to azo coupling?

1. Reaction with CuCl only
2. Reaction with activated aromatic rings (e.g., phenols/anilines) to form azo dyes ✅
3. Reaction with H2O only
4. Reduction to amine only

28. Which amine is most basic in aqueous medium among CH3NH2, (CH3)2NH and (CH3)3N?

1. (CH3)3N (tert-butyl analog)
2. (CH3)2NH (secondary amine often most basic in water due to balance of electron donation and solvation) ✅
3. CH3NH2
4. All equal

29. Which reagent converts aniline into p-nitroaniline selectively (nitration at para position preferred)?

1. Conc. HNO3 alone (gives mixture)
2. Protecting by acylation (to acetanilide) then nitration followed by hydrolysis gives para-nitroaniline selectively ✅
3. NaNO2/HCl
4. Br2 water

30. Which of the following is true for aromatic amines during electrophilic substitution?

1. Aromatic amines are deactivated toward EAS
2. They are strongly activating (if free –NH2) and direct ortho/para; often need protection to control reaction ✅
3. They direct meta positions
4. They do not undergo substitution

31. Which of the following is formed when secondary amine reacts with nitrous acid?

1. Diazonium salts
2. N-nitrosamine (R2N–NO) ✅
3. Primary amine
4. Amide

32. Which reagent will convert aniline to acetanilide?

1. NaNO2/HCl
2. Acetic anhydride (or acetyl chloride) ✅
3. SOCl2
4. H2/Pd

33. Which of the following is a classic method to prepare primary aliphatic amines without over-alkylation?

1. Direct alkylation with alkyl halide and NH3 (leads to mixture)
2. Gabriel phthalimide synthesis ✅
3. Acylation followed by Hoffmann only
4. Wurtz reaction

34. Which of the following amines will form an insoluble sulfonamide in Hinsberg test that dissolves on addition of base?

1. Tertiary amine (no reaction)
2. Primary amine (forms sulfonamide which is soluble in base) ✅
3. Secondary amine (forms sulfonamide insoluble in base)
4. None

35. Which of the following is true about N-nitrosamines?

1. They are non-toxic and inert
2. Many are carcinogenic and require control in foods and pharmaceuticals ✅
3. They are formed from primary amines only
4. They are strong bases

36. Which reagent would you use to prepare aryl azide from diazonium salt?

1. CuCl
2. NaN3 (via Sandmeyer type reaction giving ArN3) ✅
3. H2O
4. NaBH4

37. Which of the following increases basicity of aniline?

1. Electron-withdrawing groups on ring
2. Electron-donating groups (e.g., –OH, –CH3) at ortho/para positions increase basicity ✅
3. Strong resonance with electron-withdrawing group
4. Protonation of ring

38. Which method gives the best route to prepare secondary amines selectively?

1. Direct alkylation of ammonia (gives mixture)
2. Reductive amination of carbonyl compounds (condensation followed by reduction) ✅
3. Gabriel synthesis (primary only)
4. Wurtz reaction

39. Which reagent converts aryl diazonium salt to aryl chloride?

1. CuCN
2. CuCl (Sandmeyer reaction) ✅
3. NaCl alone
4. HCl only

40. Which of the following is a reason tertiary amines are typically less basic than secondary in water?

1. Electronic withdrawal by alkyl groups
2. Steric hindrance reduces solvation of protonated form, lowering observed basicity ✅
3. They have no lone pair
4. They form diazonium salts easily

41. Which amine gives Hoffmann elimination to give less substituted alkene?

1. Primary amines directly
2. Quaternary ammonium salts (via Hoffmann elimination) ✅
3. Secondary amines only
4. Tertiary amines only

42. Which of the following compounds will react with nitrous acid to evolve N2 gas?

1. Secondary aromatic amine
2. Primary aliphatic amines (unstable diazonium decomposes with N2 evolution) ✅
3. Tertiary amines
4. Phenols

43. Which reagent converts nitrile to primary amine?

1. KMnO4
2. LiAlH4 or catalytic hydrogenation (H2/Pd) ✅
3. NaNO2/HCl
4. PCC

44. Which of the following is TRUE about aromatic amines under strongly acidic conditions?

1. They become more nucleophilic
2. They get protonated on nitrogen, reducing reactivity of ring towards electrophilic substitution ✅
3. They always form diazonium salts in acid
4. They cannot be acetylated

45. Which reagent is used in reductive amination?

1. NaNO2/HCl
2. NaBH3CN or NaBH4 after imine formation ✅
3. KMnO4
4. SOCl2

46. Which amine functional group is common in amino acids?

1. Secondary amine only
2. Primary amine (-NH2) (α-amino group) ✅
3. Tertiary amine only
4. Quaternary ammonium only

47. Which test produces a color change for aromatic amines (or substituted phenols) to indicate presence?

1. Tollens' test
2. Diazo coupling (azo dye formation) ✅
3. Lucas test
4. PCC test

48. Which of the following is an example of a quaternary ammonium compound used as a phase-transfer catalyst?

1. Trimethylamine (tertiary)
2. Tetrabutylammonium bromide (quaternary ammonium salt) ✅
3. Aniline (primary aromatic)
4. Ammonia

49. Which reagent can convert a primary amine into secondary amine selectively?

1. Complete alkylation with excess alkyl halide
2. Reductive amination of aldehyde/ketone with primary amine followed by reduction ✅
3. NaNO2/HCl
4. SOCl2