Alcohols, Phenols & Ethers — Advanced Notes & 50 MCQs

1. Which reagent converts primary alcohol to aldehyde without further oxidation to acid?

1. KMnO4
2. PCC (pyridinium chlorochromate) ✅
3. HNO3
4. H2O2

2. Williamson synthesis is used to prepare:

1. Alcohols from aldehydes
2. Unsymmetrical ethers from alkoxide and alkyl halide ✅
3. Alkenes from alkyl halides directly
4. Phenols from diazonium salts only

3. Phenol reacts with bromine water to give:

1. No reaction
2. 2,4,6-tribromophenol (white precipitate) ✅
3. Benzene
4. Bromobenzene only

4. Which of the following is most acidic?

1. tert-butanol
2. ethanol
3. Phenol ✅
4. 2-propanol

5. Which reagent converts alcohol to alkyl chloride via SN2 for primary alcohols?

1. PCC
2. SOCl2 (thionyl chloride) ✅
3. KMnO4
4. H2/Pd

6. Which alcohol gives brown ring test positive when oxidized to aldehyde?

1. Tertiary alcohols
2. Primary alcohols (oxidizable to aldehydes) ✅
3. Secondary alcohols
4. Phenols

7. Which of these undergoes SN1 fastest?

1. Methyl alcohol derivatives
2. Tertiary alcohol derivatives (tertiary carbocation formation) ✅
3. Primary
4. Primary benzylic only

8. Which reagent is commonly used to dehydrate alcohols to alkenes?

1. NaBH4
2. Conc. H2SO4 or H3PO4 with heat ✅
3. PCC
4. KMnO4

9. Which compound is formed when phenol reacts with NaOH?

1. Phenyl ether
2. Sodium phenoxide (phenolate) ✅
3. Benzene
4. Phenyl alcohol

10. The Williamson synthesis fails with tertiary alkyl halides because:

1. Tertiary halides are too reactive
2. They undergo elimination (E2) rather than SN2 ✅
3. They form ethers readily
4. They do not react at all

11. Which reagent converts phenol to anisole (methyl ether)?

1. CH3Cl alone
2. CH3I with K2CO3 or dimethyl sulfate under Williamson-type conditions ✅
3. H2/Pd
4. NaBH4

12. Which of the following is TRUE about phenol acidity?

1. Electron-donating groups increase acidity
2. Electron-withdrawing groups (e.g., NO2) increase acidity ✅
3. Resonance destabilizes phenoxide ion
4. Phenol is less acidic than ethanol

13. Which reagent converts alcohol to tosylate (good leaving group) preserving stereochemistry?

1. SOCl2
2. TsCl (p-toluenesulfonyl chloride) in pyridine ✅
3. NaOH
4. PCC

14. Which of the following reacts with aluminium chloride (AlCl3) to give electrophilic aromatic substitution on phenol ring most readily?

1. Nitrobenzene
2. Phenol (activated ring, ortho/para directors) ✅
3. Chlorobenzene
4. Benzene

15. Which alcohol resists oxidation by mild oxidizing agents?

1. Primary alcohols
2. Tertiary alcohols (no H on carbon bearing OH) ✅
3. Secondary alcohols
4. Benzylic alcohols

16. In acidic medium, dehydration of 2° alcohol proceeds via:

1. SN2 mechanism
2. Carbocation intermediate (E1) ✅
3. Free radical only
4. Concerted one-step E2 always

17. Which reagent converts alkyl halide to alcohol via nucleophilic substitution?

1. NaH
2. Aqueous NaOH (or H2O as nucleophile) ✅
3. SOCl2
4. PCC

18. Which reaction gives phenol from benzene?

1. Friedel–Crafts acylation directly
2. Nitration → reduction → diazotization → hydrolysis (multi-step) ✅
3. Wurtz coupling
4. SN2 on benzene directly

19. Which ether can be cleaved by HI to give alkyl iodide(s) under heating?

1. Symmetrical ethers only
2. Both symmetrical and unsymmetrical; primary alkyl ethers yield SN2 products, tertiary yield SN1 products ✅
3. Ethers never cleaved by HI
4. Only aryl ethers

20. Which of the following is an example of a phenolic reaction giving a colored product with FeCl3?

1. Ether formation
2. Phenol gives violet/blue complex with FeCl3 (qualitative test) ✅
3. Alkene formation only
4. Oxidation to ketone only

21. Which statement about Williamson synthesis is TRUE?

1. Works best with tertiary alkyl halides
2. Works best with primary alkyl halides and alkoxides (SN2) ✅
3. Does not require base
4. Cannot form asymmetrical ethers

22. What is the product when phenol is treated with CH3Cl and AlCl3?

1. Ether only
2. O-alkylation and/or Friedel–Crafts alkylation at ortho/para — O-alkylation is less favored with strong Lewis acids; alkylation at ortho/para likely ✅
3. Formation of benzene only
4. No reaction

23. Which reagent converts secondary alcohol to ketone?

1. NaBH4
2. PCC or KMnO4 (oxidation) ✅
3. H2/Pd (reduces)
4. LiAlH4 (reduces)

24. Which of the following compounds is more acidic than phenol?

1. p-Cresol
2. p-Nitrophenol (NO2 is electron-withdrawing) ✅
3. m-Cresol
4. o-Cresol (depends but nitro-substituted is stronger)

25. Which reaction converts an alcohol into an alkyl halide with inversion of configuration?

1. Acid-catalyzed substitution on tertiary alcohol
2. Conversion with PBr3 or SOCl2 (SN2) on primary/secondary centers ✅
3. Oxidation with KMnO4
4. Williamson synthesis

26. Which of the following is an application of ethers?

1. Solvents (e.g., diethyl ether) ✅
2. Strong acids for esterification only
3. Oxidizing agents only
4. Reducing agents only

27. Which mechanism is observed when tert-butyl alcohol reacts with HBr?

1. SN2
2. SN1 (tert carbocation forms) ✅
3. E2 only
4. Radical substitution

28. Which of the following best explains why phenol is more acidic than ethanol?

1. Phenol has stronger O–H bond
2. Phenoxide ion is resonance stabilized whereas ethoxide is not ✅
3. Ethanol is aromatic
4. Phenol has less solubility only

29. Which reagent converts benzyl alcohol to benzyl chloride selectively?

1. SOCl2 (works for primary benzyl alcohols) ✅
2. PCC only
3. Br2 only
4. KMnO4 only

30. Which statement about ethers is TRUE?

1. Ethers readily undergo hydrolysis without strong acids
2. Ethers are relatively inert, good solvents, but can be cleaved by strong acids (HI, HBr) ✅
3. Ethers are strong acids
4. Ethers form hydrogen bonds with themselves strongly

31. Which reagent oxidizes primary alcohol to carboxylic acid vigorously?

1. PCC
2. KMnO4 (strong oxidant, gives carboxylic acids) ✅
3. LiAlH4
4. H2/Pd

32. Which of the following is an ortho/para director on benzene ring?

1. NO2 (meta director)
2. OH (activating, ortho/para director) ✅
3. CF3 (meta director)
4. COOH (meta director)

33. Which reagent converts alcohol to alkyl chloride via substitution with inversion of configuration on secondary alcohol?

1. Conc. H2SO4 alone
2. SOCl2 with pyridine (gives inversion via SN2) ✅
3. KMnO4
4. PCC

34. Which compound gives a positive Lucas test immediately?

1. Primary alcohols
2. Tertiary alcohols (react immediately due to SN1) ✅
3. Phenols
4. All alcohols react equally

35. Which of the following reagents converts phenol to nitrophenol (electrophilic nitration)?

1. Conc. HNO3 alone at room temp
2. Conc. HNO3 / H2SO4 mixture (nitrating mixture) ✅
3. NaNO2 alone
4. KMnO4

36. Which alcohol yields alkene via E2 predominantly with bulky base?

1. Methyl alcohol
2. Secondary and tertiary alcohols favored for elimination with bulky base ✅
3. Primary alcohols always give substitution
4. Phenols

37. Which is true about aryl ethers (e.g., anisole) compared to alkyl ethers?

1. Aryl ethers are more easily cleaved by HI
2. Aryl ethers are less reactive toward cleavage and do not undergo SN2 at aryl carbon ✅
3. Aryl ethers are strong acids
4. Aryl ethers form peroxides readily

38. Which test distinguishes phenol from alcohol?

1. Tollens reagent
2. FeCl3 test (phenol gives coloured complex), alcohols generally negative ✅
3. Lucas test only (both can vary)
4. Br2 water (both may react in some cases)

39. Which of the following is produced when ethanol undergoes complete combustion?

1. Ethane
2. CO2 and H2O ✅
3. Only CO
4. Only H2

40. Which reagent converts phenol to 2,4,6-tribromophenol selectively?

1. Br2 in CCl4 only
2. Br2 (aq) at room temperature — gives 2,4,6-tribromophenol readily ✅
3. HBr only
4. NaBr only

41. Which reaction converts an alkyl halide to ether via SN2 under basic conditions?

1. Williamson synthesis: alkoxide + alkyl halide ✅
2. Free radical halogenation only
3. Friedel–Crafts
4. Wurtz reaction

42. Which reagent is used to convert alcohol to alkyl iodide?

1. PBr3 only
2. PI3 (or red P + I2) or HI ✅
3. SOCl2 only
4. PCC

43. Which of the following gives positive iodoform test?

1. Any tertiary alcohol
2. Ethanol and methyl ketones (presence of CH3CO–) ✅
3. Ethene only
4. Phenol

44. Which of the following is used to protect OH group as tert-butyldimethylsilyl (TBDMS) ether in synthesis?

1. TBDMS-Cl with imidazole (protecting group) ✅
2. PCC only
3. H2/Pd
4. NaH only

45. Which alcohol gives ester on reaction with carboxylic acid in presence of conc. H2SO4?

1. Only tertiary alcohols
2. Primary and secondary alcohols (Fischer esterification) ✅
3. Phenols (poorly esterify directly)
4. All alkenes

46. Which reagent selectively oxidizes secondary alcohol to ketone but not oxidize further?

1. LiAlH4
2. PCC or Jones reagent under controlled conditions; PCC commonly used for primary→aldehyde but also oxidizes secondary→ketone ✅
3. H2/Pd
4. NaBH4 (reducing agent)

47. Which of the following compounds undergoes electrophilic substitution faster than benzene?

1. Nitrobenzene (deactivated)
2. Phenol (strongly activated) ✅
3. Chlorobenzene (slightly deactivated)
4. Benzonitrile (deactivated)

48. Which of these reagents will convert an alcohol to an alkene via dehydration and follow Zaitsev's rule?

1. H2 with Pd
2. Conc. H2SO4 with heat (gives more substituted alkene) ✅
3. NaBH4 only
4. LiAlH4

49. Which reagent converts phenol to p-nitrophenol predominantly?

1. Nitration under mild conditions only
2. Nitration with HNO3/H2SO4 yields mainly ortho and para; steric/electronic control can favor para (low temp, solvent control) ✅
3. KMnO4 only
4. HI only