IMO Practice Test — Alcohols, Phenols and Ethers
14 Questions • 15 min • Olympiad level
15:00
Question 1 of 14
An alcohol gives no turbidity with Lucas reagent even after 10 min and on oxidation gives a carboxylic acid. It is:
primary
tertiary
secondary
a phenol
Explanation: No Lucas turbidity rules out 2°/3°; oxidation to an acid confirms a primary alcohol.
Question 2 of 14
Increasing acidity: (I) p-nitrophenol (II) phenol (III) p-methoxyphenol. Correct order:
I < II < III
III < II < I
II < III < I
I < III < II
Explanation: –OCH3 (releasing) weakens, –NO2 (withdrawing) strengthens: III < II < I.
Question 3 of 14
Anti-Markovnikov hydration of 3-methylbut-1-ene gives no rearranged product; the reagent set is:
H3O+
Hg(OAc)2/H2O then NaBH4
B2H6 then H2O2/OH–
conc. H2SO4
Explanation: Hydroboration–oxidation is anti-Markovnikov and rearrangement-free (concerted, no carbocation).
Question 4 of 14
On warming with excess HI, 2 mol of anisole give:
2 PhI + 2 CH3OH
2 PhOH + 2 CH4
no reaction
2 PhOH + 2 CH3I
Explanation: The aryl–O bond is never cleaved; each anisole gives phenol + CH3I.
Question 5 of 14
Which pairing in Williamson synthesis fails (gives mainly alkene)?
CH3O– + (CH3)3CCl
(CH3)3CO– + CH3I
C2H5O– + C2H5Br
PhO– + CH3I
Explanation: A 3° halide with alkoxide undergoes E2; pairing CH3O– with t-BuCl gives isobutylene, not the ether.
Question 6 of 14
A compound C7H8O gives violet colour with FeCl3 and on bromination gives a tribromo derivative. It is most likely:
anisole
o-cresol
benzyl alcohol
benzaldehyde
Explanation: FeCl3 colour means a phenol; o-cresol (a methylphenol, C7H8O) fits and brominates readily.
Question 7 of 14
The order of dehydration ease (conc. H2SO4) is:
1° > 2° > 3°
2° > 3° > 1°
3° > 2° > 1°
all equal
Explanation: E1 dehydration follows carbocation stability, so 3° > 2° > 1°.
Question 8 of 14
Reaction sequence phenol → NaOH → CO2/pressure → H+ then (CH3CO)2O gives:
paracetamol
picric acid
salicylaldehyde
aspirin (acetylsalicylic acid)
Explanation: Kolbe gives salicylic acid; acetylation of its –OH gives aspirin.
Question 9 of 14
Which gives a 3° alcohol with CH3MgBr (after work-up)?
propanone
methanal
ethanal
CO2
Explanation: A ketone (propanone) has no H on the carbonyl carbon and gives a tertiary alcohol.
Question 10 of 14
Picric acid is:
2,4,6-tribromophenol
2,4,6-trinitrophenol
salicylic acid
p-cresol
Explanation: Concentrated nitration of phenol gives 2,4,6-trinitrophenol (picric acid), a strong acid.
Question 11 of 14
For cleavage of methyl tert-butyl ether by HI, the products are:
CH3I + t-BuOH
both methyl and t-Bu iodides equally
CH3OH + t-BuI
no reaction
Explanation: The 3° carbon goes via SN1 (stable 3° cation), giving t-BuI and methanol.
Question 12 of 14
Identify Z: ethanol --(Cu, 573 K)--> Z. Z is:
ethene
ethanoic acid
diethyl ether
ethanal
Explanation: Catalytic dehydrogenation of a 1° alcohol over hot copper gives the aldehyde, ethanal.
Question 13 of 14
Which order of boiling points is correct (similar mass)?
alcohol > ether > alkane
ether > alcohol > alkane
alkane > alcohol > ether
all equal
Explanation: H-bonding makes alcohols boil highest; ethers (weak dipole) above alkanes.
Question 14 of 14
Salicylaldehyde forms from phenol via:
Kolbe reaction
Reimer–Tiemann reaction
Williamson synthesis
cumene process
Explanation: Reimer–Tiemann uses CHCl3/NaOH (dichlorocarbene) to install the ortho –CHO group.