Alcohols, phenols, and ethers are fundamental organic compounds that repeatedly appear in both board and competitive exams due to their characteristic reactions (acid-base behaviour, electrophilic aromatic substitution, and ether cleavage). Mastering concepts like hydrogen bonding, acidity differences among phenols, and Williamson ether synthesis/cleavage mechanisms directly improves accuracy and speed in multiple-choice problems.
15
Minutes
10
Questions
1 / -0
Marking
Q1. A 0.10 M aqueous solution of phenol is prepared. Given for phenol and assuming ideal behaviour, the approximate pH of the solution is closest to:
6.0
4.5
5.5
7.0
Q2. An ether is treated with excess HI at room temperature. The major organic halide formed is:
Q3. Which of the following compounds has the highest boiling point? Consider intermolecular forces and molecular structure.
Q4. Which reagent sequence converts phenol () into -nitroanisole (-NO-CH-OCH) with the highest para-selectivity and overall yield?
Step 1: (nitration of phenol); Step 2: (methylation)
Step 1: (methylation to anisole); Step 2: (nitration of anisole)
Step 1: , pyridine (acetylation); Step 2: (nitration); Step 3: (methylation)
Step 1: (methylation to anisole); Step 2: excess (uncontrolled nitration → mixtures incl. dinitroanisoles)
Q5. Assertion (A): -Nitrophenol is more acidic than -nitrophenol.
Reason (R): In -nitrophenol intramolecular hydrogen bonding between the phenolic H and an oxygen of the group stabilizes the undissociated form, thereby reducing its acidity relative to the para isomer.
Both A and R are true, and R is the correct explanation of A.
Both A and R are true, but R is NOT the correct explanation of A.
A is true, but R is false.
A is false, but R is true.
Q6. Consider the equilibrium at 25°C:
Given and , which statement is correct?
Equilibrium lies predominantly to the left (starting materials);
Equilibrium lies strongly to the right (formation of );
Equilibrium is about unity () because both acids have similar acidity
The reaction does not proceed because is too sterically hindered to deprotonate phenol
Q7. Sodium phenoxide () is reacted separately with the following alkyl halides under typical Williamson conditions (polar aprotic solvent, room temperature): (i) , (ii) (2‑bromopropane), (iii) (tert‑butyl bromide). Which statement correctly describes the expected yields of the corresponding aryl ethers ?
(tert‑butyl gives the highest ether yield)
(both give high yields); tert‑butyl negligible
gives the highest yield because phenoxide reacts by SN1 on secondary halides
gives the highest ether yield (efficient SN2 at methyl); gives lower yield (competes with elimination); gives negligible ether (steric hindrance suppresses SN2; SN1 leads to side reactions)
Q8. Each ether below is treated with excess HI at room temperature: (i) methyl tert‑butyl ether (), (ii) benzyl methyl ether (), (iii) anisole (), (iv) isopropyl methyl ether (). Which set lists the major alkyl iodide(s) produced (one per ether) under typical conditions?
(i) ; (ii) ; (iii) anisole resists cleavage (no alkyl iodide); (iv)
(i) ; (ii) ; (iii) ; (iv)
(i) mixture of and (equal); (ii) mostly ; (iii) ; (iv) no reaction
(i) ; (ii) mostly ; (iii) (anisole cleavage at methyl side); (iv)
Q9. In aqueous solution ‑nitrophenol (4‑nitrophenol) is observed to be slightly more acidic than ‑nitrophenol (2‑nitrophenol). Which explanation best accounts for this observation?
The para nitro group exerts a stronger effect than the ortho nitro, so ‑isomer stabilizes the phenoxide much more
In ‑nitrophenol, intramolecular hydrogen bonding stabilizes the phenoxide ion more than the neutral phenol, increasing acidity
‑Nitrophenol forms an intramolecular H‑bond in the undissociated (neutral) form that stabilizes the molecular phenol relative to its conjugate base; this lowers its acidity compared with the para isomer
Steric hindrance at the ortho position blocks resonance between nitro and ring, making ‑nitrophenol markedly more acidic than ‑nitrophenol
Q10. Rank the following alcohols in decreasing reactivity towards substitution by HBr (aqueous), assuming an SN1 mechanism is operative: (i) tert‑butanol , (ii) 1‑phenylethanol , (iii) 2‑butanol . Which order is correct?
1‑phenylethanol > tert‑butanol > 2‑butanol
tert‑butanol > 1‑phenylethanol > 2‑butanol
2‑butanol > tert‑butanol > 1‑phenylethanol
tert‑butanol > 2‑butanol > 1‑phenylethanol