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Alcohols, Phenols and Ethers · Question 14

JEE Main 2025 (Online) 8th April Evening ShiftMCQMedium📈 Topic in 6% papers+4−1
1

Which one of the following reactions will not lead to the desired ether formation in major proportion? (iso-Bu isobutyl, sec-Bu sec-butyl, n-Pr n-propyl, tBu tert-butyl, Et ethyl)

  1. [figure]
  2. iso-Bu O Na + sec-BuBr sec-Bu–O–iso-Bu
  3. [figure]
  4. tBu O Na + EtBr tBu-O-Et

Answer

(2) iso-Bu O Na + sec-BuBr sec-Bu–O–iso-Bu

Solution

Williamson ether synthesis: R- O Na + R'-X R-O-R' + NaX (SN2).

It gives good yields only with methyl / primary alkyl halides. With secondary and tertiary halides the alkoxide (a strong base) causes E2 elimination, so an alkene is the major product.

(1) Sodium phenoxide + n-PrBr (1°) n-propyl phenyl ether ✓

(2) Sodium isobutoxide + sec-BuBr (2°) E2 elimination dominates (butenes); the ether is not the major product ✗

(3) Sodium cyclohexoxide + CH3Br methoxycyclohexane ✓

(4) Sodium tert-butoxide + EtBr (1°) tert-butyl ethyl ether ✓

Answer: (2)

JEE Main 2025 (Online) 8th April Evening Shift

Keep practising — Alcohols, Phenols and Ethers

2

Given below are two statements : In the light of given statements, choose the correct answer from the options given below

  1. Statement I is false but Statement II is true
  2. Statement I is true but Statement II is false
  3. Both Statement I and Statement II are true
  4. Both Statement I and Statement II are false
JEE Main 2025 (Online) 7th April Morning Shift
3

Benzene is treated with oleum to produce compound (X) which when further heated with molten sodium hydroxide followed by acidification produces compound (Y). The compound Y is treated with zinc metal to produce compound (Z). Identify the structure of compound (Z) from the following options.

  1. [figure]
  2. [figure]
  3. [figure]
  4. [figure]
JEE Main 2025 (Online) 4th April Morning Shift
4

An organic compound (X) with molecular formula C3H6O is not readily oxidised. On reduction it gives C3H8O (Y) which reacts with HBr to give a bromide (Z) which is converted to Grignard reagent. This Grignard reagent on reaction with (X) followed by hydrolysis gives 2,3-dimethylbutan-2-ol. Compounds (X), (Y) and (Z) respectively are:

  1. CH3CH2CHO, CH3CH2CH2OH, CH3CH2CH2Br
  2. CH3COCH3, CH3CH(OH)CH3, CH3CH(Br)CH3
  3. CH3COCH3, CH3CH2CH2OH, CH3CH(Br)CH3
  4. CH3CH2CHO, CH3CH=CH2, CH3CH(Br)CH3
JEE Main 2025 (Online) 4th April Morning Shift
5

A toxic compound "A" when reacted with NaCN in aqueous acidic medium yields an edible cooking component and food preservative "B". "B" is converted to "C" by diborane and can be used as an additive to petrol to reduce emission. "C" upon reaction with oleum at 140 C yields an inhalable anesthetic "D". Identify "A", "B", "C" & "D", respectively :

  1. Methanol; acetic acid; ethanol; diethyl ether
  2. Ethanol; acetonitrile; ethylamine; ethylene
  3. Methanol; formaldehyde; methyl chloride; chloroform
  4. Acetaldehyde; 2-hydroxypropanoic acid; propanoic acid; dipropyl ether
JEE Main 2025 (Online) 4th April Evening Shift

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