✓ Board-verified
Chemistry · 2023 · 3 marks
CBSE 2023 · Region 4 · Set 1 · Q26
(a) (i) Write hydroboration-oxidation reaction with an example. (ii) Write the products of the following reaction: (iii) Why is p-nitrophenol more…
(i)
Write hydroboration-oxidation reaction with an example.
(ii)
Write the products of the following reaction :
(iii)
Why is p-nitrophenol more acidic than phenol ?
(i)
What happens when phenol reacts with
(1)
Conc. $\displaystyle \mathrm{HNO}_{3}$, and
(2)
$\displaystyle \mathrm{CHCl}_{3}$ in presence of aqueous NaOH followed by acidification? Write equations only.
(ii)
Why does the reaction of $\displaystyle \mathrm{CH}_{3} \mathrm{ONa}$ with $\displaystyle \left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{Br}$ give $\displaystyle 2$-methylpropene and not $\displaystyle \left(\mathrm{CH}_{3}\right)_{3} \mathrm{C}-\mathrm{OCH}_{3}$ ?
Marking-scheme solution
(a)(i)
(ii)
(iii)
Because of electron-withdrawing nature or -I effect of \(\displaystyle -\mathrm{NO}_{2}\) group / p-nitrophenoxide ion is more stable than phenoxide ion / due to more effective delocalization of negative charge in p-nitrophenoxide ion.
All Alcohols, Phenols and Ethers questions2023 question paperNCERT solutions: Alcohols, Phenols and EthersPractice Alcohols, Phenols and Ethers →
More from Alcohols, Phenols and Ethers
- In the reaction R-OH+HCl →ZnCl_2 RCl+H_2 O, what is the correct order of reactivity of alcohols?2025 · asked 2×
- Assertion: Alcohols act as Bronsted bases as well as Bronsted acids. Reason (R): Alcohols react as both nucleophiles and electrophiles. []2026
- Show how you will synthesise: from a suitable alkene. from methanal using a suitable Grignard reagent.2023
- Assertion: p-nitrophenol is less acidic than phenol. Reason (R): Nitro group is electron withdrawing and helps in the stabilisation of…2024
- Sodium phenoxide when heated with CO_2 under pressure, followed by acidification, yields:2023
- Can sodium ethoxide and t-butyl chloride be used for the preparation of t-butyl ethyl ether? Give suitable explanation. Justify your answer by…2025
- Write chemical equations for the following reactions: (Do any three) Hydroboration - oxidation reaction Williamson Synthesis Friedel-Crafts…2024
- What will be formed after oxidation reaction of secondary alcohol with chromic anhydride (CrO_3)?2025
CBSE Class 12 Chemistry past-paper question from the 2023 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.