Organic Compounds Containing Nitrogen: Chemistry | JEE Main
Match List I with List II.
List I
List II
Reaction
Reagents
(A)
Hoffmann Degradation
(I)
Conc.KOH,Δ
(B)
Clemenson reduction
(II)
CHCl3,NaOH/H3O⊕
(C)
Cannizaro reaction
(III)
Br2,NaOH
(D)
Reimer-Tiemann Reaction
(IV)
Zn−Hg/HCl
Choose the correct answer from the options given below:
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Hint 1 of 3
Which reagent pair is characteristic of the Hoffmann bromamide degradation of primary amides?
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Step-by-step solutionView
Correct answer
The correct matching is (A) - III, (B) - IV, (C) - I, (D) - II.
Option analysis
Why each option works or fails
A · -III, (B) - IV, (C) - I, (D) - II
None. This option correctly matches each named reaction with its characteristic reagent. Hoffmann degradation uses Br2/NaOH, Clemmensen reduction uses Zn−Hg/HCl, Cannizzaro reaction uses concentrated alkali like Conc. KOH, and Reimer-Tiemann reaction uses CHCl3/NaOH.
B · (A) - II, (B) -I, (C) - III, (D) - IV
Confusing the halogen-containing base combinations across Hoffmann degradation and Reimer-Tiemann reaction, and swapping Clemmensen reduction with Cannizzaro reaction conditions. Remember that Hoffmann degradation specifically requires a halogen with base (Br2/NaOH) to convert amides to amines, not chloroform.
C · (A) -III, (B) -IV, (C) - II, (D) - I
Inverting the roles of concentrated base (Cannizzaro) and chloroform with aqueous base (Reimer-Tiemann). Cannizzaro reaction is a disproportionation of non-enolizable aldehydes driven solely by concentrated alkali (Conc. KOH), whereas Reimer-Tiemann specifically incorporates a formyl group using chloroform (CHCl3) in base.
D · (A) -II, (B) - IV, (C) - I, (D) - III
Mistaking the electrophilic source in the Reimer-Tiemann reaction for molecular bromine rather than dichlorocarbene from chloroform. Reimer-Tiemann introduces a formyl group using CHCl3/NaOH, while Hoffmann degradation degrades primary amides with Br2/NaOH.
Reviewed route
Solution
StepWorking
01concept
Recall the characteristic reagent combinations for each named organic reaction:
- Hoffmann bromamide degradation converts primary amides to amines using Br2 and aqueous NaOH (III).
- Clemmensen reduction reduces carbonyl groups of aldehydes/ketones to methylene groups using zinc amalgam and concentrated hydrochloric acid, Zn-Hg/HCl (IV).
- Cannizzaro reaction is the disproportionation of non-enolizable aldehydes under strong basic conditions, such as Conc. KOH,Δ (I).
- Reimer-Tiemann reaction formylates phenols using chloroform and alkali, CHCl3,NaOH/H3O+ (II).
02option_verdict
Matches (A) with III, (B) with IV, (C) with I, and (D) with II correctly.
03option_verdict
Incorrectly assigns CHCl3/NaOH to Hoffmann degradation and Conc. KOH to Clemmensen reduction.
04option_verdict
Swaps the reagents for Cannizzaro reaction and Reimer-Tiemann reaction.
05option_verdict
Matches Hoffmann degradation with CHCl3/NaOH and Reimer-Tiemann with Br2/NaOH.
✓discriminator
Knowing that Hoffmann degradation uniquely uses bromine in alkali ((A) -> III) immediately eliminates options (1) and (3). Checking Clemmensen reduction as Zn-Hg/HCl ((B) -> IV) and Cannizzaro as concentrated alkali ((C) -> I) uniquely confirms option (0).
Hints that build this answer step by step
Which reagent pair is characteristic of the Hoffmann bromamide degradation of primary amides?
Br2,NaOH (III)
What are the characteristic reagents for Clemmensen reduction and the Cannizzaro reaction?
Why is heating with concentrated KOH specific to Cannizzaro here?
Cannizzaro reaction requires a strongly alkaline medium (e.g., 50% or concentrated KOH) to initiate hydride transfer from the hydrate intermediate of an aldehyde lacking alpha-hydrogens.