The reagent 'R' in the given sequence of chemical reaction is : 2,4,6-tribromoaniline xrightarrowNaNO₂, HCl,\ 0-5^° C 2,4,6-tribromobenzenediazonium chloride xrightarrowR 1,3,5-tribromobenzene 1. H₂O 2. CH₃CH₂OH 3. HI 4. CuCN/KCN

Answer: 2. CH₃CH₂OH Key idea: replacing the diazonium group by hydrogen (hydro-de-diazoniation) needs a mild reducing agent. Ethanol (or H₃PO₂ ) replaces -N₂^+ by H, giving 1,3,5-tribromobenzene (with acetaldehyde from ethanol). Water would give a phenol, HI would give an iodoarene, and CuCN/KCN would give a nitrile.

Topic: Diazonium salts in synthesis· Organic Compounds Containing Nitrogen

The reagent 'R' in the given sequence of chemical reaction is :2,4,6-tribromoaniline NaNO_2, HCl,\ 0-5^° C 2,4,6-tribromobenzenediazonium chloride R 1,3,5-tribromobenzene

The reagent 'R' in the given sequence of chemical reaction is :

2,4,6-tribromoaniline \(\xrightarrow{NaNO_2, HCl,\ 0-5^\circ C}\) 2,4,6-tribromobenzenediazonium chloride \(\xrightarrow{R}\) 1,3,5-tribromobenzene

reaction scheme: tribromoaniline to diazonium salt to tribromobenzene with reagent R

1. \(H_2O\)

2. \(CH_3CH_2OH\)

3. HI

4. CuCN/KCN

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Answer: 2. \(CH_3CH_2OH\)

Key idea: replacing the diazonium group by hydrogen (hydro-de-diazoniation) needs a mild reducing agent.

Ethanol (or \(\mathrm{H_3PO_2}\)) replaces \(\mathrm{-N_2^+}\) by H, giving 1,3,5-tribromobenzene (with acetaldehyde from ethanol). Water would give a phenol, HI would give an iodoarene, and CuCN/KCN would give a nitrile.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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The reagent 'R' in the given sequence of chemical reaction is :2,4,6-tribromoaniline NaNO_2, HCl,\ 0-5^° C 2,4,6-tribromobenzenediazonium chloride R 1,3,5-tribromobenzene

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