JEE Challenger
More from Organic Chemistry - Basic Principles
ChemHardAdv 2022 • Paper 1

Matching Organic Compounds with Qualitative Analysis Observations

Match the compounds in LIST-I with the observations in LIST-II, and choose the correct option.

LIST-ILIST-II(I) Aniline(P) Sodium fusion extract of the compound onboiling with FeSO4, followed byacidification with conc. H2SO4, givesPrussian blue color.(II) o-Cresol(Q) Sodium fusion extract of the compound ontreatment with sodium nitroprusside givesblood red color.(III) Cysteine(R) Addition of the compound to a saturatedsolution of NaHCO3 results ineffervescence.(IV) Caprolactam(S) The compound reacts with bromine waterto give a white precipitate.(T) Treating the compound with neutral FeCl3solution produces violet color.\begin{array}{ll} \textbf{LIST-I} & \textbf{LIST-II} \\[6pt] \text{(I) Aniline} & \text{(P) Sodium fusion extract of the compound on} \\ & \hspace*{1.8em}\text{boiling with }\text{FeSO}_4\text{, followed by} \\ & \hspace*{1.8em}\text{acidification with conc. }\text{H}_2\text{SO}_4\text{, gives} \\ & \hspace*{1.8em}\text{Prussian blue color.} \\[6pt] \text{(II) } o\text{-Cresol} & \text{(Q) Sodium fusion extract of the compound on} \\ & \hspace*{1.8em}\text{treatment with sodium nitroprusside gives} \\ & \hspace*{1.8em}\text{blood red color.} \\[6pt] \text{(III) Cysteine} & \text{(R) Addition of the compound to a saturated} \\ & \hspace*{1.8em}\text{solution of }\text{NaHCO}_3\text{ results in} \\ & \hspace*{1.8em}\text{effervescence.} \\[6pt] \text{(IV) Caprolactam} & \text{(S) The compound reacts with bromine water} \\ & \hspace*{1.8em}\text{to give a white precipitate.} \\[6pt] & \text{(T) Treating the compound with neutral }\text{FeCl}_3 \\ & \hspace*{1.8em}\text{solution produces violet color.} \end{array}

Options

A

I→P,Q; II→S; III→Q,R; IV→P\text{I}\rightarrow\text{P,Q};\, \text{II}\rightarrow\text{S};\, \text{III}\rightarrow\text{Q,R};\, \text{IV}\rightarrow\text{P}

B

I→P; II→R,S; III→R; IV→Q,S\text{I}\rightarrow\text{P};\, \text{II}\rightarrow\text{R,S};\, \text{III}\rightarrow\text{R};\, \text{IV}\rightarrow\text{Q,S}

C

I→Q,S; II→P,T; III→P; IV→S\text{I}\rightarrow\text{Q,S};\, \text{II}\rightarrow\text{P,T};\, \text{III}\rightarrow\text{P};\, \text{IV}\rightarrow\text{S}

D

I→P,S; II→T; III→Q,R; IV→P\text{I}\rightarrow\text{P,S};\, \text{II}\rightarrow\text{T};\, \text{III}\rightarrow\text{Q,R};\, \text{IV}\rightarrow\text{P}

Correct

Topics & Concepts

Organic Chemistry - Basic PrinciplesAminesAlcohols and EthersAmino Acids and Proteins

Step-by-Step Solution

To determine the correct matching between the compounds in LIST-I and the qualitative observations in LIST-II, we analyze each compound and its characteristic chemical reactions:

  1. (I) Aniline (C6H5NH2\text{C}_6\text{H}_5\text{NH}_2):

    • Presence of Nitrogen: Being an organic nitrogenous compound, its sodium fusion extract contains cyanide ions (CN−\text{CN}^-). Upon boiling with FeSO4\text{FeSO}_4 and subsequent acidification with concentrated H2SO4\text{H}_2\text{SO}_4, it produces a Prussian blue precipitate of Fe4[Fe(CN)6]3\text{Fe}_4[\text{Fe(CN)}_6]_3. Thus, I→P\text{I} \rightarrow \text{P}.
    • Reaction with Bromine Water: Due to the strong activating nature of the amino group (−NH2-\text{NH}_2), aniline reacts with bromine water to yield a white precipitate of 2,4,6-tribromoaniline. Thus, I→S\text{I} \rightarrow \text{S}.
    • Combining these observations: I→P, S\text{I} \rightarrow \text{P, S}.

  2. (II) oo-Cresol (2-methylphenol):

    • Phenolic Group: Phenols react with neutral FeCl3\text{FeCl}_3 solution to form a characteristic violet-colored complex due to the formation of iron-phenoxide complexes. Thus, II→T\text{II} \rightarrow \text{T}.

  3. (III) Cysteine (HS-CH2-CH(NH2)-COOH\text{HS-CH}_2\text{-CH(NH}_2\text{)-COOH}):

    • Presence of both Nitrogen and Sulfur: The sodium fusion extract of cysteine contains thiocyanate ions (SCN−\text{SCN}^-) (or sodium sulfide/nitroprusside test characteristic reactions for compounds containing both N and S), which gives a characteristic blood-red color observation. Thus, III→Q\text{III} \rightarrow \text{Q}.
    • Carboxylic Acid Group: Cysteine contains a free carboxylic acid group (−COOH-\text{COOH}), which is sufficiently acidic to react with a saturated solution of sodium bicarbonate (NaHCO3\text{NaHCO}_3) to evolve CO2\text{CO}_2 gas, producing effervescence. Thus, III→R\text{III} \rightarrow \text{R}.
    • Combining these observations: III→Q, R\text{III} \rightarrow \text{Q, R}.

  4. (IV) Caprolactam:

    • Presence of Nitrogen: Caprolactam is a cyclic amide containing nitrogen. Its sodium fusion extract contains sodium cyanide (NaCN\text{NaCN}), which gives a Prussian blue color when treated with FeSO4\text{FeSO}_4 followed by acidification with concentrated H2SO4\text{H}_2\text{SO}_4. Thus, IV→P\text{IV} \rightarrow \text{P}.

Summary of Matchings:

  • I→P, S\text{I} \rightarrow \text{P, S}
  • II→T\text{II} \rightarrow \text{T}
  • III→Q, R\text{III} \rightarrow \text{Q, R}
  • IV→P\text{IV} \rightarrow \text{P}

This corresponds to Option D.

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