JEE MAIN - Chemistry (2023 - 8th April Morning Shift - No. 14)
Match List I with List II:
| LIST I (Reagents used) | LIST II (Compound with Functional group detected) | ||
|---|---|---|---|
| A. | Alkaline solution of copper sulphate and sodium citrate | I. | _8th_April_Morning_Shift_en_14_1.png) |
| B. | Neutral $$\mathrm{FeCl_3}$$ | II. | _8th_April_Morning_Shift_en_14_2.png) |
| C. | Alkaline chloroform solution | III. | _8th_April_Morning_Shift_en_14_3.png) |
| D. | Potassium iodide and sodium hypochlorite | IV. | _8th_April_Morning_Shift_en_14_4.png) |
Choose the correct answer from the options given below:
A-IV, B-I, C-II, D-III
A-III, B-IV, C-I, D-II
A-III, B-IV, C-II, D-I
A-II, B-IV, C-III, D-I
Explanation
(A) Fehling's solution is used to distinguish between aldehyde and ketone functional groups. Aldehydes oxidize to give a positive result but ketones won't react to the test (except for $\alpha$-hydroxy ketones). Fehling's test is used as a general test for determining monosaccharides and other reducing sugars.
_8th_April_Morning_Shift_en_14_5.png)
(B)
_8th_April_Morning_Shift_en_14_6.png)
(C) This reaction is a chemical test for detection of primary amines, in which the amine is heated with alcoholic potassium hydroxide and chloroform. If a primary amine is present, the isocyanide is formed. The reaction is known as carbylamine reaction.
$$ \mathrm{RNH}_2+\mathrm{CHCl}_3+3 \mathrm{KOH} \rightarrow \mathrm{RN}^{+} \equiv \mathrm{C}^{-}+3 \mathrm{KCl}+3 \mathrm{H}_2 \mathrm{O} $$
(D) When a methyl ketone (even acetaldehyde) is reacted with halogen in aqueous sodium hydroxide, the ketone gets oxidised to the sodium salt of acid with one carbon less than ketone and at the same time haloform $\left(\mathrm{CHX}_3\right)$ also gets formed.
$$ 2 \mathrm{NaOH}+\mathrm{X}_2 \rightarrow \underset{\text{Sodium halide}}{\mathrm{NaX}} +\underset{\text{Sodium hypohalite}}{\mathrm{NaOX}} $$
The hydroxide ion acts as a nucleophile and attacks the electrophilic carbon which is doubly bonded to oxygen. This carbon-oxygen double bond becomes a single bond making the oxygen atom anionic.
_8th_April_Morning_Shift_en_14_7.png)
(B)
(C) This reaction is a chemical test for detection of primary amines, in which the amine is heated with alcoholic potassium hydroxide and chloroform. If a primary amine is present, the isocyanide is formed. The reaction is known as carbylamine reaction.
$$ \mathrm{RNH}_2+\mathrm{CHCl}_3+3 \mathrm{KOH} \rightarrow \mathrm{RN}^{+} \equiv \mathrm{C}^{-}+3 \mathrm{KCl}+3 \mathrm{H}_2 \mathrm{O} $$
(D) When a methyl ketone (even acetaldehyde) is reacted with halogen in aqueous sodium hydroxide, the ketone gets oxidised to the sodium salt of acid with one carbon less than ketone and at the same time haloform $\left(\mathrm{CHX}_3\right)$ also gets formed.
$$ 2 \mathrm{NaOH}+\mathrm{X}_2 \rightarrow \underset{\text{Sodium halide}}{\mathrm{NaX}} +\underset{\text{Sodium hypohalite}}{\mathrm{NaOX}} $$
The hydroxide ion acts as a nucleophile and attacks the electrophilic carbon which is doubly bonded to oxygen. This carbon-oxygen double bond becomes a single bond making the oxygen atom anionic.
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