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Compounds Containing Nitrogen question

2021 · 27 Jul · Shift 2 · Q8
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  5. /2021 · 27 Jul · Shift 2 · Q8

Compounds Containing Nitrogen question

2021 · 27 Jul · Shift 2 · Q8

JEE MainChemistryCompounds Containing NitrogenMCQ+4 / −1
R−CN⟶(ii)H2O(i)DIBAL−HR−YR - CN\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{(ii){H_2}O}^{(i)DIBAL - H}} R - YR−CN(ii)H2​O⟶(i)DIBAL−H​R−Y Consider the above reaction and identify "Y"
  1. A
    −-− CH2NH2CH_2NH_2CH2​NH2​
  2. B
    −-− CONH2CONH_2CONH2​
  3. C
    −-− CHO
  4. D
    −-− COOH
View written solutionFree

Correct answer: C

  1. We are given the transformation:

R−CN→(ii) H2O(i) DIBAL-HR−YR-CN \xrightarrow[(ii)\ H_2O]{(i)\ \text{DIBAL-H}} R-YR−CN(i) DIBAL-H(ii) H2​O​R−Y

We need to identify the group YYY formed from a nitrile (−CN)(-CN)(−CN).

  1. Recall the action of DIBAL-H on nitriles:
  • DIBAL-H (diisobutylaluminium hydride\text{diisobutylaluminium hydride}diisobutylaluminium hydride) is a selective reducing agent.
  • It reduces a nitrile R−C≡NR-C\equiv NR−C≡N partially to an imine/aluminium complex.
  • On hydrolysis with water, this intermediate gives an aldehyde.

Thus,

R−C≡N→DIBAL-Himine intermediate→H2OR−CHOR-C\equiv N \xrightarrow{\text{DIBAL-H}} \text{imine intermediate} \xrightarrow{H_2O} R-CHOR−C≡NDIBAL-H​imine intermediateH2​O​R−CHO

  1. Therefore, the product group is:

Y=−CHOY = -CHOY=−CHO

  1. Check options:
  • A: −CH2NH2-CH_2NH_2−CH2​NH2​ → This would be complete reduction to a primary amine, not the typical DIBAL-H hydrolysis product.
  • B: −CONH2-CONH_2−CONH2​ → This is an amide, not formed here.
  • C: −CHO-CHO−CHO → Correct.
  • D: −COOH-COOH−COOH → This would come from hydrolysis of nitrile under acidic/basic conditions, not DIBAL-H followed by water.

Hence, the correct option is C.

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