JEE Main · 2024 · Shift-ImediumHC-073

Compound A formed in the following reaction reacts with B gives the product C. Find out A and B.

Hydrocarbons · Class 11 · JEE Main Previous Year Question

Question

Compound A formed in the following reaction reacts with B gives the product C. Find out A and B. image

Options
  1. a

    A=\ceCH3CCNa+A = \ce{CH3-C≡C^{-}Na^{+}}, B=\ceCH3CH2CH2BrB = \ce{CH3CH2CH2Br}

  2. b

    A=\ceCH3CH=CH2A = \ce{CH3-CH=CH2}, B=\ceCH3CH2CH2BrB = \ce{CH3CH2CH2Br}

  3. c

    A=\ceCH3CH2CH3A = \ce{CH3CH2CH3}, B=\ceCH3CCHB = \ce{CH3-C≡CH}

  4. d

    A=\ceCH3CCNa+A = \ce{CH3-C≡C^{-}Na^{+}}, B=\ceCH3CH2CH2CH2BrB = \ce{CH3CH2CH2CH2Br}

Correct Answera

A=\ceCH3CCNa+A = \ce{CH3-C≡C^{-}Na^{+}}, B=\ceCH3CH2CH2BrB = \ce{CH3CH2CH2Br}

Detailed Solution

Step 1: React Propyne with Na

Propyne has an acidic terminal H (pKa25\text{pKa} \approx 25). Na removes it: image Key Points:

  • Terminal alkynes form acetylide ions with Na (acidic sp C-H)
  • Acetylide ions are good nucleophiles; attack primary alkyl halides by SN2S_N 2
  • BB must be a primary alkyl halide to avoid elimination

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Compound A formed in the following reaction reacts with B gives the product C. Find out A and B. (JEE Main 2024) | Canvas Classes