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JEE Main Chemistry General Organic Chemistry 2026 JEE Main 2026 (28 January Shift 1)

JEE Main Chemistry Question (2026) — Solution

Question

CORRECT order of stability for the following is CH _ 2 = CH ^ - , CH _ 3 - CH _ 2 ^ - , CH C ^ -

Options

  1. A. CH _ 2 = CH ^ - > CH C ^ - > CH _ 3 - CH _ 2 ^ -
  2. B. CH C ^ - > CH _ 2 = CH ^ - > CH _ 3 - CH _ 2 ^ -
  3. C. CH C ^ - > CH _ 3 - CH _ 2 ^ - > CH _ 2 = CH ^ -
  4. D. CH _ 3 - CH _ 2 ^ - > CH _ 2 = CH ^ - > CH C ^ -

Answer

B. CH C ^ - > CH _ 2 = CH ^ - > CH _ 3 - CH _ 2 ^ -

Step-by-step solution

Carbanion stability is determined by the s-character of the hybrid orbital bearing the negative charge. The acetylide anion CH C^- has the carbanion on an sp hybridized carbon (50% s-character), providing optimal stabilization through efficient overlap with the charged orbital. The vinyl anion CH_2 = CH^- has the carbanion on an sp² hybridized carbon (33% s-character), offering moderate stabilization. The primary alkyl anion CH_3 - CH_2^- has the carbanion on an sp³ hybridized carbon (25% s-character), providing the least stabilization. Greater s-character enables better penetration of the nucleus and enhanced stabilization of the negative charge. Therefore, the order is CH C^- > CH_2 = CH^- > CH_3 - CH_2^-.

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Related: Chemistry — General Organic Chemistry · All PYQ Banks