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🧪 Chemistry  ·  Hydrocarbons  ·  NEET & JEE

Addition of HCl to 3-methylbut-1-ene gives mainly 2-chloro-2-methylbutane because of:

Answer: A 1,2-hydride shift to a tertiary cation.

  • A A 1,2-hydride shift to a tertiary cation
  • B Direct anti-Markovnikov addition
  • C 1-Chloro-3-methylbutane formation
  • D 2-Chloro-3-methylbutane formation

Correct answer: A. A 1,2-hydride shift to a tertiary cation

Explanation: The initial secondary carbocation rearranges by a 1,2-hydride shift to the more stable tertiary carbocation, so Cl adds there giving 2-chloro-2-methylbutane.

Hybridisation and Bonding in HydrocarbonsCCEthane: sp³, single bond109.5°, free rotationCCEthene: sp², double bond120°, planar, NO rotationCCEthyne: sp, triple bond180°, linearMore bonds between the same 2 carbons = shorter, stronger, but more reactive bond

Going from a single to a triple bond between carbons increases the s-character of hybridisation (sp³→sp²→sp), shortening the bond and locking the geometry, while increasing π-bond reactivity (alkenes and alkynes readily undergo addition reactions that alkanes don't).

Concept context

The simplest organic compounds made only of carbon and hydrogen. Covers alkanes, alkenes, alkynes, and aromatic compounds like benzene. Learn preparation methods, key reactions, and physical properties.

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