This question is about 2-methylbut-1-ene - AQA - A-Level Chemistry - Question 3 - 2022 - Paper 2

1. Protonation: The double bond of 2-methylbut-1-ene attacks the proton (H⁺) from sulfuric acid, leading to the formation of the more stable carbocation at the more substituted carbon.

2. Nucleophilic attack: The bisulfate ion (HSO₄⁻) attacks the carbocation, forming alkyl hydrogen sulfate.

3. Hydrolysis: The alkyl hydrogen sulfate can then be hydrolyzed to form the major alcohol product by reacting with water.

The minor product formed is a less stable carbocation that leads to an alternative alcohol structure.

Structure of Minor Product: The structure can be represented as:

     H   OH
      \  |
       C--C--C
      / 
     H  H

Explanation: This is the minor product due to the formation of a less stable, secondary carbocation compared to the more stable tertiary carbocation formed in the major product.

A functional group isomer of 2-methylbut-1-ene can be depicted as:

     CH₃  H
      |   |
     H-C--C
      |   ||
     CH₃  O

This structure represents an alcohol or ether functional group isomer.

The type of polymerization for 2-methylbut-1-ene is Addition Polymerisation.

The repeating unit for the polymer formed can be represented as:

   --[CH₂-CH(CH₃)-]--

This denotes the repeating structure of the polymer derived from 2-methylbut-1-ene.