This question is about 2-methylbut-1-ene - AQA - A-Level Chemistry - Question 3 - 2022 - Paper 2
Question 3
This question is about 2-methylbut-1-ene.
1. Name the mechanism for the reaction of 2-methylbut-1-ene with concentrated sulfuric acid.
Outline the mechanism for ... show full transcript
Worked Solution & Example Answer:This question is about 2-methylbut-1-ene - AQA - A-Level Chemistry - Question 3 - 2022 - Paper 2
Step 1
Name the mechanism for the reaction of 2-methylbut-1-ene with concentrated sulfuric acid.
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Answer
The mechanism for the reaction is known as Electrophilic Addition. In this reaction, the double bond of 2-methylbut-1-ene acts as a nucleophile and attacks the electrophile, which is the proton (H⁺) from sulfuric acid.
Step 2
Outline the mechanism for this reaction to form the major product.
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Answer
Protonation: The alkene (2-methylbut-1-ene) attacks the proton (H⁺) supplied by sulfuric acid, forming a carbocation intermediate.
Nucleophilic attack: The bisulfate ion (HSO₄⁻) then attacks the carbocation at the more stable carbon.
Formation of the major product: This results in the formation of alkyl hydrogen sulfate as the major product.
Step 3
Draw the structure of the minor product formed in the reaction in Question 03.1.
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The structure of the minor product is:
CH₃
|
H₃C-C-OSO₃H
|
CH₂
|
CH₃
Step 4
Explain why this is the minor product.
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This is the minor product because it is formed from a less stable carbocation. The reaction favors the formation of the major product due to the greater stability of its respective carbocation.
Step 5
Draw the skeletal formula of a functional group isomer of 2-methylbut-1-ene.
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The skeletal formula of a functional group isomer, such as 2-methylbutan-1-ol, is:
CH₃
|
H₃C-C-CH₂-CH₂OH
|
CH₃
Step 6
State the type of polymerisation.
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The type of polymerisation is Addition Polymerisation.
Step 7
Draw the repeating unit for the polymer formed.
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Answer
The repeating unit for the polymer formed from 2-methylbut-1-ene is:
