A Levels Chemistry (9701)•9701/12/O/N/24
Explanation
Addition Polymerization of Alkenes
Steps:
- Monomer is prop-2-en-1-ol (CH₂=CHCH₂OH), with double bond between C2-C3.
- Addition polymerization opens the C=C double bond, forming single bonds between monomers.
- Carbon 1 (CH₂OH) becomes a side chain on C2.
- Repeat unit is -[CH₂-CH(CH₂OH)]-.
Why B is correct:
- B depicts -[CH₂-CH(CH₂OH)]-, matching the standard addition polymer structure where the double bond adds across C2-C3, per Markovnikov-free vinyl polymerization rules.
Why the others are wrong:
- A: Shows linear -[CH₂CH₂CH₂OH]-, ignoring the branched alkene structure.
- C: Includes ester linkage, assuming condensation instead of addition.
- D: Places OH on the chain backbone, altering the monomer's connectivity.
Final answer: B
Topic: Polymerisation
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