Past exam of the chemistry course of the year 3 of the natural sciences course of the University of Cambridge / 2022 / Paper 3 / 50 / a / Solution 2026-10-20
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Addition consumes the carbon–carbon double bond of vinyl chloride and retains chlorine as a side substituent. The interior repeat of A is therefore
(1)
namely polyvinyl chloride. Benzoyl peroxide supplies initiating free radicals; head-to-tail addition gives the usual backbone connectivity. End groups and tacticity are not uniquely specified by this repeat formula.
Figure 1.
Representative backbone segments of the chloride polymer and the two copolymers
. Original labelled segments. The copolymer rows illustrate one possible sequence, not regularly repeating three-to-one blocks; the feed ratio alone does not determine incorporated composition. Details.
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