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Structures of some common polymers are given. Which one is not correctly presented?
A
Nylon 66: $-[NH(CH_2)_6NHCO(CH_2)_4-CO]_n-$
B
Teflon: $-(CF_2-CF_2)_n-$
C
Neoprene: $-[CH_2-C(Cl)=CH-CH_2-CH_2]_n-$
D
Terylene: $-[OOC-C_6H_4-COOCH_2-CH_2]_n-$
Detailed Solution
Neoprene is formed by polymerisation of chloroprene, $CH_2=C(Cl)-CH=CH_2$ (2-chloro-1,3-butadiene), which has four carbon atoms.
Its repeating unit is therefore $-[CH_2-C(Cl)=CH-CH_2]_n-$, with four carbons.
The structure given for neoprene has an extra $-CH_2-$ group (five carbons in the repeating unit), so it is not correct.
Nylon 6,6 (from hexamethylenediamine and adipic acid), teflon (from tetrafluoroethene) and terylene (from ethylene glycol and terephthalic acid) are correctly presented.
Hence the structure of neoprene is not correctly presented.
Its repeating unit is therefore $-[CH_2-C(Cl)=CH-CH_2]_n-$, with four carbons.
The structure given for neoprene has an extra $-CH_2-$ group (five carbons in the repeating unit), so it is not correct.
Nylon 6,6 (from hexamethylenediamine and adipic acid), teflon (from tetrafluoroethene) and terylene (from ethylene glycol and terephthalic acid) are correctly presented.
Hence the structure of neoprene is not correctly presented.