The name "chloroprene" gives it away! "Chloro" means it must have a chlorine atom ($Cl$). If you remember that Neoprene is just the synthetic version of natural rubber where the methyl ($-CH_3$) is replaced by chlorine ($-Cl$), you'll never miss this.
1. Identifying the Monomer: The monomer for neoprene is
chloroprene, which is 2-chloro-1,3-butadiene.
Structure of monomer: $CH_2=C(Cl)-CH=CH_2$.
2. Polymerization Process: During free radical polymerization, the double bonds break and rearrange to form a long chain. The double bond shifts to the center of the unit.
$$n [CH_2=C(Cl)-CH=CH_2] \rightarrow \text{---}[CH_2-C(Cl)=CH-CH_2]\text{---}_n$$
3. Analyzing the Options:
• Option (A) contains an ethyl group (natural rubber derivatives).
• Option (B) contains a
chlorine (Cl) atom at the second carbon, which is the defining characteristic of polychloroprene.
• Option (C) contains fluorine (related to Teflon/PVF).
• Option (D) contains a methyl group, which is the structure of
Natural Rubber (polyisoprene).
Therefore, the structure containing the chlorine atom is the correct representation of neoprene.
