Content check — Organic Chemistry, Chapter 31: Synthetic Polymers

Every problem in the chapter beside the book’s answer, a chapter at a time as you scroll.

Chapter 31: Synthetic Polymers

12 problems · 8 figures

Order the following monomers with respect to their expected reactivity toward cationic polymerization, and explain your answer:

H₂C ═ CHCH₃, H₂C ═ CHCl, H₂C ═ CH–C₆H₅, H₂C ═ CHCO₂CH₃

Answer

H₂C ═ CHCO₂CH₃ < H₂C ═ CHCl < H₂C ═ CHCH₃ < H₂C ═ CH–C₆H₅

31-2 §31.1 source ↗

Order the following monomers with respect to their expected reactivity toward anionic polymerization, and explain your answer:

H₂C ═ CHCH₃, H₂C ═ CHC ≡ N, H₂C ═ CHC₆H₅

Answer

H₂C ═ CHCH₃ < H₂C ═ CHC₆H₅ < H₂C ═ CHC ≡ N

31-3 §31.1 source ↗

Polystyrene is produced commercially by reaction of styrene with butyllithium as an anionic initiator. Using resonance structures, explain how the chain-carrying intermediate is stabilized.

Answer

The intermediate is a resonance-stabilized benzylic carbanion,

31-4 §31.2 source ↗

Vinylidene chloride, H ₂ C ═ C C l ₂ , does not polymerize in isotactic, syndiotactic, and atactic forms. Explain.

Answer

The polymer has no chirality centers.

31-5 §31.2 source ↗

Polymers such as polypropylene contain a large number of chirality centers. Would you therefore expect samples of isotactic, syndiotactic, or atactic polypropylene to rotate plane-polarized light? Explain.

Answer

The polymers are racemic and have no optical rotation.

31-6 §31.3 source ↗

Draw the structure of an alternating segment of butyl rubber, a copolymer of isoprene (2-methyl-1,3-butadiene) and isobutylene (2-methylpropene) prepared using a cationic initiator.

Answer

31-7 §31.3 source ↗

Irradiation of poly(1,3-butadiene), followed by addition of styrene, yields a graft copolymer that is used to make rubber soles for shoes. Draw the structure of a representative segment of this styrene–butadiene graft copolymer.

Answer

31-8 §31.4 source ↗

Poly(ethylene terephthalate), or PET, is a polyester used to make soft-drink bottles. It is prepared by reaction of ethylene glycol with 1,4-benzenedicarboxylic acid (terephthalic acid). Draw the structure of PET.

Answer

31-9 §31.4 source ↗

Show the mechanism of the nucleophilic addition reaction of an alcohol with an isocyanate to yield a urethane.

Answer

31-10 §31.5 source ↗

Look at the structures of Vestenamer and Norsorex and show how they might be made by olefin metathesis polymerization.

Answer

Vestenamer: ADMET polymerization of 1,9-decadiene or ROMP of cyclooctene; Norsorex: ROMP of norbornene.

31-11 §31.7 source ↗

What product would you expect to obtain from catalytic hydrogenation of natural rubber? Would the product be syndiotactic, atactic, or isotactic?

Answer

31-12 §31.7 source ↗

Propose a mechanism to account for the formation of Bakelite from acid-catalyzed polymerization of phenol and formaldehyde.

Answer

End of the book.

Problems and answers are adapted from Organic Chemistry: A Tenth Edition by John McMurry, OpenStax, and are used under the CC BY-NC-SA 4.0 licence. Access for free at https://openstax.org/books/organic-chemistry/pages/1-why-this-chapter. Illustrations: Copyright Rice University, OpenStax, under CC BY-NC-SA 4.0 license. This adaptation is released under the same licence, is non-commercial, and is neither affiliated with nor endorsed by OpenStax or Rice University.