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Unformatted text preview: 776 Chapter 29: Organic Polymer Chemistry Solutions CHAPTER 29 Solutions to the Problems Problem 29.1 Given the following structure, detennine the polymer's repeat unit, redraw the structure using the simplified parenthetical notation, and name the polymer. ~. J 'J-~ . c0f' c0f .. U Polymer- . .1 ~ This polymer is derived from propylene oxide ization ~ot; and, therefore, named poly(propylene oxide) ,<t n . . o Repeat unit Problem 29.2 Write the repeating unit of the polymer formed from the fotlowing reaction and propose a mechanism for its funnM~.' . Monomer A diepoxide A diamine . FoIlowi~g is the structural formula of the repeat unit of this polymer. As a mechanism, propose nucleophilic attack of the amine on the less hindered carbon of the epoxide followed by proton transfer from nitrogen to oxygen. Step 1: Nucleophilic ring opening of the epoxide H --.~ +I~~ Ar-N I Ar Ar'N~O~r ~ 0-" ~o Thediamine The diepoxide Step 2: Proton tramfer from nitrogen to oxygen H' H . Ar2~~~r Ar-~~"Ar I 0- W~o H . Problem 29.3 Show how to prepare polybutadiene that is terminated at both ends with primary alcohol groups. Treat 1,3-butadiene with -two moles of lithium metal to form a dianion followed by addition of monomer units as in Example 29.3 t9 form a living polymer. Cap the active end groups by treatment of the living polymer with ethylene oxide followed by aqueous acid. Chapter'29: Organic Polymer Chemistry Solluions 777 2L' Li+ ~ •• - ~ ~ ~. ~ ,,_=Ic.;....... ~ ~ •. Li+ • Butadiene A dianion i.y [HO~OH] 2. H 2 0,.HCI "'--end caps fr9m ethylene oxideJ . Problem 29 4 Wr.it~ a mechanism fO,r the polyme~iza~ion of methyl vinyl ether initi.ated by 2-chloro-2-phenylpropane and SnCJ 4 . Label the initiation, propagatIOn, and tennmatlon steps.' . The mec.han.ism for this cationic polymerization is similar to that shown in Example 29.4 for the cationic polymenzatlOn of 2-methylpropene. Treatment of 2·chloro-2-phenylpropane with SnCI 4 forms the 2-phenyl-2- propyl cation, the initiating cation. The termination step shown here is loss of H+ from the end of the polymer cham to form a carbon-carbon double bond.' . . Initiation: Ph+CI - SnCl s Ph-\+ +- 2-Chloro-2- phenylpropane . Propagation: ---l.~ Phj(J + Ph-\r)" . '0" Methyl vinyl ether ~ n 0 Ph~ Ph~+ " • /\' i'lt J + . n /\ 6' - '- ............. . " Termination: SnCI; + HCI + SnCI 4 .. Structure and Nomenclature Problem 29.5 Name the following polymers. (')~ (bl i0 y (d)~?VCF,j CF (C)n 3 J;; Poly(l-butene) Poly(ethyl vinyl ether) o Poly(perfluoroethylene) Poly(vinyl acetate) (g)~ Qf Poly(1,4-butylene terephthalate) ":::::;.. CH 2 CI Poly(2,6-dimethyl- Poly(3-chlorome thyl~ phenylene oxide) phenylethylene) 778 Solutions Chapter 29: Organic Polymer Chemistry o (h) Poly(hexamethylene decanediamide) Problem 29.6 Draw the structure(s) of the monomer(s) used to make each polymer in Problem 29.5....
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