Synthesis of Functionalized Polyisobutylenes using the Propylene Epoxide/TiCl4 Initiating System

The synthesis of sym. and asym. telechelic polyisobutylenes (PIBs) is reported.  A PIB with a primary hydroxy head group and an allyl end group (HO-​PIB-​Allyl, Mn = 4300 g​/mol, Mw/Mn = 1.2) was synthesized by living carbocationic polymn. of isobutylene (IB) using propylene epoxide as an initiator and allyltrimethylsilane as a terminating agent.  Thiol-​ene click chem. using 2-​mercaptoethanol and 1,​2-​ethanedithiol yielded an asym. HO-​PIB-​SEt-​OH (Mn = 4646 g​/mol, Mw/Mn = 1.18) and a sym. HO-​PIB-​OH (Mn = 8594 g​/mol, Mw/Mn = 1.2)​, resp.  A sym. allyl telechelic PIB (Mn = 8669 g​/mol, Mw/Mn = 1.2) was prepd. by enzymic transesterification of divinyl adipate with the primary hydroxy group of HO-​PIB-​Allyl.

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