A MECHANISTIC STUDY ON THE STEREOREGULAR POLYMERIZATION OF PROPYLENE-OXIDE BY THE PRUITT-BAGGETT CATALYST


TAKROURI F., ALYURUK K.

POLYMER, vol.35, no.7, pp.1518-1525, 1994 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 35 Issue: 7
  • Publication Date: 1994
  • Doi Number: 10.1016/0032-3861(94)90353-0
  • Title of Journal : POLYMER
  • Page Numbers: pp.1518-1525

Abstract

The structures of the Pruitt-Baggett adduct (PBA) and the Pruitt-Baggett catalyst (PBC) were studied in some detail. PBC extensively ionizes in acetonitrile (K(d)=3.48 x 10(-3) mol l-1 at 25-degrees-C) producing an anionic fragment composed of seven Fe atoms and a cationic fragment with two Fe atoms. Hittorf electrolysis showed that the anionic fragments exclusively bore the high molecular weight stereoregular poly(propylene oxide)s (K-polymers). However, study of the polymerization in the presence of anion and cation scavengers and in different dielectric media supported a previous conclusion that neither free anions nor cations were solely responsible for the stereoregular polymerization, but together with a monomer molecule they combine to yield catalytically active monomer-bound ion pairs. The study of the product showed that K-polymers were connected to each other with Fe atoms. However, these chains could be freed by extracting the Fe residues with hydrochloric acid. A mechanism for the stereoregular polymerization of propylene oxide that is consistent with the present and already published data was suggested.