Cationic polymerization of 1-chloro-2,3-epoxypropane initiated by triphenylmethylhexafluoroantimonate(V)

Abstract

The activity of Ph3CZXn in the initiation of polymerization of 1-chloro-2,3-epoxypropane decreases in dependence on ZXn in the following series AsF6(-) ≥ SbF6(-) ##i SbCl6(-) > AlCl4(-) > SnCl5(-) > TiCl5(-). The polymerization initiated by Ph3CSbF6 is a first-order reaction both with respect to the monomer and to the catalyst. The following values were determined for the rate constants of initiation, propagation, and termination, respectively: ki = 3 . 10-6 mol-1 l s-1; kp = 9 . 10-2 mol-1 l s-1; kt = 2 . 10-4 mol-1 l s-1. The initiation occurs via a hydride-ion transfer from 1-chloro-2,3-epoxypropane to the triphenylmethyl cation. The oxonium ion formed by Ph3C(+) addition on 1-chloro-2,3-epoxypropane presumably does not take part in the initiation; the equilibrium constant of formation of this adduct Ke is 3.0 . 10-1 mol-1 l. Oligomers are n-multiples of monomeric epichlorohydrine, and products of Pn 4-7 have mostly cyclic structure.