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Studies on the cationic polymerisation of some 1, 3-dioxacycloalkanes

Firat, Yurdun

Studies on the cationic polymerisation of some 1, 3-dioxacycloalkanes Thumbnail


Yurdun Firat


This thesis concerns the polymerisation of 1,3-dioxacycloalkanes.
Chapter 2 is concerned with the preparation of monomers, initiators and other compounds and with the experimental techniques.
In Chapter 3 the effects of purity on the polymerisations of 1,3-dioxolan and 1,3-dioxepan by HClO4 are re-examined. These reactions were also carried out in the presence of n-Bu4ClO4 and from the results estimates were made of the free ion and ion-pair rate-constants for dioxolan.
Chapter 4 is concerned with the polymerisation of 1,3-dioxolan with MeSO3F, TiCl4+ Acetyl Chloride, TiCl4+"tert-Butyl" Chloride, Acetyl perchlorate, "tert-Butyl" perchlorate, NO2SbF6, NOBF4, NOSbF6 and NOPF6. All these initiators gave side reactions and the active centres are not stable in these reactions.
Chapter 5 is concerned with the determination of secondary and tertiary oxonium ions. 1,3-Dioxolan, 1,3-dioxepan and 4-methyl-l,3-dioxolan were polymerised by anhydrous perchloric acid and the reactions were terminated by sodium ethoxide under high vacuum. Some of the reactions were carried out in the presence of known amounts of water. From these experiments it was shown that tertiary oxonium ions are mainly produced by water. Therefore Plesch and Vestermann's original ring-expansion mechanism was found applicable. According to this mechanism, the polymers formed were cyclic and the propagating species formed from protonic initiators must be secondary oxonium ions.
Chapter 6 concerns the polymerisation of 4-methyl-1,3-dioxolan by anhydrous perchloric acid. The equilibrium constant of polymerisation was determined analytically and from it and its temperature variation the thermodynamic characteristics of the polymerisation were calculated. It is also concerned with the polymerisation of 2-methyl-l,3-dioxolan.
Chapter 7 is concerned with some exploratory experiments:
a) 1,3-Dioxolan polymerisations by CF3SO3H.
b) The polymerisations of 4,5-disubstituted 1,3-dioxolan, i.e, cis- and trans-7,9- dioxabicyclo-[4.3.0]-nonane.
c) NMR investigations on the tertiary oxonium ions obtained from MeSO3F.

Publication Date Aug 1, 1974


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