The Polymerisation of 1,3-Dioxacycloalkanes

Some Aspects of the Polymerisation of 1,3-Dioxacycloalkanes, P. H. Plesch, Pure and Applied Chemistry, 1976, 48, 287-293. 

The Propagating Species in the Polymerisation of 1,3-Dioxacycloalkanes by Perchloric Acid (1975)... 

The object of the work described was to discriminate between the two principal rival theories concerning the polymerisation of 1,3-dioxacycloalkanes by anhydrous perchloric acid, the Mainz theory and the Keele theory . By means of Jaaks s method for determining tertiary oxonium ions we found that in polymerisations under the driest conditions the concentration of these is negligibly small. This was done with 1,3-dioxolane (1), 4-methyl-l,3-dioxolane (4), and 1,3-dioxepane (5), and the findings are supported by determinations of the content of hydroxy groups of polymers prepared and killed under different conditions. 

The Propagating Species in the Polymerisation of 1,3-Dioxacycloalkanes by Perchloric Acid, Y. Firat, F.R. Jones, P.H. Plesch and P.H. Westermann, Die Makromolekulare Chemie, Supplement 1, 1975, 203-216. 

A Some of the most interesting and informative experiments in this field were done by Pepper s group and then at Keele and elsewhere with anhydrous perchloric acid as the initiator. It is therefore historically important that in the present super-cautious, safety conscious era, few, if any, workers are ever likely to follow Pepper s pioneering work with this hazardous material, to test the reproducibility of these classical findings. The same applies of course to our studies on the polymerisation of various 1,3-dioxacycloalkanes, most of which were also done with anhydrous HC104, see Chapter 7. There is no substitute for it, as every acid behaves differently and in particular the lazy worker s substitute aq. HC104 + acetic anydride, is a very different initiator system. 

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