Haloaldehyde polymers, 12. Preparation and polymerization of bromodifluoroacetaldehyde

Abstract

Bromodifluoroacetaldehyde (5) was prepared from methyl bromodifluoroacetate (4) by reduction with lithium aluminium hydride. 4 was in turn prepared by bromination of chlorotrifluoroethylene (1) and treatment of the resulting 1,2-dibromo-l-chlorotrifluoroethane (2) with fuming H2S04 and HgO. 5, properly purified, could be polymerized with anionic and cationic initiators to poly[oxy-2-(bromodifluoro)ethylidene] (12). Certain initiators produce partially or entirely amorphous soluble 12 of relatively low molecular weight. Most polymers, however, are insoluble, crystalline, and presumably isotactic. Thermal vacuum degradation of the polymers 12 gave monomer 5 in essentially quantitative yield. The thermal stability of polymers can significantly be improved by endcapping or treating with agents which replace unstable end groups. The ceiling temperature of the polymerization of 5 was determined to be +48"C. 5 was copolymerized with trichloroacetaldehyde with cationic or anionic initiators to copolymers containing predominantly units of 5. 5 could also be copolymerized with phenyl isocyanate to a polymer containing oxycarbamido linkages.