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SYNTHESIS AND POLYMERIZATION OF PERHALOGENATED ACETALDEHYDES AND EPOXIDES
Abstract
Four monomers, bromodifluoroacetaldehyde (BDFA), chlorodifluoroacetaldehyde (CDFA) and dichlorofluoracetaldehyde (DCFA) have been prepared and polymerized with various cationic and anionic initiators. Monomer synthesis was accomplished through reduction of the corresponding methyl trihaloacetate using lithium aluminum hydride. The trihaloacetates were in turn prepared from methyl trichloroacetate and SbF(,3) and Br(,2) catalyst (DCFA) or SbF(,3) and SbCl(,5) catalyst (CDFA), by methanolysis of the oxidation products of 1,1-dibromo-2,2-difluoroethylene (BDFA and DBFA) or by bromination of chlorotrifluoroethylene followed by treatment with fuming sulfuric acid plus HgO and methanolysis (BDFA). The monomers were all found to polymerize to trihalomethyl substituted polyacetals under a variety of conditions with both cationic and anionic initiators. In contrast to polychloral and polybromochloroacetaldehydes, which are wholly insoluble, it was found that under suitable conditions soluble polymers of relatively low molecular weight could be produced from DBFA, DCFA and CDFA, but not DBFA. Most polymers were, however, insoluble, crystalline and presumably isotactic. Thermal stabilities of all polymers were found to be improved by treatment with either PCl(,5) or acid anhydrides. Degradation was quantitative to monomer. Ceiling temperatures for the polymerizations were found to decrease with increasing bromine content and increase with fluorine content. Monomer boiling points varied in the reverse fashion. Relative polymerization rates were measured through copolymerization with chloral, with isocyanates and with one another. In a separate set of experiments tetrachloroethylene oxide was synthesized by direct oxidation of tetrachloroethylene with oxygen in the presence of ultraviolet light. This preparation resulted in a mixture of tetrachloroethylene oxide and trichloroacetyl chloride in approximately equal amounts under the most favorable conditions. Tetrachloroethylene oxide rearranged readily to trichloroacetyl chloride above 60(DEGREES)C. with an activation energy E(,a) of 3.0 x 10('4) cal/mole and a pre-exponential factor A of 1.9 x 10('13). All attempts to polymerizae tetrachloroethylene oxide under a variety of conditions failed.
Subject Area
Polymers
Recommended Citation
CAMPBELL, RICHARD WILLIAM, "SYNTHESIS AND POLYMERIZATION OF PERHALOGENATED ACETALDEHYDES AND EPOXIDES" (1980). Doctoral Dissertations Available from Proquest. AAI8019447.
https://scholarworks.umass.edu/dissertations/AAI8019447