Polymerization and Copolymerization of Vinyl Lead Compounds

Many papers report the formation of lead-containing polymers but the formulations do not necessarily produce lead covalently bonded as part of a polymer. For instance, Honda and Kaetsu described the production of a transparent, easily moldable polymer useful for protection against radiation by dissolving a specified amount of an organolead compormd in a specified monomer ntixture. Thus lead acetate is dissolved in a monomer mixture containing methyl methacrylate, methacrylic acid, and a-methyl styrene, and free-radical s polymerization carried out. The resulting mixture is sandwiched between glass plates to obtain the desired product. 

While vinyl lead itself, C=C-Pb, has not been polymerized, there have been reports of its copolymerization. Korshak et al. reported that both diethyldivinyllead and triethylvinyllead decompose to lead metal under the action of peroxide polymerization catalysts at 120-130 C, but that copolymers are formed when reacted in the presence of styrene or a-methylstyrene, giving products with about 4-6% lead content. 

This compound was discussed at the 1969 lUPAC Symposium on Macromolecular Chemistry in Moscow. It was prepared from reaction of triphenyllead chloride and j9-styrenylmagnesium chloride (eq. 1). It homopolymerized readily, more readily than styrene itself It also forms copolymers with styrene or methyl methacrylate in conversions of 25%, giving transparent plastic films (eq. 2). 

The synthesis and polymerization of triphenyl-p-styrenyllead, as well as triethyl- -styrenyllead, was described by Pars et 1960. In comparison to the triphenyl-p-styrenyllead, isolation of triethyl-/ -styrenyllead was difficult because of its tendency to polymerize. 

In 1959 Korshak and co-workers also studied the same compoimds and the previously imknown triethyl-/7-a-methylstyrenyllead. This compoimd was prepared according to equation 3. Compound (3) was polymerized at 80 C imder pres-sme, giving a colorless, hard material (4) that was soluble in toluene and benzene (eq. 4). If the monomer was not purified, the resulting product was rubbery. The corresponding germanimn polymer was more stable but the tin polymer was less stable. 

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