NOVEL ORGANOBORON POLYMERS - HYDROBORATION POLYMERIZATION AND HALOBORATION POLYMERIZATION

As a novel methodology for the preparation of organoboron polymers, this paper describes ''hydroboration polymerization'' and ''haloboration polymerization''. A polyaddition between diene and terthexylborane (t-hexylborane) produced a polymer consisting of C-B bonds in the main chain. The resulting organoboron polymers can be regarded as a polymer homologue of trialkylborane and can be expected as a novel type of reactive polymers. For example, the reaction of organoboron polymer with carbon monoxide followed by the oxidative treatment produced a polyalcohol by the migration of C-B bonds. Similarly, the reaction with potassium cyanide produced a polyketone. On the other hand, hydroboration polymerization of dicyano compounds such as isophthalonitrile with t-butylborane produced an air-stable boron-containing polymer (polycyclodiborazane) having B-N four-membered rings via dimerization of iminoborane species. In haloboration polymerization, i.e., a polyaddition between diacetylene and boron tribromide, a linear poly(organoboron halide) was obtained. This polymer still has B-Br bonds in its structure and was used not only as a novel reactive polymer but also as a polymeric Lewis acid.