Carborane polymers

Figure 2 Schematic representations of the Olin polymers 2 (with —P—O—P— linkages), 3 and 4 (DEXSIL carborane polymers), and 5 (carborane polymers with tin bridges). (Adapted from ref. 7.)...

W. A. Fort, Carborane Polymers Weapons Chemistry Branch, Memo. No. 645, AWE, Aldermaston, UK (1979). 

The rapid development of carborane chemistry is mainly due to their practical applications. For instance, the potential utility of carborane polymers as gaskets, O-rings, and electrical connector inserts has been reported. Their functionality for solvent extraction of radionuchdes as well as the potential medicinal value of the isoelectronic and isostructural boron analogues of biologically important molecules has been the subject of many review articles. For example, a number of boron compounds have been found to possess anti-inflammatory and antiarthritic activity in animal model studies. Boron compounds have also been implicated in studies designed to probe the importance of the so-called anionic subsite of acetylcholine esterase and Ach receptors. But, by far the most interesting practical apphcations of carboranes are in areas of boron neutron capture therapy (BNCT) and supramolecular assembly. 

Incorporation of carborane moieties into silicone chains also leads to improved thermal properties of such semiorganic polymers. The stationary phases based on carborane polymers have been available commercially since the early 1970 s, when the first analytical results were also reported [86] for some biological compounds. Although such phases were believed to be stable up to about 400°C, only moderately successful separations have been reported. While the carborane cages can be differently incorporated into siloxane polymers to influence their consistency, functional groups (phenyl, cyanoethyl, etc.) may also be varied to influence selectivity. 

Metallorganic carborane polymers are synthesized by reaction of group-IV organo-metallic dihalides with dialkali-metal derivatives of meta- and para-carboranes . ... 

Grimes RN. (1970) Carborane polymers. In Carboranes. Academic Press, New York, p 181. 

R represents an organic side group. The polymers have found some use in hose, gaskets, and seals in aviation-fuel-handling equipment. They have better solvent resistance and low-temperature elasticity than sUoxane-carborane polymers, and are less costly. 

General Procedure for the Pd-Catalyzed Deprotection of the Benzylidene Protecting Group. To a round-bottom flask charged with the first generation protected carborane polymer, [G-l]-(Bn), was added a 1 1 mixture of CH2Cl2 methanol (total of 20 mL). Subsequently, Pd(OH)2/C (20%) was added and the flask was evacuated and back-filled with H2 three times (H2 pressure 1... 

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