Biomedical subjects
Publications and source records attributed to Stewart P Lewis.
Lewis acidic, chelating diborane 1 forms stable oxonium acids 2 in the presence of excess MeOH or water. Diborane 1 is shown to be an effective co-initiator for the suspension polymerization of isobutene in aqueous media at sufficiently low temperatures. Poly(isobutene) or butyl rubber is obtained at moderate to high conversion and with Mw < 200 K and PDI approximately 2 under these conditions.
Lewis acidic diborane 1 (J. Am. Chem. Soc. 1999, 121, 3244-3245) is highly effective for both proton- and cationogen-initiated isobutene polymerization in hydrocarbon media at low temperature. Reactions of diborane 1 with cumyl chloride and cumyl methyl ether were studied by variable-temperature 1H and 19F NMR spectroscopy. At low temperatures stable ion pairs 2a and 2b are formed; at higher temperatures these ion-pairs form phenyl-1,3,3-trimethylindan (3) with concomitant release of HCl to form 1 in the case of 2a or degradation of the anion (2b). Reaction between Ph3C-Cl and diborane 1 resulted in the generation of an ion-pair 4 consisting of the Ph3C cation very weakly associated with the chelated, mu-Cl counteranion as revealed by X-ray crystallography.