Syntheses and applications of functionalized hydrocarbon oligomers and polymers

Abstract

Both cross-linked polystyrene and linear ethylene oligomers were investigated as supports for reagents and catalysts. Use of either of these polymers as supports, reagents or catalysts had certain advantages. Selection of the best polymer support was shown to partly depend on the temperature at which the reaction was to be run. Because the ethylene oligomers dissolve at higher temperatures, they were most useful in reactions conducted at 100°C. At lower temperatures the cross-linked polymer was the preferred support. A polymeric analog of diphenylmethane, 9, was prepared and used as a regenerable base in the formation of stabilized carbanions. Different alkali-metal counterions were used in deprotonations of fluorene to see how the reactivity of the polymeric base was affected. The polymeric base's activity decreased in the order Cs+ > Rb+ > K+ > Na+ > Li+. These polymeric bases were not useful in enolate reactions. Linear ethylene oligomers which were soluble at elevated temperature were prepared and used to support reagents and catalysts. Reactions using polyethylenedi-phenylphosphine, 22, and oligomer-bound phase transfer catalysts 34, 35, and 26 were all homogeneous and comparisons of reactivity for different sized substrates showed that the diffusion effects noted for microporous cross- linked polystyrene-bound reagents or catalysts were absent. Because the supported species were insoluble in the reaction solvent at room temperature (ca. 25°C), the spent reagent or catalyst could be conveniently recovered by simple filtration.