Polymer‐supported phosphines: Reactivity of pendant and crosslink groups

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Abstract
Two groups of phosphine‐containing resins were prepared by bead copolymerization. In one the phosphine residues were introduced as pendant groups with p‐styryldiphenylphosphine, whereas in the other the phosphine residues were located specifically at crosslinked points with bis(p‐styryl)phenylphosphine. Both groups of resins were used to convert alcohols to alkyl chlorides in the presence of carbon tetrachloride and benzaldyhyde to benzal chloride and β,β‐dichlorostyrene. In the first reaction an increase in the crosslink ratio of the support reduced the reactivity of the resins, although both octanol and octadecanol substrates behaved similarly. No clear difference emerged between resins with pendant phosphine groups and those located on crosslinks and the absence of a strong substrate size effect or substrate selectivity with both series of resins was apparent. The production of benzal chloride and β,β‐dichlorostyrene requires interaction of two phosphine residues to generate the reactive intermediate, and inhibition of phosphine–phosphine interactions in these highly crosslinked networks does indeed inhibit this reaction. Again both series of resins behaved similarly. Among the possible routes by which PPh3/CCl4 converts alcohols to chlorides one involving phosphine‐phosphine interactions must also be inhibited in these supported systems.

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