Reactions with samarium diiodide in polymer synthesis

Reactions induced by Sml₂, such as reduction, coupling and cyclization are occurring in high yield upon mild conditions. It is due to the high redox potential of divalent samarium. Now reactions with Sml₂ are used in the polymer synthesis as well. By the coupling reaction of various diacid chlorides poly-α-diketones having molecular weight up to 20000 have been obtained at room temperature in quantitative yield. Isomeric difluorobenzils prepared by the one-step reaction of Sml₂ and relevant fluorobenzoyl chlorides have been used in the nucleophylic substitution reaction with bisphenols. Film-forming high molecular weight copolyetherketone-α-diketones have been synthesized when such difluorobenzils have been used as the comonomers in the polycondensation of 4,4'-difluorobenzophenone and bisphenols. All these polymers bearing α-diketogroups have been transformed into linear and network polyquinoxalines by their reaction with aromatic (bis)o-diamines. Aromatic polypinacols have been synthesized by the reaction of dialdehydes and Sml₂ in THF under mild conditions. The availability of the reactive α-hydroxy groups made it possible to carry out polymer chain reactions. It was stated that the imide cycle is reduced by Sml₂ at room temperature. The treatment of polyimides by Sml₂ leads to the change of polymer properties, mainly heat resistance and solubility. The possibility of formation of Si-Si bonds by reductive coupling of organochlorosilanes with the use of Sml₂ instead of Na has been shown. It was found that the reaction of diorganodichlorosilanes with Sml₂ easily proceeds in THF solution at room temperature to yield α,ω-dichloro-oligosilanes.