Synthesis of Oligosilyphosphaalkenes for Polymerization

    Project: Research project

    Project Details


    The purpose of the project is the synthesis of new phosphaalkenes with oligosilyl groups on phosphorus as stable monomers, suitable for subsequent polymerization. The bulky silyl substituents RSi, such as Si(SiMe3)3, SiMe(SiMe3)2, SiPh(SiMe3)2, have two functions: 1) as stabilizers of the monomer (preventing the dimerization to 1,3-diphosphetaines) and 2) as leaving groups, after the polymerization in elimination-addition pathways to new polymethylenephosphines. The synthesis of the phosphaalkenes will be attempted by the reaction between oligosilyl(trimethylsilyl)lithiumphosphides and ketones. The product will be used for a 1,2-addition of MeLi across the P=C bond to get a polymer: Eventually, treating oligosilyl(trimethylsilyl)lithiumphosphide with bis(trimethylsilyl)ketone will yield the first persilylated phosphaalkene. If the size of the RSi group is not sufficient to shield the Si-P bond (but big enough to stabilize the phosphaalkene) and the R groups on carbon are not too large, the reaction of the polymer with H2O or KOtBu, for example, should proceed by the cleavage of the SiP-bond forming a functionalized polymethylenephosphines: If the size of the RSi group is big enough to shield the Si-P bond (which is probably the case for RSi = hypersilyl group Si(SiMe3)3), in agreement with the results of my Ph.D. thesis, the reaction with KOtBu proceeds via cleavage of a Si-Si bond on RSi. The atom arrangement in P-Si-K is instable and the intermediate rearranges, forming a phosphanide anion and a silylene (which can be trapped by 2,3-dimethyl-1,3-butadiene). The obtained functionalized polymers will then be substituted using, for example, ClOR' or R'NHCl and giving new polymers.
    Effective start/end date1/10/071/10/08


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