ВИНИЛЛИТИЙ

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Vinyl lithium is a reactive intermediate for the formation of vinyl alcohols from aldehydes, vinyl ketones from organic acids, vinyl sulfides from disulfides, and monosubstituted alkenes from organic halides.

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Vinyllithium is prepared by a variety of methods. Direct metalation of Ethylene with Lithium metal in dimethoxymethane yields vinyllithium contaminated with lithium hydride, and other organolithio species, such as butyllithium and 1,4-dilithiobutane. Direct formation from ethylene can also be accomplished using Potassium t-Butoxide, n-Butyllithium, and TMEDA (N,N,N′,N′-Tetramethylethylenediamine) in hexane at -40 °C, followed by treatment of the vinylpotassium with Lithium Bromide. The lithium-halogen exchange reaction has been used, starting from vinyl chloride and lithium/sodium dispersions, or from vinyl bromide with 2 equiv of t-Butyllithium in either a Trapp solvent mixture at - 120 °C or ether at -78 °C. This is the most convenient procedure, but lithium halide is formed during the reaction and is present as a contaminant. Halide-free vinyllithium can be prepared by transmetalation of Tetravinylstannane with phenyl- or butyllithium, of tetravinyllead with either lithium metal or Phenyllithium, or of divinylmercury with lithium dispersion in pentane.