|
|
| | VINYL LITHIUM Basic information |
| | VINYL LITHIUM Chemical Properties |
| Boiling point | -57.5°C | | solubility | sol THF, ether; slightly sol pentane, hexane; insol benzene. | | form | solid | | color | white |
| | VINYL LITHIUM Usage And Synthesis |
| Uses | 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. | | Definition | ChEBI: Vinyllithium is a vinyllithium compound and an alkenyllithium compound. | | Preparation | 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. | | storage | As with most alkyllithium reagents, vinyllithium reacts readily with moisture. Solid
vinyllithium should be maintained at -25 °C or below, under an inert atmosphere. The solid suffers a loss in activity with time
and should be used immediately upon preparation. Solutions of the reagent in ether or THF, under an inert atmosphere, are
stable for up to 1 week at rt. Solid vinyllithium is violently pyrophoric, yielding a brilliant red flash on contact with air. | | Purification Methods | Purification of Vinyllithium: ether solutions can be evaporated under an inert atmosphere and the resulting solid washed with anhydrous
pentane or hexane. |
| | VINYL LITHIUM Preparation Products And Raw materials |
|