Lithium acetylide-ethylenediamine (1:1)

Lithium Acetylide Ethylenediamine Complex is a slightly yellow to light brown crystals, Lithium acetylide is an unstable solid which disproportionates to form lithium carbide (dilithium acetylide) and acetylene. It is soluble in liquid ammonia at its boiling point to the extent of just over one mole per liter. It is not sensitive to shock and presents a hazard due only to possible caustic burns and the hazards presented by ammonia and acetylene, which form when the material contacts the air.

용도Lithium acetylide ethylenediamine complex is used in the synthesis of a chiral cyclopropanol. It is also used as an alkynylating reagent for the enantioselective alkynylation of ketones catalyzed by lithium binaphtholate without using other metal sources.

생산 방법Lithium acetylide is produced both in the laboratory and industrially by dissolving lithium metal in refluxing liquid ammonia and then bubbling acetylene into the solution. The solution of monolithium acetylide thus formed is stabilized by the complexing of the lithium ion with ammonia forming a polar acetylenic anion which does not react further with lithium metal. However, if the reaction is carried out in tetrahydrofuran, for example, the lithium acetylide reacts further with lithium to form dilithium acetylide (lithium carbide). In fact, if the ammonia is removed from a solution of lithium acetylide, it disproportionates to dilithium acetylide and acetylene.

The ethylenediamine complex of lithium acetylide is produced by allowing lithium metal to react with ethylenediamine in benzene at reflux to form AMithioethylenediamine: H2NCH2CH2NH2+Li -> L1HNCH2CH2NH2+05H2.