Lithium Acetylide

Abstract

[1111-64-4] C2HLi (MW 31.97) InChI = 1S/C2H.Li/c1-2;/h1H; InChIKey = AGUDKYVAXRDJLV-UHFFFAOYSA-N (ethylenediamine complex) [6867-30-7] C4H9LiN2 (MW 92.09) InChI = 1S/C2H8N2.C2H.Li/c3-1-2-4;1-2;/h1-4H2;1H; InChIKey = QJQWXTYPTBEPGS-UHFFFAOYSA-N (reagent for addition of acetylene to ketones,1 opening of epoxides,2 and ethynylation of alkyl halides3) Solubility: sol THF; LiCCH·EDA sol alkyl amines, slightly sol THF. Form Supplied in: lithium acetylide·EDA is supplied as a powder. Preparative Method: monolithium lithium acetylide is prepared by treating a THF solution of Acetylene with n‐Butyllithium at 78 °C (eq 1).1 (1) It is critical to keep the temperature at −78 °C. The concentration should be 0.5 M or less. At higher concentrations and temperatures, a white precipitate forms (presumably Dilithium Acetylide) and yields of addition product fall appreciably. Properly formed, lithium acetylide in THF should be a clear, colorless solution. Handling, Storage, and Precautions: lithium acetylide/THF solution must be used immediately after preparation. It decomposes above −78 °C. A saturated solution of THF/acetylene should not be used during the preparation of lithium acetylide since this may lead to an acetylene atmosphere above the THF. n-Butyllithium dropping through the acetylene atmosphere may react violently. Lithium acetylide is air and moisture sensitive.