Lithium Selenide


[12136-60-6]  · Li2Se  · Lithium Selenide  · (MW 92.84)

(nucleophilic agent for synthesis of organic selenides1,2)

Physical Data: d 2.91 g cm-3; red-brown solid or milky white crystalline suspension in THF.

Solubility: sol water; sparingly sol THF.

Preparative Methods: reduction of Selenium with Lithium in liquid ammonia produces red-brown Li2Se after NH3 evaporation.3 Reaction of Se with 2 equiv Lithium Triethylborohydride in THF gives a suspension of Li2Se. The method is somewhat limited by scale and produces flammable byproducts.1 For large-scale preparations, reduction of Se with Li in THF in the presence of naphthalene as a catalyst is safe and more economical.2

Handling, Storage, and Precautions: should be used directly as prepared. Use in a fume hood.

The reaction of Li2Se with alkyl halides gives dialkyl selenides in high yields. It is less reactive than K2Se or Sodium Selenide.1,2 Benzyl, 4-chlorobenzyl, 2-phenylethyl, and pentyl bromides give selenides in yields of above 54% (eq 1), but no selenide is obtained when 2-octyl bromide is used as a substrate.1,2 Bis(trialkylsilyl) selenides are obtained when trialkylchlorosilanes are treated with Li2Se (eq 2).4,5

Related Reagents.

Hydrogen Selenide; Sodium Hydrogen Selenide; Sodium Selenide.

1. Gladysz, J. A.; Hornby, J. L.; Garbe, J. E. JOC 1978, 43, 1204.
2. Thompson, D. P.; Boudjouk, P. JOC 1988, 53, 2109.
3. Zintl, E.; Harder, A.; Dauth, B. Z. Elektrochem. 1934, 40, 588.
4. Detty, M. R.; Seidler, M. D. JOC 1982, 47, 1354.
5. Syper, L.; Mlochowski, J. T 1988, 44, 6119.

Jacek Mlochowski & Ludwik Syper

Technical University of Wroclaw, Poland

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.