Safe generation of (perfluoroethyl)lithium
Dean M. Roddick
Chemical & Engineering News (6 Oct 1997) Vol. 75, No. 40, pp. 6.
A number of years ago, we reported the use of (perfluoroethyl)lithium, generated in situ from metal-halogen exchange between C2F5Li and n-BuLi in ether at -90 C, in the synthesis of (perfluoroethyl)phosphines [Inorg. Chem., 28, 1624 (1989)]. Since then, we have found this reagent to be quite general for the alkylation of phosphorus halide compounds, but wish to report a potential hazard with this procedure.
Several times in our laboratory, we have
experienced a violent decomposition of the ethereal
C2F5Cl/n-BuLi solution after the addition of just a
few drops of (R)nPCl3=n. In each of these cases, the
metal-halogen exchange temperature was maintained below
-90 C. We believe that this problem is due to
a buildup of starting reagents at low temperatures,
and wish to caution anyone who is using our published
procedure to avoid temperatures below -90 C
for this metal-halogen exchange reaction.
page last revised December 7, 1998