Lithium 2,6-Difluoroanilide Decomposition Hazard

Paul A. Deck
Blacksburg, Va.

Chemical & Engineering News (28 February 2005) Vol. 83, No. 09, p. 8

The title compound, which we prepared from 2,6-difluoroaniline and n-butyllithium in diethyl ether solution, is a touch-sensitive explosion hazard. While transferring the vacuum-dried yellow solid from a glass fritte (inside a nitrogen-atmosphere glove box), a sudden, violent decomposition occurred in two stages, scattering pea-sized pieces of glass and sooty black powder throughout the glove box. Fortunately, the student conducting these operations was not injured, and no additional problems were encountered upon cleanup.

Although we are keenly aware that fluorinated aryllithium and alkyllithium compounds can be treacherously unstable, we did not find lithium fluoroanilides or lithium fluorophenoxides mentioned in Bretherick's "Handbook of Reactive Chemical Hazards" (6th Edition). Moreover, several fluorinated lithium anilide etherates have been crystallographically characterized. Nevertheless, we must concur with Peter Urben's cautionary advice [C&EN, July 8, 1996, page 3] against isolating, free of solvent, any compounds containing both C–F and highly reactive metal-nonmetal bonds.

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