Safety Alert: Explosion During Prep Of (C₆F₅)PH₂

While a researcher fractionally distilled the primary phosphine (C₆F₅)PH₂, which was synthesized by the reduction of (C₆F₅)PCl₂ with an excess of lithium aluminum hydride (LAH), the distillation apparatus containing the phosphine detonated. Fortunately, because the researcher was wearing appropriate personal protective equipment and working in front of a sliding blast shield, only minor injuries resulted from the explosion.

The researcher was following a literature prep for the synthesis of (C₆F₅)PH₂ (Z. Naturforschg.1966, 21b, 920), wherein (C₆F₅)PCl₂ was reduced with an excess (2.1 M equiv based on Li) of LAH. After the reaction was completed, the slurry was filtered and ether was evaporated from the filtrate, yielding an oil and some LAH. This mixture was then extracted into hexanes to remove the remaining LAH, and the resulting phosphine/hexanes mixture was fractionally distilled under N₂. After the hexanes were fractionally distilled away and the distillation apparatus was at approximately 50 °C, the apparatus detonated.

The source of the incident is being investigated. Work with this molecule and similar compounds should be conducted carefully until the exact cause of this incident is determined and reported.

By Ian Tonks
Clark Landis
Department of Chemistry
University of Wisconsin, Madison