Explosion during phosphine prep

We have a safety alert in this week’s issue of C&EN, regarding an explosion that happened at the University of Wisconsin, Madison, during distillation 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

Author: Jyllian Kemsley

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