Azide explosions discussed further
Norton P. Peet; Philip M. Weintraub
Chemical & Engineering News (14 Mar 1994) Vol. 72, No. 11, pp. 4.
Peter G. Urben pointed out that "eschewing halogenated solvents will not eliminate azide explosions" (C&EN, Dec. 13, 1993, page 4). And if we stop reading his letter at this point, he is correct; however, the remainder of the statement and the letter are either incorrect or inappropriate to the facts we described (C&EN, April 19, 1993, page 4).
We cannot speak to the specifics of the explosion described by Victor J. Hruby, Lakmal Boteju, and Guigen Li (C&EN, Oct. 11, 1993, page 2), but in our case, we used a catalytic amount of sulfuric acid and a large excess of sodium azide. The reaction was poured into water and extracted with methylene chloride. After drying and filtering the organic layer, we concentrated it on a rotary evaporator.
The explosion took place after all the solvent had been removed and the flask was being detached from the steam tube. The detonation occurred in the flask; the evaporator was destroyed by the conclusive force of the explosion. We again point to the articles by A. Hassner et al. [Angew. Chem. Int. Ed. Engl., 25, 479 (1986), and J. Org. Chem., 55, 2304 (1990)] describing the synthesis and explosive potential of polyazidomethanes.
We believe strongly that diazidomethane and not hydrogen azide was
the culprit in our explosion and that Urben should not attempt to
change our conclusion. Our intent is to warn our colleagues of the
dangers of producing this explosive chemical. We reiterate that
because of this incident we no longer permit any chemical reactions
with azide to be performed in the presence of a halogenated solvent
in our laboratories.
page last revised December 7, 1998