The wise chemist

Peter G. Urben
Editor, Bretherick's Handbook, Warwickshire, England

Chemical & Engineering News (8 Jul 1996) Vol. 74, No. 28, pp. 3.

One might define an explosive as a material that is kinetically stable but thermodynamically far from it. As organofluorine chemists have long known, but not always realized, the stability of the C-F bond is largely kinetic. Virtually any metal fluoride has very much stronger bonds; so much so that not only is replacing C-F and C-Met bonds by MetF of extreme thermodynamic favorability but so, too, is replacing C-F and -O-Met in many cases.

The hazard reported by Rupert Spence (C&EN, May 20, page 4) is not restricted to aluminium compounds of organofluorinated moieties. Bretherick's Handbook of Reactive Chemical Hazards has long had examples of lithiated organofluorine as well as aluminum compounds exploding. My files for the next editions also include instances of magnesium and sodium compounds, and I intend a group warning.

Wise chemists do not entrust their safety to kinetics alone. Thermodynamically unstable organofluorometallic molecules are best not isolated but kept dispersed among the molecular sandbags of solvent. There is too often a contagious way to overcome mere kinetic stability and to unleash the underlying thermodynamics.

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