Letter to the editor (the author replies) - Journal of Chemical Education

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LETTERS

XeOa Hazard! Nickel con wall 11 /32 in.) ruptured by explosion of less than 2 0 0 mg XeOl.

To WLe Editor: I am sure many readers will note with interest the article by J. H. Holloway on the photochemical preparation of XeF2 in the April issue of THIS JOURNAL, 43, 202 (1966). The purpose of this letter is to call readers' attention to the very real hazard that is potentially present whenever xenon and fluorine are mixed. If experimental conditions are altered, it is conceivable that XeF, will be produced. It i s therefore preferoable that an excess of xenon be used. The hazard is greatest with regard to the eventual disposal of products. While XeFz itself is relatively harmless, XeF4, if formed, could upon exposure to atmospheric moisture be hydrolyzed and disproportionate to give the extremely explosive Xe03. TWOexperienced scientists have received eye injuries as a result of such explosions. Obviously, this is not a field for the uninitiated working under less than ideal conditions. The accompanying photograph is emphatic testimony. The following should always be considered by anyone att,empting such syntheses: 1. Fluorine is the most reactive element and should be treated with respect. I t can be bought in cylinders, and the cylinders should be mounted behind a barricade in a well-ventilated hood. The commercial suppliers of fluorine have available data sheets describing in detail the precautions to be taken. I t is advisable to obtain one of these sheets and ascertain whether or not it is feasible to handle fluorine in the place where one proposes to work with it. 2. All xenon compounds must be treated as potential sources of xenon trioxide, as this is readily made by

hydrolysis of the fluorides. (Note: Although xenon difluoride does not form Xe03 on hydrolysis, the difluoride is usually contaminated with tetrafluoride which does form some trioxide on hydrolysis.) 3. Wear safety glasses (preferably supplemented by a face shield) at all times. 4. Use leather gloves with cuffs covering the wrists whenever handling XeOa in equipment subject to fragmentation (e.g., glass). This precaution should also be taken when adding aqueous solutions to xenon fluoridesor oxyfluorides. 5 . Label all containers with the nature of the contents, and designate the possibility of an explosion hazard wherever XeOa or a possible precursor is being stored. 6. Anyone planning to work in this field should consult the chapter "Safety Precautions in Handling Noble Gas Compounds" in the book "Noble Gas Compounds," H. H. HYMAN,Ed., University of Chicago Press, Chicago, 1963. I hope this warning will be brought to the attention of anyone planning to nndert,ake experiments with xenon compounds.

T o the Editor: I endorse all t,hat Dr. Chernick says about pr+ cautions when handling noble gas compounds. I trust too that readers would consult the review articles cited (e.g., Chem. Rev., 65, 199 (1965) states "XeOa is a powerful explosive"). experiment,^ with xenon and excess fluorine have yielded only trace amounts of XeF4; under these conditions, the chances of an explosion arising from the inadvertent production of XeOa are minimal. Nevertheless, as my paper pointed out, fluorine chemistry itself is hazardous. The assumption was that only laboratories where fluorine is already available (and which, therefore, have experience with the element,al gas) would he in a position to consider the synthesis described in the article. I, too, hope that t,his warning will be brought to readers' attention.

Volume 43, Number 1 1 , November 1966

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