Sulphur hexafluoride, effect

Kraut A, Lilis R Pulmonary effects of acute exposure to degradation products of sulphur hexafluoride during electrical cable repair work. BrJ Ind Med 47 829-832, 1990... 

Sulphur Hexafluoride, SF6.—Sulphur hexafluoride, the first hexahalide to be discovered, is prepared by submitting sulphur to the action of fluorine in a copper tube. The issuing gas on condensation in a spiral tube of the same metal at —80° C. becomes partly solidified by allowing the solid to vaporise gradually and passing the vapours through potassium hydroxide solution and solid potassium hydroxide successively, the substance is rendered purer, complete purification being effected subsequently by re-solidification followed by fractional evaporation.4... 

Buckingham AD, Dunmur DA (1968) Kerr effect in inert gases and sulphur hexafluoride. Trans Faraday Soc 64 1776-1783... 

There is no known mechanism that can account for these effects. Water structure has to be implicated. But there is clearly a remarkable correlation between the ions present in a salt and their effect on the coalescence phenomenon. A property a or P can be assigned to each anion or cation. The combination aa or PP results in inhibition of bubble coalescence at a critical salt concentration, whereas the combinations aP or Pa produces no effect at all. Different gases of widely different molecular size, from helium to sulphur hexafluoride, affect the transition concentration a little, but do not change the phenomenon. 

It is apparent that substitution of fluorine for hydrogen initially causes a reduction in reactivity towards the electrophilic oxy n atom, but tetra-fluoroethylene is anomalous. A further study has indicated that substitution by trifluoromethyl has a strong deactivating effect compared with methyl, which has an activating effect. A study of the reactions of nearly thermal i F atoms, produced by F(n,2n) F and moderated by collisions with an excess of sulphur hexafluoride, with fluoro-oleflns (modes of addition were identified by scavenging the radicals produced with hydrogen iodide) has indicated that F atoms react preferentially with less-fluorinated olefins, and at the less-fluorinated end of a particular olefin. ... 

The safety of ultrasound contrast agents must be considered under two categories, the agents themselves and the effects of their interaction with the ultrasound beam (ter Haar 1999). The constituents of microbubble contrast agents have been carefully chosen to be inert with biocompatible membranes and gases that are either metabohsed (oxygen in air-filled microbubbles) or breathed out (nitrogen, perfluoro-carbons and sulphur hexafluoride) and are non-toxic. No toxic effects have been attributed to their compo-... 

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