Sulfuryl fluoride
Sulfuryl fluoride (also spelled sulphuryl fluoride) is an inorganic compound with the formula SO2F2. It is an easily condensed gas and has properties more similar to sulfur hexafluoride than sulfuryl chloride, being resistant to hydrolysis even up to 150 °C. It is neurotoxic and a potent greenhouse gas, but is widely used as a fumigant insecticide to control termites. The molecule is tetrahedral with C2v symmetry. The S-O distance is 140.5 pm, S-F is 153.0 pm. As predicted by VSEPR, the O-S-O angle is more open than the F-S-F angle, 124° and 97°, respectively. One synthesis begins with the preparation of potassium fluorosulfite: SO2 + KF → KSO2F This salt is then chlorinated to give sulfuryl chloride fluoride: KSO2F + Cl2 → SO2ClF + KCl Further heating at 180 °C of potassium fluorosulfite with the sulfuryl chloride fluoride gives the desired product: SO2ClF + KSO2F → SO2F2 + KCl + SO2 Heating metal fluorosulfonate salts also gives this molecule: Ba(OSO2F)2 → BaSO4 + SO2F2 It can be prepared by direct reaction of fluorine with sulfur dioxide: SO2 + F2 → SO2F2 On a laboratory scale, sulfuryl fluoride has been conveniently prepared from 1,1'-sulfonyldiimidazole, in the presence of potassium fluoride and acid. Sulfuryl fluoride is unreactive toward molten sodium metal. Similarly it is slow to hydrolyze, but eventually converts to sulfur trioxide. Sulfuryl fluoride gas is a precursor to fluorosulfates and sulfamoyl fluorides: SO2F2 + ROH + base → ROSO2F + Hbase+F− Originally developed by the Dow Chemical Company, sulfuryl fluoride is in widespread use as a structural fumigant insecticide to control drywood termites, particularly in warm-weather portions of the southwestern and southeastern United States and in Hawaii. Less commonly, it can also be used to control rodents, powderpost beetles, deathwatch beetles, bark beetles, and bedbugs. Its use has increased as a replacement for methyl bromide, which was phased out because of harm to the ozone layer. It is an alternative to the use of phosphine, which is acutely toxic.
