Hydrogen fluoride
Sulfur tetrafluoride is a colorless gas at room temperature, although it boils at -38 °C. It is rapidly hydrolyzed in aqueous media and is corrosive and toxic; thus, reactions should be carried out in a well-ventilated fume hood with gloves and goggles. Sulfur tetrafluoride does not react with stainless steel, copper, or nickel. Ordinarily, fluorination reactions with SF4 are carried out in a stainless steel shaker apparatus. Gaseous reagents are introduced into the shaker by condensation and gaseous products are usually vented when the reaction is complete (unless the gaseous products are of interest, in which case they can be condensed into a separate vessel). Hydrogen fluoride can be separated from the desired products via pouring the reaction mixture into water followed by filtration. Solutions of calcium hydroxide can also be used in this context yielding harmless calcium fluoride.