Sodium hexafluorophosphate CAS# 21324-39-0

The reaction is to be carried out in a fume hood. The reaction is carried out in stainless steel, nickel, or copper or nickel alloy vessel, 3 in (1 in = 0.0254 m) in diameter and 7 in high. half the required amount of sodium chloride is placed in the vessel and the lid is secured. The vessel was cooled in an ice salt bath and connected to the anhydrous hydrogen fluoride tank. Open the valve and put about 400mL of HF liquid into the container, the height of the liquid in the stainless steel container is about 3/4in, insert a thin wooden strip into the middle of the pipe, the part immersed in the liquid will be blackened, so the height of the liquid can be measured roughly. To ensure that all of the sodium chlorides are dissolved, remove the lid and stir with a stainless steel spoon with a handle, 150 g (about 0.75 mol) of PCl5 is slowly added to the solution through the spoon (placing it against the wall of the container). Sodium hexafluorophosphate immediately precipitated, stirring from time to time to make the reaction complete. Since the reaction is quite violent, measures should be taken to prevent splashing of liquid hydrogen fluoride, and the operator must wear thick rubber gloves, preferably operating behind a protective shield. After all, PCl5 is added, remove the lid and put the vessel into an oil bath. Allow the remaining hydrogen fluoride to evaporate off. Pass dry nitrogen into the vessel while heating to about 150°C to remove traces of hydrogen fluoride.

The crude product yield is almost the theoretical calculated amount and the purity is over 95%, the impurities are mainly traced to iron salts and sometimes small amounts of unreacted fluoride. The crude product was dissolved in methanol (60 g of product in 100 mL of solvent). An appropriate amount of 5% NaOH methanol solution was added to keep the solution alkaline, tested with phenolphthalein, and the insoluble impurities were removed by centrifugation. The solvent was removed by concentration and crystallized under reduced pressure to obtain monohydrate, which was put into a desiccator containing concentrated sulfuric acid and dried to obtain the anhydrous salt. 0.5 mol of sodium chloride was reacted to obtain the purified product of 73 g, yielding 87%.

The purification method weighing about 80 g of crude product was dissolved in 160 mL of methanol. A few drops of water and excess ammonia were added to precipitate out the iron impurities, and the solution was filtered and evaporated to dryness in a vacuum desiccator, and the product was dried and dehydrated over H2SO4 to give a product of about 70 g with a yield of about 86%. This product may contain ammonium fluoride, which can be removed by recrystallization in water. Because of the high solubility of fluorophosphate, much is lost. The salt is dissolved in water (50 g/mL), the filtered solution is placed in a platinum dish and heated on a steam bath to evaporate until crystals appear in the hot solution, the mixture is cooled in a water bath, the crystals are filtered through a sintered glass filter, washed with a few milliliters of ice water, filtered under reduced pressure to dryness, and dried in a desiccator with concentrated H2SO4. It is used to make other hexafluorophosphates.