Anhydrous Metal Fluorides

Gadolinium is found in several other minerals, including monazite and bastnasite, both of which are commercially important. With the development of ion-exchange and solvent extraction techniques, the availability and prices of gadolinium and the other rare-earth metals have greatly improved. The metal can be prepared by the reduction of the anhydrous fluoride with metallic calcium. 

Ionic fully fluorinated alkoxides of the heavier alkali metals may be prepared by the reaction between the anhydrous metal fluoride and various perfluorinated carbonyl compounds in donor solvents (equations 40 and 41).137... 

FeCl4 ] can be used for a separation of AICI3 and FeCls anhydrous metal fluorides can be prepared using SCla compounds (156, 240). Detailed C1 nuclear quadrupole resonance studies have been reported for a number of trichlorosulfonium compounds that are in accordance with structural data on the interaction of the SCla groups with the anions (120,122,123,179). 

When metallic gold is exposed to elemental fluorine (F2) at room temperature in the presence of the ionizing solvent liquid anhydrous hydrogen fluoride (aHF) containing an alkali fluoride, the metal is quickly dissolved to give the alkali salt of the anion... 

There are also potentially important inorganic applications of COF. Most of the industrially important low-oxidation-state metal fluorides are prepared from the reaction of their oxides, hydroxides or carbonates with aqueous or anhydrous HF. However, preparation of fluorides of metals in high formal oxidation states is usually achieved by the use of elemental fluorine on the metal, because of the problem of hydrolysis from the reversible reaction of the oxide with HF ... 

Replacement of other halogens using hydrogen fluoride. It is clearly very desirable commercially to replace Cl by F using a method that does not require a metal fluoride. Anhydrous HF is relatively inexpensive and can be employed in a number of cases, e.g.,... 

The best method to prepare most HMFG (although not the cheapest) starts with anhydrous metallic fluorides MF, MF2, MF3 and MF4. Fluorides of high purity are available commercially, especially monovalent and divalent ones, but for applications where ultra high purity is required, including the ppb or sub-ppb range as in the case... 

---