Fluorophosphoric acids

Phosphoms oxyfluoride is a colorless gas which is susceptible to hydrolysis. It can be formed by the reaction of PF with water, and it can undergo further hydrolysis to form a mixture of fluorophosphoric acids. It reacts with HF to form PF. It can be prepared by fluorination of phosphoms oxytrichloride using HF, AsF, or SbF. It can also be prepared by the reaction of calcium phosphate and ammonium fluoride (40), by the oxidization of PF with NO2CI (41) and NOCl (42) in the presence of ozone (43) by the thermal decomposition of strontium fluorophosphate hydrate (44) by thermal decomposition of CaPO F 2H20 (45) and reaction of SiF and P2O5 (46). 

The three primary fluorophosphoric acids, monofluorophosphoric acid [13537-32-17, H2O2PF (1), difluorophosphoric acid [13779-41 HO2PF2 (2), and... 

All three fluorophosphoric acids are commercially available. The mono- and difluoro acids can be made as anhydrous or hydrated Hquids. Commercial hexafluorophosphoric acid is an aqueous solution. Anhydrous hexafluorophosphoric acid maybe prepared at reduced temperatures and pressures but it dissociates rapidly into PF and HF at 25°C (56). When diluted with water all the fluorophosphoric acids hydrolyze producing orthophosphoric acid. The hexafluoro acid is the most stable of the three fluorophosphoric acids. 

Experimentation with test animals and laboratory and plant experience indicate that the fluorophosphoric acids are less toxic and dangerous than hydrogen fluoride (58). However, they contain, or can hydrolyze to, hydrofluoric acid and must be treated with the same care as hydrofluoric acid. Rubber gloves and face shields are essential for all work with these acids, and full mbber dress is necessary for handling larger quantities. The fumes from these acids contain HF. 

Hexafluorophosphoric Acid. Hexafluorophosphoric acid (3) is present under ambient conditions only as an aqueous solution because the anhydrous acid dissociates rapidly to HF and PF at 25°C (56). The commercially available HPF is approximately 60% HPF based on PF analysis with HF, HPO2F2, HPO F, and H PO ia equiUbrium equivalent to about 11% additional HPF. The acid is a colorless Hquid which fumes considerably owiag to formation of an HF aerosol. Frequently, the commercially available acid has a dark honey color which is thought to be reduced phosphate species. This color can be removed by oxidation with a small amount of nitric acid. When the hexafluorophosphoric acid is diluted, it slowly hydrolyzes to the other fluorophosphoric acids and finally phosphoric acid. In concentrated solutions, the hexafluorophosphoric acid estabUshes equiUbrium with its hydrolysis products ia relatively low concentration. Hexafluorophosphoric acid hexahydrate [40209-76-5] 6 P 31.5°C, also forms (66). This... 

Ammonium hexafluorophosphate [16941-11-0] M 163.0, d 2.181, pK j 0.5, pKj 5.12 (for fluorophosphoric acid H2PO3F). Crystallises from H2O in square plates. Decomposes on heating before melting. Soluble in H2O at 20° (74.8% w/v), also very soluble in Mc2CO, MeOH, EtOH and MeOAc and is decomposed by boiling acids. [Chem Ber 63 1063 1930.]... 

Potassium hexafluorophosphate [ 17084-13-8 j M 184.1, pK 0.5, pK j 5.12 (for fluorophosphoric acid H2PO3F). Crystd from alkaline aqueous solution, using polyethylene vessels, or from 95% EtOH, and dried in a vacuum desiccator over KOH. 

Resistance to corrosion of electroless nickel, both as-deposited and, in most cases, after heating to 750°C, is listed by Metzger for about 80 chemicals and other products. Resistance was generally satisfactory, with attack at a rate below 13 /im/year. The only substances causing faster attack were acetic acid, ammonium hydroxide or phosphate, aerated ammonium sulphate, benzyl chloride, boric acid, fluorophosphoric acid, hydrochloric acid, aerated lactic acid, aerated lemon juice, sodium cyanide and sulphuric acid. 

These salts can be made easily since tetrafluoroboric acid (HBF4) and hexa-fluorophosphoric acid (HPF6) are commercially available. However, the main advantage of the diazonium salts with the anions of these acids is their stability, which is significantly higher than that of probably all other diazonium salts. 4-Nitrobenzenediazonium tetrafluoroborate is nowadays even a commercial product. Preparative diazotization methods with these two acids can be found in Organic Syntheses (tetrafluoroborate Starkey, 1943 hexafluorophosphate Rutherford and Redmont, 1973). 

In addition to the preceding fluoride transport tests, laboratory-scale tests were conducted to investigate the possibility of containing or removing fluoride from the system to allow more economical materials of construction to be used in the design of the full-scale plant (AEA, 20011). A series of nine tests was to be conducted to obtain kinetic data on the use of calcium as an agent for fluoride removal from the GB simulant, fluorophosphoric acid. Data were to be obtained for the hydrolysis reaction under acidic, neutral, and alkaline conditions. 

Isoflurophate Isoflurophate, the di-wo-propyl ester of fluorophosphoric acid (13.2.21), is made by reacting Mo-propyl alcohol with phosphorous trichloride, forming di-wo-propy-Iphosphite (13.2.19), which is chlorinated to (13.2.20), and further reacted with sodium fluoride to replace the chlorine atom with fluorine, thus giving isofluorophate (13.2.21) [50]. 

Fluoro-2-nitrophenol, 2160 Fluoronium perchlorate, 3966 4-Fluorophenyllithium, 2159 Fluorophosphoric acid, 4291... 

SYNS FLUOROPHOSPHORIC ACID, anhydrous MONOFLUOROPHOSPHORIC ACID, anhydrous... 

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