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Electrochemical fluorination (ECF), or electrofluorination, is a foundational organofluorine chemistry method for the preparation of fluorocarbon-based organofluorine compounds. [1] The general approach represents an application of electrosynthesis .
As fluorine is itself manufactured by the electrolysis of hydrogen fluoride, ECF is a rather more direct route to fluorocarbons. The process proceeds at low voltage (5 – 6 V) so that free fluorine is not liberated. The choice of substrate is restricted as ideally it should be soluble in hydrogen fluoride.
Hydrogen fluoride is typically produced by the reaction between sulfuric acid and pure grades of the mineral fluorite: [14] CaF 2 + H 2 SO 4 → 2 HF + CaSO 4 About 20% of manufactured HF is a byproduct of fertilizer production, which generates hexafluorosilicic acid .
Hydrogen bonding amongst HF molecules gives rise to high viscosity in the liquid phase and lower than expected pressure in the gas phase. Hydrogen fluoride does not boil until 20 °C in contrast to the heavier hydrogen halides which boil between −85 °C and −35 °C (−120 °F and –30 °F).
ECF is an electrolysis method whereby the precursor of octanesulfonyl fluoride is electrolyzed in a solution of hydrogen fluoride to give perfluorooctanesulfonyl fluoride. This production method also results in shorter chain perfluoroalkyl substances being formed.
Fluoroantimonic acid is a mixture of hydrogen fluoride and antimony pentafluoride, containing various cations and anions (the simplest being H 2 F + and SbF − 6).This mixture is a superacid stronger than pure sulfuric acid, by many orders of magnitude, according to its Hammett acidity function.
Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water.Solutions of HF are colorless, acidic and highly corrosive.A common concentration is 49% (48–52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling point near room temperature.
The rate constant K 1 (in units: ml/min/ml) describes the unidirectional clearance of fluoride from plasma to the whole of the bone tissue, k 2 (in units: min −1) describes the reverse transport of fluoride from the ECF compartment to plasma, k 3 and k 4 (in units min −1) describe the forward and backward transportation of fluoride from the ...