High-pressure fluorination

Polytetrafluoroethylene and fluorinated ethylene-propylene are the only resins composed wholly of fluorine and carbon. The polymer consists of fluorine atoms surrounding the carbon chain as a sheath, giving a chemically inert and relatively dense product from the strong carbon-fluorine bonds. Polytetrafluoroethylene must be molded at high pressure. Fluorinated ethylene-propylene c.m be injection molded and extruded as thin fdm. Both plastics have exceptional heat resistance... 

To decrease the risk of kilogram quantities of high-pressure fluorine on site of companies engaging in surface fluorination, on-site fluorine generation would be a very attractive alternative. This will decrease the amount of fluorine present on site at any given moment to a few kilograms with a maximum pressure of about 100 kPa. 

Fig. 10.21. Safety enclosure for a high-pressure fluorine tank.

Solid ternary fluorides prepared by high temperature, high-pressure fluorination of mixed salts have been known for a long time. Examples, relevant to the discussion... 

Caution. High-pressure fluorine reactions should be carried out only behind barricades or in a high-pressure bay using appropriately pressure-temperature-rated nickel or Monel reactors that have been well passivated with several atmospheres of Fj at the described reaction temperature. Stainless steel reactors should be avoided owing to the potential of metal fires. All [NFJ salts are moisture-sensitive and must be handled in a dry atmosphere. They are strong oxidizers—contact with organic materials and fuels must be avoided. 

Caution. Safety barricades must be used for carrying out high-pressure fluorination reactions. The CIF -CIF by-products are strong oxidizers. Contact with fuel, water, or reducing agents must be avoided. 

To decrease the risk of kilogram quantities of high-pressure fluorine on... 

Mixtures of 10 and 20% fluorine ia nitrogen or other inert gases are commercially available ia cylinders and tube trailers from Air Products and Chemicals, Inc. Blends can be safely packaged and stored at high, eg, 13.8 MPa (2000 psi), pressure. Filled with a 20% fluorine blend, tube trailers can contain up to 500 kg of fluorine. Such high pressure mixtures permit larger quantities of fluorine to be safely shipped. 

There is uncertainty about the heptafluoride, claimed to be formed as a yellow solid from fluorination under very high pressure... 

Complete dissolution of plutonium residues, especially high temperature calcined plutonium dioxide contained in residues such as incinerator ash, continues to cause problems, despite continued research since the Manhattan Project (9). Methods to improve the Rocky Flats system include the use of additives (e.g., cerium) and electrochemistry, other solvents (HCl-SnCl2) as well as high-temperature fusion methods (10). High pressure dissolution, HF preleaching, fluorination, and other methods are being investigated. 

As examples of micro-channel process intensification and the respective equipment, in particular gas/liquid micro reactors and their application to toluene and various other fluorinations and also to carbon dioxide absorption can be mentioned [5]. Generally, reactions may be amenable to process intensification, when performed via high-temperature, high-pressure, and high-concentration routes and also when using aggressive reactants [5]. 

The use of plant extracts for insect control dates into antiquity the use of Paris green as an insecticide for control of the Colorado potato beetle in 1867 probably marks the beginning of the modern era of chemical control of injurious insects. The development of lead arsenate followed later in the nineteenth century for gypsy moth control. The commercial production of nicotine insecticides, the production of calcium arsenate at the time of the first world war, and the use of fluorine, arsenical, and cyanide compounds, as well as other inorganic chemicals for insect control, were important steps in pest control. These chemicals were applied largely by dilute high pressure sprays or dusts. 

Stewart, J. W., Proc. 7th Int. Conf. Low Temp. Phys. (Toronto), 1960, 671 Dining the study of phase transitions of solidified gases at high pressures, solid fluorine reacted explosively with apparatus made from stainless steel. 

---