Hexafluoropropylene, decomposition

Among the many methods of generating difluorocarbene, the treatment of bromodifluoromethylphosphonium bromides with potassium or cesium fluoride is particularly useful at room temperature or below [II, 12 13] The sodium iodide promoted decomposition of phenyl(trifluoromethyl)mercury is very effective at moderate temperatures [S, 14] Hexafluoropropylene oxide [/5] and chlorodifluo-roacetate salts [7] are excellent higher temperature sources of difluorocarbene... 

EEP has a considerably lower thermal stability than PTFE and starts to degrade at temperatures above 200°C (392°F). There are essentially two stages in the degradation of EEP. The first involves preferential elimination of hexafluoropropylene (HEP) from the backbone in the second the remaining backbone undergoes decomposition at the same rate as that of PTFE [7],... 

Pyrolysis of hexafluoropropylene oxide generates difluorocarbene for cyclo-propanation reactions, as does the action of heat on chlorodifluoromethane. Halogenocarbenes formed in the thermal decomposition of polyhalogenomethanes at 500—650°C can be trapped by cyclopentene and cyclohexene. The primary adducts are unstable under these conditions, suffering dehydrohalogenation to halogeno-benzenes and cycloheptadienes, respectively. ... 

It does not homopolymerize easily and hence can be stored as a liquid. It undergoes many addition reactions typical of an olefin. Reactions inclnde preparation of linear dimers and trimers and cyclic dimers (21,22) decomposition at 600°C with subsequent formation of octafluoro-2-butene and octafluoroisobutylene (23) oxidation with formation of an epoxide (24), an intermediate for a number of perflu-oroalkyl perfluorovinyl ethers (25,26) and homopolymerization to low molecular weight liquids (27,28) and high molecular weight solids (29,30). Hexafluoropropylene reacts with hydrogen (31), alcohols (32), ammonia (33), and the halogens and their acids, except I2 and HI (31,34-36). It is used as a comonomer to produce elastomers and other copolymers (37-41). The toxicological properties are discussed in Reference 42. 

There are a number of ways to prepare HFP. Excellent hexafluoropropylene yields from the thermal degradation of heptafluorobutyrate (CF3CF2CF2COONa) have been reported.Cracking of tetrafluoroethylene in a stainless steel tube at 700-800°C under vacuum is an efficient route for the production of HFP. TFE conversions up to 72% and HFP yields of 82% have been reportedf lP Octa-fluorocyclobutane (TFE dimer), octafluoroisobutylene, and some polymer are the major side products of cracking. The presence of a small amount (3-10%) of chlorodifluoromethane stops the formation of poly-mer.P lThermal decomposition of PTFE under 20 ton-vacuum at 860°C yields 58% hexafluoropropylene. 1... 

Campbell and co-workers [23] studied the effect of a silyl peroxide on the compati-bilization of polysiloxane/poly(vinylidenefluoride-co-hexafluoropropylene) (PVDFHFP) blend. The peroxide used, vinyltris(t-butyl peroxy)silane, was specially synthesized in laboratory. The typical decomposition temperature of this peroxide was 150 °C, as measured by DSC. The kinetics of the decomposition reaction of this peroxide were not reported. 

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