Tetrafluoroethylene, photolysis

Tetrafluoroethylene. Grzybowska et al.69 studied the reaction of methylene with C2F4 in the pressure range 10-470 cm. at 20°C. Methylene was produced by CH2CO photolysis at X > 3100 A. with a C2F4/ CH2CO ratio of 9 1. 

Chemically, difluorodiazirine appears to be remarkably inert. Like diazirine itself, however, it is explosive. It undergoes thermal decomposition above about 160°C. Photolysis of this compound at room temperature produces only tetrafluoroethylene and nitrogen, presumably by the reactions... 

In flash photolysis, however, the absorption spectrum of CFj has been observed and Simons and Yarwood noted the presence of tetrafluoroethylene among the products of continuous photolysis of trifluoracetic acid with a high pressure xenon arc lamp, indicating the probable production of CFj radicals under these conditions. 

For example, perfluorocyclopropane 196 was formed on thermolysis of difluorodiazirine. Photolysis yielded tetrafluoroethylene. 

The initially formed adduct radicals were scavenged by an excess of methyl iodide. A study of the addition of methyl radicals, from the photolysis of biacetyl in the presence of isobutane, to hexafluoropropene has indicated that it is rather unselective, reacting at a rate similar to that with tetrafluoro-ethylene, but a further study, employing octane as scavenger, has indicated that tetrafluoroethylene is some six times as reactive (in the latter work the vinyl ethers CFa O CFiCFs and n-C8F, O CF CF2 were also studied). 

CH3F (trace). Pyrolysis of sodium trifluoroacetate alone yields trifluoro-acetyl fluoride and trifluoroacetic anhydride pyrolysis of sodium trifluoroacetate in the presence of sodium hydroxide, however, does appear to give difluorocarbene since tetrafluoroethylene is produced in at least 32% yield. Data from kinetic studies on hydrogen atom abstraction by Me and CFa (generated by photolysis of acetone and hexafluoroacetone, respectively) from methyl trifluoroacetate and methyl fluoroformate have been presented and discussed. ... 

Photolysis of AuMeCPPhs) in the presence of tetrafluoroethylene results in the formation of the fluoroalkyl insertion product. Hexafluorobutyne-2 reacts similarly to give the fluorovinyl product ... 

The rate of combination of trifluoromethyl radicals to form hexafluoro-ethane has been measured by the flash photolysis of trifluoromethyl iodide coupled with rapid-scan i.r. spectroscopy in the absence of an inert diluent (At, N2, or COt) carbon tetrafluoride and tetrafluoroethylene were also formed, presumably via fluorine atom abstraction from trifluoroiodomethane by hot trifluoromethyl radicals (c/. ref. 27). Photolysis of trifluoroiodomethane has been used in studies on (i) the direction of radical attack on 1,3,3,3-tetrafluoropropene [- CFj CHI CHFCF, (75%) + (CFa)jCH CHFl (25%)] (ii) the rates of hydrogen abstraction from ammonia, ammonia-ethylene oxide, silane, trimethylsilane, tetramethylsilane, and cycloalkanes and (iiQ the competitive addition of the CFj- radical to ethylene and vinylidene fluoride. Radicals formed by photolysis of the fluoroalkyl iodides CFJ, C FJ, n-C,F,I, (CF,)jCFI, (CFaljCHI, (CFalaCDI, (CFa)jCClI, and (CFa)iCPhI (the last was synthesized by treatment of CFs CPh CTj with CsF and iodine in DMF) have been... 

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