Photooxidation of Fluoroolefins in Liquid Carbon Dioxide

Photooxidation reactions of fluoroolefins in the presence of oxygen is one commercial method used in the production of PFPEs, generally employing either TFE or HFP. Fluorolefm concentration, oxygen level, light intensity, and temperature are all variables that have substantial impact on reaction rates, product distributions, polymer microstructure, peroxide content, and molecular weight. While HFP photooxidations are often carried out in bulk at low temperatures, TFE photooxidation must be carried out in an inert solvent, historically chlorofluor-ocarbons. 

Carbon dioxide, shown to be an ideal medium for reactions involving very electrophilic radicals, has also been shown to be useful in the photooxidation of fluorinated olefins in the synthesis of PFPEs. Table 13.4 shows some representative results of the photooxidation of HFP in liquid CO2. Overall, the resulting products of photooxidations in liquid CO2 are similar to those 

McHugh and V. J. Krukonis, Supercritical Fluid Extraction Principles and Practice, Butter-worths, Boston (1986). 

Johnson and J. M. L. Peiminger (eds). Supercritical Fluid Science and Technology, American Chemical Society, Washington D.C. (1989). 

Prausnitz, R. N. Lichtenthaler, and E. G. deAzevedo, Thermodynamics of Fluid Phase Equilibria, Prentice-Hall, Englewood Cliffs, N.J. (1986). 

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