Hexafluoropropylene synthesis

Hydrocarbon Polymers. It is difficult to produce perfluorocarbon polymers by the usual methods. Many monomers, such as hexafluoropropylene, polymerize only slowly because of the steric hindrance of fluorine. Furthermore, some monomers are not very stable and are difficult to synthesize. Direct fluorination can be used for the direct synthesis of fluorocarbon polymers (68—70) and for producing fluorocarbon coatings on the surfaces of hydrocarbon polymers (8,29,44—47,49,68—71). 

Reaction of perfluoroaLkenes and hypochlorites has been shown to be a general synthesis of perfluoroepoxides (32) (eq. 7). This appears to be the method of choice for the preparation of epoxides from internal fluoroalkenes (38). Excellent yields of HFPO from hexafluoropropylene and sodium hypochlorite using phase-transfer conditions are claimed (34). 

Shi, Z. Q., and Holdcroft, S. 2005. Synthesis and proton conductivity of partially sulfonated poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) block copolymers. Macromolecules 38 4193-4201. 

With slight modification, the methods used to prepare fluorothioacyl fluorides can also be used for synthesis of fluorothioketones. Hexafluorothioacetone, the member of this class that has been studied most extensively, is readily obtained by high-temperature reaction of hexafluoropropylene and sulfur (53). The thio-ketone is a deep-blue liquid, bp 8° C, that dimerizes on standing to 2,2,4,4-tetrakis-(trifluoromethyl)-l,3-dithietane. 

The reaction of a perfluoromercurial with sulfur is particularly well suited to synthesis of hexafluorothioacetone. The first step is addition of mercuric fluoride to hexafluoropropylene in liquid HF which gives bis(hexafluoroiso-propyl)mercury. 

A particularly important process for the synthesis of fluorinated monomers is attack of functionalized perfluoroalkoxides onto hexafluoropropylene oxide [271, 272, 273, 274] (equation 60) or other fluorinated epoxides [275, 276], resulting in ring-opening ol the epoxide and formation of a new perfluoroalkoxide or acid fluoride... 

Buhler, E. Dobrynin, A. V. DeSimone, J. M. Rubinstein, M. Light-Scattering Study of Diblock Copolymers in Supercritical Carbon Dioxide C02 Density-Induced Micellization Transition. Macromolecules 1998, 31, 7347-7355. Bunyard, W. C. Romack, T. J. DeSimone, J. M. Perfluoropolyether Synthesis in Liquid Carbon Dioxide by Hexafluoropropylene Photooxidation. Macromolecules 1999, 32, 8224-8226. 

The largest proportion of TFE is used for the polymerization into a variety of PITH homopolymers. It is also used as comonomer in the copolymerization with hexaflu-oropropylene, ethylene, perfluorinated ether, and other monomers and also as a comonomer in a variety of terpolymers. Other uses of TFE are to prepare low-molecular-weight polyfluorocarbons, carbonyl fluoride oils, as well as to form PTFE in situ on metal surfaces,13 and in the synthesis of hexafluoropropylene, perfluorinated ethers, and other oligomers.14... 

Hexafluoropropylene oxide is an important intermediate in fluoroorganic synthesis. It is useful in the production of surfactants, perfluoropolyether oils, solvents, perfluorinated alkylvinyl ethers, and other materials. 

In studies for the elaboration of a synthesis of perfluoro-n-propyl vinyl ether32), a synthetic precursor of structure 11 was obtained. The program suggested that this compound, 11, would be accessible from two molecules of hexafluoropropylene oxide 12 (Fig. 20). This appeared to be quite an astonishing reaction as extensive bond reorganizations are necessary to achieve the reaction. A chemist who had to... 

When heated above 170"C hexafluoropropylene oxide (5) is a source of difluorocarbene thus, heating 5 in the presence of an alkene allows the synthesis of fluorinated cyclopropanes under neutral conditions.14 16 The less readily available tetrafluoroethylene oxide (6) is also a precursor of difluorocarbene.17... 

Hexafluoropropylene (CF3CF=CF2, CAS number 116-15-4) was first prepared by Downing et al. by pyrolysis. The full synthesis and identification of HFP was conducted by Henne and Woalkes. A six-step reaction scheme starting with the fluorination of 1,2,3-trichloropropane led to 1,2-dichlorohexa-fluoropropane, which was dehalogenated with zinc in boiling ethanol to yield hexafluoropropylene. 

OTHER COMMENTS used as a solvent and extractant for resins, oils, fats, waxes, and chlorinated rubber used as a paint and varnish remover, and as a commercial solvent for degreasing metal parts useful in the synthesis of hexafluoropropylene has also been used in the synthesis of thiokol polysulfide elastomers if some branching of the polymer structure is required. 

Tetrafluorothiirane, 6 (n = 1), lacks a sulfur-sulfur bond and is fairly stable when formed, but it is formed in only 1-2% yield in the above reaction. A more useful synthesis of this monomer is the reaction of thiocarbonyl fluoride with hexafluoropropylene epoxide at 175 °C. At this temperature hexafluoropropylene epoxide serves as a source of di-fluoromethylene, which adds to the double bond of thiocarbonyl fluoride to give the thiirane. If close control of conditions is maintained, yields are close to 40% (6). 

The anionic oligomerisation of hexafluoropropylene oxide or tetrafluoroethylene oxide is an alternative source of the hydrophobic/oleophobic fluorocarbon fragment synthesis [126, 128] ... 

The original reports on synthesis of fluorinated p-sultones appeared from three different groups at approximately the same time in late 1950s.Addition of freshly distilled sulfur trioxide to TFE, chlorotrifluoroethylene, hexafluoropropylene, and... 

Park et al. [18] reported the synthesis of dye-sensitized solar cells (DSSCs) based on electrospun polymer blend nanofibers as electrolytes. Electrospun poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) and PVDF-HFP/polystyrene (PS) blend nanofibers were prepared as shown in Figure 1.16. The authors reported that the photovoltaic performance of dye-sensitive solar cell (DSSC) devices using electrospun PVDF-HFP/PS (3 1) nanofiber was much better as compared to DSSC devices using electrospun PVDF-HFP nanofiber. It was further observed that the overall power conversion efficiency of the DSSC device using PVDF-HFP nanofiber had a lower value than that of the DSSC device using electrospun PVDF-HFP/PS blend nanofibers... 

Scheme 9.5 Perfluoropolyether synthesis through photooxidation of hexafluoropropylene.

TEFLON" FEP was commercialized in 1959. At that time there appeared to be no hope of synthesis of a thermoplastic perfluorinated polymer of any structure other than FEP. Within two years the situation had changed as the result of a series of unexpected discoveries. For several years, research on the synthesis of perfluorocarbon epoxides had been underway in Du Pont, culminating in the discovery of a route to hexafluoropropylene epoxide (HFP0 )[5]. By 1960 sufficient HFPO had been made to permit exploration of its polymerization. This work shortly turned up an unusual polymerization system consisting of CsF initiator and polyethylene glycol ether solvent. Under the proper conditions this same system could be used to effect the condensation of HFPO with perfluorocarbon acid fluorides to produce perfluoroalkoxypropionyl fluorides [6]. These intermediates could be readily converted to perfluoroalkyl vinyl ethers by pyrolysis of their acid forms. 

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