Perfluoro-2-butene

Difluorocarbene generated by the thermolysis of trimethyltnfluoromethylsilane reacts with disilanes by insertion into the silicon-silicon bond [S] (equation 9) Thermolysis of pentafluoroethyltnfluorosilane at 200 °C gives tetrafluoro ethylidene carbene, which reacts with phosphorus trifluonde to give trifluoro vinyltetrafluorophosphorane [9] (equation 10) and with perfluorotnmethylphos-phine to give perfluorodimethyhsopropylphosphine and perfluoro-2-butene [9] (equation 10)... 

Reactions of fluorinated dipolarophiles. Electron-deficient unsaturated species generally make better dipolarophiles, therefore, fluonnated alkenes become better dipolarophiles when vinylic fluonnes are replaced by perfluoroalkyl groups For example, perfluoro-2-butene is unreactive with diazomethane, but more highly substituted perfluoroalkenes, such as perfluoro-2-methyl-2-pentene, undergo cycloadditions in high yields [5] (equation 2) Note the regiospecificity that IS observed in this reaction... 

The product is a mixture, however, the composition may be altered by the nucleophile used in the reaction For example, the reaction of perfluorobutyl iodide in the presence of sodium acetate or sodium bisulfite results mostly in perfluoro-2-butene and nonafluorobutane, whereas with potassium thiocyanate, perfluoro-1 butene is the dominant product, together with perfluoro-2-butene and a small amount of nonafluorobutane (equation 40)... 

Isomerization of olefins can be accomplished also in the gas phase m a flow reactor with alumina or nickel oxide as catalyst Thus perfluoro 2-butene can be prepared by passing perfluoro-1 butene over these catalysts at 150-400 °C [79] Similar results may be obtained in an autoclave with the same catalysts Perfluoro-1 butene isomenzes almost quantitatively at 250 °C after 100 h to perfluoro-2-butene [20]... 

Whereas access to fluoromethylene yhdes is easy, higher homologues are more difficult to prepare because of the facile -elimination of fluorine However hexafluoroisopropylidene ylides may be prepared in situ from tetrakis(tnfluoro-methyl)-1,3-dithietane and tnphenylphosphme [54 (equation 51) or 2,2-dichloro-hexafluoropropane and tnphenylphosphme [55, 56, 57] (equation 52) (Table 21) Perfluoro-2-butene reacts with tnbutylphosphine to cleanly form a solution of a fluonnated ylide [55 ] (equation 53)... 

However, this type of argument is insufficient to account for the greater reactivity of perfluoropropene (49) than perfluoro-2-butene (51) (Scheme 19) because the corresponding intermediate (51a) could only have marginally different stability from that of (49 a). There is also the greater reactivity of (52) than (53) (Scheme 20) to account for, where any difference in stability of intermediate carbanions would be marginal. 

When the pentamer (66) reacts with alkoxide anions at low temperatures (-30 to -40°C), then the products of kinetic control (102) are isolated, whereas at higher temperatures, thermodynamic control prevails and the products (103) are obtained [131,132] (Scheme 68). Similar observations have been made with sulphur nucleophiles [132], and complex products are obtained with amines, including the formation of heterocycles [132]. Reaction of (66) with ethyl acetoacetate gave a pyran derivative (104) in a reaction that may be rationalised as shown in Scheme 69 [133]. In an analogous way.furan derivatives are formed from perfluoro-2-butene and -cyclohexene in base-induced reaction with 1,3-dicarbonyl derivatives [133]. 

The synthesis of the 4,5-dimethoxy-l,3,2-dioxathiolane 2,2-dioxide (98) from perfluoro-2-butene involved reaction with sodium methoxide, resulting in a mixture of cis and trans isomers of the vinyl diether (197). Subsequent action of sulfur trioxide on (197) gave, probably via the 1,2-oxathietane 2,2-dioxide (198), the cyclic sulfate (98) (77JA1214), a convenient precursor to hexafluorobiacetyl (c/. Section 4.33.3.3.1). 

SYNS FC-1318 OCTAFLUOROBUTENE-2 OCTAFLUOROBUT-2-ENE pOT) PERFLUOROBUT-2-ENE PERFLUORO-2-BUTENE pOT)... 

OCtafluoro-2-butene. (perfluoro-2-butene). CAS 360-89-4. CF3CF CFCF3. 

Tetrafluoroethylene (TFE), hexafluoropropene (HFP) and perfluoro-2-butene (PF2B) were used as monomers. 

Figure 12. Deposition rate of plasma polymerized perfluoro-2-butene vs. power for a helical resonator at 10.17 MHz...

The deactivating effects of the CF3 groups on the double bond reactivity are evident, and the attempts at determination of absolute rate coefficients by Herron and Huie [129] (log fe = 6.6 1 mole sec at 500°K for trans-perfluoro-2-butene) and by Madhavan and Jones [135] (log k = 7.25 1 mole sec at 313°K for tetrafluoroethylene) indicates that these compounds react at a lower rate than the analogous hydrogen-containing olefins. 

Hitchcock AP, Beaulieu S, Steel T, Stohr J, Sette F (1984) Carbon -Shell electron energy loss spectra of 1- and 2-butenes, trans-l-3-butadiene, and perfluoro-2-butene. Carbon-carbon bond lengths from continuum shape resonances. J Chem Phys 80 3927-3935 Hitchcock AP, Horseley JA, Stohr J (1986a) Inner-shell excitation of thiophene and thiolane Gas, solid, and monolayer states. J Chem Phys 85 4835-4848... 

Multiphoton IR dissociations of various organohalogen compounds have been investigated. Photofragment translational spectroscopy revealed that IR multiphoton dissociations of perfluoro-1-butene and perfluoro-2-butene proceed by... 

In an earlier paper [7] the same authors reported that calcium atoms reacted with perfluoro-2-butene at liquid nitrogen temperature to give... 

Two other butene isomers are formed besides PFIB, namely perfluoro-1-butene and perfluoro-2-butene. However, as with PFIB, a mechanism of formation from TFE or other pyrolysis products is lacking. 

However, German et al. [51] did observe a 1,2 shift in perfluoro-2-butene that resulted in the isomerization of perfluoro-2-butene to perfluoro-1-butene, detailed in Scheme 5.9. 

Additionally, they also indicated a possible mechanism for the formation of perfluoro-2-butene from TFE, presented in Scheme 5.10. 

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