Fluorinated vinyl compounds

Similar behaviour is found in the variously substituted vinylic systems. In Pm fluorinated vinyl compounds, for which Cowley and Taylor have obtained the relative signs, <1969.54>55) s founcj that sign reversal may occur in gem couplings and that the trans couplings generally have the lowest values (Table XX). 

Particularly the chlorinated compounds have enjoyed range of applications vinyl chloride (chloro-ethene) as monomer for the production of PVC, tetra- and trichloroethenes as solvents for degreasing, and the insecticides l,l,l-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and isomers of hexachlorocyclohexane (HCH) (benzene hexachloride). The biodegradation of fluorinated aliphatic compounds is generally different from the outlines that have emerged from investigations on their chlorinated, brominated, and even iodinated analogues. They are therefore treated separately in Part 4 of this chapter. 

A nucleophilic mechanism can be applied in reductions with complex hydrides of highly fluori-nated aliphatic and alicyclic fluoroalkenes with electron-deficient C = C bonds the hydride anion adds as a strong nucleophilic agent to the more electrophilic carbon atom the intermediate anion can then lose a fluoride ion either from the original C = C bond, or from the allylic position finishing an SN2 displacement of the fluorine. Thus, the reductions of vinylic C-F bonds with hydrides proceed by a nucleophilic addition-elimination mechanism. Displacement of fluorine in highly fluorinated aromatic compounds proceeds by the same mechanism ... 

The decarboxylation of fluorinated compounds to form fluorinated alkenes has now become very important for the preparation of fluorinated vinyl ethers. These perfluoroalkyl per-fluorovinyl ethers are used as monomers for copolymerization with fluorinated alkenes. in particular tetrafluoroethene. 1,1-difluoroethene, and hexafluoropropene. ... 

The polymerization of unsaturated halohydrocarbons has been studied most extensively in the case of vinyl chloride and closely related compounds. Kainer 1S6) published a book recently on polyvinyl chloride and mixed polymers of vinyl chloride. In addition to chlorovinyl polymers, Schildknecht includes fluorovinyl polymers in his book Hl). Books covering plastics generally include material on the halohydrocarbon polymers (14, 144)- Several papers ISS, IS, 135,143) have been published in the last couple of years dealing with the polymerization of fluorine-containing compounds. Articles on polymerization of chloroprene 14 ), fluoroprene 1S8), chlorotrifluoroethylene 140), tetrafluoroethylene 1S9), vinylidene fluoride (157), and dichlorodifluoroethylene 1S7) have appeared in recent years. 

Reaction with Organolithium Reagents. The fluorination of vinyl lithium derivatives with NFSi has been demonstrated in good yields with complete retention of configuration about the double bond. Phenyl lithium reacts rather poorly with 7V-fluorobenzenesulfonlmlde, but more complex phenyl lithium derivatives have been fluorinated to prepare fluoro- and polyfluoro-veratraldehydes as well as complex fluorinated polyaromatic compounds. Organolithium derivatives of heterocycles have been fluorinated by reaction with NFSi at low temperature. In this manner, fluoro-pyrroles and 2-fluoro-5-methylthleno[3,2-b]pyrldlne are prepared from their corresponding llthlo-parent compounds (eq 16). ... 

Other compounds of vinyl type that are used for polymers include acrylonitrile (vinyl cyanide), H2C=CH(CN), and styrene, H2C=CH(C H3). Vinyl compounds are all polymerized by addition process. Tetrafluoroethylene, F C=CF, in which all the hydrogen atoms of ethylene are replaced by fluorine atoms, polymerizes similarly to form a polymer of unique character, teflon. 

The bulk polymerization of TFS in the presence of benzoyl peroxide at 70-75 °C and with boron trifluoride at 1-4 °C was achieved for the first time by Prober [72] in 1953. The softening points of the copolymers ranged between 207 and 225 °C. In 1981, Tevlina et al. [83] copolymerized a,, -trifluorostyrene (I) with vinyl fluoromonomers, such as A -vinylpyrrolidone (II), H2C=CF—CN (III), FHC=CF-COOMe (IV), and F2C=C(CF3)COOMe (V), in the presence of AIBN. The low reactivity of compound I was attributed to the presence of fluorine in both / -positions of the vinyl group. The high polarity of bonds in compounds III, IV, and V arises from the electron acceptor effect of the fluorine atom. Compounds II, in, and IV were highly reactive in copolymerization with compound I. 

The most common release agent used in vinyl compounds, when the lubricant system is not in itself adequate, is BBS, typically at 0.05-0.2 phr. If the article is to be printed or decorated, it is preferable to use a blend of GMS and OPE, both at 0.05-0.1 phr. The most widely used shp agent in rigid vinyl is stearamide, whereas in flexible compounds, oleamide, is used, both at 0.05-0.2 phr. The use of fluorinated die release agents has not been widely investigated as regards PVC... 

VF copolymers [FLUORINE COMPOUNDS, ORGANIC - POLY(VINYL FLUORIDE)] (Vol 11)... 

Vinyl Fluoride. Vinyl fluoride [75-02-5] C2H2F, the monomer for poly(vinyl fluoride), is manufactured by addition of hydrogen fluoride to acetylene (see Fluorine COMPOUNDS, ORGANIC, POLY(viNYL FLUORIDE)). 

In 1954 the surface fluorination of polyethylene sheets by using a soHd CO2 cooled heat sink was patented (44). Later patents covered the fluorination of PVC (45) and polyethylene bottles (46). Studies of surface fluorination of polymer films have been reported (47). The fluorination of polyethylene powder was described (48) as a fiery intense reaction, which was finally controlled by dilution with an inert gas at reduced pressures. Direct fluorination of polymers was achieved in 1970 (8,49). More recently, surface fluorinations of poly(vinyl fluoride), polycarbonates, polystyrene, and poly(methyl methacrylate), and the surface fluorination of containers have been described (50,51). Partially fluorinated poly(ethylene terephthalate) and polyamides such as nylon have excellent soil release properties as well as high wettabiUty (52,53). The most advanced direct fluorination technology in the area of single-compound synthesis and synthesis of high performance fluids is currently practiced by 3M Co. of St. Paul, Minnesota, and by Exfluor Research Corp. of Austin, Texas. 

See Fluorine compounds, organic-poly(vinyl) fluoride). 

In the 1960s and 1970s, additional elastomers were developed by Du Pont under the Viton and Kalrez trademarks for improved low temperature and chemical resistance properties using perfluoro(methyl vinyl ether), CF2=CFOCF3, as a comonomer with vinyUdene fluoride and/or tetrafluoroethylene (12,13) (see Fluorine compounds, organic-tethafluoroethylene polypous and copolyp rs). 

Fig. 3. The percent volume swell in benzene after seven days at 21°C compared with the wt % of fluorine on standard recommended compounds. A, copolymers of vinyUdene fluoride—hexafluoropropylene B, terpolymers of vinyUdene fluoride—hexafluoropropylene—tetrafluoroethylene C, terpolymers of vinyhdene fluoride—hexafluoropropylene—tetrafluoroethylene-cure site monomer D, copolymer of tetrafluoroethylene—perfluoro(methyl vinyl ether)-cure...

In summary, VH F demonstrates the same pattern of solvent dependence as does 2/h h. However, all the subtleties seem to be enhanced. Usually 2/H F decreases in solvents of higher dielectric strength, but an appropriate dipole orientation with respect to the H—C—F group can lead to the opposite result as is observed in vinyl fluoride. This situation is perhaps most likely to occur in mono-fluoro compounds where the fluorine is the principal contributor to the molecular dipole. In either case the electric field effect as postulated with the Pople expression for the contact term produces the correct prediction. 

D.F. Andres, U. Dietrich, E.G. Laurent, B.S. Marquet, Anodic fluorination of vinyl sulfides - synthesis of a-fluoro- -thio-a, -unsaturated carbonyl compounds. Tetrahedron 53 (1997) 647-658. 

Vinyl fluorides can also be prepared starting from difluorovinyl compounds via the loss of a fluorine atom by an addition-elimination process, as illustrated in Figure 2.9." ... 

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