Halogenated olefins

It might be noted that most (not all) alkenes are polymerizable by the chain mechanism involving free-radical intermediates, whereas the carbonyl group is generally not polymerized by the free-radical mechanism. Carbonyl groups and some carbon-carbon double bonds are polymerized by ionic mechanisms. Monomers display far more specificity where the ionic mechanism is involved than with the free-radical mechanism. For example, acrylamide will polymerize through an anionic intermediate but not a cationic one, A -vinyl pyrrolidones by cationic but not anionic intermediates, and halogenated olefins by neither ionic species. In all of these cases free-radical polymerization is possible. 

Esters can be obtained from halogenated olefins using a metal carbonyl catalyst (87), eg, /n j -l-bromo-2-phenylethylene is treated with nickel carbonyl in the presence of methanol to afford the corresponding methyl cinnamate (see Cinnamic acid). 

With more electrophilic halogenated olefins, additions of tnfluoromethyl hypofluonte appear to go by radical processes [139] and give oligomeric products [140] or one-to-one adducts [141,142] (equation 4) depending on reaction conditions... 

The known chemistry of the bisftrifluoromethyOnitroxyl [3i, 34] includes additions to both olefins [75, 36 37] and fluoroolefins [iaddition products with chlorotnfluoroethene or tetrafluoroethene [39] The nitroso denvative, (Cp3)3NONO, reacts with a liimted set of halogenated olefins to add the (CF3)2NO and NO moieties [40]... 

The first step is usually the formation of a halogen-olefin charge transfer complex30,70, which rapidly evolves to an ionic intermediate. Protic solvents can electrophilically assist... 

Van Duuren BL, Goldschmidt BM, Loewengart G, et al. 1979. Carcinogenicity of halogenated olefinic and aliphatic hydrocarbons in mice. J Natl Cancer Inst 63 1433-1439. 

This type of polyhalo alkane adds to halogenated olefins in the presence of A1C13 by an electrophilic mechanism. This is called the Prins reaction (not to be confused with the other Prins reaction, 6-53).694... 

Barbin, A., Planche, G, Croisy, A., Malaveille, C. Bartsch, H. (1977) Detection of electrophilic metabolites of halogenated olefins with 4-(4-nitrobenzyl)pyridine (NBP) or with Salmonella typhimurium (Abstract), In 2nd International Conference on Environmental Mutagens, Edinburgh, July 1977,p. 59... 

Infante, P.F. (1977) Carcinogenic and mutagenic risks associated with some halogenated olefins. Environ. Health Perspect., 21, 251-254... 

Rock, D. (1979) Carcinogenicity of halogenated olefinic and aliphatic hydrocarbons in... 

Table 1. Addition of Hydrogen Fluoride to Halogenated Olefins...

However, the step-wise cotelomerisation of fluoroalkenes has already shown original livingness, and the polymerisation via organometallic systems which is quite successful for hydrogenated monomers could be an encouraging route for these halogenated olefins. 

Infrared chemiluminescence measurements [581] of the HF products from the reactions of fluorine atoms with a wide range of pure and halogenated olefinic and aromatic hydrocarbons (see list in Table 7)... 

The use of zero-valent iron (Fe(0)) as a reducing agent to treat compounds recalcitrant to oxidative treatments (e.g., halogenated olefins such as TCE to ethylene) is an emerging technology, which can also convert metal ions (for example Cr(VI) to Cr(III)). For details of this promising new technology, see [92] and references therein. 

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