1-1 -Difluoro-2-2-Dichloroethylene

A mixture of iodine pentafluoride, slightly more than 2 moles of iodine, pure iron-free Al-shavings, and Al-iodide preheated in a rocking Monel autoclave at 130-135 for 2.5 hrs., cooled in Dry Ice, evacuated, charged with 1,1-difluoro-2,2-dichloroethylene, and shaken 17 hrs. in an ice bath l,l-dichloro-2,2,2-trifluoro-l-iodoethane. Gonversion ca. 80% based on maximum theoretical IF isomeric purity 95-98%. F. e. s. M. Hauptschein and M. Braid, Am. Soc. 83, 2383 (1961). 

With l,l-difluoro-2,2-dichloroethylene, butadiene yielded cyclobutane (31) in the presence of benzophenone ... 

In the case of the fluorinated ethylenes, it is known through work of Bartlett and his collaborators that the reaction is stepwise by way of a biradical intermediate.17 Much of the evidence supporting this conclusion has been obtained from the study of additions of l,l-difluoro-2,2-dichloroethylene, abbreviated 1122, to dienes. Scheme 1 outlines six possible general routes, each of which has several potential stereochemical variations, that addition of an olefin to a diene could follow. When 1122 reacts with butadiene and simple substituted butadienes, the products are entirely cyclobutanes consequently, we may restrict attention... 

Difluoro-1,2>dichloroethylene. See 1,2-Di chloro-1,2-di luoroe thy leoe in this Section... 

Halogen (X2) can be removed thermally or by use of metals (Fe, Mg, Zn, Al). E.g., 1,2-dichloroethylene is obtained industrially from 1,1,2,2-tetrachloroethane by means of iron turnings and steam,140 and l,2-dichloro-l,2-difluoroethylene from l,2-difluoro-l,l,2,2-tetra-chloroethane by means of Zn dust in ethanol.342,343... 

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