Ethylene 1,2-dichloro-1,2-difluoro

In a definitive study of butadiene s reaction with l,l-dichloro-2,2-difluoio-ethylene, Bartlett concluded that [2+4] adducts of acyclic dienes with fluorinated ethylenes are formed through a mixture of concerted and nonconcerted, diradical pathways [67] The degree of observed [2+4] cycloaddition of fluorinated ethylenes IS related to the relative amounts of transoid and cisoid conformers of the diene, with very considerable (i.e., 30%) Diels-Alder adduct being observed in competition with [2+2] reaction, for example, in the reaction of 1,1 -dichloro-2,2-difluoro-ethylene with cyclopentadiene [9, 68]... 

Earlier, Ruh [120a] reported a similar reaction for l,2-dichloro-l,2-difluoro-ethylene on reaction with sodium ethoxide to give ethyl chlorofluoroortho-acetate (Eq. 39). 

What are products E and F of the reaction of l,l-dichloro-2,2-difluoro-ethylene with methanol in the presence of sodium methoxide ... 

With CF3C=CCF3 or olefins with an internal double bond such as cis- or fraras-F-2-pentene, F-cyclobutene, or l,2-dichloro-l,2-difluoro-ethylene, or with a geminally disubstituted olefin such as 1,1-dichloro-2,2-difluoroethylene, only fully fluorinated products were obtained, likely through a nucleophilic fluorination mechanism. This fact, plus the necessity for a Lewis acid catalyst for addition to proceed, is evidence for an electrophilic addition mechanism. Others have suggested polar addition of BF3 to the olefin with RfBF2 as a reactive intermediate (294). 

A related difluoro complex involving tetrakis (dimethylamino) ethylene as a base was reported by Wiberg and Buchler (26). Dichloro cations were also reported by Noth and his students (18). 

Stereochemical investigation of the reactions of 1,1 -dichloro-2,2-difluoro-ethylene with the geometrical isomers of 2,4-hexadiene has indicated a radical addition mechanism involving intermediate formation of an open-chain diradical addition compound.57... 

Preparation. 2,2-Bistrifluoromethyl difluoro-l,3-dioxole (PDD) monomer is synthesized in four steps (2). In the first step, hexafluoroacetone and ethylene oxide are reacted to form 2,2-bistrifluoromethyl-4,5-dichloro-4,5-difluoro-l,3-dioxolane. This product is then fully chlorinated and subsequently partially fluori-nated to difluoro-l,3-dioxolane. In the last step, the fluorinated product is dechlo-rinated to obtain the final product, PDD. 

This can nicely be demonstrated with the Diels-Alder reaction of 1,1-dichloro-2,2-difluoro ethylene. 

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