Reactions of fluoroolefins

An alternative route to the reaction of mercuric fluoride with fluoroolefins in liquid hydrogen fluoride [154] was developed during the early and middle 1970s This improved method involved the reaction of fluoroolefins and mercury salts in the presence of alkali metal fluorides m aprotic solvents [i5J, 156] (equation 118)... 

Fluoride ion produced from the nucleophilic addition-elimination reactions of fluoroolefins can cataly7e isomerizations and rearrangements The reaction of per fluoro-3-methyl-l-butene with dimethylamine gives as products 1-/V,/Vdimeth-ylamino-1,1,2,2,4,4,4-heptafluoro-3-trifluoromethylbutane, N,W-dimetliyl-2,2,4,4,4-pentafluoro 3 trifluoromethylbutyramide, and approximately 3% of an unidentified olefin [10] The butylamide results from hydrolysis of the observed tertiary amine, and thus they share a common intermediate, l-Al,A -dimethylamino-l,l 24 44-hexafluoro-3-trifluoromethyl-2-butene, the product from the initial addition-elimination reaction (equation 4) The expected product from simple addition was not found... 

Photooxidation reactions of fluoroolefins in the presence of oxygen is one commercial method used in the production of PFPEs, generally employing either TFE or HFP. Fluorolefin concentration, oxygen level, light intensity, and temperature are all variables that have substantial impact on reaction rates, product distributions, polymer microstructure, peroxide content, and molecular weight. While HFP photooxidations are often carried out in bulk at low temperatures, TFE photooxidation must be carried out in an inert solvent, historically chlorofluor-ocarbons. 

The last comprehensive review on electrophilic reactions of fluoroolefins was published in 1969 [6], Since then, several reviews and papers dealing with different aspects of this chemistry, such as alkylation and alkenylation reactions [7], addition of halogen fluorosulfates [8], trifluoromethanesulfonates [9] and halogen fluorides [10] to fluoroolefins have been published. Additional information on the reactions involving carbocations could be found in two recent review articles [11,12] some data on the subject are scattered in several books and journals [13-19]. 

In the last 27 years, tremendous progress has been made in this field of organic chemistry. Since the area is broad and the subject quite complex, no attempt has been made to present comprehensive coverage of the related literature. Instead, the authors of this review attempt to describe electrophilic reactions of fluoroolefins with particular stress on the mechanistic and synthetic aspects, to make it as comprehensive as possible in the main types of electrophilic reactions and to give the most important examples. Inevitably, this approach has left out some material and we offer in advance our regrets to all whose work was omitted. 

Fluorinated carbocations play an important role as intermediates in electrophilic reactions of fluoroolefins and other unsaturated compounds. For example, F-allyl cation 1 was proposed as a reactive intermediate in reactions of HFP with fluoroolefins catalyzed by Lewis acids [7]. The difference in stability of the corresponding allylic cations was suggested as the explanation for regio-specific electrophilic conjugated addition to CF2=CC1CF=CF2 [11]. Allylic polyfluorinated carbocations were proposed as intermediates in the reactions of terminal allenes with HF [53] and BF3 [54], ring-opening reactions of cyclopropanes [55], Carbocations are also an important part of the classic mechanism of electrophilic addition to olefins (see Eq. 2). This section deals with the questions of existence and stability of poly- and perfluorinated carbocations. 

Progress in the preparation and isolation of different hypohaiites [92] results in a substantial number of publications exploring the addition of these materials to fluoroolefins. In contrast to addition of hypofluorites, which at this time is viewed as a radical process, a polar mechanism was proposed for addition of poly-fluorinated hypochlorites and hypobromites to olefins. Reactions of fluoroolefins... 

Solution of antimony pentafluoride in anhydrous HF was found to be an efficient medium for alkylation reactions of fluoroolefins. Compounds, known to give stable carbocations in superacidic media are excellent alkylating agents. For example, f-butyl chloride (57) reacts with TFE, giving the corresponding alkane 58 ... 

Formation of small amounts of a by-product - F-methylcyclobutane 69 - (in reaction of HFP and TFE) catalyzed by ACF was rationalized as a result of similar intramolecular alkylation reaction of the C=C bond in intermediate carbo-cation 70, and it is probably the first example of electrophilic 2+2 cycloaddition reaction of fluoroolefin ... 

The last 20 years or so have been a period of intensive development in the area of electrophilic reactions of fluoroolefins. Fluorine substituents impart unique reactivity to polyfluorinated olefins, and the knowledge of their behavior in reactions with electrophiles is important for synthetic chemists working in this area. 

Although this work probably does not cover all the details of the developments in electrophilic chemistry of fluoroolefins, it has nevertheless attempted to provide a strategic overview in this area, hoping that chemists working on related subjects should be able to find answers to basic questions associated with reaction conditions, types of electrophiles, reactivity of olefins and orientation of addition. We also wish to acknowledge the tremendous work accomplished in the last 30 years in the area of electrophilic reactions of fluoroolefins that has made this review possible. 

Dyatkin BL, Mochalina EP, Knunyants IL (1969) Reactions of Fluoroolefins with Electrophilic Reagents. In Tarrant P (ed) Fluorine Chemistry Reviews. Marcel Dekker Inc, New York and Basel, vol 3, p 45... 

It should be pointed out that the electrophilic [2 + 2] cycloaddition of CH2=0 and fluoroolefins carried out in HF is rather limited in the scope. For example, reaction of formaldehyde with hexafluoropropylene exclusively affords CF3CF(CF3)CH20H, and in reaction with vinylidene fluoride, the ether (CF3CH2CH2)20 is formed as the major product. More on the electrophilic reactions of fluoroolefins in anhydrous HF can be found in detailed review. ... 

Dixon, S. (1956) Ehmination reaction of fluoroolefins with organolithium compounds. The Journal of Organic Chemistry, 21, 400-403. 

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