Vinylic fluorides synthesis

Vlayl fluoride [75-02-5] (VF) (fluoroethene) is a colorless gas at ambient conditions. It was first prepared by reaction of l,l-difluoro-2-bromoethane [359-07-9] with ziac (1). Most approaches to vinyl fluoride synthesis have employed reactions of acetylene [74-86-2] with hydrogen fluoride (HF) either directly (2—5) or utilizing catalysts (3,6—10). Other routes have iavolved ethylene [74-85-1] and HF (11), pyrolysis of 1,1-difluoroethane [624-72-6] (12,13) and fluorochloroethanes (14—18), reaction of 1,1-difluoroethane with acetylene (19,20), and halogen exchange of vinyl chloride [75-01-4] with HF (21—23). Physical properties of vinyl fluoride are given ia Table 1. 

T. Ernet, G. Flaufe, Allylic hydroxylation of vinyl fluorides. Synthesis (1997) 953-956. 

Table 29 Selected examples of vinyl fluorides synthesis according to Scheme 108...

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. 

Hydrofluorocarbons are also prepared from acetylene or olefins and hydrogen fluoride (3), or from chlorocarbons and anhydrous hydrogen fluoride in the presence of various catalysts (3,15). A commercial synthesis of 1,1-difluoroethane, a CFG alternative and an intermediate to vinyl fluoride, is conducted in the vapor phase over an aluminum fluoride catalyst. 

Uses Synthetic fibers and adhesives chemical intermediate in vinylidene fluoride synthesis production of poly(vinyl dichloroethylene) and LLl trichloroethane comonomer for food packaging, coating resins, and modacrylic fibers. 

Synthesis of a-fluoro-ot, -unsaturated ketone via allylic hydroxylation of vinyl fluoride... 

M. Marhold, A. Buer, FI. Fliemstra, J.FI. van Maarseveen, G. Flaufe, Synthesis of vinyl fluorides by ring-closing metathesis. Tetrahedron Lett. 45 (2004) 57-60. 

Other methods are described in Reference 61, however, the commercial process for the synthesis of vinyl fluoride is not described in the literature for proprietary reasons.61 Addition of HF to acetylene and fluorination of vinyl chloride are the most likely industrial routes to the production of VF.62... 

The use of fluorine in molecules of pharmacological interest is well known and there has been widespread research into methodologies for the introduction of this atom. Within the discovery synthesis of maraviroc, the initial preparation required the use of diethyl amino sulfur trifluoride (DAST), which is commercially available but does require careful handling due its well known thermal instability. Initial use of DAST for the fluorination of the ketone 19 gave an inseparable 1 1 mixture of the required difluoro compound 20 and the vinyl fluoride 21. The formation of vinyl fluoride co-products from the treatment of ketones with DAST is known in the literature and is difficult to control. 

Table 1. Synthesis of Vinyl Fluorides by Reaction of Vinyltin Compounds with Xenon Difluoride...

Vapor-phase processes using vinyl fluoride employ a wide variety of catalysts as well. For example, fluorided alumina or aluminum fluoride has been widely used. The conventional chrome-based systems have also been used with success. Carbon-supported VCI3 appears to be (74) a selective catalyst for this synthesis. 

The method employing the sequential alkylation and elimination of sulfoxides, reported above, has been successfully applied to the synthesis of dienes (Scheme 86, entry c), aryl alkenes and dienes (Scheme 47), vinyl sulfides, a,3-unsaturated sulfoxides, vinyl fluorides and vinyl chlorides (Scheme 96, entry a), and 1,1-dichloro-l-alkenes (Scheme 96, entry b). ... 

Tsai, H.-J., and Burton, D.J., Synthesis of phenyl and ester substimted vinyl fluorides via reduction and olefination of esters, Phosphorus, Sulfur Silicon Relat. Elem., 140, 135, 1998. 

Bromofluoro compounds are themselves useful starting materials for the preparation of monofluorinated compounds. For example, reduction of 1-bromo-2-fluorocyclododecanes with tributyltin hydride gives fluorocyclododecane, while other methods to produce this compound have been unsuccessful.15 The elimination of hydrogen bromide from vicinal bromofluorides also gives vinyl fluorides in good yields,10 16 as is illustrated by the recent synthesis of several substituted a-fluorostyrenes for studies related to [4+2]-cycloadditions.17... 

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