No abstract
Condensation of perfluoro carboxylic acid fluorides with hexafluoropropene epoxide in the presence of N, N, N`, N`-tetraalkyldiaminomethanes was studied.Perfluoroalkoxypropanoic acid fluorides (PFPAFs) are starting compounds for preparing perfluoroalkyl vinyl ethers (monomers for fluoro rubbers, elastomers, vulcanizates with high heat, ozone, and weather resistance), emulsifiers, fluorinated surfactants, chemically and thermally stable liquids, lubricating oils, and polymeric materials [1]. Procedures for preparing PFPAFs are based on the reaction of hexafluoropropene epoxide (HFPE) with perfluoro carboxylic acid fluorides (PFAFs) in polar aprotic solvents in a wide temperature range (from 380 to 200oC) in the presence of various catalysts, e.g., alkali metal halides [2], quaternary ammonium salts [3], tris(dimethylamino)difluorophosphorane [4], sulfonium salts [5], tetraalkylurea [6], and N, N, N`, N`-tetraalkyldiaminodifluoromethane [7].As a rule, reactions with low-boiling PFAFs, e.g., with carbonyl fluoride, trifluoroacetyl fluoride, or pentafluoropropionyl fluoride, are performed at a pressure ranging from 0.7 to 24 atm. As solvents are used mixtures of polar aprotic solvents [dinitriles of saturated aliphatic dicarboxylic acids (C 5 3C 8 ), dimethyl ethers of polyethylene glycols CH 3 O(CH 2 CH 2 O) n . CH 3 , n = 23 6] [8] or of polar aprotic (acetonitrile, diglyme) and nonpolar (pentane, hexane, cyclohexane, or a halogenated alkane, e.g., trifluorotrichloroethane) solvents [7]. The PFPAF yield in these procedures does not exceed 50%, being in some cases as low as 6 312%.
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