Esters of fluorinated acids

Because of thetr electron deficient nature, fluoroolefms are often nucleophihcally attacked by alcohols and alkoxides Ethers are commonly produced by these addition and addition-elimination reactions The wide availability of alcohols and fliioroolefins has established the generality of the nucleophilic addition reactions The mechanism of the addition reaction is generally believed to proceed by attack at a vinylic carbon to produce an intermediate fluorocarbanion as the rate-determining slow step The intermediate carbanion may react with a proton source to yield the saturated addition product Alternatively, the intermediate carbanion may, by elimination of P-halogen, lead to an unsaturated ether, often an enol or vinylic ether These addition and addition-elimination reactions have been previously reviewed [1, 2] The intermediate carbanions resulting from nucleophilic attack on fluoroolefins have also been trapped in situ with carbon dioxide, carbonates, and esters of fluorinated acids [3, 4, 5] (equations 1 and 2)... 

Preparation of syndiotactic polymers of vinyl esters of fluorinated acids [233]. 

Esters of fluorinated acids can be hydrolyzed to obtain the parent acid [116,123]. Thus, hydrolysis of hydrocarbon-segmented fluorinated carboxylic... 

The carbon-oxygen bond is strong, like the normal carbon-fluorine bond, it is difficult to reduce However, some structural features facilitate its reductive cleavage Aryl esters of perfluoroalkanesulfomc acids can be cleaved in good yield by... 

Isoflurophate Isoflurophate, the di-wo-propyl ester of fluorophosphoric acid (13.2.21), is made by reacting Mo-propyl alcohol with phosphorous trichloride, forming di-wo-propy-Iphosphite (13.2.19), which is chlorinated to (13.2.20), and further reacted with sodium fluoride to replace the chlorine atom with fluorine, thus giving isofluorophate (13.2.21) [50]. 

Pyrethrinoids are powerful natural insecticides that act on the nervous system of insects. They are esters of chrysantemic acid with a substituted cyclopentenol. The replacement of this motif by a more photochemically stable group affords products that are utilizable in agrochemistry. These compounds exhibit a high insecticide activity and are nontoxic for mammals consequently, they are established in very important markets (e.g., deltamethrin, permethriri). Some fluorinated pyrethrinoids have been synthesized and marketed. One goal of these compounds is to enhance the acaricide activity. Some examples are given in Figure 4.46. 

The acute toxicities of some esters of />-toluenesulfonic acid with fluorinated alcohols have been reported.41 The acute toxicity of the acrylic ester of 1H, l//-perfluoroheptanol has been determined.42... 

Trialkylaryltin derivatives 30 are converted into fluoro-substituted derivatives 31. 37-38 (4-Mcth-oxyphenyl)trimethylsilane (32) in acetonitrile gives 4-fluoroanisole and (3-fluoro-4-meth-oxyphenyl)trimethylsilane in the ratio 1 2. A -Methyldiethanol esters of arylboronic acids 33 (l-aryl-5-methyl-2,8-dioxa-5-azonia-l-boranuidabicyclo[3.3.0]octanes) are converted into tluoroaromatic compounds with cesium fluoroxysulfate in acetonitrile in the presence of 1,3-dinitrobenzene at room temperature.39-40 Regiospecific synthesis of 2-fluoro-3-0-methyles-trone in 27 % yield occurs upon fluorination of the corresponding arylboronic acid with cesium fluoroxysulfate.41... 

Reaction of esters of hydroxyalkanoic acids with sulfur tetrafluoride, unless forcing conditions arc applied, generally results in selective replacement of the hydroxy group by fluorine to give almost equimolar mixtures of fluoroalkanoates 3 and alkoxycarbonylalkyl fluorosulfites 4 in high total yield.65... 

In contrast to phosphorus esters, sulfur esters are usually cleaved at the carbon-oxygen bond with carbon-fluorine bond formation Cleavage of esters of methanesulfomc acid, p-toluenesulfonic acid, and especially trifluoromethane-sulfonic acid (triflic acid) by fluoride ion is the most widely used method for the conversion of hydroxy compounds to fluoro derivatives Potassium fluoride, triethylamine trihydrofluoride, and tetrabutylammonium fluoride are common sources of the fluoride ion For the cleavage of a variety of alkyl mesylates and tosylates with potassium fluoride, polyethylene glycol 400 is a solvent of choice, the yields are limited by solvolysis of the leaving group by the solvent, but this phenomenon is controlled by bulky substituents, either in the sulfonic acid part or in the alcohol part of the ester [42] (equation 29)... 

Esters of carboxylic acids are resistant toward sulfur tetrafluoride up to 300 °C. However, in the presence of an excess of hydrogen fluoride, they react like the acids to give trifluoromethyl compounds [187,235] In contrast, esters of highly fluorinated acids or alcohols react with sulfur tetrafluonde in a hydrogen fluoride solution under mild conditions without cleavage of the ester bond and give products of the replacement of carbonyl oxygen by fluorine a,a-difluoroethers [235, 236, 237, 238] (equations 124 and 125). 

Quinolinones can be made by the reaction of 2-aminophenones with a ketene ylide via an intramolecular Wittig reaction (Equation 122) <2003JOC4170>. The nucleoside unit in this example survives the reaction conditions. The reaction of (2-fluoromethyl)aniline with esters of arylacetic acid yielded 4-fluorinated 2-quinolinones (Scheme 66) <20040L4061 >. 

Borate esters of fluorinated alcohols, simply prepared by the free-radical addition of trialkyl borates to fluorinated alkenes, are cleaved by chlorine to yield fluorinated acid chlorides (equation 141)949. 

The esters of aliphatic a- and /J-hydroxy carboxylic acids react with sulfur tetrafluoride to form mixtures of the corresponding esters of fluorocarboxylic acids and alkoxycarbonyl fluoro-sulfites. If there are electron-withdrawing substituents, such as trifluoromethyl groups, in the a-position the carbonyl oxygen is substituted by two fluorine atoms without substitution of the hydroxy group. ... 

The fluorination of gibbcrellins - and kaurenoids with the Yarovenko reagent (1) has been investigated. Thus, the allylie 2/i-hydroxy group in esters of gibberellic acid reacts with... 

Fluorination of Esters of Carboxylic Acids, Lactones, and Related Compounds... 

Esters of carboxylic acids are, in general, not suitable starting materials for the synthesis of fluorides because the ester group cannot be substituted by fluorine. However, ft- and y-fluoro alcohols 1 and 2 can be obtained by treatment of the cyclic carbonates of 1.2- and 1,3-glycols, respectively, with anhydrous potassium fluoride. 

Carboxylic esters, usually methyl or ethyl esters, can be converted into trifluoromethyl compounds by reaction with sulfur tetrafluoride in the presence of an excess of hydrogen fluoride. In comparison to carboxylic acids more vigorous conditions are needed." Substitution of the ester group carbonyl oxygen is observed with fluoroalkyP or phenyl esters " of polyfluorocarboxylic acids, fluorine-containing a-oxo esters,fluorine-containing a- and j -hydroxy esters, " and furancarboxylic esters. ... 

Of a large number of possible fluorinated acrylates, the homopolymers and copolymers of fluoroalkyl acrylates and methacrylates are the most suitable for practical applications. They are used in the manufacture of plastic lightguides (optical fibers) resists water-, oil-, and dirt-repellent coatings and other advanced applications [14]. Several rather complex methods to prepare the a-fluoroalkyl monomers (e.g., a-phenyl fluoroacrylates, a-(trifluoromethyl) acrylic and its esters, esters of perfluoromethacrylic acid) exist and are discussed in some detail in [14]. Generally, a-fluoroacrylates polymerize more readily than corresponding nonfluorinated acrylates and methacrylates, mostly by free radical mechanism [15], Copolymerization of fluoroacrylates has been carried out in bulk, solution, or emulsion initiated with peroxides, azobisisobutyronitrile, or y-irradiation [16]. Fluoroalkyl methacrylates and acrylates also polymerize by anionic mechanism, but the polymerization rates are considerably slower than those of radical polymerization [17]. 

This method is an extension of the monoester fluorination reactions reported earlier by Sheppard (1). Initial effort was placed on developing conditions that would result in high yields in the fluorination of the nitrophenyl ester of perfluoroglutaric acid. This was followed by fluorination of the nitrophenyl esters of the higher 1 1, 2 1, and 3 1 fluorocarbon ether oligomer acids. The products were the corresponding nitrophenoxy derivatives represented by IV where x + y = 1,2, and 3. 

A distinctly different method of synthesizing the esters of phosphorofluoridic acid consisted in the partial fluorination of phosphorus oxychloride with antimony trifluoride (using a specially designed apparatus and phosphorus pentachloride as catalyst) to give phosphorus oxydichlorofluoride, POClaF. In the latter compound the chlorine atoms proved to be much more reactive than the fluorine atom, and with an alcohol the dialkyl phosphorofluoridate was readily obtained in high yield. ... 

In the polymerization of vinyl esters of perfluorinated acids, ordinary organic solvents are not suitable because of the low solubility, particularly of the higher esters. Therefore, fluorinated solvents have been suggested. Methyl perfluoro-butyrate is considered satisfactory. While benzotrifluoride may be used, the polymers produced in this solvent are low molecular weight [91]. 

In the quinolone series when the halogen in position 7 is a chlorine atom, the condensation of amines is effective only on free carboxylic acids. If a fluorine atom is present at C-7, then the nucleophilic displacement can be realized on esters of carboxylic acids. 

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