Boron fluoride etherate, reaction with

The reactions of some fluorinated ethers may result in the elimination of alkyl fluorides In the case of 2-methoxyperfluoro-2-butene, treatment with antimony pentafluoride gives perfluoro-3-buten-2-one and methylfluoride [107] By reacting 2-chloro-l,l,2-trifluorodiethyl ether with boron trifluoride etherate or with aluminum chloride, chlorofluoroacetyl fluoride can be obtained with the elimination of ethyl fluonde [108] (equations 76 and 77)... 

In a similar reaction of ketene with diethyl phosphite in the presence of boron fluoride etherate as catalyst, diethyl 1-acetoxyvinylphosphonate is formed [113] see Eq. (69) ... 

According to the Keele theory the incorporation of styrene would be represented by Reaction (E). Since Yamashita s experiments were done with the catalyst boron fluoride etherate, whose mode of action is still quite obscure, we denote the activating group derived from the catalyst by Y (which may be Et). 

Additional acylation studies were also reported (24), (26). In the first case it is claimed that acylation of thiophene is achieved by means of HC104 and acetic anhydride affording a 65 % yield of 2-acetylthiophene. In the second paper Levine and coworkers reported that while 2,5-dimethylthiophene could be readily acetylated, 2,5-dichlorothiophene acetylated sluggishly. This is, however, readily explained, since the presence of chlorine atoms on the thiophene ring decreased its reactivity in electrophilic substitution reactions. In the case of methyl substitution, however, the 3 and 4 positions of the ring are activated toward electrophilic substitution by the inductive and hyperconjugative effects. Thus 2,5-dimethylthiophene was successfully acylated by the boron fluoride etherate method in high yield with three aliphatic anhydrides. 

Goldsmith DJ (1962) Cyclization of epoxy olefins reaction of geraniolene monoepoxide with boron fluoride etherate. J Am Chem Soc 84 3913-3918... 

The behavior of 2-boron fluoride etherate under anhydrous conditions has also been examined in some detail.4 From thiB reaction a crystalline boron fluoride complex was obtained which was spectroscopically characterised as that of the ritf-isomer (XXVII) of A-fert-butylbenzaldoxime. On standing or recrystaUisation from solvent this isomer was converted to the [Pg.326]

Note that acetic acid is eliminated during the reaction. What effect would sodium acetate have How might boron fluoride etherate or sulfuric acid affect the nucleophilic attack of the phenolic oxygen on acetic anhydride With what might the base, pyridine, associate ... 

BORON TRIFLUORIDE DIETHYL ETHERATE (109-63-7) Combustible liquid (flash point 147°F/64°C). Forms unstable peroxides, unless inhibited. Violent reaction with moist air, water, steam, forming hydrogen fluoride. Violent reaction with oxidizers, etherral lithium aluminum hydride, and other powerful reducing agents. Attacks metals, glass, concrete in the... 

Boron Trifluoride Ltherate. Boron fluoride ethyl ether boron fluoride etherate ethyl ether-boron trifluoride complex. C4HltBF30 mol wt 141.94. C 33.85%, H 7.10%, B 7.62%. F 40.16%, O 11.27%. (CH,CHj),O.BF,. Prepd by vapor-phase reaction of anhydr ether with BF, Lauben gayer, Finlay, J. Am. Chem. Soc. 65, 884 (1943). 

Acetylcyclohexanone. Method A. Place a mixture of 24-6 g. of cyclohexanone (regenerated from the bisulphite compound) and 61 g. (47 5 ml.) of A.R. acetic anhydride in a 500 ml. three-necked flask, fitted with an efficient sealed stirrer, a gas inlet tube reaching to within 1-2 cm. of the surface of the liquid combined with a thermometer immersed in the liquid (compare Fig. II, 7, 12, 6), and (in the third neck) a gas outlet tube leading to an alkali or water trap (Fig. II, 8, 1). Immerse the flask in a bath of Dry Ice - acetone, stir the mixture vigorously and pass commercial boron trifluoride (via an empty wash bottle and then through 95 per cent, sulphuric acid) as fast as possible (10-20 minutes) until the mixture, kept at 0-10°, is saturated (copious evolution of white fumes when the outlet tube is disconnected from the trap). Replace the Dry Ice-acetone bath by an ice bath and pass the gas in at a slower rate to ensure maximum absorption. Stir for 3 6 hours whilst allowing the ice bath to attain room temperature slowly. Pour the reaction mixture into a solution of 136 g. of hydrated sodium acetate in 250 ml. of water, reflux for 60 minutes (or until the boron fluoride complexes are hydrolysed), cool in ice and extract with three 50 ml. portions of petroleum ether, b.p. 40-60° (1), wash the combined extracts free of acid with sodium bicarbonate solution, dry over anhydrous calcium sulphate, remove the solvent by... 

Unlike boron fluoride, titanium tetrachloride does not catalyze the liquid phase polymerization of isobutylene under anhydrous conditions (Plesch et al., 83). The addition of titanium tetrachloride to a solution of the olefin in hexane at —80° failed to cause any reaction. Instantaneous polymerization occurred when moist air was added. Oxygen, nitrogen, carbon dioxide, and hydrogen chloride had no promoting effect. Ammonia and sulfur dioxide combined with the catalyst if these were added in small quantity only, subsequent addition of moist air permitted the polymerization to occur. Ethyl alcohol and ethyl ether, on the other hand, prevented the polymerization even on subsequent addition of moist air. They may be regarded as true poisons. 

The first reported instance of stereoselective polymerization was probably the cationic polymerization of isobutyl vinyl ether in 1947 [Schildknecht et al., 1947]. A semicrystalline polymer was obtained when the reaction was carried out at —80 to —60°C using boron tri-fluoride etherate as the initiator with propane as the solvent. The full significance of the polymerization was not realized at the time as the crystallinity was attributed to a syndiotactic structure. X-Ray diffraction in 1956 indicated that the polymer was isotactic [Natta et al., 1956a,b], (NMR would have easily detected the isotactic structure, but NMR was not a routine tool in 1947.)... 

Boron trifluoride and boron trifluoride-diethyl ether complex can be used as a source of fluoride ions in the presence of hypobromites and hypochlorites, e.g. methyl hypobromitc, tert-butyl hypobromite, methyl hypochlorite in carbon tetrachloride at 25 C. The addition of bromine monofluoride" and chlorine monofluoride" to various alkenes is accompanied by the formation of the corresponding alkoxybromides and alkoxychlorides which hinder the isolation of the halofluorinated products.57 jV-Bromo- and A -chloro-substiluted alkyl- and arylamines. -amides, and -imides, A -chloro-A,-methylamine, A -bromo-A -methylamine, A -chloro-A, /V-dimethylamine, A-bromo-A.A-dimethylamine, ACV-dichloro-A -methylamine, V,fV-dibromo-,V-mcthylaminc, A -bromosuccinimide, -V-chlorosuccinimide, Af-bromoacct-amide, A.A -dichlorourethane, can be used in the reaction instead of the hypohalites. The reactions with various alkenes conducted in dichloromethane at room temperature in the presence of boron trifluoride-diethyl ether complex produce bromofluoro and chlorofluoro addition products in 40-80 % yield. However, the reactions are complicated by the addition of A -halo-succinimides and Af.A-dichlorourcthane to the C = C bonds.58... 

The method of choice for adding hydrogen fluoride to oxiranes is the use of boron trifluoride-diethyl ether complex without added hydrogen fluoride. The reaction proceeds with rearrangements to yield the desired fluorohydrins and other byproducts. In some cases the ratio of products depends strongly on the reaction conditions used. 

Covalent fluorides of group 3 and group 5 elements (boron, tin, phosphorus, antimony, etc) are widely used in organic synthesis as strong Lewis acids Boron trifluoride etherate is one of the most common reagents used to catalyze many organic reactions. A representative example is its recent application as a catalyst in the cycloadditions of 2-aza-l,3-dienes with different dienophiles [14] Boron trifluoride etherate and other fluormated Lewis acids are effective activators of the... 

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