Reaction with antimony fluoride

Organic fluorine compounds were first prepared in the latter part of the nineteenth century. Pioneer work by the Belgian chemist, F. Swarts, led to observations that antimony(Ill) fluoride reacts with organic compounds having activated carbon—chlorine bonds to form the corresponding carbon—fluorine bonds. Preparation of fluorinated compounds was faciUtated by fluorinations with antimony(Ill) fluoride containing antimony(V) haUdes as a reaction catalyst. 

Xeaoa difluoride behaves as a fluoride ioa doaor toward many metal pentafluorides to form complex salts containing the XeF" and Xe2F" 2 cations (10). In reactions with the pentafluorides of arsenic, antimony, and mthenium, for example, it forms the salts Xe2F" 2AsF(, [21308-45-2], XeF" AsF(, [26024-71-5], [12528-47-1], XeF+Sbp-g [36539-18-1], [17679-45-7], [15364-10-0], [36539-19-2], [26297-25-6],... 

At 225—275°C, bromination of the vapor yields bromochloromethanes CCl Br, CCl2Br2, and CClBr. Chloroform reacts with aluminum bromide to form bromoform, CHBr. Chloroform cannot be direcdy fluorinated with elementary flourine fluoroform, CHF, is produced from chloroform by reaction with hydrogen fluoride in the presence of a metallic fluoride catalyst (8). It is also a coproduct of monochlorodifluoromethane from the HF—CHCl reaction over antimony chlorofluoride. Iodine gives a characteristic purple solution in chloroform but does not react even at the boiling point. Iodoform, CHI, may be produced from chloroform by reaction with ethyl iodide in the presence of aluminum chloride however, this is not the route normally used for its preparation. 

Carbon tetrachloride is used to produce chlorofluorocarbons by the reaction with hydrogen fluoride using an antimony pentachloride (SbCls) catalyst ... 

In view of the high toxicity of (II), it seemed that the sulphur analogue, dimethylaminosulphonyl fluoride (VI), might be of some interest. We therefore studied the fluorination of dimethylaminosulphonyl chloride. The reaction with potassium fluoride was incomplete, and that with zinc fluoride unsatisfactory, but that with antimony trifluoride using benzene as a solvent proved to be very satisfactory, and an 80 per cent yield of (VI) was obtained. Physiological examination showed that (VI) caused no irritation when small animals were exposed to a concentration of 1 mg./l. for 10 min., and no deaths took place. With the sulphonyl chloride at the same concentration, lacrimation and nasal irritation were caused no deaths were recorded, and all the animals recovered almost immediately on being removed from the chamber. 

Antimony pentafluoride is prepared by the reaction of antimony pentachlo-ride with anhydrous hydrogen fluoride ... 

A number of routes to thiocarbonyl fluoride that do not involve tetrafluoro-dithietane have been developed. In one (50), phosgene is chlorinated to give tri-chlorosulfenyl chloride, which is converted to chlorodifluorosulfenyi chloride by reaction with antimony trifluoride, and the fluorinated compound is then dehalogenated by reaction with tin. 

The first long-lived fluorine-containing carbocation was discovered by Olah and coworkers.32 Thus, the fluorodimethylcarbcnium ion [Me2CF+] was obtained by protonation of 2-fluoropropene and also from 2,2-difluoropropane by reaction with antimony(V) fluoride. In the course of these investigations it was found that a-F stabilizes a cationic state, whereas fi-F is destabilizing. Attempts to prepare the simplest member of this class, the trifluoromethyl carbocation CF3+ failed. The ionization of trifluoromethyl halides with antimony(V) fluoride at — 80 C yielded only carbon tetrafluoride. 

Bromo-l-chloro-l,l-difluoroethane (3) is prepared from l,2-dibromo-l,l-dichloroethane (1) in good yield when the fluorination reaction with antimony(III) fluoride/antimony(V) chloride is conducted in two steps. 

The relative fluorination activity of the aromatic antimony(V) fluorides can be judged by comparing the products of their reaction with (trichloromethyl)benzene conducted in l-2mL of dichloromethane for 2 hours at a fluorinating agcnl/substrate ratio of 1 -1.2 1 (Table 4).104... 

Similarly l-chloro-2,3,4,5-tetrakis(trifluoromethylsulfanyl)pyrrole (14) is converted to the 1-fluoro derivative 15 by reaction with sodium fluoride in the presence of antimony(III) oxide in 76% yield.16... 

A series of functionalized alkenes has been subjected to selective epoxidation reactions. Oxidation of perfluorinated vinyl polyethers by bubbling oxygen through the liquid that contains a catalytic amount of a Lewis acid, e.g. antimony(V) fluoride, results in the formation of acid fluorides together with a smaller amount of C = C bond cleavage.76 Perfluorinated pentaaIkyI-2.3-dihydrofuran 38, an example of an unsaturated cyclic ether that is quite stable owing to perfluoroalkylation. is epoxidized by hypochlorite to the product 39 at 45 C.62... 

The vapor-phase pyrolysis of pcrfluorohept-1-ene at 400 C in the presence of carbon results in complete conversion into the isomeric hept-2- and hept-3-enes in a ratio of 1 3.4.34 As noted above, mixtures are also obtained with cesium fluoride and letraelhylammonium fluoride. Only the antimony(V) fluoride reaction allows selective rearrangement to the alk-2-ene. 

Trisubstituted perfluorooxirane 12 does not react with antimony(V) fluoride alone, even at 300 C. Reaction with the combination antimony(V) fluoride/perfluorotoluene, however, results in rearrangement to perfluorotetrahydrofuran 13 in good yield at only 100°C.48... 

In the same way as intramolecular displacement leads to particularly stable atomic groupings within a molecule, the disproportionation reactions between several molecules are attributable to the tendency for the more stable compound with the higher fluorine content to form. Reactions of this kind are sometimes used to obtain highly fluorinated compounds from products with lower fluorine contents, for example, the catalytic fluorination of chloroalkanes with hydrogen fluoride or with fluorination agents such as antimony(V) fluoride or antimony(III) fluoride. The chlorine compound formed as the second product of the disproportionation process is reused as the starting material for the preparation of the compound to be dispropor-tionated. 

A very reactive halogen atom, such as that of mi acyl or sulfonyl halide, is replaced by fluorine by the action of almost any inorganic fluoride. The most convenient method consists in heating gently a mixture of an acyl or sulfonyl chloride with zinc or antimony fluoride in an apparatus which permits the acyl fluoride to distil as it is formed. The acyl fluoride usually boils about 40° lower than the chloride, and its removal from the reaction mixture results in quantitative yields. Com- plete interchange also can be effected with hydrogen fluoride, but more elaborate equipment is required. Good results have been reported for the synthesis of formyl and acetyl fluorides from mixtures of fonnic or... 

Hydrogen fluoride alone undergoes exchange reactions only with very reactive organic halides. However,. because it reacts with antimony chloride to form antimony fluoride and hydrogen chloride,34 it can be used to transform a large amount of organic halide to the fluoride with the aid of only small.amounts of antimony salts. This is the method used in industry for the preparation of dichlorodifluoromethane.34-36... 

It has not yet been possible to employ hydrogen fluoride in conjunction with mercuric fluoride in a process comparable to that with hydrogen fluoride and antimony fluorides (p. 56). At room temperature there is practically no reaction between hydrogen fluoride and mercuric chloride, and at temperatures high enough to permit the reaction the practical difficulties of operation are such that the process is without value.6 ... 

Preparation of Antimony Trifluorodichloride (SbF3Cl2). This is made in the steel reaction vessel, described on p. 59. A known quantity of antimony fluoride is placed in the vessel the vessel is evacuated, the needle valve is closed, and the whole is weighed. Connection is established to a chlorine cylinder, and the needle valve is opened to permit qhlorine to fill the vessel. Part of it is absorbed rapidly by the salt, with evolution of heat. Soon the reaction slows down as indicated by the rate of pressure fall when the needle valve is dosed. Weighing indicates the amount of chlorine present in the vessel. When the absorption practically ceases, the valve is closed, and the connection with the chlorine tank is removed. The reaction vessel is alternately heated gently, then allowed to cool in order to permit SbFsCl2, which is a viscous liquid, to flow and expose fresh surfaces of crystalline antimony trifluoride. The operation is ended after the absorption of the desired quantity of chlorine. 

Xenon difluoride reacts also with some halosubstituted alkanes18,19 at room temperature in chloroform, carbon tetrachloride, dichloromethane or bromoform, and depending on the nature of the solvent used chloro or bromo derivatives are isolated with imidazo-(l,2-fr)-pyridazine18. Carbon tetrachloride reacts with xenon difluoride at 180°C, while room-temperature transformations are achieved when various catalysts [antimony trifluoride, tantalum(V) fluoride or silica dioxide] are used, whose structure also influences the product distribution20. Tris(fluorosulfonyl)methane gives a fluoro-substi-tuted product in its reaction with xenon difluoride in difluorodichloromethane21. 

Delay compositions are mixtures of materials which, when pressed into delay tubes, react without evolution of gaseous products and thus ensure the minimum variation in the delay period. Examples of such mixtures are potassium permanganate with antimony lead dioxide or minium with silicium redox reactions with fluorides and other halides (- also Coruscatives and -+ delay gasless). 

Haloethenes can be fluorinated at the double bond by the reaction with antimony(V) fluoride,... 

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