Fluorides antimony

The effectiveness of antimony fluoride is increased if it is used in conjunction with chlorine or with antimony pentachloride. The formation of either SbCl2F2 or a complex of SbF and SbCl probably accounts for the increased activity (4). 

The standard synthesis method features side-chain chlorination of a methylpyridine (picoline), followed by exchange-fluoriaation with hydrogen fluoride or antimony fluorides (432,433). The fluoriaation of pyridinecarboxyHc acids by sulfur tetrafluoride (434) or molybdenum hexafluoride (435) is of limited value for high volume production operations due to high cost of fluorinating agent. 

Fluor-, of or combined with fluorine, fluoro-, fluo-, fluoride of (see instances following),. ammonium, n. ammonium fluoride, -an-thenchinon, n. fluoranthenequinone. -anti-mon, n. antimony fluoride, -arson, n. arsenic fluoride, -baryum, n. barium fluoride, -benzol, n. fluorobensene, fluobenaene. -bor, n. boron fluoride. -borsMure, /. fluo-boric acid. -brom, n. bromine fluoride, -chrom, n. chromium fluoride, -eisen, n. iron fluoride. 

CsCl HgCl2=3 1, 2 1, 1 1, 2 3, 1 2, and 1 5 and five caesium antimonious fluorides where CsF SbF3=l 1, 3 4, 4 7, 1 2, and 1 3. According to I. Remsen s rale (1889) When a halide of any element combines with a halide of an alkali metal to form a double salt, the number of molecules of the alkali salt which are added to one molecule of the other halide is never greater, and is generally less than the number of halogen atoms contained in the latter—for instance, in the double fluoride of sodium and aluminium, where the negative halide has three fluorine atoms, no more than three molecules of sodium fluoride will be found united with one of aluminium fluoride. 

Bromine trifluoride, neat or dissolved in liquid bromine, has found application for the selective substitution of fluorine for bromine (Table 3).108,109 The reactions are carried out at temperatures of no more than 60 C. Under these conditions no hydrogen substitution is observed. As established for bromofluoroethanes. the relative ease of replacement of bromine in various groups decreases in the order tribromomethyl > dibromofluoromethyl > dibromomethyl > bromofluoromethyl > bromomethyl. The presence of fluorine at either the same or an adjacent carbon tends to retard the substitution. Bromine trifluoride is more effeetive than antimony fluorides as it replaces bromine in bromodifluoromethyl and bromomethyl groups. 

Introduction of Fluorine with Organo-Substituted Antimony Fluorides (PhnSbF5 n, n = 1-3)... 

Thus, aryl-substituted antimony fluorides provide replacement of chlorine by fluorine atoms in aromatic compounds containing trichloromethyl and pentachloro- or dichlorotri-fluoroethyl groups. Their activity as fluorinating agents decreases in the order tetrafluoro(phenyl)-A5-stibane > trifluorodi(phenyl)-25-stibane >antimony(lIl) fluoride dill uorotri(phenyl)-/i.5-stibane. 

Hydrogen fluoride can displace chlorines on either side chain or nucleus (especially 2-chloro), and antimony fluoride is specific for all chlorinated methyl groups. Sodium fluoride initially replaces a 4-chloro group (82JFC495). Some of these processes have been subjected to kinetic investigation, which demonstrated that in polar, aprotic solvents fluorine-chlorine exchange is a pseudo first-order, consecutive reaction (87JFC373). 

The Use of Potassium Fluoride, Zinc Fluoride, Antimony Fluorides, and Hydrogen Fluoride... 

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. 

The first step is set up to produce hydrogen fluoride and the second yields trichlo-romethane (chloroform). Chloroform is then partially fluorinated with hydrogen fluoride to chlorodifluoromethane using antimony fluoride as catalyst in the third step. Finally, in the fourth step, chlorodifluoromethane is subjected to pyrolysis in which it is converted to tetrafluoroethylene. The pyrolysis is a noncatalytic gas-phase process carried out in a flow reactor at atmospheric or subatmospheric pressure and at temperatures 590 to 900°C (1094 to 1652°F) with yields as high as 95%. This last step is often conducted at the manufacturing site for PTFE because of the difficulty of handling the monomer.9... 

Recently, various kinds of solid superacids have been developed. The first group is metal oxides and mixed oxides containing a small amount of sulfate ion, and those modified with platinum. The second group is metal oxides, mixed oxides, graphite, metal salts, etc. treated or combined with antimony fluoride or aluminum chloride. The third group is perfluorinated polymer sulfuric acid (Nafion-H). The fourth and fifth groups are H-ZSM-5 and a type of heteropolyacids, respectively. The last group is simply mixed oxides. 

Two structures of antimony fluorides with this empirical formula were mentioned in Section III.I because they were related to structures... 

---