Antimony trifluoride fluorination

Antimony trifluoride fluorination of m- or p-fluorophenyldichloro-phosphines affords only the pentavalent derivatives (266). 

A series of methylphosphonofluoridous esters has been synthesized recently using either the low-temperature reaction between methyl-difluorophosphine and the sodium alcoholate, or via antimony trifluoride fluorination of the corresponding chloridous ester 185). Alkylphos-... 

Antimony trifluoride, Sbp3, m.p. 292°C, sublimes319 C(Sb203 in HFsolution). Forms complex ions, e.g. [SbFJ". Widely used as a fairly mild fluorinating agent. 

Alkoxy fluorides are prepared using acetyl fluoride. Alternatively, antimony trifluoride can be used to replace one alkoxyl by fluorine (58) ... 

In the presence of catalysts, trichloroethylene is readily chlorinated to pentachloro- and hexachloroethane. Bromination yields l,2-dibromo-l,l,2-trichloroethane [13749-38-7]. The analogous iodine derivative has not been reported. Fluorination with hydrogen fluoride in the presence of antimony trifluoride produces 2-chloro-l,l,l-trifluoroethane [75-88-7] (8). Elemental fluorine gives a mixture of chlorofluoro derivatives of ethane, ethylene, and butane. 

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. 

An attempt to prepare 1 -bromo-2-fluoroethane by the partial fluorination of ethylene dibromide by means of antimony trifluoride was not very successful. The compound was best prepared by the action of phosphorus tribromide on F.E.A. The compound was relatively non-toxic and the bromine atom rather unreactive, but considerably more reactive than the chlorine atom in chlorofluoroethane. For example, bromofluoroethane was readily converted by means of potassium thiocyanate into 2-fluoroethyl thiocyanate. As a lethal inhalant the toxicity of the thiocyanate was inferior to that of M.F.A. Toxicity by injection, however, appeared to be higher. 

Several methods are available for the synthesis of CFsSBr. Either CF2BrSBr is fluorinated at 100°C with antimony trifluoride (186) or CFsSCl is reacted with bromine cyanide over activated carbon at 70°C (86). Apart from that it is obtained always contaminated with CFsSSCFj in the reaction between Hg(SCF8)2 and bromine (31) these compounds react at 0°C to give a mixture composed of 56% CFsSBr and 45% CFjSSCFs. 

It may also be prepared from antimony trifluoride and fluorine, or by treating antimony pentaoxide with aqueous hydrofluoric acid and evaporing water. 

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. 

It must be concluded, therefore, that fluorophosphines are strongly reducing, a fact which was confirmed in further attempts at their preparation, using different reagents in the fluorination of chlorophosphines. There was either no reaction at all under the experimental conditions—e.g., with alkali fluorides in benzene as a solvent—or the trivalent phosphorus in the starting chlorophosphine was readily converted to the quinquevalent state—e.g., when phenyldichlorophosphine reacted with sodium fluoride in the presence of an antimony trioxide catalyst in a polar solvent such as acetonitrile to give phenylphosphonic difluoride. Recent Russian work showed that phenyldichlorophosphine was converted into phenyltetrafluoro-phosphorane, C6H5PF4, when it reacted with antimony trifluoride (34),... 

A slightly exothermic reaction took place when the antimony trifluoride was gradually added to the chlorophosphine. The temperature in flask I was maintained sufficiently high to allow distillation of the volatile fluorination products immediately after their formation. Material boiling at 35° to 55° was carefully redistilled at a slow rate. Chloromethyldifluorophosphine was collected, boiling at 33.5°-34.5°. Yield was 29.7 grams (83.5%). 

Organic compounds Organic fluorine compounds arc made by reaction of the corresponding alkane chloro-compounds with silver fluoride, mercurous fluoride, antimony trifluoride, titanium tetrafluoridc. and the arene fluoro-compounds by the diazo-reaction using hydrogen fluoride, and otherwise. The effect of the continued replacemenl of hydrogen atoms by fluorine atoms is an initial increase in reactivity, followed by a reversal of this effect, so lhal the highly substituted compounds arc relatively inert, See also Fluorocarbon. 

SWARTS REACTION. Fluorination of organic polyhalides with antimony trifluoride (or zinc and mercury fluorides) in the presence of a trace of a pentavalent antimony salt. 

Replacement of either one or two of the chlorines of carbon tetrachloride by fluorine can be achieved readily with antimony trifluoride containing some antimony pentachloride. The reaction stops after two chlorines have been replaced. The antimony trifluoride can be regenerated continuously from the antimony chloride by addition of anhydrous hydrogen fluoride ... 

The only fluoropentaborane known is the 2-substituted derivative which was obtained by the reaction of 2-IB5H8 with antimony trifluoride in a flow system at low pressure 184). The compound is a liquid which is moderately stable at room temperature. No boron-fluorine spin coupling is evident in the boron-11 nmr spectrum, but a poorly resolved quartet (Jpb = 60 hz) is observed in the fluorine-19 nmr spectrum. The analogous reaction of I-IB5H8 with antimony trichloride gave a product which was too unstable to characterize 184>. 

First, antimony trifluoride is treated with chlorine and thus antimony dichlorotrifluoride is formed. This compound catalyzes intramolecular rearrangement of fluorine with the simultaneous allylic shift of the double bond. As in Explanation 99, the tendency is to accumulate fluorine at the same carbon. The product is 1-chloroperfluoropropene Z [756]. 

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