Bromine trifluoride reactions

Bromine Trifluoride. Reaction with bromine trifluoride gives solid that ignites when dry.3... 

The halogen fluorides are binary compounds of bromine, chlorine, and iodine with fluorine. Of the eight known compounds, only bromine trifluoride, chlorine trifluoride, and iodine pentafluoride have been of commercial importance. Properties and appHcations have been reviewed (1 7) as have the reactions with organic compounds (8). Reviews covering the methods of preparation, properties, and analytical chemistry of the halogen fluorides are also available (9). 

Liquid Halogen Fluorides as Reaction Media. Bromine trifluoride and iodine pentafluoride are highly dimerized and behave as ionizing... 

Bromine Trifluoride. Bromine trifluoride is produced commercially by the reaction of fluorine with bromine ia a continuous gas-phase process where the ratio of fluorine to bromine is maintained close to 3 1. It is also produced ia a Hquid-phase batch reaction where fluorine is added to Hquid bromine at a temperature below the boiling poiat of bromine trifluoride. 

Bromine monofluoride [13863-59-7], BrF, can be prepared by the direct reaction of Br2 and F2, but because it readily disproportionates it has never been prepared in pure form (57). However, BrF can be prepared in situ by the reaction of Br2 with AgF in benzene (58) or by the reaction of A/-bromoacetamide and HF in ether (59). BrF adds to simple alkenes at room temperature to give products of trans-addition. Bromine trifluoride [7787-71-5], BrF, can be formed from gaseous fluorine and Hquid bromine (60). Bromine pentafluoride [7789-30-2], BrF, is formed from the reaction of BrF vapor with gaseous fluorine at 200°C (60). The tri- and pentafluorides are commercially available. As strong fluorinating agents they are useful in... 

Reactions of the halogen iluorides with other unsaturated functional groups are generally reported only with highly fluorinated substrates Hexafluorobenzene and denvatives [118] and octaflvoronaphthalene [119] react with mixtures of bromine and bromine trifluoride by 1,4 addition of fluorine followed by addition of bromine fluoride across a reniatning double bond (equation 22)... 

Pt is attacked by bromine trifluoride at 280° in the presence of K fluoride (Ref 5). Finely divided Pt and some other metals will cause a mixt of Hj and 02 to explu at ordinary temps (Ref 1). A little Pt black dropped into a hydrogen peroxide soln can cause an expln (Ref 2). Pt and molten Ii react violently at 540° 20° (Ref 7), and an incandescent reaction occurs when it is wanned gently in gaseous oxygen difluoride (Ref 6). The decompn of 92% per-monosulfuric acid is expl in the presence of smooth or finely divided Pt (Ref 3). The re-. acting mass formed by the mixt of P and Pt can become incandescent when heated (Ref 8). Dry, used Pt catalyst has exWd while being screened (Ref 4)... 

N2, and bromine trifluoride at 25-35°C " are also highly regioselective for tertiary positions. These reactions probably have electrophilic, not free-radical mechanisms. In fact, the success of the F2 reactions depends on the suppression of free-radical pathways, by dilution with an inert gas, by working at low temperatures, and/or by the use of radical scavengers. 

C21-0093. Some pure liquid interhalogen compounds are good electrical conductors, indicating that they contain cations and anions. Show a Lewis acid-base reaction between two bromine trifluoride molecules that would generate ionic species. 

During evaporation of solvent hydrogen fluoride, an exothermic reaction between residual ketone and bromine trifluoride set in and accelerated to explosion. 

Bromine trifluoride has also been used extensively as a nonaqueous solvent that behaves in some reactions as if it ionized slightly according to the equation... 

For the more vigorous reactions, a twin-cell calorimeter was devised (188). It consisted of two nickel cylinders connected by a stainless steel needle valve and tubing and held rigidly to a metal top-plate. The cylinders and connections were immersed in a wide-necked Dewar vessel containing carbon tetrachloride which would react mildly with any BrF3 that escaped. Bromine trifluoride contained in one cylinder was transferred to the solid contained in the other cylinder by opening the valve and applying controlled suction. All measurements were made externally on probes in the carbon tetrachloride. 

Safety precautions applicable to direct liquid phase fluorination of aromatic compounds are discussed [1]. Attention is drawn to the hazards attached to the use of many newer fluorinating agents [2], In a study of fluorination reactions of hafnium and zirconium oxides by the fluoroxidisers xenon difluoride, chlorine trifluoride and bromine trifluoride, reactivity decreased in the order given [3],... 

It is possible to titrate an acid with a base in bromine trifluoride solution and to follow the reaction conductimetrically (e.g. BrFgSbFg + KBrF = KSbFg + 2 BrFg). Moreover, with the dibasic acid (BrF2)aSnF6 and JKBrF4 the equivalence point is observed at a 1 2 ratio of acid to base ... 

These neutralization processes may be used for the preparation of various complex fluorides without actually isolating the acid or the base. Thus, for example, if equivalent quantities of metallic silver and gold are dissolved in bromine trifluoride and all volatile material is removed in vacuum, the salt AgAuFg remains. The usefulness of this method is increased by the apparent existence in bromine trifluoride solution of both acids and bases which are not sufficiently stable to be isolated. This is well illustrated by the reaction of potassium metaphosphate with bromine trifluoride, which gives a quantitative yield of KPFg ... 

Reaction of Bromine Trifluoride with Carbon Tetrachloride, Tetrabromide and Tetraiodide and with Tetraiodoethylene. J. Chem. Soc. 1948, 2188-... 

Fluorine also reacts with other halogens, forming interhalogen compounds. While with bromine and iodine it reacts vigorously at ordinary temperatures, with chlorine the reaction occurs at 200°C. Such interhalogen products with these halogens include iodine heptafluoride, bromine trifluoride, bromine pentafluoride, and chlorine trifluoride. Metalloid elements, such as arsenic, silicon, selenium, and boron also inflame in a stream of fluorine, forming fluorides. 

Bromine monofluoride or iodine monofluoride can be prepared from the corresponding elements in trichlorofluoromethane at — 781 and — 45 C,2,3 respectively. The compounds are unstable and decompose at low temperatures, iodine monofluoridc at — 14 C2,3 and bromine monofluoride, in part, even at — 78 C.1 Therefore, they are used, without separation and purification, in Freon solutions at low temperatures or, most frequently, as stoichiometric mixtures bromine trifluoride/bromine and iodine pentafluoride/iodine. A solution of iodine monofluoride, obtained by bubbling nitrogen-diluted fluorine gas into a suspension of iodine in trichlorofluoromethane at — 75 C, was used for addition to alkene C = C bonds. The reaction is regioselective and in most cases obeys the Markovnikov rule.4 Iodine monofiuoride prepared in situ reacts quite efficiently with steroidal alkenes.4... 

The mixtures bromine trifluoride/bromine and iodine pentafluoride/iodine can be successfully employed to prepare bromo- and iodo-substituted fluoroalkanes by addition to poly-fluoroalkenes. The reactions are carried out, in the presence of catalysts aluminum, aluminum/ aluminum triiodide9 or without a catalyst,10 in steel reactors at room temperature or with heating. In most cases the addition products are obtained in high yield (see Table 1). 

The equimolar mixture of bromine trifluoride and bromine can be employed for the bro-mofluorination of fluorine-free alkcncs such as (Z)- and( )-l,2-dichloroethene, methyl acrylate and its a-substituted derivatives.1 The reactions are carried out in l,l,2-trichoro-l,2,2-tri-fluoroethane (CFC-113) using a 25-35 % excess of bromine trifluoridc/ bromine. The direction of the bromine monofluoride" addition to multiple bonds in the esters, much as in other electrophilic reactions, depends on the electronic nature of the substituent R. 

This method can be applied to introduce CF, and CF3 groups at oxygen and nitrogen atoms in various molecules. oe,a-Difluoro ethers are prepared from O-alkyl(aryl) carbothioales in moderate to good yields by reaction with tetrabutylammonium dihydrogen trifluoride and /V-bromosuccinimide or /V-iodosuccinimide,64 or with bromine trifluoride.65... 

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. 

Table 3. Reactions of Bromine Trifluoride with Fluoroalkyl Bromides108...

Bromine trifluoride is used to selectively substitute fluorine for bromine in brominated alkanes and esters. The reactions are carried out by gradual addition of bromine trifluoride to a solution of the substrate in CFC-113 or CFC-112 at 10-20nC. The bromine-fluorine exchange in mono-bromohaloalkanes is nonstereoselective and accompanied, in some eases, by skeletal rearrangements, hydride shifts, and halogen migrations. All three fluorine atoms in bromine trifluoride are involved in the fluorination reaction. Chlorine atoms in the substrate molecules remain intact.109... 

The reactivity of bromine trifluoride is significantly enhanced by Lewis acids, such as tin(IV) chloride, antimony(V) chloride, titanium(IV) chloride, which are exchanged to the corresponding fluorides and give complexes with bromine trifluoride. Thus, the reaction of 2,2,2-tri-fluoroethyl or 2,2,3,3-tetrafluoropropyl 2,3-dibromopropanoate with bromine trifluoride in the presence of 1 mol% tin(IV) chloride affords the corresponding 2,3-difluoropropanoates in 85-87% yield.110... 

When the same reaction is performed with adamantanone dinitrophenylhydrazone (DNP) or adamantanone O-mcthyloxime (OMO), the yields of 2,2-difluoroadamantanc are 65 and 50%, respectively. 4-tert-Butylcyclohexanone is converted via its azine, DNP or OMO into 4-tert-butyl-l.l-difluorocyclohexanc in 65, 75 or 50% yield, respectively. Similar results are obtained with aliphatic straight-chain ketones. Decan-2-one azine and decan-2-one DNP can be transformed into 2,2-difluorodecane in 60 and 80% yield. Deactivated aromatic rings, e.g. in 3-nitroacetophenone, do not undergo bromination with bromine trifluoride and the action of 2 equivalents of bromine trifluoride on 3-nitroacetophenone O-methyloxime results in 90% yield of 1-(1. l-difluorocthylj-S-nitrobenzene.122... 

Bromine trifluoride is also used to convert the cyano group in acetonitrile, chloroacetonitrile, and propionitrile into the trifluoromethyl substituent. The reaction is carried out using hydrofluoric acid as a solvent.126... 

In some esters, bromine trifluoride selectively replaces the tertiary hydrogen atom with fluorine.127 The reaction is carried out in CFC-113 at 25-35 C with 60-80% excess bromine trifluoridc. The products are obtained in 40-50% yield. 

With Freon 112orll3asa solvent, fluonnation of primary butyl halides with bromine trifhionde can give mixtures of primary and secondary fluorides When 1,4 dibromobutane is the substrate, 93% l-bromo-4-fluorobutane and 7% 1-bro-mo-3-fluorobutane is obtained, with 1,4 dichlorobutane, the product contains 65% l-chloro-3-fluorobutane and 35% 1-chloro 4 fluorobutane When 4-bromo- or 4-chlorobutyl trifluoroacetate is used, the ratio of 4-fluorobutyl tnfluoroacetatE to 3 fluorobutyl trifluoroacetate is 1 4 The effect of solvent is measured m another set of experiments When the reaction of bromine trifluoride and 1,3-dichloro-2-fluoropropane in either Freon 113 or hydrogen fluoride is allowed to proceed to 40% conversion, the product mixture has the composition shown in Table 1 [10] When 1 chloro 2,3-dibromopropane is combined with one-third of a mole of bromine trifluoride, both 1 bromo 3 chloro-2-fluoropropane and 1 -chloro-2,3-di-fluoropropane are formed [17] (equation 10)... 

JCS 1948, 2135-38 (Reaction of bromine trifluoride with metallic halides) 58)J.Prat,... 

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