Oxygen Difluoride, OF

Oxygen difluoride (Of d Nitrogen fluorides MulticomiMHtent fuel Polymcri/ation of hypergohe fuel Analysis Rcfcrcnecs... 

OXYGEN DIFLUORIDE OF, Difluorine monoxide. Fluorine monoxide All combustible materiab. chlorine, bromine, iodine. pIMinum. metal oxides, mobt olr Not combustible, but strong oodizer ... 

PTFE is by far the most chemically resistant polymer among thermoplastics. The exceptions include molten alkah metals, gaseous fluorine at high temperatures and pressures and a few organic halogenat-ed compounds such as chlorine tri fluoride (CIF ) and oxygen difluoride (OF ). A few other chemicals have been reported to attack PTFE at or near its upper... 

Oxygen difluoride OF2 is obtained when a rapid stream of gaseous fluorine is passed through 2% caustic soda solution ... 

In the presence of excess caustic, the oxygen difluoride is gradually reduced to oxygen and fluoride ... 

In a caustic scmbbing system, caustic potash, KOH, is preferred to caustic soda, NaOH, because of the higher solubiUty of the resulting potassium fluoride. Adequate solution contact and residence time must be provided in the scmb tower to ensure complete neutralization of the intermediate oxygen difluoride, OF2. Gas residence times of at least one minute and caustic concentrations in excess of 5% are recommended to prevent OF2 emission from the scmb tower. 

In aqueous solution, OF2 oxidizes HCl, HBr, and HI (and thek salts), Hberating the free halogens. Oxygen difluoride reacts slowly with water and a dilute aqueous base to form oxygen and fluorine. The rate of this hydrolysis reaction has been determined (23). 

Nitric oxide and OF2 inflame on contact emission and absorption spectra of the flame have been studied (24). Oxygen difluoride oxidizes SO2 to SO, but under the influence of uv kradiation it forms sulfuryl fluoride [2699-79-8] SO2F2, and pyrosulfuryl fluoride [37240-33-8] S20 F2 (25). Photolysis of SO —OF2 mixtures yields the peroxy compound FSO2OOF [13997-94-9] (25,26). 

Oxygen Difluoride as a Source of the OF Radical. The existence of the OF radical [12061 -70-0] was first reported in 1934 (27). This work was later refuted (28). The OF radical was produced by photolysis of OF2 in a nitrogen or argon matrix at 4 K. The existence of the OF species was deduced from a study of the kinetics of decomposition of OF2 and the kinetics of the photochemical reaction (25,26) ... 

Carbonyl fluoride, COF2, and oxygen difluoride react in the presence of cesium fluoride catalyst to give bis(trifluorylmethyl)trioxide [1718-18-9] CF OOOCF (31). CF OOF has been isolated from the reaction in the presence of excess OF2 (32). 

Analytical Procedures. Oxygen difluoride may be determined conveniently by quantitative appHcation of k, nmr, and mass spectroscopy. Purity may also be assessed by vapor pressure measurements. Wet-chemical analyses can be conducted either by digestion with excess NaOH, followed by measurement of the excess base (2) and the fluoride ion (48,49), or by reaction with acidified KI solution, followed by measurement of the Hberated I2 (4). 

Handling and Safety Factors. Oxygen difluoride can be handled easily and safely in glass and in common metals such as stainless steel, copper, aluminum. Monel, and nickel, from cryogenic temperatures to 200°C (4). At higher temperatures only nickel and Monel are recommended. The compatibihty of OF2 with process equipment depends largely on the cleanliness of the equipment contaminants such as dkt, moisture, oil, grease, scale... 

Oxygen difluoride must be regarded as a highly poisonous gas, somewhat more toxic than fluoriae. It has a foul odor with a limit of detectabiUty of 0.1—0.5 ppm. Repeated exposure of rats to 0.5 ppm OF2 produced death repeated exposure to 0.1 ppm, however, caused no discernible effects. 

Perfluoroepoxides have also been prepared by anodic oxidation of fluoroalkenes (39), the low temperature oxidation of fluoroalkenes with potassium permanganate (40), by addition of difluorocarbene to perfluoroacetyl fluoride (41) or hexafluoroacetone (42), epoxidation of fluoroalkenes with oxygen difluoride (43) or peracids (44), the photolysis of substituted l,3-dioxolan-4-ones (45), and the thermal rearrangement of perfluorodioxoles (46). 

Chemical Reactivity - Reactivity with Water Reacts with water to form hydrogen fluoride, oxygen and oxygen difluoride Reactivity with Common Materials Reacts violently with all combustible materials, except the metal cylinders in which it is shipped Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

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)... 

Koepke, J.W. Jolly, W.L. The Core Binding Energies of Oxygen Difluoride J. Electron Spectros. Relal. Phenom. 1976, 9, 413-416. 

The acidic properties of methanesulphonic acid that have just been mentioned have been responsible for two other accidents. When this acid is contact with methyl and vinyl oxide, this caused the latter to polymerise violently. The electrolysis of methanesulphonic acid with an aqueous solution of hydrogen fluoride gives rise to a violent detonation that was put down to the formation of oxygen difluoride that is explosive. 

Electrolysis of a mixture produced oxygen difluoride which exploded. 

Mixtures of silica gel and the liquid difluoride sealed in tubes at 334 mbar exploded above -196°C, presence of moisture rendering the mixture shock-sensitive at this temperature [1], Reaction of oxygen difluoride with silica, alumina, molecular sieve or similar surface-active solids is exothermic, and under appropriate conditions may be explosive [2], A quartz fibre can be ignited in the difluoride [3],... 

Presence of water or water vapour in oxygen difluoride is dangerous, the mixture (even when diluted with oxygen) exploding violently on spark ignition, especially at 100°C (i.e. with steam). 

No interaction occurred at ambient temperature and at pressures up to 8 bar, but violent explosions occurred at low temperatures in the liquid phase, even in absence of the impurity oxygen difluoride. 

The use of liquid oxygen difluoride (40 or 90%) to stabilise liquid ozone as oxidant for gaseous hydrogen in a rocket motor was not entirely successful, explosions occurring at both concentrations. 

Used industrially in the manufacture of fluorocarbons as a chemical intermediate in the manufacture of sulfur hexafluoride, chlorine trifluoride, bromine trifluoride uranium hexafluoride, molybdenum hexafluoride, perchloryl fluoride, and oxygen difluoride and as a rocket propellant. 

Using Lewis symbols, write a balanced chemical equation showing the formation of oxygen difluoride, OF2, from isolated oxygen and fluorine atoms. 

R. C. King, G. T. Armstrong. Constant Pressure Flame Calorimetry with Fluorine II. The Heat of Formation of Oxygen Difluoride. J. Res. Nat. Bur. Stand. 1968, 72A, 113-131. 

The above book [1] deals, in 26 chapters in 5 sections, with theoretical and practical aspects of the use and safe handling of powerful oxidants and their complementary reactive fuels. Materials include nitrogen pentaoxide, perfluoroam-monium ion and salts, nitronium tetrafluoroborate, hydrazinium mono- and diperchlorates, nitronium perchlorate, tricyanomethyl compounds, difluoramine and its alkyl derivatives, oxygen difluoride, chlorine trifluoride, dinitrogen tetraoxide, bromine trifluoride nitrogen fluorides, and liquid ozone-fluorine system. 

ACGIH Oxygen difluoride. Documentation of the TLVS and BEIs, 6th ed, p 1153-54. Cincinnati, OH, American Conference of Governmental Industrial Hygienists, 1991... 

Davis UV Acute toxicity of oxygen difluoride, Proceedings of the First Annual Conference on Environmental Toxicology, AMRL-TR-70-102, pp 329-340. Wright-Patterson Air Force Base, OH, Aerospace Medical Research Laboratory, 1970... 

Antimony pentachloride reacts explosively with phosphonium iodide, PH4I (Mellor, J. W. 1947. A Comprehensive Treatise on Inorganic and Theoretical Chemistry, Oxford, UK Longmans and Green) and explodes mildly when treated with oxygen difluoride at 150°C (Bretherick, L. 1995. Handbook of Reactive Chemical Hazards, 5 h edition, ed. P.G.Urben, p. 1420. Oxford, UK ... 

Reaction of fluorine with an aqueous alkah solution is complex and depends on reaction conditions. A major product of such reaction is oxygen difluoride, OF2. In cold alkah solution, the products constitute metal fluoride, oxygen difluoride, water, and oxygen ... 

Commercial applications of oxygen difluoride are bmited. It is used in organic synthesis to prepare fluoropropylenes and acylfluorides. It is used as an oxidizing and fluorinating agent in many preparative reactions and as a monomer in diolefin copolymerization. 

Oxygen difluoride may be prepared by passing buorine gas slowly through a ddute solution of caustic soda. Usually a 2% solution of NaOH is suitable for the preparation ... 

Oxygen difluoride can be produced by electrolysis of an aqueous solution of HF or, alternatively, electroylzing molten potassium hydrogen difluoride, KHF2, in the presence of water. 

Oxygen difluoride reacts with many common metals forming fluorides. The reaction stops when the metal surface is covered with a protective layer of fluoride ... 

Oxygen difluoride may be analyzed by GC, GC/MS, IR, and NMR methods. The compound may be identified by GC/MS, the characteristic mass ions are 54, 38 and 35. The compound can be measured quantitatively by wet methods based on its strong oxidizing ability (see Reactions). It liberates I2 from an acidified solution of potassium iodide and the liberated I2 can be measured by iodometric titration using Na2S20s titrant and starch indicator. Alternatively, the compound may he treated with a measured amount of excess NaOH and the unreacted excess NaOH measured hy titrating against a standard solution of HCl. Also, the fluoride ion, F, may he measured by fluoride selective electrode. 

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