Nitrogen trifluoride preparation

Nitrogen trifluoride and trichloride can both be prepared as pure substances by the action of excess halogen on ammonia, a copper catalyst being necessary for the formation of nitrogen trifluoride. 

Nitrogen trifluoride is prepared by electrolysis of either molten ammonium fluoride, NH4F, or melted ammonium acid fluoride, NH4HF2 (or ammonium fluoride in anhydrous HF). Whde the NH4F method is preferred because it forms nitrogen trifluoride as the only product, electrolysis of ammonium acid fluoride yields a small amount of dinitrogen difluoride, N2F2, and NF3. 

Also, nitrogen trifluoride can he prepared by reaction of ammonia with fluorine diluted with nitrogen in a reactor packed with copper. Other nitrogen fluorides, such as N2F2, N2F4, and NHF2 also are produced. The yield of major product depends on fluorine/ammonia ratio and other conditions. 

Watanabe, N., Ishigaki, I., Yoshizawa, S. Preparation of fluorine and its compounds. X. Electrode kinetics of the formation of nitrogen trifluoride. Denki Kagaku 32, 674 (1964). - Chem. Abstr. 63, 250 (1965). 

Nitrogen trifluoride and tetrafluorohydrazine were obtained from Peninsular ChemResearch, Inc., and Air Products Inc., respectively. Difluorodiazine was prepared by the reaction of N2F4 with A1C13 at -78° C. (9). 

Although nitrogen trifluoride can be prepared by several chemical procedures, only two methods are technically and economically feasible for a large-scale production The electrolysis of molten ammonium acid fluoride and the direct fluorination of NH3 in the presence of molten NH4F [71]. The direct fluorination is carried out in specially designed reactor [72] in which NF3 is produced by the reaction of F2 with NH3 in the presence of molten ammonium fluoride. As no hydrogen is generated in the direct fluorination process, it is considered safer than electrolytic process. In the later process, NF3 is produced at the anode and H2 at the cathode. 

These preparations, as well as the reaction of nitrogen trifluoride with mercury vapor in an electric discharge, and the fluorination of sodinm azide yield mixtnres of both isomers. The pure trans isomer is produced in 45% yield by the reaction of tetraflnorohydrazine with alnminnm trichloride, or by the reaction of a mixture of the N2F2 isomers with aluminnm trichloride. 

Preparation. The starting material for the preparation of this reagent is tetra-fluorohydrazine, made by reaction of nitrogen trifluoride with various metals at 375° (I). Conversion into difluoroamine is accomplished by heating tetrufluoro-hydrazine with Ihlophenol In an evacuated bulb yield 74%. ... 

Nitrogen Fluoride. Nitrogen trifluoride. F3N mol wt 71-01. F 80,27% N 19.73%, NF3. Prepd by electrolysis of melted ammonium acid fluoride NH4F2H Ruff et at, Z. Anorg. Ailgem. Chem. 172, 417 (1928) Ruff ibid. 197, 273 (1931) Ruff, Staub, ibid. 198 32 (1931) Kwasnik in Hand book of Preparative Inorganic Chemistry vol. S G. Brauer, Ed. (Academic Press New York 2nd ed. 1963) pp 181 -183. Reviews of prepn and chemistry Hoffman Neville, Chem. Rev. 62 1-18 (1962) Kemmitt, Sharp, Advan. Fluorine Chem. 4, 189-190 (1965). 

Nitrogen trifluoride reacts with activated charcoal at 150°C to give CF4 and N2 [4]. When nitrogen trifluoride is passed over petroleum coke in a fluidized bed at about 400 C, N2F4, CF4, C2F6, and NO are formed [5]. For the preparation of N2F4 by this method, see p. 301. 

Write an equation for the preparation of nitrogen trifluoride from ammonia. 

C Fj-NFa), trifluoromethyliminosulphur diiluoride [- - CFj-NFa, (CFa)2NF], pentafluoroethyliminosulphur difluoride CaFs NFa), cyanuric fluoride CFs-NF, (CFa)jNF], thiocyanuric acid [-< CFj-NFj, (CF8)aNF], melamine [- CF3 NF2, (CFs)aNF, CFa(NFa)a], methyl thiocyanate (-> CFa NFj), and methyl isothiocyanate CFs-NFa) carbon tetra-fluoride and nitrogen trifluoride were the major products from these fluorina-tions, and a study has been made of the production of the latter via electrochemical fluorination of urea and related compounds. Details of the production of AtALdifiuorotrifluoromethylamine via injection of carbon tetrafluoride into a nitrogen plasma at 1500—6000 K and direct fluorination of potassium cyanide" have appeared in the patent literature preparation of this difluoroamine by u.v. irradiation of a mbcture of hexafluoro-acetone and tetrafluorohydrazine has also been described, and the new compounds CFCla-NFa, CClj-NFg, and ClS-CCIj-NF, have been obtained by photolysis of the hydrazine in the presence of thiocarbonyl chloride. ... 

The controlled thermal decomposition of dry aromatic diazonium fluoborates to yield an aromatic fluoride, boron trifluoride and nitrogen is known as the Schiemann reaction. Most diazonium fluoborates have definite decomposition temperatures and the rates of decomposition, with few exceptions, are easily controlled. Another procedure for preparing the diazonium fluoborate is to diazotise in the presence of the fluoborate ion. Fluoboric acid may be the only acid present, thus acting as acid and source of fluoborate ion. The insoluble fluoborate separates as it is formed side reactions, such as phenol formation and coupling, are held at a minimum temperature control is not usually critical and the temperature may rise to about 20° without ill effect efficient stirring is, however, necessary since a continuously thickening precipitate is formed as the reaction proceeds. The modified procedure is illustrated by the preparation of -fluoroanisole ... 

The Balz-Schiemaim reaction is a useful laboratory and industrial method for the preparation of fluoroaromatics. The water-insoluble diazonium fluoroborate is filtered, dried, and thermally decomposed to give the aryl fluoride, nitrogen, and boron trifluoride (28—30). 

Preparation. Hexagonal boron nitride can be prepared by heating boric oxide with ammonia, or by heating boric oxide, boric acid, or its salts with ammonium chloride, alkaU cyanides, or calcium cyanamide at atmospheric pressure. Elemental nitrogen does not react with boric oxide even in the presence of carbon, though it does react with elemental boron at high temperatures. Boron nitride obtained from the reaction of boron trichloride or boron trifluoride with ammonia is easily purified. 

Bromine trifluoride may be prepared by fluorination of bromine at 80°C. The halogen mixtures may be diluted in nitrogen or an inert gas. 

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... 

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... 

Aryl fluorides also may be prepared from arenamines by way of dia-zonium salts if the procedure is slightly modified. The amine is diazotized with nitrous acid in the usual way then fluoroboric acid or afluoroborate salt is added, which usually causes precipitation of a sparingly soluble diazonium fluoroborate. The salt is collected and thoroughly dried, then carefully heated to the decomposition point—the products being an aryl fluoride, nitrogen, and boron trifluoride ... 

Borane can be prepared in situ as described in Expts 5.44 and 5.89. Alternatively, a separate solution of borane in tetrahydrofuran can be prepared by adding a solution of sodium borohydride to boron trifluoride-etherate and sweeping the resulting borane into tetrahydrofuran with the aid of a nitrogen gas stream. 

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