Fluorination xenon difluoride

Cerium and terbium tetrafluoride can be prepared by the action of fluorine, xenon difluoride, and chlorine trifluoride on Ce02 or CeFs, and Tb407 or TbFs, respectively. These reactions are carried out at temperatures of 300-400 C in nickel or monel containers with exclusion of moisture and oxygen, For further details see the Gmelin Handbook (1976) and the literature cited therein. The preparation of... 

In xenon difluoride, the electronic structure shows three lone pairs around the xenon, and two covalent bonds to the two fluorine atoms hence it is believed that here xenon is using one p (doublepear) orbital to form two bonds ... 

K [14881-07-3], Rb [72151 -96-3], and Cs [72138-72-8]), are prepared by reaction of elemental fluorine, chlorine trifluoride, or xenon difluoride and a mixture of nickel fluoride and alkaH metal fluorides or other metal haHdes (16,17). If the fluorination is carried out using mixed fluorides, a lower temperature can be used, yields are quantitative, and the final products are of high purity. Bis(tetrafluoroammonium) hexafluoronickelate [6310540-8], (NE 2N iF6> prepared from Cs2NiF3 and NE SbE by a metathesis in anhydrous HE, is also known (18). 

Stable noble-gas compounds have no industrial uses as of this writing but are frequently utilized in laboratories as fluorinating and oxidizing agents. Xenon difluoride and xenon tetrafluoride are relatively mild oxidative fluorinating agents and have been used for the preparation of phosphoms, sulfur, tellurium. 

In addition, fluonne [97, 98], trifluoromethyl hypofluorite [99, 100], bisftri-fluoromethyOperoxide [100, 101], trifluoromethyl disulfide [100]. and xenon difluoride [102, lOi, 104] react with phosphines to give the corresponding diflu-orophosphoranes in yields ranging from 25% to near quantitative. Phosphites are fluorinated by carbonyl fluoride [95, 96] or 2-hydroperfIuoropropyl azide [f05J (equation 15). 

Trimethylarsine gives a 98% yield of trimethylarsine difluoride when treated with xenon difluoride [102] in fluorotrichloromelhane. and tnsfpentafluorophen-yl)arsine gives a 94% yield of tris(pentafluornphenyl)arsme difluoride after reaction with dilute fluorine in fluorotnchloromethane at 0 C [106] Other trivalent arsenic compounds have also been fluorinated with xenon difluoride [103] In addition, arsines have been oxidatively fluorinated by iodine pentafluoride [107] or electrochemically in 26-34% yield [108]... 

Xenon difluoride has been used to oxidize a number of antimony compounds [102, 109] in yields ranging from 73 to 98%. Elemental fluorine oxidized tris(pen-tafluorophenyl)stibine to tris(pentafluorophenyl)stibine difluoride in 98% yield [706]. Oxidative fluonnation of stibines has also been accomplished with iodine pentafluoride [707]. 

Pentafluorophenylditelluridc yields 79-80% pentafluorophenyltellunum tri fluoride on treatment with fluorine or xenon difluoride [105] The fluonnated tetravalent tellurium can be further oxidized to hexavalent tellurium with either xenon difluoride [/22] or fluorine [123]... 

Xenon difluoride is used to prepare methyliodine difluoride from methyl iodide [102, 128] as well as to convert miscellaneous aryl [103, 129, 110] heptafluorapropyl [129], and 2,2,2-trifluoroethyl [103] iodides to the corresponding organo iodine difluorides in yields ranging from 60 to 100% Elemental fluorine transforms aryl iodides to their corresponding aryliodine difluoride turn pounds [131 132], which are known to add fluorine to alkenes ]133] (equation 21)... 

Polymer-bound phenyliodine difluoride, which also has been used as a reagent to add fluorine to alkenes, can be prepared by the addition of xenon difluoride to the polymer [134, 135 136] Methyl iodide is converted to trifluoro methyliodine difluoride by treatment with fluorine at -110 C [137] Perfluoro-alkyliodine tetrafluorides could be synthesized from the perfluoroalkyliodine difluorides and fluorine [138] or chlorine trifluoride [139] Perfluoroalkyl [140] and perfluoroaryl [141] iodides are oxidized to the corresponding iodine difluorides by chlorine trifluoride. 

Electropositive fluorinating agents are categorized in distinct classes as (1) fluoroxy reagents, in which the fluorine is bound to an oxygen atom (for reviews, see references 1,2,3, 4, 5, and 6) (2) fluoraza reagents, in which the fluorine atom IS bound to the nitrogen atom of either an amide or ammonium ion structure (for a partial review, see reference 6), (3) xenon difluoride, in which the fluorine atoms are bound to xenon (for reviews, see references 5, 7, 8, and 114) and (4) perchloryl Iluoride, in which the fluorine atom is bound to the chlorine atom of the perchloryl function (for a review, see reference 9). 

Xenon difluoride [4, 5, 7, 8,10] is a white crystalline material obtained through the combination of fluorine and xenon m the presence of light The reagent is commercially available and possesses a relatively long shelf-life when stored cold (freezer) Xenon difluoride is very effective for small-scale fluormation of alkenes and activated nucleophilic substrates. The reactions are usually conducted between 0 °C and room temperature in chloroform or methylene chloride solutions Hydrogen fluoride catalysis is sometimes helpful Xenon difluoride reacts in a manner that usually involves some complexation between the substrate and reagent followed by the formation of radical and radical cation intermediates... 

Xenon difluoride fluorinates adamantane in low yield [45] (equation 22) When the carbon-hydrogen bond is activated by an a-sulfur atom, fliiorination occurs readily The reactions involve intermediates that contain sulfur-fluorine bonds. At-Fluoropyridinium reagents behave similarly [99, 100, 101, 102] (equations 55-57)... 

Preparation of 2-Fluoro-4-methylacetamlide, 166 Fluorination with A-ferf-Butyl-Al-fluorobenzenesulfonamide Preparation of 1-Fluoro-l-octene, 166 Fluorination with A-Fluoro-2,4,6-trimethylpyridinium Triflate Preparation of Diethyl Fluorophenylmalonate, 166 Fluorination with Xenon Difluoride... 

The most stable binary compounds of xenon are the three fluorides, XeF2, XeF4, and XeFB. Xenon difluoride can be prepared quite simply by exposing a 1 1 mol mixture of xenon and fluorine to ultraviolet light colorless crystals of XeF2 (mp = 129°C) form slowly. 

The starting point for the synthesis of xenon compounds is the preparation of xenon difluoride, XeF2, and xenon tetrafluoride, XeF4, by heating a mixture of the elements to 400°C at 6 atm. At higher pressures, fluorination proceeds as far as xenon hexafluoride, XeFfi. All three fluorides are crystalline solids (Fig. 15.27). In the gas phase, all are molecular compounds. Solid xenon hexafluoride, however, is ionic, with a complex structure consisting of XeF< + cations bridged by F anions. 

CF3OCI has been discussed ), fluorine (F2, diluted with inert gases), xenon difluoride (XeF2), acetyl hypofluorite (MeC02F), and related compounds. As basic aspects of reactions using some of these reagents have been described by Penglis in this Series, developments after 1978 will mainly be described. 

Though a powerful oxidant, the difluoride is not explosively unstable. Safe procedures for the use of xenon difluoride in fluorination reactions are detailed. Residual traces of the fluoride are rapidly destroyed by dichloromethane at ambient temperatures. 

Oxidative fluorination of 3-iodo-4-methylfurazan 216 with xenon difluoride in an atmosphere of dry argon at 20 °C in anhydrous MeCN yielded the corresponding difluoroiodanyl azole 217 (Equation 42) <2004RCB1130>. 

Oxidative Fluorination of Nitrones to a-Fluorosubstituted Nitroxyl Radicals Formation of nitroxyl radicals by the radical cation route was observed in reactions of various nitrones with xenon difluoride in dry methylene chloride (520, 523). In this reaction, more than 40 nitrones, including 4H -imidazole N,N -dioxides (219), 4H -imidazole TV-oxides (223) and (224), 2H -imidazole N -oxides (225), 2H -imidazole TV,TV-dioxides (226), 3,3,5,5-tetramethylpyrroline N -oxide (TMPO), derivatives of 3-imidazoline-3-oxides (231) and (232), have been examined. ESR spectra of nitroxyl radicals containing one or two fluorine atoms at a-C have been registered (Scheme 2.108) (523). In the case of... 

Surface Fluorination of Polymers Using Xenon Difluoride... 

POLYMER SURFACE FLUORINATION WITH XENON DIFLUORIDE... 

Xenon difluoride has proved to be an effective fluorinating agent for surface fluorination of polymers. 

Ill,A. Another fluorine bomb calorimeter is described (18) and further heats of formation of lanthanide trifluorides measured (1, 11, 16). A revised heat for UF differs appreciably from previous values (7). Xenon difluoride has been used as a thermochemical oxidant (19). 

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