Xenon difluoride, hydrolysis

Unsaturated sugars, namely glycals, such as 3,4,6-tri-Oacetyl-l, 5-anhydro-2-dcoxy-D-r//v/-/w7o-hex-1-enetol and the d-/v.yo epimer react with xenon difluoride in the presence of a boron trifluoride-diethyl ether complex to give a mixture of C2 epimeric fluorides.45,46 Tri-O-acctyl-D-galactal treated with xenon difluoride in trichlorofluoromcthane below 5 C forms after hydrolysis (0.5 M HC1) 2-deoxy-2-fluoro-D-galactose in 63% overall yield.47... 

Hydroxy-3-methoxy-L-phenylalanine reacts with xenon difluoride to form after acidic hydrolysis by hydrogen bromide 6-fluoro-3,4-hydroxy-i.-phenylalanine (6-F-DOPA) in 25 % yield.66... 

Xenon difluoride dioxide cannot be Isolated as an Intermediate between the partial hydrolysis to form XeOF4 and complete hydrolysis to Xe03. bin may be prepared by combining these two species ... 

By comparison, hydrolysis of xenon difluoride results only in decomposition ... 

Korytnyk and coworkers have shown that reactions of xenon difluoride with acetylated glycals in the presence of boron trifluoride are a convenient route for the synthesis of 1,2-difluoro sugars, while the addition of fluorine to the double bond occurred predominantly from the less hindered side and cis adducts were mainly formed75, 76. Stereoselective transformation of tri-O-acetyl-D-galactal with xenon difluoride at -20 to +5 °C, without a catalyst in CFC13, after hydrolysis, afforded 2-deoxy-2-fluoro-D-galactose in 63% yield77. 

Xenon difluoride is easy to make, and relative to other xenon fluorides, safe to handle. It is therefore attractive as a reagent. Because of its low average bond energy ( 30 kcal. mole- ) and the "inertness of its reduction product (Xe) it has considerable potential in oxidative fluorinations. However, others have shown that the compound has considerable kinetic stability, e.g. it may be retrieved from aqueous solution in which it is thermodynamically unstable towards hydrolysis. 

Xenon difluoride dissolves in water, yielding a solution which contains undissociated XeFa molecules which have a half-life of about 7 hours at 0°. It eventually hydrolyzes to yield the expected products, xenon, hydrogen fluoride, and oxygen. The hydrolysis reactions of the tetrafluoride and hexafluoride are somewhat more complicated. The addition of the stoichiometric amount of water to the hexafluoride results in the formation of xenon oxide tetrafluoride. Hydrolysis of either fluoride with an excess of water or acid yields in solution a stable xenon(VI) species, which has been shown to be hydrated xenon trioxide. Removal of the excess water leaves xenon trioxide as a solid residue. Inasmuch as this solid is an extremely sensitive explosive, such solutions must be handled with care. 

Robins, M. J., Wnuk, S. F., Mullah, K. B. and Dailey, N. K. (1994) Nucleic Acid related compounds. 80. Synthesis of 5 -5-(alkyl and aryl )-5 -(l uoro-5 -thioadenosi ncs with xenon difluoride or (diethylamido)sulfur trifluoride, hydrolysis in aqueous buffer, and inhibition of S-adenosyl-L-homocysteine hydrolase by derived adenosine 5 -aldehyde species. J. Org. Chem., 59, 544-555. 

Xenon difluoride. This is best obtained by interaction of F2 and an excess of Xe at high pressure, but there are other methods such as the interaction of Xe and 02F2 at — 118° and procedures in which XeF2 is trapped from mixtures of F2 and Xe at low pressures. It is soluble in water, giving solutions 0.15M at 0°, that evidently contain XeF2 molecules. The hydrolysis is slow in dilute acid but rapid in basic solution ... 

The bicyclic fused iodoxole oxide 531, the aliphatic analog of IBX, has been prepared by the fluorination of a tricoordinate 1,2-iodoxetane 234 (Section 2.1.8.9) with xenon difluoride followed by hydrolysis of the intermediate, non-isolable, difluoride 530 (Scheme 2.149) [701]. Compound 531 has a similar reactivity to that of IBX and can oxidize alcohols and sulfides to the corresponding carbonyl compounds and sulfoxides, respectively, in good yields under mild conditions. 

The reaction of phenol with aqueous xenon difluoride has been investigated at pH 3—4, the primary stable product being p-benzoquinone. Under these conditions, the rate of consumption of XeFg in water is independent of the substrate present. The initial hydrolysis reaction is followed by a series of rapid redox steps depending on the substrate present ... 

Xenon.—Several studies have been reported by Russian workers on the reactions of xenon difluoride in aqueous solution. The oxidation of phenol to p-benzo-quinone is suggested to involve an intermediate in the hydrolysis of xenon difluoride, possibly xenon monoxide. The rate of disappearance of xenon difluoride in the presence of phenol is the same as the rate of hydrolysis in the absence of the latter. A competition method has been used to study the role of this postulated intermediate. The kinetics of reaction of xenon difluoride with 2,3,6,6-tetramethylpiperidin-l-oxyl have been studied. In a review of recent developments in the chemistry of some electronegative elements there is a brief summary of fluxional behaviour in the proposed tetramer of XeF in solution. ... 

Previous suggestions on the mechanism of hydrolysis of xenon difluoride have been confirmed/ The first intermediate is XeO, which interacts with water to give hydrogen peroxide. Oxidation of hydrogen peroxide by Xep2 has already been investigated, and involves a chain reaction initiated by reaction between XeO and H2O2. 

The xenon fluorides were synthesized by the direct reaction of the element shortly after Bartlett s announcement. The tetrafluoride is the stablest and best characterized, although its hydrolysis yields the dangerously explosive xenon trioxide. Xenon difluoride is an excellent oxidizing agent and fluoride ion donor. Xenon hexafluoride is both a fluoride donor and acceptor. 

Analyze the change in oxidation numbers for the hydrolysis of xenon difluoride found in Equation (19.8), repeated below. Identify the oxidizing and reducing agents in this reaction. 

Although uncontrolled reaction of xenon hexafluoride and moisture produces explosive xenon trioxide, controlled action by progressive addition of limited amounts of water vapour with agitation to a frozen solution of the hexafluoride in anhydrous hydrogen fluoride at —196° C to give xenon oxide tetrafluoride or xenon dioxide difluoride is safe [1], Controlled hydrolysis in solution in hydrogen fluoride is, however, described as hazardous [2],... 

Xenon Tetrahydroxide. Xe(OH)4. mw 199.34 mp, explds violently on heating. Prepn is by hydrolysis of Xe difluoride Refs 1) G. Sorbe, Giftige und Explosive Substanzen , Unischau, Veriag (1968), 158 2) J.C. Bailar et al, Eds, Comprehensive Inorganic Chemistry , Vol 1, Pergamon Press, Oxford (1973), 268... 

Xe02p2 was observed in the early mass spectra of xenon fluorides and can be obtained by hydrolysis of XeFe. The best method for its preparation in macroscopic quantities is by the reaction of XeOs and XeOp4. The XeOp4 and Xep2 impurities may be removed by fractional distillation. Xenon dioxide difluoride forms colorless crystals at room temperature, which have a vapor pressure between that of XeOs and XeOp4 and melts at 303.95 K to give a colorless liquid. It can decompose to Xep2 and O2. 

In view of the instability of the trioxide it is interesting to speculate on the stability of the oxyfluorides. Xenon oxide tetrafluoride should be an exothermic compound since the atomic heat of formation using average bond energies of 32 kcal. and 17 kcal. respectively for Xe-F and Xe-O is —160 kcal. mole-. The combined heat of atomization of four fluorine atoms (4 x 18.3 kcal.) and one oxygen atom (59.2 kcals.), 132.4 kcal., is less than this. Xenon dioxide difluoride, by such considerations, should be endothermic. It is of interest that xenon oxide tetrafluoride is easily made by controlled hydrolysis of xenon hexafluoride and is a thermally stable entity (m.p. —28) whereas xenon dioxide difluoride has been observed only mass spectrometrically < >. 

Like xenon hexafluoride or xenon tetrafluoride, krypton difluoride reacts with water, giving highly explosive hydrolysis products. The best way for disposing of krypton difluoride is to allow it to react with carbon tetrachloride (see caution note under xenon tetrafluoride procedure). 

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