Xenon fluoride synthesis

These compounds can be prepared by using either classical processes for synthesis of amino acids (starting from the ad hoc precursor bearing fluorine on the aromatic moiety) or electrophilic fluorination of the arene moiety (e.g., elemental fluorine, xenon fluoride, acetyl hypofluorite). Although these methods are often poorly regioselective, they are useful for the preparation of F labeled molecules used in PET, for example, F tyrosine and dihydrophenylalanine (L-Dopa). ... 

Weinstock, B., Record of Chemical Progress, 23, 23(1963). Apparatus for the synthesis and characterization of xenon fluorides is presented. 

The first synthesis of XeFe was also reported in 1962. All syntheses are best carried out in nickel or monel reaction vessels. From the equilibrium constants for the formation of xenon fluorides, " it is evident that an excess of fluorine is necessary to minimize the formation of Xep4. In addition, the reaction temperature should be as low as possible, yet consistent with a reasonable reaction rate. In the presence of Nip2 as catalyst the activation energy for the xenon-fluorine reaction is lowered and the reaction proceeds rapidly at 393 K, in contrast to 523 K without catalyst. 

Plasma-Chemical Synthesis of Xenon Fluorides and Other Fluorine Oxidizers... 

Unlike the binary xenon fluorides, Krp2 cannot be prepared by photolysis of the elements at room temperature nor by high temperature-high pressure methods. Also unlike the binary xenon fluorides, there has been little success in achieving a higher yield (i.e. multiple grams per hour) synthesis of KrF2- Aside from oxidative... 

Describe the synthesis and properties of the most common xenon fluorides, and explain why their melting points do not follow the trend expected of nonpolar molecules. 

All three of these xenon fluorides are colorless, volatile solids. Notice that, for each synthesis, the Xe F2 mole ratio is significantly different from the... 

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. 

R.E. Ehrenkaufer, R.R. MacGregor, Synthesis of [ F]-perchloryl fluoride and its reactions with functionalized aryllithiums, Int. J. Appl. Radiat. Isot. 34(1983)613-615. R. Chirakal, G. Firnau, J.G. Schrobilgen, J. McKay, E.S. Garnett, The synthesis of [ F]xenon difluoride from [ F]fluorine gas, Int. J. Appl. Radiat. Isot. 35 (1984) 401-404. 

Not only were the fluorides the first compounds of xenon to be prepared, but also they serve as starting materials for the synthesis of most other xenon compounds. Xenon difluoride can be prepared by the reaction of excess xenon with fluorine aided by heat or electromagnetic radiation ... 

Table 1. Synthesis of Vinyl Fluorides by Reaction of Vinyltin Compounds with Xenon Difluoride...

Fluorination of aryltrimethylsilanes with xenon difluoride is a method for the synthesis of F-labelcd eompounds, since [ F]XeF2 be prepared. F-Labeled aryl fluorides are also prepared by reaction of aryltrimethylsilanes with F-labeled acetyl hypofluorite and elemental fluorine. ... 

Radical cations derived from Mrfluoro aromatic molecules were first described by Bazhin et al. > The species were made in super acid or oleum solutions and were unambiguously characterized by ESR spectroscopy. Such species have also been proposed as interm tates in the oxidative fluorination of aromatic molecules by high-valent metal fluorides such as cobalt trtfluoride, by bromine trifluoride, and by xenon difluoride. They have also been invoked in the electrochemical fluorination of aromatic molecules in the presence of F. Salts of such radical cation species were unknown prior to the synthesis of C6F6 AsF6 in these laboratories. ... 

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