Xenon hexafluoride preparation

The higher fluorides are prepared using excess fluorine (Figure A). All these compounds are stable in dry air at room temperature. However, they react with water te form compounds in which one or more of the fluorine atoms has been replaced by oxygen. Thus xenon hexafluoride reacts rapidly with water to give the trioxide... 

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. 

It is a powerful explosive [1] produced when xenon tetrafluoride or xenon hexafluoride are exposed to moist air and hydrolysed. Some tetrafluoride is usually present in xenon difluoride, so the latter is potentially dangerous. Although safe to handle in small amounts in aqueous solution, great care must be taken to avoid solutions drying out, e.g. around ground stoppers [2], Full safety precautions have been discussed [2,3,4], Precautions necessary for use of aqueous solutions of the trioxide as an epoxidation reagent are detailed [5,6], A safe method of preparation,... 

XeOp4 was first detected as an impurity by mass spectrometry among the xenon fluorides prepared by thermal methods. It was obtained in macroscopic quantities by the partial hydrolysis of xenon hexafluoride (equation 7). Umeacted XeFe and HF formed in the reaction are removed... 

The Compound [XeFsl+CAsFg]" Xenon hexafluoride (0.79 mmole) prepared as... 

Although it may prove possible to prepare xenon nitride trifluoride (e.g. by interaction of ammonia with xenon hexafluoride) in all probability, since the heat of atomization of nitrogen is great (AHf(N) = 113 kcal.), it will be an endothermic compound. 

Xenon hexafluoride may be prepared in essentially the same way as xenon tetrafluoride (synthesis 66), except for increasing the fluorine-to-xenon ratio and the final pressure at reaction temperature.Variations of temperature, pressure, mol ratio, and time make possible the formation of xenon difluoride, xenon tetrafluoride, or xenon hexafluoride. The conditions described below have been found to give good yields and purity for xenon hexafluoride. 

The xenon hexafluoride for this synthesis is best prepared by reaction of xenon with an excess of fluorine at 300° in a nickel or Monel apparatus. Extremely pure XeFs is not required. Xenon hexafluoride attacks glass, and should be stored in a nickel or Monel container until ready for use. The hydrolysis reaction is violent, and if more than a hundred milligrams of XeFe is to be hydrolyzed, special safety precautions must be taken. Face shields, heavy gloves, and a sturdy plastic explosion barrier between the hydrolysis apparatus and the experimenter are strongly recommended. No more than about 3 g. of XeFg should be hydrolyzed in one batch. 

Solid xenon hexafluoride is prepared by allowing xenon gas and fluorine gas to react. 

Preparation by hydrolysis of either xenon tetrafluoride or xenon hexafluoride. Oxidizing action,2 Xenic acid reacts readily with u/c-diols in neutral or alkaline solution the products are xenon (gas) and carboxylic acids. 

Xenon hexafluoride. This preparation requires more severe conditions, but at high pressures (>50 atm) and temperature (>250°) quantitative conversion may be obtained. The solid is colorless but becomes yellow when heated and gives a yellow liquid and vapor. It reacts rapidly with quartz 2XeF6 + Si02 -> 2XeOF4 + SiF4 and it is extremely readily hydrolyzed. 

A number of compounds containing the heavier noble gases, and especially xenon, have been prepared. One of these is xenon hexafluoride (XeF ), which can be prepared by heating a mixture of xenon and fluorine gases. XeF is a white crystalline soUd at room temperature and melts at about 325 K A mixture of 0.0600 g of Xe and 0.0304 g of F2 is sealed into a 100.0-mL bulb. (The bulb contains no air or other gases.) The bulb is heated, and the reaction above goes to completion. Then the sealed bulb is cooled back to 20.0°C. What will be the final pressure in the bulb, expressed in torr ... 

In the preparation of xenon tetrafluoride oxide from the hexafluoride and caesium nitrate, the former must always be used in excess to prevent formation of explosive xenon trioxide. 

Interaction of the yellow hexafluoride with silica to give xenon tetrafluoride oxide must be interrupted before completion (disappearance of colour) to avoid the possibility of formation and detonation of xenon trioxide [1]. An attempt to collect the hexafluoride in fused silica traps at — 20°C after separation by preparative gas chromatography failed because of reaction with the silica and subsequent explosion of the oxygen compounds of xenon so produced [2],... 

Although xenon has the stable octet configuration and is thought to be as inert as other noble gases, several xenon compounds have been prepared. The first xenon compound synthesized by N. Bartlett in 1962 was a red sohd, XePtFe, made by the reaction of xenon with platinum hexafluoride undergoing the following oxidation sequence (Cotton, F. A., Wilkinson G., Murillo, C. A. and M. Bochmann. 1999. Advanced Inorganic Chemistry, ed., pp. 588. New York John Wiley Sons) ... 

Xenon also forms many fluoroanions and their salts, mostly prepared from xenon tetrafluoride and hexafluoride. Such compounds include Na+XeFs and Cs" XeF7- formed by reactions of xenon fluorides with sodium fluoride or cesium fluoride. The dicesium xenon octafluoride, Cs2XeFs, is a stable yellow solid that decomposes above 400°C. 

Uranium can be analysed as the hexafluoride, but the procedure requires modification of the chromatographic apparatus, nickel coating of metallic parts and nickel filaments in the katharometer [606], Tin in zirconium—tin alloys can be analysed as the chloride, prepared by treatment with chlorine [607]. Selenium and tellurium are converted into fluorides by treatment of their oxides with xenon difluoride [608]. 

Xenon and platinum hexafluoride interact at room temperature to form a red solid of composition Xe(PtF6)a where x lies between 1 and 2. That the platinum is present in the -f-S oxidation state, no matter what the composition of the adduct, is indicated by the preparation of alkali metal hexafluoroplatinates(V) from material of composition XePtFe and Xe(PtF6)2. Material containing more than one mole of platinum hexafluoride per gram atom of xenon combines with more xenon at 130° to approach the composition XePtFe. 

Reagents.—Platinum hexafluoride and rhodium hexafluoride were prepared from 0.03-in. diameter pure metal wire supplied by Johnson, Matthey, and Mallory Ltd., Toronto. The reaction with fluorine was initiated by electrical heating of the wire, the metal reactor used being similar to that described by Weinstock, Malm, and Weaver [2]. Airco Reagent Grade xenon was used. 

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