Thermal dismutation

FIO2 has been prepared both by direct fluorination of I2O5 in anhydi ous HF at room temperature and by thermal dismutation of F3IO ... 

Iodine oxide trifluoride, a colorless crystalline solid, is prepared by dissolving I2O5 mboilmgIFs followed by cooling. Above 110 °C it thermally dismutates into FIO2 and IF5. 

Recently, the formation of both colloidal copper and films on the nanometer scale by irradiation of ethanol solutions of commercially available Cu(acac)2 has been described "" . During the optimization of the experimental conditions, the authors could demonstrate that some of the mechanisms of photoreduction should be reformulated. In particular, the authors did not get evidence of copper(I) derivatives and their eventual thermal dismutation reaction. It appeared that the photoreduction is sensitized by the acacH released during the reaction. 

In the case of the amines or alcohols arylation catalyzed by nickel(II), it is possible, as a result of a thermal dismutation of the nickel(II) into nickel(I) and nickel(III) to consider the similar intervention of a nickel(I) complex as a catalytically active species but then the formation of this intermediate still has to be proved. Another possibility of mechanism is based on an oxidative addition process directly on the nickel(II) entity (ref. 4d). However this reaction, well known for the metals in their low oxydation degrees is disadvantaged by higher oxydation degrees, and further it would result in a transient nickel(IV) complex, a non usual oxidation degree for this metal. 

Intramolecular migration of fluorine and chlorine atoms is described in Section 5. The rearrangement of fluorine and chlorine atoms likewise can occur intermolecularly between a number of chlorofluorocarbon molecules. This disproportionation (dismutation) takes place catalyti-cally or thermally. With aluminum trichloride as a catalyst, for example, enrichment of the fluorine atoms takes place in one molecule 1 and enrichment of the chlorine atoms in the other 2. 

There is only a small number of reactions known whereby a perfluorinated aromatic compound is formed by thermal disproportionation perfluorotoluene is disproportionated at temperatures above 500 C to form perfluorobenzene and perfluoroxylcnc.42 44 The perfluoroxylene itself can be dismutated at 550°C to yield perfluorotoluene and 1,2.4- and 1,3,5-perfluoro-... 

The changes occurring during the initial activation stage of chromia are illustrated in Fig. 1 on the basis of coupled thermal analysis mass spectrometry measurements for the dismutation reactions of CHC1F2 and CHC12F, Eqns (2) and (3). 

Although there has been some recent interest in the catalytic fluorination of CCI4, notably over chromium(III) fluoride derived from thermal decomposition of (NH4)3CrF6 [42], most attention has been paid to dismutations within the HCFC—CHCl3 F series. Reactions on several metal oxides and halides have been studied by Kemnitz and coworkers and evidence for dismutation behaviour adduced from thermodynamic considerations and... 

Most studies on stable nitroxide radical-mediated poljmeiization are made with TEMPO or a substituted TEMPO, such as, 4-methoxy-2,2,6,6-tetramethyl-piperidine-l-oxy (MTEMPO) as the stable counter radical. However, the bond formed between the polymer radical and these nitroxides becomes labile around 120°C. This high temperature favors thermal polymerization as also side reactions, such as transfer or termination by dismutation between the growing chain and the stable radical (Jousset et al., 1997). To minimize these reactions, a more hindered radical, namely, di-ieri-butyl nitroxide (II), produced from the compound (III) can be used. 

The hterature, incidentally, often does not clarify the meaning of the most stable , but it normally means either the most thermodynamically or the most kineti-cally resistant to thermal decomposition, to dismutation, to oxidation by air and to hydrolysis, oxidation or reduction by water (liquid or vapor) at ambient T. 

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