. Can. J. Chem. 55,3845 (1977). Intermolecular fluorine exchange in the systems SiF4-SiF,-, MeSiF3-MeSiF4-, PhSiF3-PhSiF4-, SiF,--SiFs2-, SiF4-SiFs2-, and MeSiF,-SiFs2-has been studied by fluorine and proton nmr spectroscopy. Exchange is postulated to involve fluorine-bridged intermediates; alternative pathways of exchange, such as fluoride dissociation or impurity (HF and H20) catalyzed exchange, have been eliminated. Addition of NH3 to SF,--SiFs2-slows down exchange whereas addition of Et2NH to MeSiF, promotes exchange.RONALD KIRK MARAT et ALEXANDER F. JANZEN. Can. J. Chem. 55,3845 (1977). On Btudie par rmn du proton et du fluor 1'Cchange intermolCculaire du fluor dans les systtmes SF4-SiF5-, MeSiF3-MeSiF4-, PhSiF,-PhSiF4-, SiF,--SiFs2-, SiF4-SiF,2-et MeSiF3-SiFs2-. On fait I'hypothese que 1'Cxchange implique des intermediaires a fluor pontC; on Climine la possibilite d'un autre mode d'echange comme la dissociation du fluor ou de 1'6change catalysee par une impurete (HF et H20). L'addition de NH, au systeme SiF5--SiFs2-a pour effet de ralentir I'khange; par contre l'addition de Et2NH a MeSiF, la favorise.[Traduit par le journal]
. Can. J. Chem. 53,3044 (1975).Reaction of alkyl(ary1)phosphines with xenon difluoride gives alkyl(aryl)hydridofluorophosphoranes which were characterized by proton and fluorine n.m.r. spectroscopy. With phenylchlorophosphines, substitution of chlorine by fluorine accompanied oxidative-fluorination to give phenylfluorophosphoranes, (C6H5).PF5-.. With tert-butylchlorophosphines, chlorination of the tert-butyl group accompanied oxidative-fluorination, and a mixture of products was obtained. Reaction of xenon difluoride with methyl iodide gives methyliodine(II1) difluoride, characterized by proton and fluorine n.m.r. spectroscopy.Silicon-sulfur and silicon-nitrogen bonds are cleaved by xenon difluoride and an intermedi-' ate containing a xenon-nitrogen bond is postulated.Reaction of xenon difluoride with hexafluoroacetone, perfluoropinacol, or disodium perfluoropinacolate failed to give stable xenon esters.
Intramolecular axial-equatorial exchange and base-initiated intermolecular fluorine exchange in phenyltrifluorophosphorane have been studied by the dynamic NMR technique. Axial-equatorial exchange appears to be a unimolecular process with *298 = 13.3 ± 0.5 kcal/mol, l\H* = 12.6 ± 0.4 kcal/mol, AS* = -2.1 ± 1.3 eu, and £a = 13.2 ± 0.4 kcal/mol. Addition of triethylamine or pyridine to C6H5PF3H leads to intermolecular fluorine exchange. Rate studies of the intermolecular process support a mechanism involving slow production of C6H5PF4H~f ollowed by rapid fluorine transfer between fiveand six-coordinate species C6H5PF3H and C6H5PF4H~. Although traces of HF and H20 impurities did not interfere with this study, the impurity C6H5PF4 markedly affected the NMR results. The intramolecular process is not correlated with the intermolecular process, and phosphorus-hydrogen coupling is retained throughout the rapid intermolecular fluorine-exchange process.
The reaction of XeF2 with aryl and alkyl sulfides and thiols has been investigated. Oxidative-fluorination of diphenyl sulflde and tert-butylphenyl sulfide gives diphenylsulfur difluoride and tert-butylphenylsulfur difluoride, respectively. The presence of an α-hydrogen substituent leads to α-fluorination and, in some cases, to olefin formation while reaction of XeF2 with thiols gives disulfldes. HF catalyzed decomposition of products and intermolecular fluorine exchange is inhibited by the addition of [(CH3)3Si]2NH.On a étudié la réaction de XeF2 avec des sulfures et des thiols d'aryles et d'alkyles. La fluoration oxydative du sulfure de diphényle et du sulfure de tert-butylphényle conduisent respectivement au difluorure de diphénylsulfure et au difluorure de tert-butylphénylsulfure. La présence d'un hydrogène comme substituant en α conduit à une α fluoration et dans quelques cas à la formation d'oléflne; la réaction de XeF2 avec les thiols conduit aux disulfures. La décomposition catalysée par HF des produits et l'échange intermoléculaire du fluorure sont inhibés par l'addition de [(CH3)3Si]2NH. [Traduit par le journal]
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.