Electrophilic nitration of alkanes with nitronium hexafluorophosphateGeorge A. Olah,* Pichika Ramaiah, and G. K. Surya PrakashProc. Natl. Acad. Sci. USA. 1997 October 28; 94 (22): 11783–11785 (http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=23573)
(http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=23573)
Nitration of alkanes such as methane, ethane, propane, n-butane, isobutane, neopentane, and cyclohexane was carried out with nitronium hexafluorophosphate in methylene chloride or nitroethane solution. Nitration of methane, albeit in poor yield, required protolytic activation of the nitronium ion. The results indicate direct electrophilic insertion of NO2 + into CH and CC ó-bonds.
nitronium hexafluorophosphate
Ouch - how is this made? It sounds like an awfully expensive reagent - nitronium tetrafluoroborate is €150/25g in the Aldrich catalog and the hexafluorophosphate isn't even listed...
I think gas-phase nitration with HNO3 wins over this method for all purposes except to write a fancy publication.
Ouch - how is this made? Not that i'm interested in it, but, - since you asked... :)
It's made by adding PF
5 to the mixture of anh. HNO3/HF and filtering the pptated salt ;D Sounds like fun, doesn't it? :)
HF can bee formed in situ from the same pentafluoride, yield in this case sucks, though - see
Patent US3092459 (http://l2.espacenet.com/dips/viewer?PN=US3092459&CY=gb&LG=en&DB=EPD)
Other perfluoro Lewis acids may bee used as well, see
Patent US3403987 (http://l2.espacenet.com/dips/viewer?PN=US3403987&CY=gb&LG=en&DB=EPD)
Antoncho