Low-temperature alkane C-H bond activation by zeolites: an in situ solid-state NMR H/D exchange study for a carbenium concerto

Chemistry : a European Journal
Mohamed HaouasJ Sommer

Abstract

Isotopic H/D exchange has been monitored by in situ MAS NMR spectroscopy of 2-[D(14)]methylpentane with H-USY to probe the controversy over the alkane conversion mechanism. The probe molecule has distinct exchangeable sites with different accessibility to the zeolite surface. In the early stages of the process, the regioselectivity of exchange demonstrates that the slow step of the mechanism is controlled by a carbenium ion intermediate. At a later stage of exchange, intramolecular hydride migrations, typical of carbenium chemistry, replace D by H also on other carbon atoms, resulting in a loss of regioselectivity. Therefore, the first and the subsequent steps of the H/D exchange proceed at this temperature through a carbenium intermediate species.

References

Jan 15, 2004·Journal of the American Chemical Society·Mohamed HaouasJean Sommer
Feb 9, 2006·Journal of the American Chemical Society·Matthew J TruittJeffery L White
Oct 20, 2006·The Journal of Physical Chemistry. B·Laura S SremaniakJeffery L White
Feb 3, 2009·Solid State Nuclear Magnetic Resonance·Matthew J Truitt, Jeffery L White
Nov 18, 2009·Chemistry : a European Journal·Benoit LouisJean Sommer
Jan 29, 2010·Chemistry : a European Journal·Abdelkarim Sani Souna SidoJean Sommer

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Citations

Jun 10, 2014·Annual Review of Chemical and Biomolecular Engineering·Marie-Françoise Reyniers, Guy B Marin
Feb 5, 2016·Journal of the American Chemical Society·Sambhu RadhakrishnanJohan A Martens

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