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Issue 8, 2011
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Neutral species from “non-protic” N-heterocyclic ionic liquids

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Possible isomerisation of 1,2,3-trialkylimidazolium and 1-alkylpyridinium ion pairs by proton transfer and by the nucleophilic addition of the anion to the cation have been investigated at the B3LYP/6-31+G* and B3LYP/6-311+G** levels of density functional theory. The deprotonation energies of 1,2,3-trialkylimidazolium and 1-alkylpyridinium cations to diaza-pentafulvene and pyridinium-ylide, respectively, were only slightly larger than that of 1,3-dialkylimidazolium salts yielding N-heterocyclic carbenes. Accordingly, in the case of 1,2,3-dialkylimidazolium salt ion pairs the stability of the H-bonded complex between the fulvene and the corresponding acid can be comparable to that of the ion pair in the presence of sufficiently basic anions, such as acetate. In the case of the pyridinium salts the nucleophilicity of the cation dominates over the acidity, and the formation of 1,2- or 1,4-dihydropyridine derivatives is preferred over proton transfer.

Graphical abstract: Neutral species from “non-protic” N-heterocyclic ionic liquids

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The article was received on 04 Jan 2011, accepted on 10 Feb 2011 and first published on 14 Feb 2011

Article type: Paper
DOI: 10.1039/C1OB00007A
Org. Biomol. Chem., 2011,9, 2634-2640

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    Neutral species from “non-protic” N-heterocyclic ionic liquids

    O. Hollóczki and L. Nyulászi, Org. Biomol. Chem., 2011, 9, 2634
    DOI: 10.1039/C1OB00007A

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