Anion–π interactions influence pKa values

Autor: Christopher J. Cadman, Anna K. Croft
Jazyk: angličtina
Rok vydání: 2011
Předmět:
Zdroj: Beilstein Journal of Organic Chemistry, Vol 7, Iss 1, Pp 320-328 (2011)
Druh dokumentu: article
ISSN: 1860-5397
DOI: 10.3762/bjoc.7.42
Popis: Five 8-(4-R-phenyl)-1-naphthol derivatives were prepared by PdCl2-catalysed electrophilic aromatic substitution. The pKa' values for these 1,8-disubstituted arene naphthols have been measured in acetonitrile/water (R = NO2, 8.42; R = Cl, 8.52; R = H, 8.56; R = Me 8.68; and R = OMe, 8.71) and indicate a correlation with the electronic nature of the arene substituent, as determined through LFER analysis. Contributions to the relative pKa' values have been interpreted, using M06-2X DFT calculations, as consisting of two components: A small contribution from initial OH–π bonding in the starting materials and a larger contribution from anion–π interactions in the products. Such effects have implications for a range of other systems.
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