Aleksandra Konopacka, A. Filarowski, Z. Pawełka
Aug 1, 2005
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0
Influential Citations
12
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Journal
Journal of Solution Chemistry
Abstract
DFT (B3LYP/6-31+G(d,p)) calculations performed on 2-hydroxy-5-methyl-3-nitroacetophenone (I) indicate that the isomer with the intramolecular hydrogen bond (IMHB) to the nitro group (Ia) is more stable by 7.3 kJ-mol−1 than that with the H-bond to the acetyl group (Ib). The calculated polarities of both isomers are quite different with the dipole moment of Ib being five times higher. Dipole moment and infrared studies of the Ia ⇌ Ib conformational equilibrium in different solvents show that the IMHB transformation is controlled by the solvent polarity. In polar dichloromethane and acetonitrile the Ia ⇌ Ib equilibrium is strongly shifted towards the polar Ib isomer. The simple continuum dielectric model for a heterogeneous medium and polarizable solute allows a quantitative explanation of the influence of the solvent on the Ia ⇌ Ib equilibrium.