کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1404680 | 1501921 | 2006 | 10 صفحه PDF | دانلود رایگان |

Formation of intramolecular hydrogen bonds leads to structural modifications in the whole molecule, which are discussed on the basis of B3LYP/6-31G(d,p) calculations. The energy and the structure of various hydrogen-bonded and open conformers are considered for two groups of ortho-substituted phenols–N-dimethylaminomethylphenols (Mannich bases) and N-methylbenzylideneamines (Schiff bases). The energy of intramolecular hydrogen bond formation in Mannich bases was corrected for non-bonded interactions within the molecules, based on a thermodynamic cycle. Structural data were used to estimate the fraction of the ortho-quinoid (keto) form in particular tautomers. It is shown that proton transfer in Schiff bases leads to an increase of this fraction to about 40%, while opening of the hydrogen bond in the proton transferred form increases the keto fraction to 70%.
Journal: Journal of Molecular Structure - Volume 790, Issues 1–3, 5 June 2006, Pages 55–64