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Eiravani, Hossaen | 2010

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 40399 (03)
University: Sharif University of Technology
Department: Chemistry
Advisor(s): Fattahi, Alireza
Abstract:
It is believed that intramolecular hydrogen bonding and also conjugation can affect the acidity power of organic molecules. But simultaneous effects of intramolecular hydrogen bonding and conjugation have not investigated systematically yet. In this project, we choose Ascorbic acid as a basic structure. Then we have changed its structure conveniently, and have explored the roles of hydrogen bonding and conjugation on the acidity of this molecule by using B3LYP functional with the 6-311++G(d,p) basis set. After that we similarly investigate these effects on the acidity of three different systems, including enols, enamines and alcohols. In this project we probe the effect of different hydrogen bonding types, including cooperative HB, multiple HB, and resonance assisted HB, on the acidity of molecules. We also investigate the influence of conjugated systems length. We found that cooperative hydrogen bonding and Conjugation effects on acidity seem to be additive. We also probe the role of hydrogen bonding and conjugation on the decrease of bonding dissociation energy of OH in the enols.
Keywords:
Acidity ; Bond Dissociation Energy ; Conjugation ; Density Functional Theory (DFT) ; B3LYP

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