| Journal Articles: 19 results |
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The Mechanism of Covalent Bonding: Analysis within the Hückel Model of Electronic Structure Sture Nordholm, Andreas Bäck, and George B. Bacskay
Hckel molecular orbital theory is shown to be uniquely useful in understanding and interpreting the mechanism of covalent bonding. Using the Hckel model it can be demonstrated that the dynamical character of the molecular orbitals is related simultaneously to the covalent bonding mechanism and to the degree of delocalization of the electron dynamics.
Nordholm, Sture; Bäck, Andreas; Bacskay, George B. J. Chem. Educ. 2007, 84, 1201.
Covalent Bonding |
MO Theory |
Quantum Chemistry |
Theoretical Chemistry
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Electronic Structure Principles and Aromaticity P. K. Chattaraj, U. Sarkar, and D. R. Roy
Electronic structure principles dictate that aromatic molecules are associated with low energy, polarizability, and electrophilicity but high hardness values, while antiaromatic molecules possess the opposite characteristics. These relationships are demonstrated through B3LYP/6-311G** calculations on benzene and cyclobutadiene.
Chattaraj, P. K.; Sarkar, U.; Roy, D. R. J. Chem. Educ. 2007, 84, 354.
Aromatic Compounds |
Molecular Properties / Structure |
Quantitative Analysis |
Theoretical Chemistry |
Alkenes |
Quantum Chemistry
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Quantitative Thermodynamic Descriptions of Aromaticity. A Computational Exercise for the Organic Chemistry Laboratory Terrence Gavin
This article describes an exercise that enables students to establish a quantitative scale of aromaticity via computer-driven quantum mechanical calculations using Spartan software. The method utilizes a group of analogous isodesmic reactions from which the energy difference between two isomeric cyclic polyenes is calculated from their optimized geometries. The energy differences found are used to characterize structures as aromatic, nonaromatic, or antiaromatic depending on the value obtained. A representative group of structures, including hydrocarbons, hydrocarbon ions, and heterocycles are studied.
Gavin, Terrence. J. Chem. Educ. 2005, 82, 953.
Aromatic Compounds |
Computational Chemistry |
Heterocycles |
Molecular Modeling |
Thermodynamics
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Why Chemical Reactions Happen (James Keeler and Peter Wothers) John Krenos
By concentrating on a limited number of model reactions, this book presents chemistry as a cohesive whole by tying together the fundamentals of thermodynamics, chemical kinetics, and quantum chemistry, mainly through the use of molecular orbital interpretations.
Krenos, John. J. Chem. Educ. 2004, 81, 201.
Mechanisms of Reactions |
Thermodynamics |
Kinetics |
Quantum Chemistry |
MO Theory
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Colorful Azulene and Its Equally Colorful Derivatives Robert S. H. Liu
Analysis of azulene and related compounds for an explanation of their respective colors.
Liu, Robert S. H. J. Chem. Educ. 2002, 79, 183.
Atomic Properties / Structure |
MO Theory |
UV-Vis Spectroscopy |
Aromatic Compounds |
Alkenes
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Organizing Organic Reactions: The Importance of Antibonding Orbitals David E. Lewis
It is proposed that unoccupied molecular orbitals arbitrate much organic reactivity, and that they provide the basis for a reactivity-based system for organizing organic reactions. Such a system is proposed for organizing organic reactions according to principles of reactivity, and the system is discussed with examples of the frontier orbitals involved.
Lewis, David E. J. Chem. Educ. 1999, 76, 1718.
Covalent Bonding |
Mechanisms of Reactions |
MO Theory
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The Use of MO Calculations to Teach Students Some Concepts of Aromatic Substitution Reactions Petrus Zeegers
The experiments described here are an attempt to help students unify the theoretical and practical aspects of their studies in organic chemistry. Simple aromatic compounds (4-X-phenols) have been used to illustrate the relationship between theoretical molecular orbital calculations and an industrially useful multi step organic synthesis.
Zeegers, Petrus. J. Chem. Educ. 1997, 74, 299.
MO Theory |
Aromatic Compounds |
Phenols
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An Attention-Getting Model for Atomic Orbitals Kiefer, Edgar F.
Tapping a spoon on a coffee mug to illustrate the circular orbitals of benzene.
Kiefer, Edgar F. J. Chem. Educ. 1995, 72, 500.
MO Theory |
Aromatic Compounds
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ESR studies and HMO calculations on benzosemiquinone radical anions: A physical chemistry experiment Beck, Rainer; Nibler, Joseph W.
For this laboratory study, several benzosemiquinone radical anions were chosen since they are long-lived and are easily made from inexpensive source materials. The effects of molecular symmetry and of different substituents attached to the aromatic ring system are also readily seen.
Beck, Rainer; Nibler, Joseph W. J. Chem. Educ. 1989, 66, 263.
Spectroscopy |
MO Theory |
Aromatic Compounds
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Synthesis of azulene, a blue hydrocarbon Lemal, David M.; Goldman, Glenn D.
A procedure of the synthesis of this simple, beautiful, and theoretically interesting compound with many unusual properties.
Lemal, David M.; Goldman, Glenn D. J. Chem. Educ. 1988, 65, 923.
MO Theory |
Aromatic Compounds |
Diastereomers |
Synthesis
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Structure-resonance theory for pericyclic transition states Herndon, William C.
The purpose of this article is to show that structure-resonance theory can be used to understand the effects of structure or substituents on the rates of thermal pericyclic reactions.
Herndon, William C. J. Chem. Educ. 1981, 58, 371.
Aromatic Compounds |
Resonance Theory |
Molecular Properties / Structure
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Novel pictorial approach to teaching MO concepts in polyatomic molecules Hoffman, D. K.; Ruedenberg, K.; Verkade, J. G.
Methods used in a one-quarter course to familiarize students with the general applicability of delocalized and localized molecular orbitals to polyatomic systems; includes examples of delocalized and localized molecular orbitals of XeF2, C3H3+, CH4, and CO2.
Hoffman, D. K.; Ruedenberg, K.; Verkade, J. G. J. Chem. Educ. 1977, 54, 590.
MO Theory |
Atomic Properties / Structure
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Where does resonance energy come from? A nonmathematical approach to the theory of aromaticity Sardella, D. J.
In confronting the central issue of why aromatic systems are aromatic, the author provides a verbal application of perturbational molecular orbital theory.
Sardella, D. J. J. Chem. Educ. 1977, 54, 217.
Aromatic Compounds |
MO Theory
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Dewar resonance energy Baird, N. C.
In the present paper, some of the general properties of the Dewar Resonance Energy definition are developed. In particular, the DRE value for a compound is shown to be independent of the numerical values used to bond energies, and the use of DRE in judging the aromaticity of organic molecules is illustrated.
Baird, N. C. J. Chem. Educ. 1971, 48, 509.
Resonance Theory |
Aromatic Compounds |
Molecular Properties / Structure
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Localized and delocalized molecular orbital description of methane Bernett, William A.
The purpose of this article is to show that the relationship between localized and delocalized molecular orbitals can be easily demonstrated for the case of methane.
Bernett, William A. J. Chem. Educ. 1969, 46, 746.
Molecular Properties / Structure |
MO Theory
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Teaching aromatic substitution: A molecular orbital approach Meislich, Herbert
This paper presents a way of teaching aromatic substitution using the concepts of alternate polarity and electron delocalization through extended pi-bonding.
Meislich, Herbert J. Chem. Educ. 1967, 44, 153.
Aromatic Compounds |
MO Theory |
Nucleophilic Substitution |
Covalent Bonding |
Molecular Properties / Structure
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Aromatic substitution Duewell, H.
Reports on the use of the molecular orbit theory in a qualitative approach to the activation and orientation of substitution in aromatic systems.
Duewell, H. J. Chem. Educ. 1966, 43, 138.
Aromatic Compounds |
MO Theory |
Mechanisms of Reactions
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Rules for molecular orbital structures Meislich, Herbert
In view of the fact that molecular orbital theory makes more correct predictions and avoids the misconceptions that arise in the minds of novice students when they are exposed to resonance theory, it would be better to use M.O. theory as much as possible in teaching organic chemistry.
Meislich, Herbert J. Chem. Educ. 1963, 40, 401.
MO Theory |
Resonance Theory
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Note on the representation of the electronic structures of acetylene and benzene Noller, Carl R.
The three dimensional nature of molecular orbitals in acetylene and benzene are illustrated.
Noller, Carl R. J. Chem. Educ. 1955, 32, 23.
Alkenes |
Alkynes |
Aromatic Compounds |
Molecular Properties / Structure |
Covalent Bonding |
MO Theory
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