| Journal Articles: 14 results |
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The Aromaticity of Pericyclic Reaction Transition States Henry S. Rzepa
Presents an approach that combines two fundamental concepts in organic chemistry, chirality and aromaticity, into a simple rule for stating selection rules for pericyclic reactions in terms of achiral Hckel-aromatic and chiral Mbius-aromatic transition states.
Rzepa, Henry S. J. Chem. Educ. 2007, 84, 1535.
Alkanes / Cycloalkanes |
Alkenes |
Aromatic Compounds |
Mechanisms of Reactions |
Stereochemistry
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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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An Acid Hydrocarbon: A Chemical Paradox Jeffrey T. Burke
This article explores the use of paradox as a teaching and learning strategy. Specifically, students observe the acid-like paradoxical behavior of the hydrocarbon cyclopentadiene. This observation then serves as a springboard to an understanding of the non-benzenoid aromatics.
Burke, Jeffrey T. J. Chem. Educ. 2004, 81, 65.
Acids / Bases |
Aromatic Compounds
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Using Hydrocarbon Acidities To Demonstrate Principles of Organic Structure and Bonding Andrew P. Dicks
This article demonstrates the utility of hydrocarbon acidity as a teaching tool within the undergraduate classroom. Acidities of compounds containing only hydrogen and carbon vary by at least 50 orders of magnitude. Differences in acidities are rationalized by invoking principles of hybridization, resonance, induction, and aromaticity.
Dicks, Andrew P. J. Chem. Educ. 2003, 80, 1322.
Acids / Bases |
Aromatic Compounds |
Alkanes / Cycloalkanes
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Melting Point and Molecular Symmetry R. J. C. Brown and R. F. C. Brown
In 1882 Thomas Carnelley observed that high molecular symmetry is associated with high melting point. The application of the rule to a number of different molecular crystals is discussed. The rule applies to different categories of crystal for different reasons, which can be explained by thermodynamic analysis.
Brown, R. J. C.; Brown, R. F. C. J. Chem. Educ. 2000, 77, 724.
Liquids |
Molecular Properties / Structure |
Phases / Phase Transitions / Diagrams |
Solids |
Thermodynamics |
Physical Properties |
Aromatic Compounds |
Crystals / Crystallography
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Comments on the Treatment of Aromaticity and Acid-Base Character of Pyridine and Pyrrole in Contemporary Organic Chemistry Textbooks Hugh J. Anderson and Ludwig Bauer
Presentations of aromaticity and acid-base character of pyridine and pyrrole in 18 contemporary organic chemistry textbooks were surveyed.
Anderson, Hugh J.; Bauer, Ludwig. J. Chem. Educ. 1999, 76, 1151.
Acids / Bases |
Aromatic Compounds
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A Simple and Convenient Method for Generation and NMR Observation of Stable Carbanions Hamid S. Kasmai
A simple and convenient method for the generation and NMR study of stable carbanions is described. The data and sample spectra illustrate that reliable and good quality NMR spectra of stable carbanions may be obtained. The experiments described provide a good opportunity for students to apply the basic principles of 1H and 13C NMR spectrometry and the interesting topic of the exchange phenomenon in NMR.
Kasmai, Hamid S. J. Chem. Educ. 1999, 76, 830.
Acids / Bases |
Reactive Intermediates |
NMR Spectroscopy |
Aromatic Compounds
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Correction
Correction in equation 1.
J. Chem. Educ. 1997, 74, 480.
Aromatic Compounds |
Molecular Properties / Structure
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Don't stop with benzene! The educational value of the cyclooctatetraene (C8H8) molecule Samet, Cindy
Educators often ignore larger molecular ring systems, suggesting to students that benzene covers all the important aspects of the chemistry of annulenes.
Samet, Cindy J. Chem. Educ. 1993, 70, 291.
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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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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Teaching aromaticity, conjugation, and enolization Schambach, Robert A.
An understanding of the delocalization of electrons in organic compounds is central knowledge. In teaching undergraduates about aromaticity, conjugation, and enoliztion, this author has found it useful to present examples of compounds in which delocalization. Effects are sustained in the presence of potentially interfering saturated carbon atoms.
Schambach, Robert A. J. Chem. Educ. 1976, 53, 711.
Aromatic Compounds |
Reactions
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