|
|
| Home > JCE Print > Journal of Chemical Education > Issues >
2000
>
March
> |
|
In the Laboratory
|
|
|
|
Molecular Modeling to Predict Regioselectivity of Hydration Reactions
|
Kate J. Graham, Kathleen Skoglund, Chris P. Schaller, William P. Muldoon, and John B. Klassen
Department of Chemistry, College of Saint Benedict, Saint John's University, St. Joseph, MN 56374-2099
|
|
March 2000
Vol. 77 No. 3
p. 396
|
|
|
|
|
|
|
| Abstract |
|
In a series of introductory organic chemistry laboratory experiments, students oxidize several
isomeric alkenes using acid-catalyzed hydration, oxymercuration/demercuration, and hydroboration
to compare the regioselectivity of the different techniques. The product mixtures are subsequently
analyzed by GC and IR. To explain the results fully, students use the Spartan 5.0 molecular
modeling package to predict the regioselectivity of these hydration reactions. For the acid-
catalyzed hydration reaction, they predict the products by calculating the stability of the
possible carbocation intermediates using the semiempirical AM1 program. Using semiempirical
MNDO calculations, they determine the activation energies for the different possible transition
states of the hydroboration reaction. With the activation energies, they can easily predict the
preferred products. Semiempirical calculations with a PM3 (tm) basis set to determine the
geometry and electrophilicity of the LUMO of the mercuronium ion formed when 1-propene undergoes
a reaction with Hg(OAc)2 allow students to investigate the regioselectivity of the
oxymercuration
reaction. Using this information, they are able to explain the ratio of products obtained in the
laboratory experiment. The calculation and visualization of these reaction pathways greatly enhances
students' understanding of the oxidation experiments performed in the lab.
|
| Supplement |
Rationale, procedures, Hydration of an Alkene via Three Different Synthetic
Routes, Pre-Lab and Post-Lab notes, and Disposal Procedures are included.
|
 Contents |
|
| Download |
|
|
| More Information |
Citation |
Graham, Kate J.; Skoglund, Kathleen; Schaller, Chris P.; Muldoon, William P.; Klassen, John B. J. Chem. Educ. 2000 77 396.
|
Keywords |
Organic Chemistry; Laboratory Instruction; Computational Chemistry; Mechanisms; Reactive Intermediates
|
History |
Created:
Last Updated: |
February 14, 2000
August 31, 2005
|
|
|
|
|
|
| Home > JCE Print > Journal of Chemical Education > Issues >
2000
>
March
> Page
396
|
|
|
| JCE HS CLIC |
|
Our Secondary School editors work hard to distill all the JCE materials to produce a fraction of particular interest to high school teachers. We call it CLIC.
|
| Contributions Welcome |
| JCE welcomes your submission |
| Advertisers |
| In recent years we have worked hard to better match our advertisers with our readers. When shopping for chemistry education materials, visit our advertisers' WWW sites first. |
| Be An Ambassador |
| Take JCE along on your outreach missions. Copies of the Journal, guest access to JCE Online, our publications catalog, and more are available for your participants. |
|
