The incorporation of molecular modeling into undergraduate chemistry courses at UMass began in 1994, as an initiative funded by the National Science Foundation, the Howard Hughes Medical Institute, and our College of Natural Sciences and Mathematics. Since then, modeling has been used increasingly in the Organic Chemistry Laboratory courses.

At the very beginning of the organic laboratory course for Chemistry Majors, modeling is introduced in the form of molecular mechanics (MM2) using a tutorial on the use of Chem 3D, which includes exercises demonstrating the three-dimensional nature and conformational flexibility of organic molecules, and the use of molecular mechanics for predicting conformational energies. During the first semester, the dehydration of 2-butanol is studied using both MM2 and semi-empirical AM1 MO calculations on the SPARTAN computer program. In this case, molecular mechanics is shown to fail at predicting product distributions. We feel that this lesson, that is, that every calculational result is not necessarily correct, is an important one. A tutorial on the use of SPARTAN is given.

In the second semester, semi-empirical MO calculations (AM1) are used in SPARTAN to correctly predict the regioselectivity of the nitration of methyl benzoate. In another computational exercise, students study Aromatic Resonance Effects in Cyclic Ketones. In the Spring of 1997, a project-type lab experiment, "The Conformational Properties of 2-Halocyclohexanones", part of which included molecular modeling, was developed by an undergraduate senior, and was incorporated into the laboratory curriculum. The project consisted of a literature search, the synthesis of 2-halocyclohexanones, an FT-IR conformational study, and a molecular modeling study using molecular mechanics (MM2) and semi-empirical MO (AM1) calculations. Molecular mechanics was shown to fail at predicting the correct direction of equilibrium, while the AM1 calculations were successful, thus encouraging the student to critically compare two different modeling methods.

The tutorial on the use of Chem 3D has also been used with a group of up to 250 students in the first semester of the Nonmajors Organic Chemistry course.

Further development of experiments using molecular modeling as a tool to help understand experimental data is an ongoing project at UMass. The textbook used in the organic laboratory courses, Macroscale and Microscale Organic Experiments, 3rd Ed, by K. L. Williamson also integrates molecular modeling with several experiments and has proven to be useful in our endeavors.

Acknowledgements. Funds for equipment used in this work were provided by the Howard Hughes Medical Institute (Undergraduate Biological Sciences Education Program, Grant No. HHMI # 71195-516702), the National Science Foundation Division of Undergraduate Education (Instrumentation and Laboratory Improvement Program Grant # DUE-9551312), and the College of Natural Sciences and Mathematics, University of Massachusetts, Amherst.

Questions about material on this page should be directed to Peter Samal, samal@chem.umass.edu.

UMass Organic Laboratory Courses.

UMass Chemistry Department.