Computational Investigations for Undergraduate Organic Chemistry: Modeling a TLC Exercise to Investigate Molecular Structure and Intermolecular Forces

Abstract

An effort is being made to engage students more deeply in their laboratory work, to provide them with experiences in the applications and limitations of computational chemistry, and to develop their skill in experimental design. In this exercise students carry out a pre-lab exercise in which they compute the dipole moment for a set of similar models representing a variety of functional group categories. Using their data, and supported by guided class discussion, students propose a working hypothesis about how TLC can be used to demonstrate the manner in which the relevant forces lead to predictable rates (extent, Rf) of elution. They design a sequence of paired chromatographic elutions that will permit verification of their hypothesis, or its clear contradiction, and use their experimental data to draw conclusions about the type and strength of the intermolecular forces and the relation of these forces to molecular structure.See Correction to this article.