Exploring the Inductive Effect through Computational Modeling: A General and Organic Chemistry Lab Experiment

A straightforward, laptop-friendly computational chemistry laboratory exercise has been developed that facilitates students' understanding of the inductive effect. Students implement DFT modeling of acetic acid and its methyl and fluoro analogues: trifluoroacetic, fluoroacetic, propanoic, and 2,2-dimethylpropanoic (pivalic) acids, all at a modest level of theory (revPBE/6-31G*). Individually, students complete all computational aspects in similar to 45 min using a quad-core laptop computer. Students analyze carbonyl (C=O) vibrational frequencies, C=O bond lengths, and Mulliken charges for the acidic hydrogen in each structure. Students use collected data to compare with literature pK(a) values to identify trends of chemical properties (i.e., acidity) and electronic effects (i.e., electron-donating and -withdrawing groups).