Student-Determined Values for the Calculation of Chemical Shifts of Methylene Protons in Different Chemical Environments

Abstract

Many tables of values exist for the rapid calculation of approximate chemical shifts of protons in organic molecules. These tables are usually simply handed to students to use without discussion of the source of such data. Herein we describe a laboratory experiment in which students themselves determine values for the calculation of chemical shifts of methylene protons in a variety of chemical environments. Although these values come from single determinations of representative compounds from several different classes, the alpha-parameter values obtained are in close agreement with literature data. Students also gain valuable hands-on experience preparing samples, operating the NMR spectrometer, and interpreting the 1H NMR spectra of a variety of compounds.