Structure Determination Using 19F NMR: A Simple Fluorination Experiment of Cinnamyl Alcohol

Abstract

Described here is the nucleophilic substitution of a hydroxyl group, in cinnamyl alcohol, by fluorine, and analysis of the product using 19-F NMR spectroscopy. This experiment brings important innovations to the teaching of experimental organic chemistry at the undergraduate level. The fluorination of cinnamyl alcohol requires only a mild fluorinating agent and so it provides the student with a direct contact with organofluorine, chemistry. The allylic nucleophilic substitution typified by our experiment will enhance the instruction of nucleophilic substitution in the laboratory, traditionally limited to SN1 or SN2 substitutions. Because the ratio of SN2 to SN2' derived products cannot be determined directly using 1-H NMR spectroscopy but it can be measured easily using 19-F NMR spectroscopy. The experiment gives the student a firsthand experience of the usefulness of NMR spectra of different nuclei.