Direct Regioisomer Analysis of Crude Reaction Mixtures via Molecular Rotational Resonance (MRR) Spectroscopy 

Published in Chemical Science, June 2020
Authors: Leo A. Joyce, Danielle M. Schultz, Edward C. Sheer, Justin L. Neill, Reilly E. Sonstrom, Brooks H.Pate

Summary

Originally published in Chemical Science, this paper demonstrates the use of molecular rotational resonance (MRR) spectroscopy for the direct analysis of crude reaction mixtures. The authors show that MRR can identify and quantify regioisomers without sample purification or isolated reference standards, simplifying analytical workflows for reaction characterization. Two applications are presented: a photocatalytic C-H arylation reaction and the generation of an intermediate used in natural product synthesis.

In both examples, MRR spectroscopy was used to distinguish structurally similar regioisomers that can be difficult to characterize using conventional approaches. Quantitation was achieved by comparing experimental spectra with calculated molecular parameters, producing results that agreed well with chromatographic measurements. The study also revealed previously unknown impurities, highlighting the value of MRR as a powerful tool for reaction analysis and impurity detection.