The suitability of
broadband dielectric spectroscopy (DS) as a
tool for in-line (in situ) reaction monitoring is demonstrated. Using
the esterification of 4-nitrophenol as a test-case, we show that multivariate
analysis of time-resolved DS data—collected across a wide frequency
range with a coaxial dip-probe—allows reaction progress to
be measured with both high precision and high accuracy. In addition
to the workflows for data collection and analysis, we also establish
a convenient method for rapidly assessing the applicability of DS
to previously untested reactions or processes. We envisage that, given
its orthogonality to other spectroscopic methods, its low cost, and
its ease of implementation, DS will be a valuable addition to the
process chemist’s analytical toolbox.