Monitoring of a batch organic synthesis by near‐infrared spectroscopy: modeling and interpretation of three‐way data

Three‐way data of the type batch × time × NIR wavelength were obtained by NIR spectroscopic multivariate monitoring of an organic synthesis as a batch process. The model synthesis, an ester synthesis, was carried out as an experimental design. Unexpected technical problems caused a blocking effect that forced a modification of the design. After preprocessing of a reduced three‐way array, the spectral data in the three‐way array were subjected to parallel factor analysis (PARAFAC). The loadings from this analysis could be interpreted and explained as a function of the synthesis studied. For the spectral interpretation, spectra of pure chemicals were needed. The paper is an illustration of what can be done with three‐way modeling in order to increase the understanding of a reaction, and it attempts to show how the results can be interpreted and presented. The data sets are available from the authors. Copyright © 2002 John Wiley & Sons, Ltd.