Monitoring of the acid catalysed esterification of ethanol by acetic acid using Raman spectroscopy

The acid catalysed esterification of ethanol by acetic acid has been monito red using Raman spectroscopy. It was found that noise and baseline shift du e to fluorescence spectra and process dynamics obscured the essential chemi cal information in the data. Principal components analysis and regression a nalyses have been applied progressively to de-noise the data and to extract the Raman signal. It was found that the first principal component (PC1) co ntained the fluorescence, while the second principal component (PC2) contai ned the pure Raman spectra. It was then possible to reconstruct the origina l data using only the second principal component, and then use this reconst ructed data to follow the progress of the reaction. To be sure that the dat a in PC2 represented the real chemical process, the kinetics of the reactio n were calculated using selected wavelength profiles in PC2. It was shown t hat the reaction follows theoretical second order kinetics, which is expect ed of this esterification.