Fourier Transform Infrared Spectrometry/Attenuated Total Reflectance Study of the Reaction of Pentanal and Propanal with 2-(Hydroxymethyl)Piperidine

Abstract

The reactions of propanal and pentanal with 2-(hydroxymethyl)piperidine were investigated by Fourier transform infrared spectrometry/attenuated total reflectance in both the solution phase and at the gas/solid interface. The reactions were studied with the use of a flow-through cylindrical internal reflection (“circle”) cell. Reaction intermediates were tentatively identified by their characteristic infrared absorption frequencies. At the gas/solid interface the reaction is thought to yield a hemiaminal intermediate. In the solution phase a hemiaminal intermediate is believed to form initially, followed by loss of water to generate an enamine product. In both gas-phase and solution-phase studies, an oxazolidine product is prepared only after an ultrasound treatment. The FT-IR/ATR technique reveals detailed mechanistic information concerning reactions between aldehydes and ethanol amines.