A. Potthast, T. Rosenau, P. Kosma, N. Schelosky, T. Baldinger
Thermal Reactions of N-Methyl-morpholine-N-oxide (NMMO): A General Method for Separation and Quantification of N-Methyl-morpholine-N-oxide and its Main Degradation Products N-Methylmorpholine and Morpholine by Capillary Electrophoresis (CE)
Summary
A general analytical method based on capillary electrophoresis with indirect UV detection has been
developed to separate and quantify N-methylmorpholine-N-oxide (NMMO) and its main degradation
products N-methylmorpholine (NMM) and morpholine (M). The electrolyte is based on the two major
components 4-methylbenzylamine and 2-hydroxy-2-methylpropanoic acid (hydroxy-isobutyric acid,
HIBA), the latter being used to adjust the pH to a value below 3.5 which is crucial for the electrophoretic
mobility and, thus, for a good detectability of the amine oxide. The present method is widely applicable
to monitor kinetics of reaction mixtures containing NMMO. NMM and M can be determined simultaneously
even in a 1000-fold excess of NMMO.
To monitor the fast and exothermic thermal degradation of NMMO by the electrophoretic method,
special reaction conditions had to be developed for separating the initial decomposition step from super-imposed
subsequent reactions. Reactive degradation products were removed by flushing with nitrogen,
and the reaction rate was decreased by dilution with o-dichlorobenzene as an inert solvent. The initial
phase of the decomposition reaction has been shown to follow second-order kinetics.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 54, 10/2000
Pages: 641 - 646
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