V. Serra-holm et al., Aldolization of butyraldehyde with formaldehyde over a commercial anion-exchange resin - kinetics and selectivity aspects, APP CATAL A, 198(1-2), 2000, pp. 207-221
Butyraldehyde was aldolized with formaldehyde at 40-80 degrees C over an an
ion-exchange resin catalyst in aqueous and methanolic solutions. The reacti
on mixture was analyzed with gas and liquid chromatography as well as nucle
ar magnetic resonance (NMR) spectroscopy. Two main products were detected:
2-ethyl-3-hydroxy-2-hydroxymethylpropanal (trimethylolpropane aldol) and 2-
ethylpropenal (ethylacrolein). The molar ratio of the main products was dep
endent on the formaldehyde-to-butyraldehyde ratio and the solvent compositi
on but independent of the temperature. The yield of 2-ethyl-3-hydroxy-2-hyd
roximethylpropanal increased with increasing formaldehyde-to-butyraldehyde
ratio and with increasing water-to-methanol content of the reaction mixture
. Besides the main reactions, self-condensation and acetalization of butyra
ldehyde were detected as side reactions of minor importance. The self-conde
nsation of butyraldehyde was suppressed in the presence of formaldehyde and
the acetalization of butyraldehyde was minimized by the use of water as re
action solvent. Rate equations were derived starting from molecular reactio
n mechanisms and adsorption of formaldehyde on the catalyst structure. It t
urned out that the rate equations can predict the distribution of the main
products. (C) 2000 Elsevier Science B.V. All rights reserved.