V. Serra-holm et al., Comparison of activity and selectivity of weakly basic anion-exchange catalysts for the aldolization of butyraldehyde with formaldehyde, ORG PROC R, 5(4), 2001, pp. 368-375
Aldols are important intermediates in the production of polyols, which are
raw material for lubricants, surface coatings, and synthetic resins. The ac
tivities and selectivities of gel-type and macroporous anion-exchange resin
catalysts in the aldolization of butyraldehyde with formaldehyde in an aqu
eous environment were investigated at 60 degreesC. The experiments were car
ried out batchwise in a stirred glass reactor, and the reaction products we
re analyzed with high performance liquid chromatography. Two main products
were observed, 2-ethyl-3-hydroxy-2-hydroxy-methylpropanal (trimethylolpropa
ne aldol) and 2-ethylpropenal (ethylacrolein). The product ratio was strong
ly dependent on the catalyst. The selectivity with respect to trimethylolpr
opane aldol varied within the range 2.7-7.3 for the catalysts investigated.
Systematic kinetic experiments were carried out at 50-70 degreesC with the
gel-type resin catalyst displaying the highest aldol selectivity. A kineti
c model based on molecular mechanisms was able to describe the product dist
ribution.