The synthesized [Nb.sub.2][O.sub.5] catalysts and commercial niobium compounds show a low Lewis Acid
acidity, incapables of active effectively the carbonylic active site on the fatty acid to promote the transesterification reaction of soybean oil with methanol.
Compared to pure Zr[O.sub.2], the Zr[O.sub.2]-[Al.sub.2][O.sub.3] catalysts contained more Lewis acid
sites and fewer base sites.
The second trial was carried out using ethanolic solutions of aromatic aldehydes, malononitrile, and primary amines in the presence of Lewis acids
as catalysts such as Al[Cl.sub.3], Zn[Cl.sub.2], and Fe[Cl.sub.3].
Magnacca, "IR spectroscopic and microcalorimetric characterization of Lewis acid
sites on (transition phase) [Al.sub.2][O.sub.3] using adsorbed CO," Langmuir, vol.
The second unexpected finding occurred during the course of examining various Lewis acids
as potential accelerators for the coupling reaction of glycosyl fluorides and alcohols.
Relatively high polymerization activities are achieved if strong Lewis acids
or combinations thereof are selected which achieve both, (i) alkylation of the metal complex and (ii) formation of separated non-coordinating ions upon contact with the alkylated lanthanide complex.
New stage in living cationic polymerization: An array of effective Lewis Acid
catalysts and fast living polymerization in seconds.
Presence of the Si[O.sub.2]-[Al.sub.2][O.sub.3] Lewis acid
as well as Br0nsted acid increases the number of sites that has a chance to absorb large amounts of pyridine.
Carbon dioxide also has several other favorable advantages including: being a quadrupolar solvent; having the potential to act as both a weak Lewis acid
and Lewis base; being able to be easily removed, enabling rapid recovery of isolated compounds; and, when used for SFC, it can be recovered from the atmosphere, making it a "green" solvent.
Mori et al developed a fast-curing adhesive using silyl groups and a Lewis acid
such as metal halides or boron halides as curing catalysts.
Their frustrated pair comprised of the Lewis base tetramethylpiperidine or TMP and the Lewis acid
Martra, G., "Lewis Acid
and Base Sites at the Surface of Microcrystalline TiO2 Anatase: Relationships between Surface Morphology and Chemical Behaviour," Appl.