This study explores the potential of titanium oxide impregnated on calcium oxide (CaO-TiO2) as catalyst in transesterification of vegetable palm oil (VPO) to produce biodiesel. The biodiesel yield increased with catalyst calcination temperature and reaction time, and the usage of CaO-TiO2 led to higher biodiesel production when compared to reaction catalyzed by CaO. Biodiesel yield of 93.33% wa...

Efforts to trap early intermediates of the gold-catalyzed phenol synthesis failed. Neither inter- nor intramolecularly offered vinyl groups, ketones or alcohols were able to intercept the gold carbenoid species. This indicates that the competing steps of the gold-catalyzed phenol synthesis are much faster than the steps of the interception reaction. In the latter the barrier of activation is hi...

Metal ions play essential roles in about one third of enzymes [1]. These ions can modify electron flow in a substrate or enzyme, thus effectively controlling an enzyme-catalyzed reaction. They can serve to bind and orient substrate with respect to functional groups in the active site, and they can provide a site for redox activity if the metal has several valence states. Without the appropriate...

[figure: see text] A conceptually new palladium-catalyzed amidation reaction is described for the synthesis of beta-amido ketones based on derailing the Wacker oxidation of enones. This reaction generates a new carbon-nitrogen bond via a palladium-catalyzed conjugate addition of a carbamate nucleophile to an enone. The regiocontrol, mild and neutral conditions, lack of preactivation of the nucl...

Allene chemistry has attracted considerable attention in recent years. In particular, the transition-metal-catalyzed reaction of allene derivatives bearing an a substituent, such as hydroxy, carbonyl, carboxy, thio (sulfanyl), and amino groups, has led to many synthetically useful transformations. 2] One important reaction among them is the transition-metal-catalyzed cyclization of allenyl keto...

A friendly benign, green, rapid and facile strategy for synthesis a series of arylquinoxalines was achieved by condensation of aromatic 1,2-diamines with arylglyoxals under clay-catalyzed as an inexpensive and eco-friendly catalyst using grindstone chemistry. Significant decreases in reaction times and high yields have been observed by this green chemistry approach in comparison with previously...