Ca(OH)2-Catalyzed Condensation of Aldehydes with Methyl ketones in Dilute Aqueous Ethanol: A Comprehensive Access to α,β-Unsaturated Ketones

Evaluation of pectin extractions and their application in the alkaline Maillard reaction

A 2³ factorial design was used to evaluate the influence of temperature, catalyst and time and esterification degree (DE) of pectin obtained from mango, orange and tangerine peels as well as tamarind seeds by using the acid hydrolysis method. The study showed that a high temperature positively influenced the percentage of pectin yield for the four second generation biomasses. Nevertheless, the temperature showed a greater influence in the solubility and diffusion of the acid solvent in the tamarind seed matrix, resulting a pectin recovery 32.9%. Concerning the %DE, the most statistically significant value observed was dependent on the type of biomass studied. The %DE and the nature of the pectin are determining factors in the pectin's final use, in the present work the pectin extracted was used to produce furfural, a precursor of high value chemicals. The furfural production was achieved through alkaline hydrolysis and enhanced using the Maillard reaction, reaching a maximum concentration of 71.8 g/L which represents a 42.1% increase from the alkaline hydrolysis.

Calcium-catalyzed reactions of element-H bonds

Investigation on organocalcium catalysis is just unfolding during the past decade. Beside conventional Ca salts with strong electron-withdrawing counter anions that may serve as Lewis acid catalysts, many Ca complexes have also been designed recently and found to be good catalysts in activation of element-H (EH) bonds like transition metal catalysts. These findings are interesting and may attract the interest of the chemists. Due to the great abundance, non-toxicity, and biocompatible features of Ca element, Ca-catalyzed reactions can be of great significance from the viewpoint of industry. This short review summarizes the recent advances on Ca-catalyzed reactions of EH bonds. We hope that it may provide a useful guide for interested readers from both the academy and industry.

Poly(N-isopropylacrylamide-co-l-proline)-catalyzed Claisen–Schmidt and Knoevenagel condensations: unexpected enhanced catalytic activity of the polymer catalyst

The heterogeneous catalyst is more active than the homogeneous one! The abnormal phenomenon is probably caused by the polymer, which enriches the reactants around the reaction sites.