A Rare Carbon Skeletal Oxidative Rearrangement of Camphene Catalyzed by Al‐Exchanged Keggin Heteropolyacid Salts

Abstract

In this work, aluminum-exchanged Keggin heteropolyacid salts (i. e., AlPW 12 O 40 , AlPMo 12 O 40 , and Al 4/3 SiW 12 O 40 ) were synthesized and evaluated as catalysts on the camphene oxidation with hydrogen peroxide. The aluminum silicotungstate salt (i. e., Al 4/ 3 SiW 12 O 40 ) was the most active and selective toward formation of borneol and two novel products; 1-(3-(2-hydroxypropan-2-yl) cyclopentyl) ethan-1-one, and 3-(3-hydroxycyclopentyl)-3methylbutan-2-one), which were spectroscopically character-ized (FT-IR, 13 C and 1 H NMR analyses). All the catalysts were characterized by FT-IR/ ATR spectroscopy, BET, XRD, EDS/SEM, and TG/DSC analyses. After the characterization of the HPA salts, it was possible to link their structural properties to their catalytic activity. The effects of the main reaction variables were assessed. The aluminum cation as well as the silicotungstic anion showed to be essential to formation of three goalproducts.

Efficient biodiesel production from oleic acid using metal–organic framework encapsulated Zr-doped polyoxometalate nano-hybrids

“…. 26 In addition, the four typical peaks also were observed with some shi from ZrSiW/Fe-BTC and ZrSiW/UiO-66 nano-hybrids, this is probably due to the robust interaction between the Keggin unit and framework structure owing to the strong adsorption at the interface, 27 determining the ZrSiW molecules were embedded on MOFs matrix. Compared with Fe-BTC, the same absorption peaks (1636, 1585, 1454, 759, and 710 cm À1 ) of ZrSiW/Fe-BTC catalyst also was observed and related to the Fe-BTC framework structure.…”

Copper Phosphotungstate-Catalyzed Microwave-Assisted Synthesis of 5-Hydroxymethylfurfural In A Biphasic System

“…The characterization of all the metal transition-exchanged catalysts used in this work was previously discussed by us in two previous papers; the rst one [43], where the metal exchanged catalysts were used in glycerol esteri cation reactions, and the second one, where the Aluminum salts were used as catalysts in ole n oxidations [45]. However, in this work, to check if the catalysts were correctly synthesized, we carried out UV-Vis and infrared spectroscopy analyses, and acidity measurements.…”

Vanadium-doped sodium phosphomolybdate salts as catalysts in the terpene alcohols oxidation with hydrogen peroxide

“…A simple protons exchange by metal cations allows that their properties such as acidity strength, porosity, and surface area can be adequately tuned, making them efficient catalysts in redox or acid-catalyzed reactions. [28][29][30][31][32] In addition, if the protons are exchanged by large ionic radius cations such as cesium, potassium, or ammonium, they become insoluble catalysts in polar solvents. 33,34 This modication keeps untouched the Keggin anion, which is the primary structure of these catalysts.…”