Solid acids have received considerable attention as alternatives to traditional corrosive and hazardous homogeneous acids because of their advantages in practical applications, including their low corrosion of equipment and high catalytic activity and recyclability. In this work, a strong solid acid was prepared by anchoring thiol group terminated chains on layered α-zirconium phosphate (ZrP) single-layer nanosheets, followed by oxidation of thiol groups to form sulfonic acid groups. The obtained solid acids were thoroughly characterized and the results proved that sulfonic acid group terminated chains were successfully grafted onto the ZrP nanosheets with a high loading density. Such a strong solid acid based on inorganic nanosheets can be well-dispersed in polar solvents, leading to high accessibility to the acid functional groups. Meanwhile, it can be easily separated from the dispersion system by centrifugation or filtration. The strong solid acid can serve as an effective heterogeneous catalyst for various reactions, including the Bayer-Villiger oxidation of cyclohexanone to ε-caprolactone in the absence of organic solvents.
Here, a new proton-exchange-membrane electrolysis is presented, in which lignin was used as the hydrogen source at the anode for hydrogen production. Either polyoxometalate (POM) or FeCl was used as the catalyst and charge-transfer agent at the anode. Over 90 % Faraday efficiency was achieved. In a thermal-insulation reactor, the heat energy could be maintained at a very low level for continuous operation. Compared to the best alkaline-water electrolysis reported in literature, the electrical-energy consumption could be 40 % lower with lignin electrolysis. At the anode, the Kraft lignin (KL) was oxidized to aromatic chemicals by POM or FeCl , and reduced POM or Fe ions were regenerated during the electrolysis. Structure analysis of the residual KL indicated a reduction of the amount of hydroxyl groups and the cleavage of ether bonds. The results suggest that POM- or FeCl -mediated electrolysis can significantly reduce the electrolysis energy consumption in hydrogen production and, simultaneously, depolymerize lignin to low-molecular-weight value-added aromatic chemicals.
Diamondoids, a group of hydrocarbon cage molecules that resemble diamond lattice, are attracting increasing interest in the past decade. Their diamond-like structure warrants that diamondoids inherit the superior properties of diamond at nanoscale, including exceptional hardness and stiffness, high thermal stability, high chemical resistance, unique optical properties and fluorescence, and excellent biocompatibility. To effectively take advantage of the fascinating properties of diamondoids, they must be properly functionalized so that they can be covalently incorporated into the host systems or compatibly mixed with the hosts. Herein, the origin, synthesis, derivatization, and application of diamondoids are reviewed. In particular, how the derivatized diamondoids for various functional applications, including pharmaceuticals, polymers, fine chemicals, nanomaterials, and optical devices, are discussed. It is hoped that this review article can attract more interest in diamondoids, which in turn helps motivate the development of new synthesis and application of diamondoids and their derivatives so that this group of unique molecules can bring more benefits.
Scheme 3 Bromination of adamantane under phase-transfer conditions.Scheme 4 Synthesis of 1,3,5,7-tetrabromoadamantane.Scheme 5 Preparation of 1-adamantanol by the ozonation of adamantane over silica gel.Scheme 6 Preparation of adamantyl amine.Scheme 7 Preparation of 1,3-adamantanedicarboxylic acid.
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