Abiotic CO2 reduction on transition metal minerals has been proposed to account for the synthesis of organic compounds in alkaline hydrothermal systems, but this reaction lacks experimental support, as only short-chain hydrocarbons (
Formation of formic acid from renewable biomass resources is of great interest since formic acid is a widely used platform chemical and has recently been regarded as an important liquid hydrogen carrier. Herein, a novel approach is reported for the conversion of glucose, the constituent carbohydrate from the cellulose fraction of biomass, to formic acid under mild hydrothermal conditions with simultaneous reduction of Ag2O to Ag. Results showed that glucose was selectively converted to formic acid with an optimum yield of 40.7% and glycolic acid with a yield of 6.1% with 53.2% glucose converting to carbon dioxide (CO2) immediately at a mild reaction temperature of 135 °C for 30 min. In addition, Ag2O was used as a solid oxidant for glucose oxidation, which avoids the use of traditionally dangerous liquid oxidant H2O2. Furthermore, complete conversion of Ag2O to Ag can be achieved. This study not only developed a new method for value-added chemical production from renewable biomass but also explored an alternative low-carbon and energy-saving route for silver extraction and recovery.
Conversion of CO2 into value-added chemicals with a facile hydrogen source such as water is always of great interest for sustainable development. In this work, a simple and efficient method of reduction of bicarbonate to formate on a simple Ni powder catalyst with water as the facile hydrogen source and Zn as the regenerable reductant is proposed. The Ni catalyst and in situ formed Zn/ZnO exhibited a synergetic catalytic activity in the conversion of bicarbonate into formate, and a good formate yield of 81% was obtained. Detailed studies revealed that the synergetic catalytic activity between Ni and the in situ formed Zn/ZnO was mainly attributed to (i) the inhibited oxidation of Zn by Ni, leading to more interface of Zn/ZnO; (ii) the decreased growth of ZnO crystal along the [0001] direction, and thus increasing the more polar (0001) Zn face and the (0001Ì ) O face, which have high activity; and (iii) the enhanced generation of more oxygen vacancies at the Zn/ZnO interface to promote the formate yield. This research demonstrates an efficient method of using a simple and nonprecious metal catalyst for the CO2 reduction into value-added chemicals and provides a better understanding of the synergistic catalytic mechanism of Ni and Zn/ZnO.
H2S is considered to be an important reductant in abiotic CO2 reduction to organics, however, almost no experimental support has been reported. Herein, the first observation of CO2 reduction to formate with H2S under alkaline hydrothermal conditions is reported, and water is found to act as a hydrogen donor.
Reaction of PdCl2 with N,N-bis-(diphenylphosphanylmethyl)-2-aminopyridine (bdppmapy) afforded a mononuclear complex [(bdppmapy)PdCl2] (). Compound was characterized by elemental analysis, IR, (1)H, (13)C and (31)P NMR, electrospray ion mass spectra (ESI-MS) and X-ray single crystal crystallography. The Pd(ii) center in is chelated by bdppmapy, showing a cis-square planar geometry. With the assistance of additive Cu2O, complex exhibited good catalytic activity toward the decarboxylative cross-coupling reactions between 4-picolinic acid and aryl bromides. In the presence of only 2 mol% catalyst, a family of 4-aryl-pyridines could be isolated in up to 83% yield.
The reaction of [Ag(MeCN)(4)]ClO(4) with N,N,N',N'-tetra(diphenylphosphanylmethyl)ethylenediamine (dppeda) in CH(2)Cl(2)/MeOH afforded an unexpected cationic binuclear complex [Ag(2)(L(1))(2)(η,η-µ-ClO(4))(2)](ClO(4))(2) (L(1) = N,N'-bis(diphenylphosphanylmethyl)-3H-4,5-dihydroimidazole-1-ium) (1). Compound 1 was also prepared in high yield from reactions of [Ag(MeCN)(4)]ClO(4) with N,N'-bis(diphenylphosphanylmethyl)ethylenediamine (bdppeda) in the presence of formaldehyde (HCHO) or formic acid (HCOOH). Analogous reactions of AgCl with bdppeda and HCHO resulted in the formation a neutral binuclear complex [Ag(2)(L(2))(2)(µ-Cl)(2)] (L(2) = N,N-bis(diphenylphosphanylmethyl)-tetrahydroimidazole) (2). Treatment of 1 with concentrated HCl gave rise to a partially anion-exchanged product [Ag(2)(L(1))(2)(µ-Cl)(2)](ClO(4))(2) (3). Compounds 1 and 3 have a similar cationic binuclear structure, in which a [Ag(2)(η,η-µ-ClO(4))(2)] or [Ag(2)(µ-Cl)(2)] ring is sandwiched by two in situ-formed cationic L(1) ligands. The L(1) ligand may be generated by the Ag(I)-assisted condensation reaction between bdppeda and HCHO or HCOOH. Compound 2 holds a neutral binuclear structure, in which a [Ag(2)(µ-Cl)(2)] ring is connected by two in situ-formed L(2) ligands from its top and bottom sites. The neutral ligand L(2) may be produced from another Ag(I)-assisted condensation reaction between bdppeda and HCHO. The in situ formation of the L(1) and L(2) ligands provides a new route to the N-heterocyclic diphosphine ligands, and an interesting insight into the coordination chemistry of their metal complexes.
