Aerobic oxidation of formaldehyde mediated by a Ce-containing polyoxometalate under mild conditions

An evaluation of over 50 polyoxometalates (POMs) identified the complex NaH3[SiW11Ce(IV)O39] (NaH3(1)) as a selective and effective catalyst for the aerobic oxidation of formaldehyde to formic acid under very mild (including ambient) conditions. 183W NMR, UV-vis, cyclic voltammetry, and potentiometric titration establish that the catalyst is a monomer (Cs symmetry), 1, in solution, while X-ray crystallography (a = 12.9455(15) A, b = 13.2257(16) A, c = 14.5288(17) A, alpha = 81.408(2) degrees , beta = 85.618(2) degrees , gamma = 80.726(2) degrees , P, Z = 1, R1 = 5.79% based on 17244 independent reflections) and IR establish it to be a dimer (Ci symmetry), 1(2), in the solid state. Several lines of evidence, including the parabolic kinetic order in 1, nonlinear Arrhenius plot, independence of the rate on O2 pressure, presence of titratable H2O2 and HCO3H intermediates, and inhibition by conventional radical scavengers, all indicate the O2-based oxidations proceed by complex homolytic chemistry (autoxidation and Haber-Weiss radical-chain processes) likely initiated by protonated 1.     

Study of the P2O5?MoO3 system in acrolein oxidation

Catalytic properties of the binary phosphorus-molybdenum system with Mo/P=3–24.5 in acrolein oxidation have been studied. The selectivity to acrylic acid and carbon oxides practically does not depend on the chemical composition of the system, and the maximum activity is observed for Mo/P=12. The catalytic properties of the system are determined by an X-ray amorphous phase, apparently molybdenyl phosphate.     

Methods of preparing the heteropolyacid H3PW12O40

Ionexchange and electrochemical methods of preparing the heteropolyacid H₃PW₁₂O₄₀ are studied. Conditions are found for preparing H₃PW₁₂O₄₀ in quantitative yield using electrodialysis without ether extraction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1944–1947, September, 1990.The authors thank K. I. Matveev for initiating the work with electrodialysis at the Institute of Catalysis, Siberian Branch, Academy of Sciences of the USSR.     

Oxidation of methylbenzenes by heteropoly compounds in solution

Conclusions heteropoly compounds in acetic acid solution oxidize methylbenzenes to form mixtures of aromatic alcohols, aldehydes, di- and polyarylmethanes. The reaction may be carried out catalytically in the presence of oxygen. Results were obtained indicating the formation of an intermediate radical-cation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheska, No. 5, pp. 1010–1017, May, 1984.     

New Multifunctional Agents Based on Conjugates of 4-Amino-2,3-polymethylenequinoline and Butylated Hydroxytoluene for Alzheimer’s Disease Treatment

New hybrids of 4-amino-2,3-polymethylenequinoline with different sizes of the aliphatic ring linked to butylated hydroxytoluene (BHT) by enaminoalkyl (7) or aminoalkyl (8) spacers were synthesized as potential multifunctional agents for Alzheimer’s disease (AD) treatment. All compounds were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with selectivity toward BChE. Lead compound 8c, 2,6-di-tert-butyl-4-{[2-(7,8,9,10- tetrahydro-6H-cyclohepta[b]quinolin-11-ylamino)-ethylimino]-methyl}-phenol exhibited an IC₅₀(AChE) = 1.90 ± 0.16 µM, IC₅₀(BChE) = 0.084 ± 0.008 µM, and 13.6 ± 1.2% propidium displacement at 20 μM. Compounds possessed low activity against carboxylesterase, indicating likely absence of clinically unwanted drug-drug interactions. Kinetics were consistent with mixed-type reversible inhibition of both cholinesterases. Docking indicated binding to catalytic and peripheral AChE sites; peripheral site binding along with propidium displacement suggest the potential of the hybrids to block AChE-induced β-amyloid aggregation, a disease-modifying effect. Compounds demonstrated high antioxidant activity in ABTS and FRAP assays as well as inhibition of luminol chemiluminescence and lipid peroxidation in mouse brain homogenates. Conjugates 8 with amine-containing spacers were better antioxidants than those with enamine spacers 7. Computational ADMET profiles for all compounds predicted good blood-brain barrier distribution (permeability), good intestinal absorption, and medium cardiac toxicity risk. Overall, based on their favorable pharmacological and ADMET profiles, conjugates 8 appear promising as candidates for AD therapeutics.