KF/Al2O3 as a Highly Efficient,Green, Heterogeneous,and Reusable Catalytic System for the Solvent-Free Synthesis of Carboacyclic Nucleosides via Michael Addition Reaction

KF/Al₂O₃ acts as an efficient catalytic system for the synthesis of carboacyclic nucleosides via Michael addition of pyrimidine and purine nucleobases to α,β-unsaturated esters under solvent-free and microwave conditions. Using this method, the title compounds are produced in good to excellent yields and short reaction times.     

Enhanced photocatalytic activity of ZnO nanoparticles by surface modification with KF using thermal shock method

ZnO nanoparticles were modified with KF using thermal shock method at various temperatures in order to improve the photocatalytic activity of ZnO under both UVA and visible light irradiation. The influences of KF-modification on the crystal structure, morphology, UV–visible absorption, specific surface area as well as surface structure of ZnO were respectively characterized by XRD, FE-SEM, UV–Visible diffuse reflectance, N₂ adsorption and XPS spectroscopy. The photocatalytic activity was evaluated via the degradation of methylene blue under UVA irradiation. According to the results, the thermal shock process with KF did not modify the structure, the particle size and the optical properties of ZnO nanoparticles but successfully increase their UVA and visible light induced photocatalytic activity. This enhancement of activity may be attributed to the increase of surface hydroxyl groups and zinc vacancies of modified ZnO samples.     

Insulating properties of ultrathin KF layers on Cu(1 0 0): Resonant Auger spectroscopy

Solid-state effects in the creation and decay of K 2p core excitations in thin KF films on Cu(1 0 0) surface have been studied in resonant Auger spectra, excited using synchrotron radiation. The spectra of films of various thickness starting from a single monolayer were measured.The photoabsorption spectra reveal crystal field splitting already at film thickness of about 1 monolayer. The Auger decay spectra of the K 2p⁻¹3d core excitations in films of thickness up to 2 monolayers exhibit a band characteristic of the decay of core ionised states, showing that the excited electron delocalises into substrate before the core hole decays. In thicker films the coexistence of the decay of excited states in the bulk of the KF crystalline film and of ionised states at the KF-metal interface is observed, indicating that the charge transfer probability from the upper layers of the film into the metallic substrate is strongly reduced.     

芳并呋喃类化合物的—锅化合成法

本文报道用KF/Al_2O_3作为碱催化剂,由水杨醛或2-羟基-1-萘醛分别和α-溴代乙酸酯、α-溴代苯乙酮、苄基氯、4,4’-二氯甲基联苯和1,5-二氯甲基萘等进行一锅化缩合反应,以38～89％的产率合成了14种芳并呋喃化合物。     

An efficient preparation of 1-phenylsulfonylindolyl methyl sulfoxides using KF/m-CPBA

A variety of 1-phenylsulfonylindolylmethyl sulfides are selectively oxidized to the corresponding sulfoxides using a hitherto unexplored KF/m-CPBA system. A major advantage is the absence of over-oxidation.     

Single step fluorination of dialkylphosphites: trichloroacetonitrile-KF as an efficient reagent for the synthesis of dialkyl fluorophosphates

The use of trichloroacetonitrile and KF mixture is described as an efficient reagent for the direct conversion of dialkylphosphites to their corresponding dialkyl fluorophosphates via in situ formation of dialkyl chlorophosphates in one-pot.     

Electrochemical Study of Potassium Fluoride in a Cryolite-Aluminum Oxide Molten Salt

Selective and efficient electrochemical methods to characterize aluminum are necessary. Current methods are based on potentiodynamic polarization, recurrent potential double pulses, chronopotentiometry, open-circuit chronopotentiometry, and potentiostatic electrolysis, but have not been used to characterize the deposition of aluminum in Na₃AlF₆-Al₂O₃-KF molten salts. The control processes of the formation of aluminum-tungsten intermetallic compounds, and the deposition of aluminum have been investigated by using steady-state potentiodynamic cathodic polarization curves. The dissolution loss rate of aluminum was determined with an increase in KF concentration by the analysis of recurrent potential double pulses. Using chronopotentiometry, it was confirmed that the deposition potential of aluminum shifted more negative as the KF concentration increased, and a higher KF concentrations induced a higher cathodic overpotential. From open-circuit potential measurements and scanning electron micrographs, it was concluded that aluminum(III) ions react with tungsten substrates to form an aluminum-tungsten compound, and the reaction mechanism of aluminum was determined. These electrochemical methods applied with aluminum electrolysis were accurate, efficient, and reliable.     

SEM Modeling with Singular Moment Matrices Part I: ML-Estimation of Time Series

A structural equation model (SEM) with deterministic intercepts is introduced. The Gaussian likelihood function does not contain determinants of sample moment matrices and is thus well-defined for only one statistical unit. The SEM is applied to the dynamic state space model and compared with the Kalman filter (KF) approach. The likelihood of both methods are shown to be equivalent, but for long time series numerical problems occur in the SEM approach, which are traced to the inversion of the latent state covariance matrix. Both approaches are compared on several aspects. The SEM approach is now open for idiographic (N = 1) analysis and estimation of panel data with correlated units.     

KF-Al2O3催化下3-芳基-3-(5，5-二甲基-3-羟基-2-环己烯-1-酮-2-基)丙酰胺衍生物的合成

芳醛、5，5—二甲基—1，3—环己二酮、丙二酸亚异丙酯、芳胺在KF-Al2O3催 化下，在DMF中反应生成3—芳基—3—(5，5—二甲基—3—羟基—2—环己烯—1— 酮—2—基)丙酰胺衍生物，产率良好。     

KF—Al2O3催化二苯胺的苄基化

氟阴离子(主要指无水碱金属氟化物、它的季铵盐及其载体试剂)作为一种碱性催化剂,近年在有机合成中的应用得到迅速发展。与其它催化剂比较有下述优点:反应条件温和、催化活性好、选择性强、后处理简单、产率高且可再生重复使用。