The Effect of Surfactants On the Chromatographic Separation of Phenols On Papers Impregnated With Hydrated Cerium Oxide

Abstract

The effect of surfactants on the chromatographic behaviour of 16 phenols of different nature have been observed on Whatman No 2 paper strips impregnated with hydrated cerium oxide. the movement of phenolic spots was observed in various mobile phase solvents with or without 4m ML^?1 8m ML^?1 and 12m ML^?1 sodium dodecyl sulphate (SDS). It is observed that the use of micellar mobile phase systems, which improve the selectivity and compactness of the spots, offered significant advantages over traditional solvents. On the basis of appreciable differences in the af values of phenols a variety of bioanalytically important binary and ternary separations were achieved without using separate detecting reagents, as most of the phenols appear as coloured spots with cerium oxide papers.     

DFT Study of the Active Site of the XoxF‐Type Natural,Cerium‐Dependent Methanol Dehydrogenase Enzyme

Rare‐earth metal cations have recently been demonstrated to be essential co‐factors for the growth of the methanotrophic bacterium Methylacidiphilum fumariolicum SolV. A crystal structure of the rare‐earth‐dependent methanol dehydrogenase (MDH) includes a cerium cation in the active site. Herein, the Ce–MDH active site has been analyzed through DFT calculations. The results show the stability of the Ce^III–pyrroloquinoline quinone (PQQ) semiquinone configuration. Calculations on the active oxidized form of this complex indicate a 0.81 eV stabilization of the PQQ⁰ LUMO at cerium versus calcium, supporting the observation that the cerium cation in the active site confers a competitive advantage to Methylacidiphilum fumariolicum SolV. Using reported aqueous electrochemical data, a semi‐empirical correlation was established based on cerium(IV/III) redox potentials. The correlation allowed estimation of the cerium oxidation potential of +1.35 V versus saturated calomel electrode (SCE) in the active site. The results are expected to guide the design of functional model complexes and alcohol‐oxidation catalysts based on lanthanide complexes of biologically relevant quinones.     

铈对液态共晶Fe—C合金粘度的影响

利用液态高温回转振荡粘度仪分别对共晶Fe-C合金和Fe-C-Ce合金(铈含量分别为0.08%,0.21%,0.59%)的粘度进行了研究.结果表明,在熔点以上至1420℃的范围内,共晶Fe-C合金的粘度在8.30～5.50mPa@s之间变化,而在熔点附近合金粘度的异常现象与液体合金中石墨的形成有关;铈含量大于0.21%明显降低了共晶Fe-C合金的粘度,分析表明,粘度的降低与液态合金自由体积的增加有关.Fe-C-Ce合金的粘度在1340～1370℃范围内出现反常变化,高温差示扫描量热(DSC)实验发现几乎在同样的温度范围存在异常峰位,分析表明这与液体合金内部的Ce-C化合物原子团簇有关.     

Immobilization of cerium (IV) and erbium (III) in mesoporous MCM‐41: Two novel and highly active heterogeneous catalysts for the synthesis of 5‐substituted tetrazoles,and chemo‐ and homoselective oxidation of sulfides

Two well‐ordered 2D ‐ hexagonal cerium (IV) and erbium (III) embedded functionalized mesoporous MCM ‐ 41(MCM‐41@Serine/Ce and MCM ‐ 41@Serine/Er) have been developed via functionalization of mesoporous MCM ‐ 41. The surface modification method has been used in the preparation of serine‐grafted MCM ‐ 41 and led to the development of MCM‐41@Serine. The reaction of MCM‐41@Serine with Ce (NH₄)₂(NO₃)₆·2H₂O or ErCl₃·6H₂O in ethanol under reflux led to the organization of MCM‐41@Serine/Ce and MCM‐41@Serine/Er catalysts. The structures of these catalysts were determined using scanning electron microscopy, mapping, energy‐dispersive X‐ray spectroscopy, Fourier transform‐infrared, thermogravimetric analysis, X‐ray diffraction, inductively coupled plasma, and Brunauer–Emmett–Teller analysis. These MCM‐41@Serine/Ce and MCM‐41@Serine/Er catalysts show outstanding catalytic performance in sulfides oxidation and synthesis of 5‐substituted tetrazoles. These catalysts can be recycled for seven repeated reaction runs without showing a considerable decrease in catalytic performance.     

Scaled‐up,selective and green synthesis of sulfoxides under mild conditions using (CeIII‐MoVI)Ox/aniline hybrid rods as an efficient catalyst

A novel hybrid material, (Ce^III‐Mo^VI)O_x/aniline, with rod‐like morphology is synthesized through a wet chemical method using Mo₃O₁₀(C₆H₅NH₃)₂.2H₂O nanowires as precursor. The synthesized materials are characterized by XRD, XPS, SEM, TEM, FTIR, Raman, UV–Vis, TGA, and elemental analysis. Also, their catalytic activities as a hybrid catalyst are tested in the selective oxidation of sulfides using hydrogen peroxide as a green oxidant. The proposed novel hybrid catalyst shows an excellent performance under green conditions at mild temperature. Furthermore, the scalability of the oxidation reaction is shown by making multi‐gram quantities at optimized conditions.     

Studies on the oxidative cyclization of 3-hydroxyalkyl-1,2,4-trialkoxynaphthalenes and synthetic application for the biologically active natural compound rhinacanthone

The oxidative intramolecular cyclization of 3-hydroxyalkyl-1,2,4-trimethoxynaphthalenes was investigated. A series of 1,2-naphthoquinone fused cyclic ethers were synthesized directly from 3-hydroxyalkyl-1,2,4-trimethoxynaphthalenes by exposure to diammonium cerium (IV) nitrate. To understand the reaction mechanism, the intramolecular cyclization of 3-hydroxyalkyl-naphthoquinones that were formed as reaction intermediates was also examined. The results suggested that the reaction proceeds by a stepwise oxidation–cyclization mechanism. Using this methodology, five-step synthesis of rhinacanthone was achieved with high yield.     

Catalytic Ketonization of Carboxylic Acids Synthesis of Saturated and Unsaturated Ketones

Activity of 20wt% MO₂/Al₂O₃ catalysts, where M = Mn, Ce and Zr has been studied in ketonisation of the mixtures of propanoic/pentanoic, ethanoic/10-undecenoic and hexanoic/(Z)-9-octadecenoic (oleic) acids. Irrespective of the molecular weights and molar ratios of reacting acids, high yields of ketones were obtained over Mn and Ce oxide catalysts at approximately 673 K. Isomerization of C=C double bonds and partial pyrolysis occurred during catalytic ketonization of 10-undecenoic and oleic acids, diminishing slightly the yield of ketones. The preparation of (Z)-14-tricosen-6-one has been performed, being the starting material for the synthesis of (Z)-9-tricosene - sex attractant of male house fly.     

An expeditious synthesis of isoxazoline using cetyltrimethylammonium cerium nitrate: A phase transferring oxidative 1, 3-diplor cycloaddition

An expeditious and effective method for synthesis of isoxazoline from aldoximes and activated alkenes using cetyltrimethylammonium cerium nitrate at room temperature is described. Reaction was completed within short time period in high yields at room temperature.     

Assembly of Large Purely Inorganic Ce‐Stabilized/Bridged Selenotungstates: From Nanoclusters to Layers

A versatile one‐pot strategy was used to synthesize two large, purely inorganic selenotungstates, nanocluster K₆Na₁₆[Ce₆Se₆W₆₇O₂₃₀(OH)₆(H₂O)₁₇]?47 H₂O ( 1 ) and layer K₉Na₅Ce(H₂O)₄[Ce₆Se₁₀W₅₁O₁₈₇(OH)₇(H₂O)₁₈]?45 H₂O ( 2 ), by combining cerium centers and SeO₃^2? heteroanion templates. Compound 1 displays a Ce‐stabilized hexameric nanocluster with one rhombus‐like {W₄O₁₅(OH)₃} unit in the center, whereas compound 2 is the first example of a Ce‐bridged layer selenotungstate network based on linkage of the unusual {Ce₆Se₁₀W₅₁O₁₈₇(OH)₇(H₂O)₁₈} clusters and additional Ce(H₂O)₄ fragments via Ce‐O‐Se bridges. The compounds were characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses, powder and single‐crystal X‐ray diffraction, and electrospray ionization mass spectrometry. Moreover, the electrochemical property of compound 1 was also investigated.