Salen-Mn（Ⅲ）-Complex-Catalyzed Oxidations of Secondary Alcohols

Secondary alcohols were catalytically oxidized with diace-toxyiodobenzene as oxidant in the presence of salen-Mn(Ⅲ)complex to aiTord the eorrespoltding ketones, in up to 99% yield, using CH2Cl2 or water as reaction media.     

Selective Oxidation of Alcohols with a New Reagent: Iron(III) Nitrate Supported on Aluminum Silicate

A selective and effective oxidation of alcohols, except aliphatic alcohols, such as 1‐hexanol or 1‐octyl alcohol, to the corresponding aldehydes and ketones using a new reagent, iron(III) nitrate supported on aluminum silicate, under heterogeneous conditions with reflux with 85–98% yield is described.     

Ferric(III) Nitrate Supported on Kieselguhr: A New Reagent for Selective Oxidation of Alcohols

A selective and effective oxidation of alcohols into the corresponding aldehydes and ketones, respectively, with a new reagent, ferric(III) nitrate supported on kieselguhr, under heterogeneous conditions is reported.     

CoFe2O4@SiO2@ Co (III) salen complex nanoparticle as a green and efficient magnetic nanocatalyst for the oxidation of benzyl alcohols by molecular O2

In the presence of cobalt (III) salen complex, selective oxidation of alcohols to carbonyl compounds was studied by molecular oxygen using isobutyraldehyde as an oxygen acceptor. The effect of cobalt (III) salen complex in the oxidation reaction was studied, and the results showed that Co (III) salen complex is very active and selective in the oxidation of various alcohols. Also, the effect of important factors including catalyst amount, solvent and temperature was investigated on the reaction. Furthermore, the catalytic activities of CoFe₂O₄@SiO₂‐supported Schiff base metal complex as well as the effect of molecular oxygen (O₂) as a green oxidant were studied. The results showed that benzaldehyde was the major product and the heterogeneous catalyst was highly reusable.     

分子印迹聚合物负载Fe(III)催化剂的底物识别性能

分别以o-, m-和p-硝基苯甲醇与FeCl₃的配合物为模板分子,丙烯酰胺为功能单体,二甲基丙烯酸乙二醇酯为交联剂,采用本体聚合法制备了三种Fe(III)含量相同的分子印迹聚合物(MIP)o-Fe(III)-MIP,m-Fe(III)-MIP和p-Fe(III)-MIP.并采用扫描电镜、N₂吸附-脱附及红外光谱等方法对催化剂结构进行了表征.在以水为溶剂,过氧化氢(30%)为氧化剂的苯甲醇衍生物氧化反应中,该类催化剂表现出优异的催化活性和独特的底物识别性能.当以p-Fe(III)-MIP为催化剂时,p-硝基苯甲醇的转化率达到80%,而在其他两个催化剂上均低于58%.这表明Fe(III)-MIP催化剂结构中具有与底物分子匹配的印迹空腔与识别位点,对底物分子表现出专一识别性,因而提高了催化剂对底物的选择性.     

Direct synthesis of Fe(III) immobilized Zr‐based metal–organic framework for aerobic oxidation reaction

A Zr‐based metal–organic framework with bipyridine units (UiO‐67) has been utilized for the immobilization of catalytically active iron species via a post‐synthetic metalation method. UiO‐67 bipyridine MOF was synthesized through a simple solvothermal method and was shown to have a UiO‐type structure. Post‐synthetic metalation of UiO‐67 MOF was performed for the immobilization of the catalytically active FeCl₃. FT‐IR and EDX element map suggested that FeCl₃ is coordinately bonded to the UiO‐67 bipyridine framework. The synthesized UiO‐67‐FeCl₃ catalyst was used for the aerobic oxidation of alcohols and benzylic compounds in the presence of molecular oxygen. In addition, the UiO‐67‐FeCl₃ catalyst can be reused as a solid heterogeneous catalyst without compromising its activity and selectivity.     

Osmium (VIII)-mediated oxidation of arsenic (III)/antimony (III) by 1-equivalent oxidants

Os(VIII) catalysis of oxidation of As(III)/Sb(III) by 1-equivalent oxidants like Ce(IV) and Mn(III) in acid medium is studied. A multistep mechanism involving the intervention of the intermediate oxidation states of osmium is found to apply. Specific rates of different steps in the mechanism are estimated and used to calculate reaction rates which are in reasonable agreement with those of experiment.     

Liquid-Phase Oxidation of Some Aromatic Aldehydes,Hydrocarbons, and Alcohols by Cerium(IV) Catalyzed by Iridium(III) in Acidic Medium

Addition of traces of iridium(III) chloride with cerium(IV) sulfate (catalyst–substrate ratio (1:2994 to 1:10,000) in traditional water-bath heating resulted in the oxidation of p-chlorobenzaldehyde, p-nitrobenzaldehyde, benzyl alcohol, p-methoxy benzyl alcohol, p-xylene, and p-nitrotoluene dissolved in acetic acid to give 77%, 90%, 21.7%, 88.6%, 86.2%, and 18% yields of the products, respectively, while catechol and resorcinol polymerized. Oxidation of aldehydes and alcohols resulted as usual in the corresponding acids and aldehydes, respectively, while p-xylene and p-nitrotoluene gave p-tolualdehyde and p-nitrobenzoic acid. Conditions were obtained for getting the highest yields under the experimental conditions.     

稀土配合物的发光特性及其能量传递研究

利用激光诱导荧光技术研究了稀土铕等金属配合物的发光特性及其能量传递动力学过程．得到了这些稀土配合物中中心离子Eu（3 ）的激发光谱，配体的三线态发时光谱和单线态发射光谱；在实验上观察到由于中心离子Eu（3 ）的5D2←7F0马跃迁吸收造成的配体发射光谱中的凹陷行为     

以氯醌酸二价阴离子为桥联配体的Fe(Ⅲ)-Fe(Ⅲ)和Mn(Ⅱ)-Mn(Ⅱ)双核配合物的合成与磁性

基于铁和锰的双核配合物在生物氧化还原过程中的重要作用及在化学的氧化还原过程中可能做为催化剂的应用前景,本文合成了两个新的以氯醌酸二价阴离子为桥联配体的Fe(Ⅲ)双核和Mn(Ⅱ)双核配合物:[Fe_2(phen)_4(μ-CA)](ClO_4)_4·2H_2O(1)和[Mn_2(phen)_4(μ-CA)](ClO_4)_2·3H_2O(2)(phen=1,10菲咯啉;CA=氯醌酸二价阴离子)。经元素分析、IR、电子光谱及磁性等测定,对两配合物进行了表征。     

Effective oxidation of alcohols by Iron(III)-Schiff base-triphenylphosphine complexes

Iron(III)-Schiff base-triphenylphosphine complexes catalyze the oxidation of alcohols to their corresponding carbonyl compounds in presence of hydrogen peroxide in good yields.     

N-溴代丁二酰亚胺水相氧化醇类化合物反应研究

以水为反应介质、NBS为氧化剂,在水相无催化剂条件下实现了醇的氧化.芳香醇、脂肪醇都可以达到95%以上的醛(或酮)产率,但该体系对一些含供电子取代基的醇的反应活性不高,选用salen-Co(Ⅲ)配合物作为催化剂,可拓宽反应的底物适用范围.     

SYNTHESIS AND CHARACTERISATION OF A NEW NIOBATE COMPLEX WITH CHROMIUM(III)

Abstract

A new hexaniobate complex with chromium(III) was prepared and characterised by analytical and spectroscopic techniques. The compound is a violet, non-crystalline solid, formulated as [Cr₂(μ-OH)(H₃Nb₆O₁₉)(en)₃(H₂O)]. It was synthesised in aqueous solution by reaction of [Cr(en)₃]³⁺, en = ethylenediammine, with the hexaniobate anion [Nb₆O₁₉]^8-, at pH 8. Thermal decomposition yielded a mixture of CrNbO₄ and Nb₂O₅. The synthesis of this compound shows that the hexaniobate anion may form complexes at lower pH values than previously reported.     

A Three-dimensional Neodymium(III)-potassium(I) Coordination Polymer

The title compound [NdK(btec)(H2O)2]n 1 was synthesized via the hydrothermal reaction of Zn(OAc)2·H2O, Nd(NO3)3 and KOH with 1,2,4,5-benzenetetra-carboxylic acid (H4btec), and characterized by elemental analysis and infrared spectra.The crystal of 1 crystallizes in monoclinic, space group P21/c with a = 8.9023(3), b = 7.8954(1), c = 17.6249(5)A, β = 91.857(1)o, V = 1238.16(6) -3, Z = 4, C10H6KNdO10, Mr = 469.49, Dc = 2.519 g/cm3, F(000) = 900 and μ(MoKα) = 4.585 mm-1.The final R = 0.0404 and wR = 0.0832 for 2197 observed reflections with I > 2σ(I) and R = 0.0431 and wR = 0.0854 for all data.X-ray diffraction reveals that the btec ligand serves as a (16-bridging ligand to link the Nd(III) and K(I) atoms into a three-dimensional coordination polymer.Photoluminescent investigation shows that the title compound displays strong emission in the blue region, which may be attributed to an intraligand emission state.     

无溶剂条件下锰 (Ⅲ)-席夫碱配合物催化过氧化氢氧化醇

 Aliphatic and aromatic alcohols are efficiently oxidized to ketones or carboxylic acids using aqueous hydrogen peroxide as an oxidant in the presence of a Mn(III) Schiff-base complex as a catalyst under solvent-free conditions. The oxidation of alcohols occurred at 50 °C to give the corresponding ketones or carboxylic acids with a yield higher than 60%.     

Complex formation followed by internal electron transfer: The reaction between cysteine and iron(III)

Summary A kinetic study of the anaerobic oxidation of cysteine (H₂ L) by iron(III) has been performed over thepH-range 2.5 to 12 by use of a stopped-flow high speed spectrophotometric method. Reaction is always preceded by complex formation. Three such reactive complex species have been characterized spectrophotometrically: FeL ⁺ (_max=614 nm, =2 820 M^–1cm^–1); Fe(OH)L (_max=503 nm; shoulder at 575 nm, =1 640 M^–1cm^–1); Fe(OH)L ₂ ^2– (_max=545 nm; shoulder at 445 nm, =3 175 M^–1 cm^–1). Formation constants have been evaluated from the kinetic data: Fe³⁺+L ^2– FeL ⁺: logK ₁ ^M =13.70±0.05; Fe(OH)²⁺+L ^2– Fe(OH)L: logK ₁ ^MOH =10.75±0.02; Fe(OH)L+L ^2– Fe(OH)L ₂ ^2– ; logK ₂ ^MOH =4.76±0.02. Furthermore the hydrolysis constant for iron(III) was also obtained: Fe(OH)²⁺+H⁺ Fe _aq ³⁺ : logK ^FeOH=2.82±0.02). Formation of the mono-cysteine complexes, FeL ⁺ and Fe(OH)L, is via initial reaction of Fe(OH)²⁺ with H₂ L (k=1.14·10⁴M^–1s^–1), the final product depending on thepH. FeL ⁺ (blue) formed at lowpH decomposes following protonation with a second-order rate constant of 1.08·10⁵M^–1s^–1. Fe(OH)L (purple) decomposes with an apparent third order rate constant ofk=3.52·10⁹M^–2s^–1 via 2 Fe(OH)L+H⁺ products, which implies that the actual (bimolecular) reaction involves initial dimer formation. Finally, Fe(OH)L ₂ ^2– (purple) is remarkably stable and requires the presence of Fe(OH)L for electron transfer. A rate constant of 8.36·10³M^–1s^–1 for the reaction between Fe(OH)L and Fe(OH)L ₂ ^2– is evaluated.Dedicated to Prof. Dr. mult. Viktor Gutmann on the occasion of his 70th birthday     

Ruthenium(III)-catalyzed oxidation of thallium(i) by 12-tungstocobaltate(III) in hydrochloric acid medium

The reaction between thallium(I) and [Co^IIIW₁₂O₄₀]^5- in the presence of ruthenium(III) as catalyst proceeds viainitial outer-sphere oxidation of the catalyst to ruthenium(VI). The ruthenium(IV) thus generated will oxidize thallium(I) to an unstable thallium(II) which by reacting with oxidant gives the final product, thallium(III). The formation of ruthenium(II) by direct two-electron reduction of the catalyst by thallium(I) is thermodynamically less favorable. The reaction rate is unaffected by the [ H⁺ ], whereas it is catalyzed by chloride ion . The formation of reactive chlorocomplex,TlCl, in a prior equilibrium is the reason for the chloride ion catalysis. Increasing the relative permittivity of the medium increases the rate of the reaction, which is attributed to the formation of an outer-sphere complex between the catalyst and oxidant. This revised version was published online in June 2006 with corrections to the Cover Date.     

Highly ordered mesoporous La(III)-substituted 5-oxopyrrolidine-2-carboxylic acid (Glp) immobilized on SBA-15 as a very efficient nanocatalyst for green aerobic oxidative coupling of thiols to disulfides

Selective aerobic oxidative coupling of thiols that are catalyzed by La(III)-substituted 5-oxopyrrolidine-2-carboxylic acid (Glp) immobilized on SBA-15 (SBA-15@Glp–La; SBA = Santa Barbara amorphous) was studied. Using SBA-15@Glp–La, the complete conversion was achieved at room temperature in the presence of air without producing any over-oxidized yields. SBA-15@Glp–La was prepared by post-grafting technique. 5-Oxopyrrolidine-2-carboxylic acid (Glp) condensation followed by La(III) impregnation caused this La(III)-grafted 5-oxopyrrolidine-2-carboxylic acid (Glp) to immobilize on SBA-15. This SBA-15@Glp–La catalyst shows excellent catalytic activity in the selective aerobic oxidative coupling of thiols. Effects of amount of the catalyst, polarity of the solvent, effects of substrate, and catalyst reusability were investigated. It has been observed that seven repetitive reaction cycles did not cause any appreciable loss in the catalytic activity of this catalyst. The catalyst characterization by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, transmission electron microscopy, inductively coupled plasma, elemental mapping, and N₂ adsorption–desorption is reported. The procedure developed is heterogeneous and environmentally benign.     

Some novel manganese(III) porphyrins with catalytic properties

Abstract

A series of manganese(III) porphyrins with 4-methylimidazole have been prepared. These are high-spin complexes having general formula [Mn^III(THMPP)X(4-MeIm)], where THMP?=?5,10,15,20-tetra(4-hydroxy-3-methoxyphenyl)porphine ligand, X?=?Cl^?, Br^?, NCS^?, or N₃^? and 4-MeIm?=?4-methylimidazole. All the complexes have been characterized by UV-visible, FT-IR, ESI-MS spectra, elemental analyses and magnetic susceptibility measurements. These manganese(III) porphyrins oxidize aromatic alcohols to aldehydes. The oxidation reactions have been carried out at room temperature in the presence of oxidants such as NaIO₄, H₂O₂, and NaOCl. The comparative studies proved that NaIO₄ behaves as the most efficient oxidant in these oxidative transformation reactions.