Catalytic Activity of Tetraarylporphyrins in the Oxidation Reactions of Saturated Hydrocarbons

The oxidation of cyclic hydrocarbons by potassium peroxymonosulfate catalyzed by the iron and manganese complexes of tetra-(4-N-butylpyridinium)porphyrin, tetraphenylporphyrin, and mixed porphyrins containing phenyl and butylpyridyl substituents was studied in an aqueous acetonitrile medium. The test catalysts were dissolved in the reaction medium or adsorbed on layered aluminosilicates. It was found that the immobilization of metal complexes on layered aluminosilicates, as well as the bromination of porphyrins, decreased the activity of catalysts in a number of cases, although it improved their stability. The addition of pyridine in an equimolar amount with respect to metal complexes to the reaction mixture increased the activity of dissolved manganese complexes. An increase in the number of butylpyridyl meso-substituents in a porphyrin molecule improved the catalytic activity of a metal complex.     

Photochemistry of porphyrins: a model for the origin of photosynthesis

A series of porphyrins and catalysts has been prepared as a model for the origin of photosynthesis on the primordial earth. These compounds have been used to test the hypotheses that (1) the biosynthetic pathway to chlorophyll recapitulates the evolutionary history of photosynthesis, and (2) the proto-photosythetic function of biogenetic porphyrins (biosynthetic chlorophyll precursors) was the oxidation of organic molecules by photoexcited porphyrins with the attendant emission of molecular hydrogen. This paper describes experiments in which photoexcited biogenetic porphyrins oxidize ethylenediamine tetraacetic acid (EDTA). The concomitant reduction of protons to hydrogen gas occurs in the presence of a colloidal platinum catalyst. The addition of methyl viologen, a one-electron shuttle, increases the amount of molecular hydrogen generated during long irradiations and the quantum yield of hydrogen production. When the porphyrin and catalyst are held in association by molecular complexes, the increased efficiency of electron transfer produces higher yields of hydrogen gas.     

高分子担载卟啉及其金属络合物研究进展

本文介绍了高分子担载卟啉及其金属络合物在模拟细胞色素Ｐ－４５０，光学灭菌材料，阴离子载体及光敏化学材料等领域的最新研究进展。     

Studies on catalytic fluorescence formation with peroxidase-like metallotetrakis(N-methylpyridiniumyl) porphyrins

The relative ability of peroxidase-like metallotetrakis(N-methylpyridiniumyl)porphyrins [Me-TMPyP, Me = Mn(III), Fe(III), Co(III), Ni(II), Cu(II), and Zn(II)] to catalyse the hydrogen peroxide oxidation of homovanillic acid to a fluorescent dimer has been studied. The complexes of Mn, Fe and Co are effective catalysts in the reaction, but the complexes of Ni, Cu and Zn are not. The catalytic behaviour of Mn-TMPyP, Fe-TMPyP and Co-TMPyP has been compared with that of HRP in both enzymatic and kinetic analysis. The sequence of peroxidase-like catalytic activity is Mn-TMPyP> Co-TMPyP> Fe-TMPyP. The catalytic activity of Mn-TMPyP is 84% of that of HRP. These Me-TMPyP (Me = Mn, Fe, and Co) compounds are good substitutes for HRP in enzymatic analysis. Traces of hydrogen peroxide and glucose can be determined with the Me-TMPyP systems.     

Further study on the synthesis of F-containing porphyrins and their catalytic activity on oxidation of cyclohexene

Reaction of tetrakis(p-allyloxyphenyl)porphyrin and perfluoroalkanesulfonyl bromides givestetrakis(p-polyfluoroalkoxylphenyl)substituted porphyrins.The yields are over 90%.The synthesis ofthe metal ion complexes of these F-containing porphyrins is also reported.Preliminary results on thestudy of the catalytic activity of the manganese(Ⅲ)complexes of various fluorinated porphyrins onoxidation of cyclohexene indicate that the introduction of R_F group into porphyrin contributes to thestability of the catalysts.     

Water oxidation catalysed by manganese compounds: from complexes to 'biomimetic rocks'

One of the most fundamental processes of the natural photosynthetic reaction sequence is the light-driven oxidation of water to molecular oxygen. In vivo, this reaction takes place in the large protein ensemble Photosystem II, where a μ-oxido-Mn(4)Ca- cluster, the oxygen-evolving-complex (OEC), has been identified as the catalytic site for the four-electron/four-proton redox reaction of water oxidation. This Perspective presents recent progress for three strategies which have been followed to prepare functional synthetic analogues of the OEC: (1) the synthesis of dinuclear manganese complexes designed to act as water-oxidation catalysts in homogeneous solution, (2) heterogeneous catalysts in the form of clay hybrids of such Mn(2)-complexes and (3) the preparation of manganese oxide particles of different compositions and morphologies. We discuss the key observations from the studies of such synthetic manganese systems in order to shed light upon the catalytic mechanism of natural water oxidation. Additionally, it is shown how research in this field has recently been motivated more and more by the prospect of finding efficient, robust and affordable catalysts for light-driven water oxidation, a key reaction of artificial photosynthesis. As manganese is an abundant and non-toxic element, manganese compounds are very promising candidates for the extraction of reduction equivalents from water. These electrons could consecutively be fed into the synthesis of "solar fuels" such as hydrogen or methanol.     

Calix[4]pyrrole Schiff base macrocycles. Novel binucleating ligands for mu-oxo iron complexes

New bimetallic mu-oxo diferric complexes of several previously reported calix[4]pyrrole Schiff base macrocycles are described. The synthesis of a new member of this class of macrocycles is also reported; it was prepared via an acid-catalyzed condensation between 1,9-bisformyl-5,5-dipropyldipyrromethane and o-phenylenediamine. Reactions of the free base macrocycles or their bis-HCl salts with Fe(II) mesitylene, followed by air oxidation, gave the binuclear mu-oxo bis-Fe(III) compounds 6-10 in moderate yield. X-ray crystallography data reveal two different coordination environments for the Fe-O-Fe subunit in 6-10 that it is suggested can be controlled by altering the reaction conditions. Structural properties of these metalated pyrrolic macrocycles are also compared to those of mu-oxo diferric porphyrins and mu-oxo diferric texaphyrin. Complexes 6-10 exhibit two distinct types of M-N bonds that are similar in length to the bonds observed in metallotexaphyrin complexes. However, the electronics of the present systems are very different from those of texaphyrins and porphyrins in that no delocalized bonding patterns are observed within the ligands as a whole.     

Polyfunctional activity of metal complexes containing 2,6-Di-tert-butylphenol in catalytic oxidation

The results of the investigations of metal complexes containing 2,6-di-tert-butilphenol in the ligand environment in catalytic homogeneous oxidation of organic compounds are reviewed. The liquid-phase oxidation of hydrocarbons, olefins, aminophenol and unsaturated fatty acids by molecular oxygen in the presence of phthalocyanines, porphyrins, σ-aryl and π-allyl transition metal complexes is described. The change of the reactivity of organometallic and coordination compounds by oxidation of the redox active phenolic group opens up the possibility to use them as polyfunctional catalytic systems showing positive and/or negative catalytic effects.     

Schiff base complexes and their versatile applications as catalysts in oxidation of organic compounds: part I

Schiff bases and their complexes are good candidates as versatile compounds which are synthesized by the condensation of a primary amino compound with either aldehydes or ketones for a variety of industrial applications. They can act as catalysts in the catalytic oxidation of organic compounds. Recent researches in oxidation catalysis have focused on how to employ the metal‐catalyzed oxidation of organic substrates. This review summarizes the current developments of the last few decades for the oxidations of organic compounds that proceed through Schiff base complexes. The chemical syntheses of Schiff bases and their complexes are outlined.     

Synthesis,characterization and catalytic activity of polymer anchored transition metal complexes toward oxidation reactions

The polymer-anchored Schiff base complexes of Cu(II), Co(II), Ni(II), Mn(II) and Fe(III) were prepared by reacting polystyrene amine with 2-pyridinecarbaldehyde followed by loading of metal atom in methanol. These complexes were characterized by using different physico-chemical and spectroscopic methods. The catalytic activity of these polymer-supported metal catalysts was tested for the oxidation of various olefins and alcohols. Influence of various reaction parameters, such as reaction temperature, reaction time, oxidant, substrate-to-oxidant mole ratio and nature of solvent, was studied for the oxidation of cyclohexene with these catalysts. Among the catalysts studied, Cu-Cat showed higher catalytic activity toward oxidation reactions than the other catalysts. Moreover, hot filtration experiments proved that these catalysts are truly heterogeneous and can be reused a number of times without significant loss of activity.     

Metalloporphyrin and heteropoly acid catalyzed oxidation of CNOH bonds in an ionic liquid: biomimetic models of nitric oxide synthase

Water soluble iron(III) porphyrins and phosphotungstic acid in an ionic liquid are effective catalysts for the H₂O₂ mediated oxidation of the CNOH bond in N-hydroxyarginine and other oximes. The carbonyl compounds generated as the oxidation products can be easily isolated from the reaction media. These systems serve as biomimetic models of nitric oxide synthase (NOS) and the catalyst immobilized in an ionic liquid can be easily recycled and reused.     

Oxorhenium complexes as aldehyde-olefination catalysts

Several oxorhenium compounds in the formal oxidation states V and VII are examined as catalysts for the aldehyde-olefination starting from diazo compounds, phosphines, and aldehydes. Of these, [ReMeO2(eta2-alkyne)] complexes provide the simplest catalysts to study, although [ReOCl3(PPh3)2] still remains the most efficient rhenium catalyst for aldehyde-olefination described to date. Prior to the reaction with the Re catalysts the phosphine and the diazo compound react to form a phosphazine. No catalytic reaction occurs in cases where no phosphazine formation is observed. The first step of the catalytic cycle involves the formation of a carbene intermediate by the reaction of phosphazine and catalyst under extrusion of phosphine oxide and dinitrogen. In a second step the carbene reacts with aldehyde under olefin formation and catalyst regeneration. Excess of alkyne as well as the presence of ketones slows down the catalytic reaction. The olefination of 4-nitrobenzaldehyde with diazomalonate is possible with these Re catalysts. In contrast, this reaction does not take place either in the classical Wittig fashion from Ph3P=C(CO2Et)2 and aldehyde or by use of all other catalysts for aldehyde olefination reactions reported to date. Catalytic ylide formation from diazo compounds seems therefore not to be the only pathway through which catalytic aldehyde-olefination reactions can proceed.     

铜催化卤代芳烃氨解反应的研究进展

铜催化卤代芳烃进行氨解反应是构建碳氮键的重要方法。铜作为催化剂不仅便宜、丰富、相对低毒,而且可以通过几个氧化态进行循环催化。配体的发展则扩展了底物的适用范围,提高了官能团的兼容性和反应的选择性,使得该反应成为一种通用的制备芳胺的方法。本文以铜盐催化剂为线索,对该反应机理进行了简介,对近年来铜催化卤代芳烃的氨解反应的研究进展进行了综述和展望,并指出高活性和高选择性的催化体系依然有限,铜催化剂使用量仍然较大,氨和氯代芳烃的使用还不够广泛,而且关于该类反应详细机理的文献报道还缺乏。此外,发展一个新的、高效的和通用的氨解方法仍然显得极为迫切。     

四氯苯基卟啉锰配合物催化苯乙烯不对称环氧化反应

金属卟啉;催化剂;对映体过量;四氯苯基卟啉锰配合物催化苯乙烯不对称环氧化反应     

Effective biaryl compound synthesis using cross-coupling reaction with nickel complexes coordinated by diaminophosphine ligands

The cross-coupling reaction of aryl halides and aryl Grignard reagents was effectively catalyzed by the diaminophosphine complex catalysts and the reaction was much faster than that catalyzed by aminophosphine complexes and the nickel complexes were more active than palladium complexes. Various biaryl compounds were easily prepared by the reaction with nickel diaminophosphine catalysts.     

次卟啉二甲酯钴络合物均相选择性催化氧化环己烷

以次卟啉二甲酯钴[Co(DPDME)]为仿生催化剂,分子氧（空气）为氧给体,无其它辅助催化剂的条件下研究了催化氧化环己烷的反应。考察了反应温度、空气压力、催化剂用量和卟啉配体结构对醇酮的产率及选择性的影响。结果表明,在相同条件下,次卟啉二甲酯钴的催化活性明显高于其它的钴卟啉催化剂。以次卟啉合钴为催化剂,浓度为0.015 mmol/L,反应温度423 K,在空气压强为0.8 MPa的条件下反应5 h,环己烷的转化率达到18.17％,选择性为87.43％。温度对次卟啉钴的催化活性影响较大,温度高于443 K时,催化剂的稳定性降低,但是其转化数仍达到了66 646。对次卟啉二甲酯钴催化空气氧化环己烷的反应路径作了初步探讨。     

Electrocatalytic Reduction of Dioxygen at Co(II) Complexes Supported Carbon Electrode

Phthalocyanines or porphyrins of cobalt and iron are known as effective catalysts of oxygen reduction. Carbon based electrodes are modified by.the adsorption of these macromolecular compounds, which mediate the electron transfer. Oxygen is reduced to hydrogen peroxide and/or water at these modified electrodes via a two- or four- electron transfer reaction.     

Aerobic cascade oxidation of substituted cyclopentane-1,2-diones using metalloporphyrin catalysts

A method for the aerobic cascade oxidation of cyclopentane-1,2-diones using metal porphyrins as catalysts, yielding hydroxydiacids 2, ketoacid 3 and diketoacids 4 which are the intermediates of important biologically active compounds is reported. This method is operationally simple and can be employed under ambient conditions.     

Selective oxidation of naphthalene derivatives with ruthenium catalysts using hydrogen peroxide as terminal oxidant

The selective oxidation of naphthalene and its derivatives to give naphthoquinones has been investigated in detail. The reaction can be carried out effectively in the presence of a catalytic amount of Ru complexes (0.2 mol%) and phase transfer catalysts (PTC) using H₂O₂ as the terminal oxidant and water as the solvent. The effect of different ruthenium complexes, phase transfer catalysts, and the concentration of hydrogen peroxide were studied. Compared to previous procedures for this type of reactions, acidic solvents and high concentration of hydrogen peroxide are not necessary, which makes the reaction more environmentally friendly.     

Cu(II) 2-quinoxalinol salen catalyzed oxidation of propargylic,benzylic, and allylic alcohols using tert-butyl hydroperoxide in aqueous solutions

The synthesis of carbonyl compounds by oxidation of alcohols is a key reaction in organic synthesis. Such oxidations are typically conducted using catalysts featuring toxic metals and hazardous organic solvents. Considering green and sustainable chemistry, a copper(II) complex of sulfonated 2-quinoxalinol salen (sulfosalqu) has been characterized as an efficient catalyst for the selective oxidation of propargylic, benzylic, and allylic alcohols to the corresponding carbonyl compounds in water when in combination with the oxidant tert-butyl hydroperoxide. The reactions proceed under mild conditions (70 °C in water) to produce yields up to 99% with only 1 mol % of catalyst loading. This reaction constitutes of a rare example of propargylic alcohol oxidation in water, and it makes this process greener by eliminating the use of hazardous organic solvents. Excellent selectivity was achieved with this catalytic protocol for the oxidation of propargylic, benzylic, and allylic alcohols over aliphatic alcohols. The alcohol oxidation is thought to go through a radical pathway.