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1.
Majid Moghadam Shahram Tangestaninejad Valiollah Mirkhani Iraj Mohammadpoor‐Baltork Shadab Gharaati 《应用有机金属化学》2009,23(11):446-454
In this paper, rapid and highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) in the presence of catalytic amounts of high‐valent [SnIV(TPP)(OTf)2] is reported. This catalytic system catalyzes trimethylsilylation of primary, secondary and tertiary alcohols as well as phenols, and the corresponding TMS‐ethers were obtained in high yields and short reaction times at room temperature. It is noteworthy that this method can be used for chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times without loss of its catalytic activity. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
2.
Thasan Raju Sankar Manivasagan Balachandran Revathy Kumarasamy Kulangiappar Arunachalam Muthukumaran 《Tetrahedron letters》2007,48(21):3681-3684
Electrochemical oxidation of benzylic and substituted benzylic alcohols by two-phase electrolysis yields the corresponding aldehydes as products. The reaction was carried out in a single compartment cell with platinum electrodes at room temperature in chloroform using an aqueous sodium bromide solution (25%) containing a catalytic amount of HBr. The two-phase electrolysis resulted in high yields (74-96%) of benzaldehyde from primary alcohols and secondary alcohols were oxidized to the corresponding ketone but only in low yields under these conditions. 相似文献
3.
A new and highly efficient homogeneous [Ph3PAuCl]/AgOTf catalytic system was developed in N-alkylation reaction of primary amines with alcohols through a hydrogen autotransfer process. This Au(I) catalytic system shows excellent selectivity for mono-alkylation of primary amines with benzyl alcohol under moderate temperature of 100 °C (only secondary amines as product). The possible mechanism of this hydrogen autotransfer reaction with the catalytic system was proposed. 相似文献
4.
Highly selective, recyclable epoxidation of allylic alcohols with hydrogen peroxide in water catalyzed by dinuclear peroxotungstate 总被引:2,自引:0,他引:2
Kamata K Yamaguchi K Mizuno N 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(19):4728-4734
The highly chemo-, regio-, and diastereoselective and stereospecific epoxidation of various allylic alcohols with only one equivalent of hydrogen peroxide in water can be efficiently catalyzed by the dinuclear peroxotungstate, K2[[W(=O)(O2)2(H2O)]2(mu-O)].2H2O (I). The catalyst is easily recycled while maintaining its catalytic performance. The catalytic reaction mechanism including the exchange of the water ligand to form the tungsten-alcoholate species followed by the insertion of oxygen to the carbon-carbon double bond, and the regeneration of the dinuclear peroxotungstate with hydrogen peroxide is proposed. The reaction rate shows first-order dependence on the concentrations of allylic alcohol and dinuclear peroxotungstate and zero-order dependence on the concentration of hydrogen peroxide. These results, the kinetic data, the comparison of the catalytic rates with those for the stoichiometric reactions, and kinetic isotope effects indicate that the oxygen transfer from a dinuclear peroxotungstate to the double bond is the rate-limiting step for terminal allylic alcohols such as 2-propen-1-ol (1a). 相似文献
5.
Dr. Michiel Langerman Micha van Dorth Dr. Dennis G. H. Hetterscheid 《欧洲无机化学杂志》2023,26(24):e202300218
The pyridylalkylamine copper complex [Cu(tmpa)(L)]2+ has previously been proposed to reduce dioxygen via a dinuclear resting state, based on experiments in organic aprotic solvents using chemical reductants. Conversely, a mononuclear reaction mechanism was observed under electrochemical conditions in a neutral aqueous solution. We have investigated the electrochemical oxygen and hydrogen peroxide reduction reaction catalyzed by [Cu(tmpa)(L)]2+ in acetonitrile, using several different acids over a range of pKa. We demonstrate that strong acids lead to the loss of redox reversibility and to the destabilization of the copper complex under non-catalytic conditions. Under milder conditions, the electrochemical oxygen reduction reaction (ORR) was shown to proceed via a mononuclear catalytic intermediate, similar to what we have previously observed in water. However, in acetonitrile the catalytic rate constants of the ORR are dramatically lower by a factor 105, which is caused by the unfavorable equilibrium of formation of [CuII(O2⋅−)(tmpa)]+ in acetonitrile. This results in higher catalytic rates for the reduction of hydrogen peroxide than for the ORR. 相似文献
6.
Liu Yang Huan-Huan Lu Chu-Hui Lai Dr. Gang Li Prof. Dr. Wei Zhang Prof. Dr. Rui Cao Prof. Dr. Fengyi Liu Dr. Chao Wang Prof. Dr. Jianliang Xiao Prof. Dr. Dong Xue 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12814-12819
A highly effective C−O coupling reaction of (hetero)aryl electrophiles with primary and secondary alcohols is reported. Catalyzed by a NiII-aryl complex under long-wave UV (390–395 nm) irradiation in the presence of a soluble amine base without any additional photosensitizer, the reaction enables the etherification of aryl bromides and aryl chlorides as well as sulfonates with a wide range of primary and secondary aliphatic alcohols, affording synthetically important ethers. Intramolecular C−O coupling is also possible. The reaction appears to proceed via a NiI–NiIII catalytic cycle. 相似文献
7.
Liu Yang Huan‐Huan Lu Chu‐Hui Lai Gang Li Wei Zhang Rui Cao Fengyi Liu Chao Wang Jianliang Xiao Dong Xue 《Angewandte Chemie (International ed. in English)》2020,59(31):12714-12719
A highly effective C?O coupling reaction of (hetero)aryl electrophiles with primary and secondary alcohols is reported. Catalyzed by a NiII‐aryl complex under long‐wave UV (390–395 nm) irradiation in the presence of a soluble amine base without any additional photosensitizer, the reaction enables the etherification of aryl bromides and aryl chlorides as well as sulfonates with a wide range of primary and secondary aliphatic alcohols, affording synthetically important ethers. Intramolecular C?O coupling is also possible. The reaction appears to proceed via a NiI–NiIII catalytic cycle. 相似文献
8.
Maryam YadegariMajid Moghadam Shahram TangestaninejadValiollah Mirkhani Iraj Mohammadpoor-Baltork 《Polyhedron》2012,31(1):332-338
In the present work, highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by high-valent [TiIV(salophen)(OTf)2] is reported. Under these conditions, primary, secondary and tertiary alcohols as well as phenols were silylated in short reaction times and high yields. It is noteworthy that this method can be used for chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times without loss of its catalytic activity. 相似文献
9.
《国际化学动力学杂志》2017,49(9):635-642
Rate constants for the nitrate (•NO3) radical reaction with alcohols, alkanes, alkenes, and several aromatic compounds were measured in aqueous and tert‐butanol solution for comparison to aqueous and acetonitrile values from the literature. The measured trends provide insight into the reactions of the •NO3 radical in various media. The reaction with alcohols primarily consists of hydrogen‐atom abstraction from the alpha‐hydroxy position and is faster in solvents of lower polarity where the diffusivity of the radical is greater. Alkenes react faster than alkanes, and their rate constants are also faster in nonpolar solution. The situation is reversed for the nitrate radical reaction with the aromatic compounds, where the rate constants in tert‐butanol are slower. This is attributed to the need to solvate the NO3− anion and corresponding tropylium cation produced by the •NO3 radical electron transfer reaction. A linear correlation was found between measured rate constants in water and acetonitrile, which can be used to estimate aqueous nitrate radical rate constants for compounds having low water solubility. 相似文献
10.
The solvent‐free O‐acylation of some alcohols with benzoyl chloride was carried out to the corresponding benzoylated products in good to excellent yields by the mediation of a catalytic amount (5 mol%) of the commercially available and inexpensive zinc oxide in short reaction times. This methodology represents an eco‐friendly and simple catalytic alternative for benzoylation of primary, secondary, tertiary, and benzylic alcohols with ZnO. This catalytic system was homogeneous because of high solubility of zinc oxide in the reaction medium. Findings showed that ZnO was dissolved in hydrochloric acid, created in situ, after a few minutes. Although, others argued on the catalytic role of solid phase zinc oxide under a heterogeneous condition, it is not surprising to emphasize on the catalytic function of Zn2+ in the benzoylation of alcohols under homogeneous reaction conditions. Zinc oxide served as pre‐catalyst to form Zn2+, as the catalytically active species. 相似文献
11.
Bikshandarkoil R. Srinivasan 《Journal of Chemical Sciences》2004,116(5):251-259
The complexes [MoX4]2− (M = Mo; X = O or S) exist as the monomeric tetrahedral species in aqueous alkaline solutions. Acidification of tetraoxomolybdate
results in the condensation of the tetrahedral units via a series of polyoxomolybdates leading to the ultimate formation of
the trioxide MoO3. Heptamolybdate [Mo7O24]6− is the first major polyanion of the acidification reaction. In contrast, acidification of tetrathiomolybdates leads to the
formation of amorphous molybdenum trisulphide via a dinuclear Mo(V) complex. The formation of the dinuclear Mo(V) complex
precludes the formation of any higher nuclearity Mo(VI)-S complexes in aqueous solution. Thus it is shown that the all-sulphur
analogue of heptamolybdate [M07S24]6− does not exist in alkaline medium and also cannot be isolated from aqueous acidic medium 相似文献
12.
Abdolreza Rezaeifard Maasoumeh Jafarpour Mohammad Ali Nasseri Reza Haddad 《Helvetica chimica acta》2010,93(4):711-717
A novel and practical catalytic method for efficient and highly selective oxidation of a wide range of benzylic, allylic, aliphatic, primary, and secondary alcohols to the corresponding aldehydes and ketones using tetrabutylammonium peroxomonosulfate catalyzed by tetradentate Schiff base–MnIII complexes has been developed. Electron‐deficient and hindered alcohols required longer reaction times for oxidation in this catalytic system. The electron‐poor and hindered salicylidene ring of the ligand enhanced the catalytic activity and stability of Mn catalysts. The desired turnover numbers obtained in the oxidation reactions indicated the high efficiency and relative stability of these simple Schiff base complexes in this catalytic system. 相似文献
13.
Selective tetrahydropyranylation of alcohols and phenols using titanium(IV) salophen trifluoromethanesulfonate as an efficient catalyst
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Titanium(IV) salophen trifluoromethanesulfonate, [TiIV(salophen)(OSO2CF3)2], as a catalyst enables selective tetrahydropyranylation of alcohols and phenols with 3,4‐dihydro‐2H‐pyran. Using this catalytic system, primary, secondary and tertiary alcohols, as well as phenols, were converted to their corresponding tetrahydropyranyl ethers in high yields and short reaction times at room temperature. Investigation of the chemoselectivity of this method showed discrimination between the activity of primary alcohols in the presence of secondary and tertiary alcohols and phenols. This heterogenized catalyst could be reused several times without loss of its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
14.
Phalguni Chaudhuri Martina Hess Ulrich Flrke Karl Wieghardt 《Angewandte Chemie (International ed. in English)》1998,37(16):2217-2220
Two reaction pathways are catalyzed by the dinuclear copper(II )–phenoxyl complex 1 —a functional model for the metalloenzyme galactose oxidase—by the oxidation of primary and secondary alcohols with dioxygen (air) in homogeneous solution to their corresponding aldehydes or ketones and/or 1,2-glycols (oxidative C–C coupling). The reduction product formed is H2O2, not water. 相似文献
15.
Rate constants have been measured for the reactions of the sulfate radical, SO4˙?, with alkanes, alkenes, alcohols, ethers, and amines in 95% acetonitrile solution. The rate constants were in the range of 106 L mol?1 s?1 for the abstraction reactions and 107?109 L mol?1 s?1 for the addition and electron transfer reactions. These values are 20 to 80 times lower than those measured in aqueous solutions. Furthermore, the rate constants for the reactions of SO4˙? with the primary alcohols increase with the number of carbon atoms and then level off, in contrast to the behavior observed in aqueous solution, where the rate constant increases more sharply for the larger alcohols. © 1993 John Wiley & Sons, Inc. 相似文献
16.
The reaction of iron sulfate with 1-carboxymethyl-4,7-dimethyl-1,4,7-triazacyclononane (L) and hydrogen peroxide in aqueous ethanol gives a brown dinuclear complex considered to be [Fe2(N3O-L)2(mu-O)(mu-OOCCH3)] + (1), which converts upon standing in acetonitrile solution into the green tetranuclear complex [Fe4(N3O2-L)4(mu-O)2]4+ (2). A single-crystal X-ray structure analysis of [2][PF6]4.5MeCN reveals 2 to contain four iron(III) centers, each of which is coordinated to three nitrogen atoms of a triazacyclononane ligand and is bridged by one oxo and two carboxylato bridges, a structural feature known from the active center of methane monooxygenase. Accordingly, complex 2 was found to catalyze the oxidative functionalization of methane with hydrogen peroxide in aqueous solution to give methanol, methyl hydroperoxide, and formic acid; the total turnover numbers attain 24 catalytic cycles within 4 h. To gain more insight into the catalytic process, the catalytic potential of 2 was also studied for the oxidation of higher alkanes, cycloalkanes, and isopropanol in acetonitrile, as well as in aqueous solution. The bond selectivities of the oxidation of linear and branched alkanes suggest a ferroxy radical pathway. 相似文献
17.
Majid Moghadam Shahram Tangestaninejad Valiollah MirkhaniIraj Mohammadpoor-Baltork Shadab Gharaati 《Polyhedron》2010
Tin(IV)tetraphenylporphyrinato tetrafluoroborate, [SnIV(TPP)(BF4)2], was used as an efficient catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). High-valent [SnIV(TPP)(BF4)2] catalyzes trimethylsilylation of primary, secondary and tertiary alcohols as well as phenols, and the corresponding TMS-ethers were obtained in high yields and short reaction times at room temperature. While, under the same reaction conditions [SnIV(TPP)Cl2] is less efficient to catalyze these reactions. One important feature of this catalyst is its ability in the chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times without loss of its catalytic activity. 相似文献
18.
A novel dinuclear copper complex CuI2(pip)2 was used as a catalyst for alkyne–azide cycloaddition (CuAAC) reaction. High yields (95–99%) were obtained for various substrates at a low loading of 0.2 mol %. The unique structure, high stability of the dinuclear structure in solution, and easy preparation make this complex not only a high-efficiency catalyst but also a model for understanding the mechanism of the CuAAC reaction. 相似文献
19.
Copper(II) and Zinc(II) Complexes of Conformationally Constrained Polyazamacrocycles as Efficient Catalysts for RNA Model Substrate Cleavage in Aqueous Solution at Physiological pH
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Daniel Bím Dr. Eva Svobodová Václav Eigner Dr. Lubomír Rulíšek Prof. Jana Hodačová 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10426-10437
As part of a quest for efficient artificial catalysts of RNA phosphodiester bond cleavage, conformationally constrained mono‐ and bis‐polyazamacrocycles in which tri‐ or tetraazaalkane chains link the ortho positions of a benzene ring were synthesized. The catalytic activities of mono‐ and dinuclear copper(II) and zinc(II) complexes of these polyazamacrocycles towards cleavage of the P?O bond in 2‐hydroxypropyl‐4‐nitrophenylphosphate (HPNP) in aqueous solution at pH 7 have been determined. Only the complexes of the ligands incorporating three nitrogen atoms in a macrocycle proved to be capable of efficiently catalyzing HPNP transesterification. The dinuclear complexes were found to be approximately twice as efficient as their mononuclear counterparts, and exhibited Michaelis–Menten saturation kinetics with calculated rate constants of kcat≈10?4 s?1. By means of quantum chemical calculations (DFT/COSMO‐RS), several plausible reaction coordinates were described. By correlating the calculated barriers with the experimental kinetic data, two possible reaction scenarios were revealed, with activation free energies of 20–25 kcal mol?1. 相似文献
20.
Cofacial dinuclear metalloporphyrins exhibited a catalytic activity for the electrochemical reduction of carbon dioxide. The cofacial dinuclear porphyrin was automatically generated by mixing a cationic cobalt porphyrin (CoTMPyP) and an anionic metalloporphyrin (MTPPS) in solution. The redox system of this complex was examined by electrochemical methods. According to the cyclic voltammogram, the catalytic active species was generated at −1.8V vs. Ag/Ag+, which was considered to be a monovalent cobalt porphyrin, Co(I)TMPyP. The catalytic activity of the dinuclear complex was two times greater than that of the mononuclear one because the anionic porphyrin acted as an electron mediator. 相似文献