Dioxygen Affinities and Catalytic Oxidation Performance of Cobalt (II)Complexes with N-Aryl Hydroxamic Acid

It is well known that the study on biomimetic oxygen carriers not only has important theoretic significance to discover the mechanism of reversible bonding, activating oxygen as well as the oxidation reaction in organism, but also has potential application in separating oxygen from air and realizing the high efficiency and selectivity of catalytic oxidation reaction under a mild condition1. Metal- porphyrin and metal- phthalol- gaunine have been extensively used as biomimetic oxygen carriers u…     

Dioxygen affinities and catalytic oxidation performance of cobalt（Ⅱ） hydroxamates with benzo-15-crown-5 pendants

The oxygenation constants(Ko_2)of cobalt(Ⅱ)hydroxamates(CoL_2~1-CoL_2~3)with benzo-15-crown-5(B15C5)pendants were measured over the range of-5 to 20℃,and the values of thermodynamic parameters(ΔH~0 andΔS~0)were calculated based on these(No_2)values.Meanwhile,these crowned complexes were employed to the oxidation for p-xylene to p-toluic acid with air at 110Δunder normal atmospheric pressure.The effects of B15C5 pendant and the length of chain bonded to B15C5 in these complexes on the O_2-binding capabilities and oxidation for p-xylene were investigated with the comparison of crown-free analogues CoL_2~4.     

Dioxygen Affinity and Catalytic Performance of Bis-(furaldehyde) Schiff Bases Co(II) Complexes in Cyclohexene Oxidation

As mimetic oxygen carrier or oxidation catalyst, Schiff base cobalt complexes such as Co (II) salen have been widely studied1-4. However their high-price greatly limited their application. The synthesis of cheap furaldehyde Schiff bases and their complexes with Co (II), as well as the dioxygen affinity and biomimetic catalytic oxidation performance of these complexes are worth trying to study. In this paper, the saturated dioxygen uptake of cobalt complexes with different bis-(furaldehyd…     

An efficient aerobic oxidation for p -xylene to p -toluic acid catalyzed by cobalt (II) hydroxamates with benzo-15-crown-5

Cobalt (II) hydroxamates with the benzo-15-crown-5 (B15C5) pendant have been synthesized and characterized. These complexes were successfully employed to the oxidation of p-xylene to p-toluic acid with air at 110°C under normal atmospheric pressure. The effects of the B15C5 pendant, the length of chain bonding of B15C5 in these complexes and the addition of alkali metal ions on the oxidation for p-xylene are also investigated by the comparison with the crown-free analogue.     

Dioxygen Affinities and Catalytic Oxidation Performance of Co (II) Complexes with Phenol Ether Bridged Dihydroxamic Acids

Synthetic oxygen carriers are of great interest as models to mimic oxygen-carrying metalloenzymes for oxygen storage and transport1,2. Moreover, they possess great significance to realize high efficiency and selectivity catalytic oxidation of organic subs…     

羟胺酸钴配合物催化混合二甲苯的选择性氧化

合成并表征了羟胺酸配体N 苯甲酰基 N 苯基羟胺 (BPHA)及钴配合物Co(BPHA) 2 ,通过对反应过程的跟踪 ,证明 1∶1型超氧配合物Co(BPHA) 2 ·O2 是反应催化活性中间体。用该配合物为催化剂 ,以纯氧为氧源 ,在0 .5MPa压力下评价了不同的混合二甲苯液相催化氧化的活性 ,证明催化剂具有良好的活性 ,三种二甲苯反应活性大小的顺序为 :对 二甲苯 >邻 二甲苯 >间 二甲苯。当异构二甲苯 1∶1的比例下 ,反应温度 12 5℃ ,催化剂浓度 1.0× 10 - 3mol L时 ,反应 2小时 ,对 二甲苯氧化速度比间 二甲苯快 7倍 ,邻 二甲苯氧化速度比间 二甲苯快 4倍     

Dioxygen Affinities and Catalytic Oxidation Performance of Cobalt （Ⅱ）Complexes with N—Aryl Hydroxamic Acid

The oxygenation of cobalt(Ⅱ) hydroxamates(CoL2) and its catalytic performance in oxidation of p-xylene to p-toluic acid (PTA) were examined.The effects of X and Y bonded to hydroxamate group on dioxygen affinities and catalytic oxidation performance were also investigated.     

Synthesis of N-(4-Salicylideneiminoaryl)monoaza Crown Ethers and Dioxygen Affinities of Their Cobalt(II) Complexes

IntroductionSchiffbasesandtheirmetalcomplexeshavebeenap pliedwidelyinthefieldofcatalyticchemistry ,liquidcrystalsandphotochromism .1 3ManySchiffbaseligandscontainingcrownetherpossessdifferentrecognitionsitesforbothalkaliandtransitionmetalguestcations,4 forexample ,theNa(I)orK(I) /Co(II)hetero nuclearcomplexesofcrownedSchiffbasecanbindoxygenmolecule (O2 )toformstablesoliddioxygenadducts .5 7Gebbinkandco workershavereportedaK(I) /Cu(II)sandwichcomplexwhichcanacceleratethefor mationofdioxyg…     

Synthesis of N—（4—Salicylideneiminoaryl）monoaza Crown Ethers and Dioxygen Affinities of Their Cobalt（Ⅱ）Complexes

The Schiff base‐containing pendant monoaza crown ether HL¹, HL², HL³ and HL⁴ have been synthesized by condensation of salicylaldehyde with N‐(4‐aminoaryl) monoaza crown ethers, which were prepared conveniently from 4‐nitro‐N, N‐di(hydroxyethyl) aniline or 4‐nitrobenzyl chloride via cyclization or condensation and reduction. The structures of HL¹—HL⁴ were verified by ¹H NMR, IR spectra, MS and elemental analysis. Moreover, the oxygenation constants (KO2) and thermodynamic parameters (δH⁰ and δS⁰) of their cobalt(II) complexes were determined in the range of ?5 °C to 25 °C, and the effect of crown ring bonded to a Schiff base on the dioxygen affinities of cobalt(II) complexes was also observed as compared to the uncrowned analogue (CoL).     

Synthesis,characterization and catalytic studies of ruthenium(II) chalconate complexes

Stable ruthenium(II) carbonyl complexes of the type [RuCl(CO)(EPh₃)(B)(L)] (E = P or As; B = PPh₃, AsPh₃ or Py; L = 2′‐hydroxychalcones) were synthesized from the reaction of [RuHCl(CO)(EPh₃)₂(B)] (E = P or As; B = PPh₃, AsPh₃ or Py) with 2′‐hydroxychalcones in benzene under reflux. The new complexes were characterized by analytical and spectroscopic (IR, electronic ¹H, ³¹P and ¹³C NMR) data. They were assigned an octahedral structure. The complexes exhibited catalytic activity for the oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of N‐methylmorpholine‐N‐oxide (NMO) as co‐oxidant and were also found to be efficient transfer hydrogenation catalysts. Copyright © 2008 John Wiley & Sons, Ltd.     

钴/碳纤维电化学催化氧化甲苯性能研究

以纤维状活性碳吸附Co2+作为电极,在水溶液体系中,高效吸附-电化学催化氧化两步联动法矿化处理气态甲苯。实验结果显示,甲苯通过电化学反应器后能够被有效的降解。在电流密度为0.05 A·cm-2,电解电压为12 V,鼓气速率为80 L·h-1的条件下,甲苯的去除率达90%以上。甲苯降解后的主要产物为苯甲酸。     

Evidence for synchronous cleavage of N-H and C-C bonds: bis(2,2￠-bipyridyl)copper(II) permanganate oxidation of cobalt(III) bound and unbound α-amino acids

Summary Oxidation of pentaamminecobalt(III) complexes of α-aminoacids by bis(2,2¢-bipyridyl) copper(II) permanganate in 50% HOAc-50% H₂O (v/v) aqueous acetic acid medium. This oxidation as a diagnostic tool to find out the fraction proceeding by synchronous cleavages of N-H and C-C bonds.     

The oxidation of alkanols with air oxygen in the catalytic system copper(ii) acetate—hydroquinone promoted by visible light

2-Propanol or 1-propanol in acetonitrile, when exposed to air and irradiated with a tungsten lamp in the presence of catalytic amounts of copper(ii) acetate and hydroquinone, are oxidized to give acetone or propanal, respectively.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1147–1149, June, 1994.We express our gratitude to the administration of the University of Neuchfitel (Switzerland) for having provided the possibility and means to complete this work. We also thank Dr. S. Claude, Mr. A. Béguin, and Mr. G. Meister of the same University for their assistance in the experiments.The financial support of the Russian Foundation for Basic Research (Grant No. 93-03-5226) and the International Science Foundation (Grant MMS 000) is gratefully acknowledged.     

Co(II)Schiff碱配合物的合成、氧合反应热力学及热分解动力学的研究

合成了两种新的钴(II)schiff碱配合物水杨醛L-甲硫氨酸-水合钴(II)(1), 邻香兰素L-甲硫氨酸-水合钴(II)(2)。通过元素分析、红外光谱、热分析等测试手段研究了配合物的性质, 并确定了配合物的组成。用气体吸收装置测定配合物在乙腈溶液中不同温度下的饱和吸氧量, 求得氧合反应的平衡常数及热力学参数, 同时探讨了温度和配体结构对配合物氧合性能的影响。用TG-DTG法研究了配合物的热稳定性及非等温热分解动力学, 并采用积分法和微分法相结合的方法,推断了两种配合物的第一步热分解反应机理, 得到了热分解反应动力学参数及其动力学方程。     

Formation and reactivity of cobalt(III)-dioxygen complexes promoted by 2-methylpropanal: Oxidation of alkenes and alcohols

2-Methylpropanal promotes the formation of cobalt(III)-dioxygen species from catalysts1 or2 and dioxygen. The cobalt(III)-dioxygen complexes efficiently catalyse the oxidation of various alcohols to carbonyl compounds in the presence of dioxygen and 2-methylpropanal. Similarly substituted alkenes are smoothly transformed to the corresponding monoepoxides under these reaction conditions. EPR study of these reactions indicates that different activated dioxygen species are formed in the presence of catalysts1 and2.     

Cobalt(II)-catalyzed oxidation of alcohols into carboxylic acids and ketones with hydrogen peroxide

The oxidation of aliphatic and aromatic alcohols into the corresponding carboxylic acid analogues and ketones has been carried out using 30% H₂O₂ and cobalt(II) complex 1 in good to high yields. The reaction is safe, clean and functions in the absence of additives.     

Homo- and heterometallic trinuclear nickel(ii) and cobalt(ii) pivalate complexes

The reaction of the dinuclear complex Co₂(bpy)₂(OOCBu^t)₄ with the tetranuclear complex Ni₄(₃-OH)₂(OOCBu^t)₆(EtOH)₆ afforded the trinuclear heterometallic complex M₃(bpy)₂(₃-OH)(-OOCBu^t)₄(OOCBu^t) (6) (M = Ni, Co; Ni : Co = 1.2 : 1) in which two metal atoms are in an octahedral environment and one metal atom is in a tetrahedral environment. The reaction of 2,2"-bipyridine with Co₄(₃-OH)₂(OOCBu^t)₆(HOEt)₆ (reagent ratio was 2 : 1) or the reaction of bpy with Co₈(₄-O)₂( _n -OOCBu^t)₁₂ (reagent ratio was 4 : 1) produced a homometallic analog of 6, viz., the trinuclear cluster Co₃(bpy)₂(₃-OH)(-OOCBu^t)₄(OOCBu^t) (8). The reaction of 1,10-phenanthroline (phen) with the [Co(OH) _n (OOCBu^t)_2–n ] _x polymer gave the analogous trinuclear cluster (phen)₂Co₃(₃-OH)(₂-OOCBu^t)₄(¹-OOCBu^t). Compounds 6 and 8 exhibit antiferromagnetic spin-spin exchange interactions.     

Dioxygen Affinities and Catalytic Epoxidation Performance of Transition-Metal Hydroxamates

Hydroxamicacidsandtheirderivativesareeasilysynthesizedandhavebeenextensivelyusedasanalyticreagentsandmedicinesl'2.Besides,palladiumhydroxamateswereemployedtocatalyzeolefinspreparingunsaturatedestersbymeansofmolecularoxygen'.Hydroxamicacidcanformsquar...