Catalytic Kinetics of the Schiff Base Metal Complexes Bearing Side Chain of Cyclic morpholine in Carboxylic Ester Hydrolysis

It has been reported that two Schiff base transition metal complexes bearing the side chain of the morpholine ring were synthesized and characterized, and two complexes with the same base agent but different metal ions were used as a simulant hydrolase in the catalytic hydrolysis of p-nitrophenyl picolinate in this paper. The mechanism of PNPP catalytic hydrolysis is proposed and supported by the results of the spectral analysis and the kinetic calculation. A kinetic mathematical model, applied to the calculation of the kinetic and thermodynamics parameters of PNPP catalytic hydrolysis, has been established on the foundation of the mechanism proposed. The result of the study shows that the two complexes have a good catalytic activity in PNPP catalytic hydrolysis, and the rate of the PNPP catalytic hydrolysis was increased with the increase of the pH values in the buffer solution and affected by the polarization effect of metal ion of the complexes.     

Studies on PNPP Hydrolysis Catalyzed by Schiff Base Cobalt（Ⅱ） Complexes Containing Benzoaza-15-crown-5

Three novel Schiff base cobalt（Ⅱ） complexes containing benzoaza-15-crown-5, CoL^1, CoL^2 and CoL^3 were synthesized and characterized, and these complexes were used in catalytic hydrolysis of carboxylic ester （PNPP, p-nitrophenyl picolinate） as mimic hydrolytic metalloenzyme. The analysis of specific absorption spectra of the hydrolytic reaction systems indicated that the catalytic hydrolysis involved the key intermediates formed by PNPP with cobalt（Ⅱ） complexes. The CoL^3 bearing the electron withdrawing group shows better catalytic activity due to its stabilization effect on active species MLS^-. The catalytic mechanism of PNPP hydrolysis was also proposed. The kinetic parameter of PNPP catalytic hydrolysis has been calculated and the activation energy for the catalytic hydrolysis is 43.69, 39.76 and 35.44 kJ·mol^-1, respectively.     

DECARBOXYLATION OF ALLYL β-KETO ESTERS TO UNSATURATED KETONES ON POLYMER BOUND PHOSPHINE- PALLADIUM (0)COMPLEXES*

Polystyrylphosphine-Pd(0) and silica supported polysiloxane-phosphine-Pd(0) complexeswere synthesized and characterized. Their catalytic properties for the decarboxylation of allyl β-keto esters were investigated. It was found that these complexes have good catalytic activities undermild condition for this decarboxylation in which many novel unsaturated ketones were obtained.The selectivity of this catalytic decarboxylation depends on the polymer ligand and the P/Pd ratioof catalyst. The stabilities of polymer phosphine-Pd(O) complexes catalysts are better than theirhomogeneous analogue.     

Synthesis,O_2-binding ability and catalytic oxidation performance of cobalt(Ⅱ) complexes with dihydroxamic acid functionalized N-pivot lariat ethers

Novel Co(Ⅱ) complexes with dihydroxamic acids functionalized N-pivot lariat ether CoL~1-CoL~4 were synthesized and characterized.Their oxygenation constants(ln K_(O2)) and thermodynamic parameters(△H°,△S°) were measured.And their catalytic performance in oxidation of p-xylene to p-toluic acid(PTA) was investigated.The enhancement of O_2-binding and catalytic oxidation activity by the oxa aza crown ether ring of the cobalt complexes were discussed.     

STUDIES ON THE CATALYTIC BEHAVIORS OF SOME BIPOLYMER——PALLADIUM COMPLEXES FOR HYDRO-GENATION OF NITRO-COMPOUNDS AND OLEFINS

Some water-soluble bipolymer-Pd complexes were prepared. It was found that the bipolymer-Pd complexes exhibited remarkably higher catalytic activity and stability than that of the single polymer-Pd complex for hydrogenation of nitro-compounds and olefins under mild conditions.     

SYNTHESIS OF DI（ETHYLMERCAPTOETHYL） AMINO GROUP—CONTAINING POLYSESQUISILOXANE PLATINUM COMPLEX AND ITS CATALYSIS IN HYDROSIL YLATION OF OLEFINS WITH TRIETHOXYSILANE

Three new polysesquisiloxane-bound platinum complexes were synthesized via hydrolysis of N,N-di(β-ethylmercaptoethyl)γ-(triethoxysilyl)propylamine or cohydrolysis of the monomer with dodecyltriethoxysilane or with phenylpropylthiethoxysilane and immobilixation on fumed silica,followed by reacting with potassium platinite in acetone under argon atmosphere.The platinum complexes exhibited high catalytic activity for the hydrosilylation of olefins by triethoxysilane. The effects of temperature and the amount of complex on the catalytic activity,as well as the recovery and reusability of the catalysts were investigated.     

STUDIES ON ORGANO-MOLYBDENUM AND TUNGSTEN COMPOUNDS(Ⅲ)——CATALYTIC POLYMERIZATION OF ACETYLENE BY M-O-C BOND-CONTAINING COMPLEXES OF Mo AND W

Catalytic polymerization of acetylene in the presence of n5-C5H5-M-(CO)3 R (M=Mo,W;R=CH3-,C2H5-) has been studied.The results show that these complexes possess catalytic activities for the polymerization and copolymerization of monosubstituted acetylene.The catalytic mechanism has been preliminarily discussed.It is suggested that the active species be metal-car-bene.In our previous publications we reported the synthesis of some new Fischer's molybdenum and tungsten-carbene complexes and catalytic activity for alkyne polymerization.The results show that the activity of Fischer's molybdenum-carbene is higher than that of tungsten.The catalytic polymerization of alkyne by M-σ-c bond-containing complexes of molybdenum and tungsten has not been reported yet in literature.Therefore,four M-σ-C bondontaining complexes of molybdenum and tungsten were synthesized by using the method reported in the literature,and catalyst polymerization of alkyne by these complexes was examined.     

SYNTHESES OF POLYMER-BOUND RHODIUM COMPLEXES AND THEIR APPLICATION AS CATALYSTS FOR THE HYDROFORMYLATION OF DIISOBUTYLENE (Ⅱ)

Five kinds of polymer-anchored aminophosphine-rhodium complexes were synthesizedby ionic and covalent bonding methods. These anehored rhodium complexes synthesizedpossess good catalytic activity and aldehyde-formation selectivity in the hydroformylationof diisobutylene. The complexes anchored via covalent bonds on polymers showedexcellent reproducibility on recycling. After reaction, it indicated that the loss of rhodiumof the catalysts was very small as shown by analysis.     

Studies on PNPP Hydrolysis Catalyzed by Schiff Base Cobalt（Ⅱ） Complexes

Two cobalt（Ⅱ） complexes of the Schiff base with morpholino or aza-crown ether pendants, CoL^1 and CoL^2, as mimic hydrolytic metalloenzyme, were used in catalytic hydrolysis of carboxylic ester （PNPP）. The analysis of specific absorption spectra of the hydrolytic reaction systems indicates that key intermediates, made up of PNPP and Co（Ⅱ） complexes, have been formed in reaction processes of the PNPP catalytic hydrolysis. The mechanism of PNPP catalytic hydrolysis has been proposed based on the analytic result of specific absorption spectrum. A kinetic mathematical model, applied to the calculation of the kinetic parameter of PNPP catalytic hydrolysis, has been established based on the mechanism proposed. The acid effect of buffer solution, structural effect of the complexes, and effect of temperature on the rate of PNPP hydrolysis catalyzed by the complexes have been also discussed.     

Novel cobalt(Ⅱ) complexes of amino acids-Schiff bases catalyzed aerobic oxidation of various alcohols to ketones and aldehyde

<正>Two cobalt(Ⅱ) complexes 1 and 2 of Schiff bases derived from amino acids were synthesized and used for oxidation of benzyl alcohol with molecular oxygen at different conditions of pH,solvent,temperature and complex/alcohol molar ratio to optimize reaction conditions and to evaluate the catalytic efficiency of new cobalt Schiff base complexes.Under obtained optimum conditions,various alcohols were oxidized to corresponding aldehydes and ketones.     

Mono-and Binuclear Cobalt(Ⅱ) Complexes Supported by Quinoline-2-imidate Ligands:Synthesis,Characterization,and 1,3-Butadiene Polymerization

A series of mono-and binuclear Co(II) complexes(Co1–Co7) supported by quinoline-2-imidate ligands were synthesized and thoroughly characterized.Measured by single crystal X-ray crystallography,complexes Co1 and Co3 adopted distorted tetrahedral structures around the cobalt center.Upon activation by ethylaluminium sesquichloride(EASC),these cobalt complexes exhibited high catalytic activity and cis-1,4-selectivity towards 1,3-butadiene polymerization.The effects of ligand environment,polymerization temperature,and cocatalyst types on the polymerization were investigated in detail.Interestingly,the binuclear Co(II) complexes exhibited high thermal stability,and the polymer yields were up to 97.2% even at a high temperature of 70 °C.     

SYNTHESIS AND CHARACTERIZATION OF BIS-[2-[[(2-ALKOXYPHENYL)IMINO]METHYL]-PHENOLATO-O,N,O]NICKEL(II)COMPLEXES AND THEIR NORBORNENE POLYMERIZATION

A series of salicylaldimines,synthesized in high yield via microwave-assisted condensation of salicylaldehyde and 2-alkoxyaniline were allowed to react with nickel chloride to form six-coordinated nickel complexes.These nickel complexes were carefully characterized,and the solid structure of la was elucidated by X-Ray diffraction.Activated with MAO,the nickel complexes showed good activity for homopolymerization of norbornene.Reaction parameters,such as the ratio of nickel precursor to MAO,monomer concentration,reaction time and the reaction temperature,as well as the nature of the ligands were found to have significant effects on the catalytic activity and some properties of the resulting polynorbornene.     

Synergistic Catalytic Action of Cobalt（ Ⅱ ） Hydroxamates and N-Hydroxyphthalimide in the Aerobic Oxidation ofp-Xylene

The catalytic performance of a series of cobalt( Ⅱ ) hydroxamates (COL2) and the synergistic catalytic action of the cobalt complexes combined with N-hydroxyphthalimide (NHPI) in the aerobic oxidation ofp-xylene top-toluic acid (PTA) were investigated. The results showed that the existing synergistic action in the catalytic oxidation can shorten the induction period of theradical reaction and improve the yield of PTA.     

Synthesis,characterization, and catalytic ethylene oligomerization of pyridine-imine palladium complexes

Two neutral five-membered pyridine-imine palladium complexes with the bulky dibenzhydryl (CH(Ph)2) substituted aniline were synthesized and fully characterized by nuclear magnetic resonance (NMR) and X-ray crystal diffraction.Well-defined cationic palladium complexes were further obtained by treatment of chloromethylpalladium complexes with sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (NaBArF) in CH3CN.Cationic palladium complexes were capable of catalyzing ethylene oligomerization without any cocatalysts.The influences of catalyst structure,reaction temperature,and ethylene pressure on ethylene oligomerization were studied in detail.The introduction of bulky benzhydryl (CH(Ph)2) on the ortho position of the aniline moiety enhanced catalytic activity,thermal stability of the catalyst,and molecular weight of the obtained products.Highly branched oligomers with molecular weights of 600-800 g/mol and narrow polydispersities (1.03-1.12) were produced.     

SYNTHESIS, CHARACTERIZATION OF IMIDAZOLATE-BRIDGED HETEROPOLY- NUCLEAR COMPLEXES AND THEIR ACTIVITY IN DISMUTATION OF O~(-)_(2)

A series of imidazolate-bridged heteropolynuclear complexes containing Cu2+ or Zn2+ were synthesized and characterized by reflectance spectroscopy, NMR and X-ray diffraction analysis. The bonding nature and the stability of imidazolate bridges in the complexes were studied by ESR spectroscopy, and the catalytic activity of the complexes in dismutation of O-2 was determined by NBT method. Results obtained indicate that the central Cu with N4 and N2O2 square planar or N4O square pyramidal coordination in which there is a weak bond H2O or ClO-4 on axial position, has a comparatively higher activity, but that with N5 square pyramidal having a strong bond axial ligand has almost no activity. Thus the results imply a possible formation of Cu-O-2 intermediate adduct in the catalytic process by Cu, Zn-SOD.     

Rare-earth metal amido complexes supported by bridged bis(β-diketiminato) ligand as efficient catalysts for hydrophosphonylation of aldehydes and ketones

A series of rare-earth metal amides supported by a cyclohexyl-linked bis(β-diketiminato) ligand were synthesized,and their catalytic activities for hydrophosphonylation of aldehydes and ketones were developed.Reaction of [(Me3Si)2N]3 RE(Cl)Li(THF)3 with the cyclohexyl-linked bis(-diketimine) H2L(1)(L=Cy[NC(Me)CHC(Me)NAr]2,Cy = cyclohexyl,Ar=2,6-i-Pr2C6H3) gave the rare-earth metal amides LREN(SiMe3)2(RE = Nd(2),Sm(3),Dy(4),Er(5),Y(6)).All complexes were fully characterized by elemental,spectroscopic and single-crystal X-ray analyses.Investigation of the catalytic properties of the complexes reveals that these complexes exhibited a high catalytic activity towards the hydrophosphonylation of aldehydes and ketones in the presence of a very low loading of rare-earth metal amides(0.1-1 mol%) at room temperature in a short time.     

THE EFFECT OF MODIFICATION OF COORDINATING GROUPS ON THE CATALYTIC BEHAVIORS OF POLYMER CATALYSTS

Several polymer-supported palladium complex catalysts containing two different coordinatinggroups were prepared and the cooperative effect of the coordinating groups on the catalytic behaviorsof polymer catalysts was studied. It was found that poly(acrylic acid-co-acrylonitrile)-Pd complex(PAA-AN-Pd) is a more active and stable catalyst for hydrogenation than both poly(acrylic acid)-Pd and poly(acrylonitrile)-Pd complexes. A marked change of catalytic behaviors of poly(N-substituted maleamic acid-co-styrene)-Pd complexes was observed in comparison with poly(maleicacid-co-styrene)-Pd complex. Acetophenone was reduced to 1-phenyl ethanol by poly(N-phenylmaleamic acid-Co-styrene)-Pd complex (N-1-Pd), but ethylbenzene was obtained using poly(maleicacid-co-styrene)-Pd complex as a catalyst. The influence of solvents, additives and N/Pd gramatomic ratio on the catalytic behaviors of the polymer complexes was investigated.     

Dioxygen Affinities and Biomimetic Catalytic Oxidation Performance of Transition-metal Complexes with Unsymmetrical Bis-Schiff Bases

Bis-Schiff base complexes as mimetic monooxgenase have been extensively reported1, 2. The bis-Schiff bases transition-metal complexes modified by crown ethers ring or pseudo-macrocylic polyethers have significantly improved dioxygen affinities and biomimetic catalytic performance in comparison with uncrowned analogues3, 4. However, most of them were symmetric and oxacrown ether substituted, the bis-Schiff bases bearing an azacrown ether, with special configuration and possibility to approach…     

Syntheses of Some New Group 4 non-Cp Complexes Bearing Schiff-base, Thiophene Diamide Ligands Respectively and Their Catalytic Activities for a-Olefin Polymerization

Totally sixteen new titanium and zirconium non-Cp complexes supported by Schiff-base, or thiophene diamide ligands have been synthesized. The complexes are obtained by the reaction of M(OPr-i)4(M=Ti,Zr) with the corresponding Schiff-base ligand in 1:1 molar ratio in good yield. The thiophene diamide titanium complex has been prepared from trimethylsilyl amine [N,S,N] ligand and TiCl4 in toluene at 120℃. All complexes are well charac-terized by ^1H NMR, IR, MS and elemental analysis. When activated by excess methylaluminoxane (MAO), complexes show moderate catalytic activity for ethylene polymerization, and complex If (R^1=CH3,R^2=Br) exhibits the highest activity for ethylene and styrene polymerization. When the complexes were preactivated by triethylaluminum (TEA), both polymerization activities and syndiotacticity of the polymers were greatly improved.     

Enantioselective epoxidation of nonfunctionalized alkenes catalyzed by recyclable new homochiral bis-diamine-bridged bi-Mn(salen) complexes

Three new homochiral bis-diamine-bridged bi-Mn(salen) complexes were synthesized. Their catalysis on asymmetric epoxidation of α-methylstyrene, styrene and indene was studied with NaClO and m-CPBA as oxidants respectively. This homogeneous catalyst exhibited comparable catalytic activity and enantioselectivity to the Jacobsen’s catalyst in the asymmetric epoxidation of unfunctionalized olefins. Furthermore, the catalyst could be conveniently recovered and reused at least five times without significant losses of both activity and enantioselectivity. Specially, it also could be efficiently used in large-scale reactions with superior catalytic disposition being maintained at the same level, which provided the potential for the applications in industry. The effect of axial bases, temperature and solvent on activity and enantioselectivity of the catalytic system were also studied.