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.     

CATALYTIC ACTIVITY OF Pd-Sn COMPLEX CARBONYLATION OF ACETYLENE

The influence of different concentration of HO, SnCl2, Cl- and n-BuOH on the carbonylation of acetylene has been studied. The results show that the yield of n- butyl propionate increases with the increase of HC1 concentration and the catalytic activity is depressed when Cl" concentration increases. However, the stability of catalytic complex is promoted by Cl-. The key to the carbonylation of acetylene lies in the addition of SnCl2, which promotes the formation of the complex of C2H2, CO with catalyst and plays an important role in the hydrogen removal from n-BuOH. The hydrogen removed from n BuOH is the hydrogen source of this reaction. Meanwhile, the principle of the effect of HCl, Cl- and SnCl2 on reaction has been discussed. The reaction model has also been proposed.     

ROLE OF MoO_3 AND La_2O_3 PROMOTERS IN Ni-CATALYZED METHANATION REACTIONS OF CO

A series of catalysts containing nickel were prepared by impregna-tion.The activity,heat resistance and sulfur resistance of catalysts were inves-tigated using catalytic microreactor.The experimental results show that the Ni/γ-Al_2O_3 catalysts containing molybdenum or lanthanum possess higher activity,better heat resistance and sulfur resistance than Ni/γ-Al_2O_3 catalyst.The sur-face behaviour of catalysts and the role of molybdenum or lanthanum in Ni-Mo-La/γ-Al_2O_3 system have been studied by XRD,TEM,XPS and TPY.It hasbeen shown that the addition of molybdenum or lanthanum can increase theconcentration of nickel atoms on the surface of catalysts,make the crystallinegranule of nickel smaller,increase the number of active centers of nickel andaffect the electronic structure of nickel.All these avtions will improve thecatalytic activity and surface behaviour of catalllysts.     

PREPARATION AND CATALYTIC BEHAVIOUR OF POLYMER-BOUND METALLOPORPHYRIN IN HYDROGENATION OF OLEFIN

The meso- tetraarylporphyrin has been anchored to styrene- divinylbenzenecopolymers by reaction of meso- tetra (4-hydroxylphenyl ) porphyrin with chloromethylatedresin under mild condition. A number of polymer transition metal complexes have beenprepared with the polymer ligand and metal salts. The polymeric ligand and its complexeshave been characterized by electronic spectra, and vibrational spectra. Cyclohexene can behydrogenated with the polymeric porphyrin palladium complex(P-THPPPd) as catalyst,and its catalytic activity was influenced by the polarity of solvents, the contents of water inethanol or reaction temperature. However, its catalytic activity was lower for nitro groups,carbonyl groups and olefins with steric hindrance substituents, and showed no activity foraromatic rings under these conditions.     

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.     

聚醚桥连二异羟肟酸单核和双核过渡金属配合物催化PNPP水解

Two polyether bridged dihydroxamic acids and their mono-and binuclear manganese(Ⅱ), zinc(Ⅱ) complexes have been synthesized and employed as models to mimic hydrolase in catalytic hydrolysis of p-nitrophenyl picolinate (PNPP). The reaction kinetics and the mechanism of hydrolysis of PNPP have been investigated. The kinetic mathematical model for PNPP cleaved by the complexes has been proposed. The effects of the different central metal ion, mono-and binuclear metal, the pseudo-macrocyclic polyether constructed by polyethoxy group of the complexes, and reactive temperature on the rate for catalytic hydrolysis of PNPP have been examined. The results showed that the transition metal dthydroxamates exhibited high catalytic activity to the hydrolysis of PNPP, the catalytic activity of binuclear complexes was higher than that of mononuclear ones, and the pseudo-macrocyclic polyether might synergetically activate H20 coordinated to metal ion with central metal ion together and promote the catalytic hydrolysis of PNPP.     

Living polymerization of 1,3-butadiene catalyzed by half-titanocene complex bearing dibenzhydryl-substituted aryloxide ligand

Half-titanocene complexes bearing dibenzhydryl-substituted aryloxide ligands(2a-2d) were prepared. Among them, 2c adopted a three-legged distorted tetrahedral geometry evidenced by X-ray crystallography. The poly-1,3-butadiene with high molecular weight and narrow molecular weight distribution was obtained by using these complexes as the catalysts activated with methylaluminoxane(MAO). The catalytic activities of the complexes depended on their structures. The Ti―O―C bond in the complexes with large angle afforded them with higher activity, while Cp*-based complexes exhibited lower activities than the Cp-based analogues. The activity of complex increased with increasing the polymerization temperature while the selectivity remained no change, indicating the high thermal stability. Furthermore, the polymerization of 1,3-butadiene catalyzed by 2a/MAO at 0 °C has been found in a living fashion.     

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.     

PLASMA POLYMERIZATION OF ACETYLENE/CO_2/H_2

A study has been made on the plasma polymerization of acetylene/CO_2/H_2 in a capacitively coupled RF plasma. The monomer mixture yielded a crosslinked film with light brown color. A kinetic study is reported for the plasma polymer ization of acetylene/CO_2/H_2. The effects of discharge power level and reactor geometry on the rate of polymer formation are reported. The structure of the plasma polymer is investigated by IR study.     

Synthesis and Crystal Structure of a Co(II) Complex with Schiff Base and Imidazole Ligand

1 INTRODUCTION The chemical behavior of metal complexes with Schiff base ligand has attracted much attention be- cause of their catalytic activity in some industrial[1, 2] and biochemical processes[3~5]. As some metal com- plexes have shown the catalytic activity in some polymerization reactions[2, 6], we are recently inte- rested in polymerizartion of organo-silicon com- pounds catalyzed by Schiff base complexes of tran- sition metals. A series of Schiff base complexes have been prepare…     

SYNTHESIS OF BRANCHED POLYETHYLENE USING (α-DIIMINE)NICKEL(Ⅱ)TiCl4 COMBINED AND SUPPORTED CATALYST*

(α-Diimine)nickel(Ⅱ) {[C6H5 -N = C(CH3)-C(CH3) = N -C6H5]NiBr2}-TiCl4 abbreviated as NiL-TiCl4 combined catalyst which is supported on MgCl2-SiO2 carrier has been prepared, by using alkyl aluminum (AIR3) as the cocatalyst in place of methylaluminoxane (MAO) to catalyze ethylene oligomerization and copolymerization in situ. The influences of procedure for supporting NiL-TiCI4, the molar ratio of NiL to TiCI4, cocatalyst type and polymerization temperature on the catalytic performance were studied. The degree of branching and the composition of the branched chain of polymers produced have been investigated by IR and ^13C-NMR spectra. The results show that the combined catalyst can synthesize the branched polyethylene with various banched chains .The polymerization reaction was monitored by gas chromatography and mass spectrometry (GC-MS). The results show that this catalyst promotes the oligomerization and copolymerization in situ for ethylene.     

Peroxo Complexes of Molybdenum(VI) Containing Mannich Base Ligands

The molybdenum(VI)-peroxo complexes containing Mannich base ligands having a formula as [MoO(O2)2(L-L)] [where L-L＝morpholinobenzyl benzamide (MBB), piperidinobenzyl benzamide (PBB), morpholinobenzyl urea (MBU), piperidinobenzyl urea (PBU), morpholinobenzyl thiourea (MBTU), piperdinobenzyl thiourea (PBTU)] have been synthesized and characterized by physico-chemical, electrochemical techniques and TGA/DTA studies. The complexes have been prepared by stirring ammonium molybdate and excess of 30% aqueous-H2O2 and then treatment with ethanolic solution of the ligand. Studies revealed that these complexes were non-electrolytes and diamagnetic in nature. The ligands are bound to metal in a bidentate mode through carbonyl oxygen/thiocarbonyl sulphur and the ring nitrogen. The cyclic voltammograms of the complexes show two quasi-reversible steps involving complexes. The complexes have also been tested for antibacterial activity against Salmonella and Kleibsella. The antibacterial study of the ligands and complexes indicate that the complexes exhibit higher activity than the free ligands.     

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.     

Lewis acid/base modulation in β-diiminate zinc-catalyzed switchable ring-opening polymerization of rac-lactide

Two β-diiminate zinc complexes were prepared and found to show high activity and well-controlled catalytic behavior in the ring-opening polymerization of rac-lactide. Coordination of the Lewis acid to the zinc complexes completely terminated the polymerization. The coordinated Lewis acid was easily cleaved by using a Lewis base, so that the polymerization could resume.Thus, switchable polymerization could be realized by the subsequent addition of a Lewis acid and a Lewis base. This work provides a new strategy to control the ring-opening polymerization of rac-lactide.     

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.     

SYNTHESIS AND PROPERTIES OF POLY-1,3,5-TRIAZINES

Two new polytriazines: poly[2-methyl-4, 6-(4,′4″-diphenylene)-1, 3, 5-triazine] (Ⅰ) and poly[2-phenyl-4, 6-(4′, 4″-diphenylene)-1, 3, 5-triazine] (Ⅱ) were synthesized from the solution condensation of biphenyl-4, 4′-diamidine dihydrochloride with acetic anhydride and biphenyl-4, 4′-diamidine with benzaldehyde respectively. These two polymers were characterized by TGA, DTA, elemental analysis and IR spectroscopy. They exhibited good thermal oxidative stability as shown by the fact that the powders of these polymers suffered 5.4%, 2.4% weight loss after isothermal aging in air at 300℃for 200 hours. The decomposition temperature of (Ⅱ) was 583℃in air and 590℃in N_2. These linear poly-1, 3, 5-triazines were soluble in concentrated sulfuric acid, phosphoric acid and trifluoroacetic acid whereas the erosslinked poly-1, 3, 5-triazines reported in the literature were insoluble and infusible.It is interesting that these polymers can form complexes with metal halides as determined by X-ray photoelectron spectroscopy (XPS). The polymer metal complex (Ⅲ). PdCl_2 possesses catalytic activity for hydrogenation.     

POLYMER-SUPPORTED RARE EARTH CATALYSTS FOR STYRENE POLYMERIZATION

The neodymium complex supported on styrene-maleic anhydride copolymer (SMA·Nd) has been prepared for the first time and found to be a highly effective catalyst for the polymerization of styrene. The SMA·Nd polymeric complex is characterized by IR and its catalytic activity, and the polymerization features have been investigated in comparison with that of the conventional Ziegler-Natta catalysts. When [Nd]=1×10~(-3) mol/L, [M]=5mol/L, Al/Nd=170(mol ratio) and CCl_4/Nd=50(mol ratio), the polymerization conversion of styrene gets to 51.6% in six hours, and the catalytic activity reaches 1852 gPS/gNd, which is much higher than that of conventional rare earth catalysts. The polymerization reaction has an induction period and shows some characteristics of chain polymerization. The polymerization rate is the first order with respect to the concentration of styrene monomer. Addition of FeCl_3 does not suppress the polymerization.     

SYNTHESIS OF DBN AND ITS CATALYTIC PERFORMANCE FOR METHANOL CARBONYLATION TO METHYL FORMATE

1 , 5-diazabicyclo['1, 3, 0]non-5-ene(DBN) has been synthesized in our laboratory, and its catalytic activity and selectivity for methanol carbonylation to methyl formate (MF) have been studied. The experimental results have demonstrated that the synthetic processes of DBN used for the present work are reasonable and feasible. The total yield of three steps of DBN synthsis is approximate to 80%. The activity evaluation has shown that DBN can effectively catalyze the carbonylation reaction of methanol in the presence of propylene oxide (PO) promoter. PO-promoted DBN is a novel catalytic system superior to sodium methoxide.     

INTERACTION AND REGULATION OF PLASMINOGEN ACTIVATORS AND THEIR INHIBITOR IN RAT FOLLICLES DURING PERIOVULATORY PERIODS

Ovarian follicles produce two types of plasminogen activator (tPA and uPA), and their inhibitor(PAI). We have examined the interaction and regulation of these factors in ovarian intact follicles aswell as granulosa and theca-interstitial cells. The results show that only tPA, but not uPA, is regulated bythe gonadotropins and reaches maximum prior to ovulation. PAI is secreted mainly by theca-interstitialcells and is stimulated also by the gonadotropins. The formation of complexes between PA and PAI com-pletely blocks or decreases PA activity. It is suggested that the interaction between plasminogen activatorsand their inhibitor in the follicles may play a very important role in maintaining normal ovarian functionand the machnism of ovulation.     

SYNTHESIS, CHARACTERIZATION AND STRUC-TURE OF BIS(1,8-NAPHTHYRIDINE-N-OXIDE) STRONTIUM NITRATE CON-TAINING DOUBLE BIDENTATE AND BRIDGING NITRATE GROUP

A new complex formed from strontium nitrate and 1,8-naphthyridine-N-oxide with a 1:2 stoichiometry has been synthesized and characterized by elemental analyses, infrared spectra, Raman spectra, fluorescence spectra, DTA-TG, solubility and molar conductance measurements. A single crystal X-ray structural analysis indicates that a kind of double bidentate and bridging nitrate group which has never been reported in literature is present in the new complex. The coordination number of the strontium ion is 10.