UV LASER INITIATED STEREOSELECTIVE HOMOGENEOUS CATALYSIS POLYMERIZATION OF PHENYLACETYLENE

In this paper, the stereoselective homogeneous catalysis polymerization of phenylacetylene by using two kinds of catalysts W(CO)_5CH_3I and W(CO)_4I_2 produced from UV laser photolysis of W (CO)_6 in CH_3I, I_2—C_6H_6 and CHI_3—C_6H_6 respectively was studied. The effects of laser energy, laser irradiation time and lifetime of catalyst on the polymerization of phenylacetylene were discussed. The photoproducts of W (CO)_6 in CH_3I, I2—C_6H_6 and CHI_3—C_6I_6 were determined by IR spectra. The structures of polyphenylacetylene obtained by W (CO)_5CH_3I and W (CO)_4I_2 catalysts were characterized by IR spectra and ~1H NMR spectra.

Graft Copolymerization of N,N-Dimethylacrylamide to Cellulose in Homogeneous Media Using Atom Transfer Radical Polymerization for Hemocompatibility

In homogeneous media, N,N-Dimethylacrylamide (DMA) was grafted copolymerization to cellulose by a metal-catalyzed atom transfer radical polymerization (ATRP) process. First, cellulose was dissolved in DMAc/LiCl system, and it reacted with 2-bromoisobutyloyl bromide (BiBBr) to produce macroinitiator (cell-BiB). Then DMA was polymerized to the cellulose backbone in a homogeneous DMSO solution in presence of the cell-BiB. Characterization with FT-IR, NMR, and GPC measurements showed that there obtained a graft copolymer with cellulose backbone and PDMA side chains (cell-PDMA) in well-defined structure. The proteins adsorption studies showed that the cellulose membranes modified by the as-prepared cell-PDMA copolymer owns good protein adsorption resistancet.

Synthesis,Crystal Structure and Characterization of a Nickel Complex Based on Phenoxyimine Ligand and Catalysis of the Vinyl Polymerization of Norbornene

The title complex N,O-bis{2-[[（2-benzhydryl-4,6-dimethylphenyl）imino]-methyl]-phenol}-nickel（II）（C56H48N2NiO2） has been synthesized by the reaction of 2-[[（2-benzhydryl-4,6-dimethylphenyl）mino]-methyl]-phenol with Ni（CH3COO）2·4 H2O, and characterized by elemental analysis and IR spectrum. The spatial structure of the complex has been confirmed by single-crystal X-ray diffraction analysis. The compound belongs to the monoclinic system, space group C2/c with a = 39.035（8）, b = 13.276（3）, c = 17.679（4） A°, β = 98.06（3）°, V = 9071（3） A°^3, C56H48N2NiO2, Mr = 839.67, Z = 8, Dc = 1.230 Mg/m^3, μ = 0.472 mm^-1, F（000） = 3536, T = 293（2） K, the final R = 0.0675 and w R = 0.1345（I 〉 2s（I））. The compound showed excellent catalytic activity up to 1.268 × 10^7 g of PNB（mol of Ni）^-1h^-1 for the addition polymerization of norbornene by using methylaluminoxane（MAO） as a cocatalyst.

SIMULTANEOUS POLYMERIZATION AND FORMATION OF POLYPHENYLACETYLENE FILMS BY RARE-EARTH COORDINATION CATALYSIS Ⅳ.KINETICS AND MECHANISM OF POLYMERIZATION

The CO_2 quenching method has been used for the first time to determine the active complex concen- tration in Nd(naph)_3-Al(i-Bu)_3 catalyst system for polymerization of phenylacetylene into polyphenylacetylene(PPA)films.The kinetics and mechanism of this polymerization have been investigated by CO_2 quenching and IR,UV analytical methods.The kinetic equation can be expressed as Rp=k[M][Cp],and the apparent activation energy is about 13.6 kJ/mol.There is self-termination of chain propagating.Models for formation of the active complex and polymerization mechanism are proposed.

Synthesis and Characterization of a Palladium Complex Supported by Bidentate Ligand and Catalysis of the Vinyl Polymerization of Norbornene

The title complex N,O-bis{[2-[（2,4-dimethylphenyl）imino]-5-methoxyl]-phenol}-palladium（Ⅱ）（CC_（32）H_（32）N_2O_4Pd） has been synthesized by the reaction of 2-[（2,4-dimethylphenyl）imino]-5-methoxyl-phenol with Pd（CH_3COO）_2,and characterized by elemental analysis,IR spectrum and single-crystal X-ray diffraction analysis.The crystal belongs to the monoclinic system,space group P2_1/c with a = 12.058（2）,b = 8.3624（17）,c = 14.735（3） ？,β = 107.66（3）°,V = 1415.7（5）？~3,C_（32）H_（32）N_2O_4Pd,Mr = 615,Z = 2,D_c = 1.443 Mg/m^3,μ = 0.695 mm^（-1）,F（000） = 632,T = 293（2） K,the final R = 0.0514 and w R = 0.1356（I 〉 2s（I））.Under the co-catalysis of methylaluminoxane（MAO）,the palladium compound exhibited favorable catalytic activity for the polymerization of norbornene（NB）.

POLYMERIZATION MECHANISM OF DIENES WITH HOMOGENEOUS RARE EARTH CATALYSTS

The reaction mechanisms of diene polymerization with homogeneous rare earth catalyst are studied by means of the spectra of ~1H-NMR, one-and two-dimensions ^(13)C-NMR. Based on the data of above NMR spectra, it is proposed that the polymerization reaction proceeds according to the following mechanism: η~4-diene (cis-trans-)and η~3-allyl (syn-anti-).

Transesterification Reaction of Waste Cooking Oil and Chicken Fat by Homogeneous Catalysis

In the last years, biodiesel production has been on a steady increase due to it is renewable and biodegradable fuel. The process to obtain biodiesel can be carried out using different raw materials. It is conlmonly performed by transesterification reaction of vegetable oils with methanol and using a homogeneous or heterogeneous catalyst. This work seeks to compare the results produced in transesterification of wasted cooking oil and chicken fat by homogeneous catalysis with NaOH. Due to in each case triglyceride comes from different raw materials, operation conditions differ slightly, which is more evident in the values used for the temperature. For chicken fat was used temperature variations between 35 ℃ and 55 ℃, varying catalyst in percentages between 0.3% and 0.7% with a molar ratio 6：1 in all cases and a reaction time of I h. Likewise, the conditions used in the tmnsesterification process of waste cooking oil were temperature between 50 ℃ and 60 ℃ with a molar ratio 6/1 and 9/1 for alcohol and oil, and catalyst percentage between 0.5% and 0.7% by weight. The yields obtained were between 78% and 94%, or 83% and 95%, for chicken fat and wasted cooking oil, respectively.

Homogeneous,heterogeneous,and enzyme catalysis in microfluidics droplets

Microfluidics has received extensive attention due to its ability to rapidly prepare a large number of microdroplets with controlled sizes and defined morphologies.In addition to having large surface areas and controllable confinement environments,these prepared microdroplets can be used as analytical detection devices to screen and optimize various kinetic parameters.This review summarizes recent advances in the microfluidic control of droplet-based catalytic reactions and discusses the role of these droplets in both homogeneous and heterogeneous catalyzes and in the catalysis of macromolecular biological enzymes in water-in-oil and oil-in-oil environments.Additionally,the existing problems and future development directions of droplets in catalysis are highlighted to promote the development of catalytic reactions in droplet media and provide guidance for the high-throughput screening of catalysts and the directed evolution of biological enzymes.

Identification of origin of insulating polymer maneuvered photoredox catalysis

Solid non-conjugated polymers have long been regarded as insulators due to deficiency of delocalizedπelectrons along the molecular chain framework.Up to date,origin of insulating polymer regulated charge transfer has not yet been uncovered.In this work,we unleash the root origin of charge transport capability of insulating polymer in photocatalysis.We ascertain that insulating polymer plays crucial roles in fine tuning of electronic structure of transition metal chalcogenides(TMCs),which mainly include altering surface electron density of TMCs for accelerating charge transport kinetics,triggering the generation of defect over TMCs for prolonging carrier lifetime,and acting as hole-trapping mediator for retarding charge recombination.These synergistic roles contribute to the charge transfer of insulating polymer.Our work opens a new vista of utilizing solid insulating polymers for maneuvering charge transfer toward solar energy conversion.

Single-atom catalysis: Bridging the homo-and heterogeneous catalysis

Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneous catalysts(isolated active sites)and heterogeneous catalysts(stable and easy to separate),and are thus predicted to be able to bridge the homo-and heterogeneous catalysis.This prediction was first experimentally demonstrated in 2016.In this mini-review,we summarize the few homogeneous catalysis progresses reported recently where SACs have exhibited promising application:a)Rh/ZnO and Rh/CoO SAC have been used successfully in hydroformylation of olefin of which the activity are comparable to the homogeneous Wilkinson’s catalyst;b)a Pt/Al2O3 SAC has shown excellent performance in hydrosilylation reaction;and c)M-N-C SACs(M=Fe,Co etc.)have been applied in the activation of C–H bonds.All of these examples suggest that fabrication of suitable SACs could provide a new avenue for the heterogenization of homogeneous catalysts.These pioneering works shed new light on the recognition of single-atom catalysis in bridging the homo-and heterogeneous catalysis.

Synthesis of polyurea from 1,6-hexanediamine with CO_2 through a two-step polymerization

Activation and transformation of CO_2 is one of the important issues in the field of green and sustainable chemistry. Herein, CO_2 as a carbonoxygen resource was converted to CO_2-polyurea with 1,6-hexanediamine through a two-step polymerization. The reaction parameters such as temperature, pressure and reaction time were examined; and several kinds of catalysts were screened in the absence and presence of NMP solvent. The formed oligomer and the final polyurea were characterized by FT-IR, VT-DRIFTS, NMR, XRD, AFM and their thermal properties were examined by TGA and DSC. It was confirmed that the final polyurea has a high thermal stability; the melting temperature is 269℃ and the decomposition temperature is above 300℃. It is a brittle polymer with a tensile strength of 18.35 MPa at break length of 1.64%. The polyurea has a stronger solvent resistance due to the ordered hydrogen bond in structure. The average molecular weight should be enhanced in the postpolymerization as the appearance, hydrogen bond intensity, crystallinity, melting point and the thermal stability changed largely compared to the oligomer. The present work provides a new kind of polyurea, it is expected to have a wide application in the field of polymer materials.

Influence of polymer additives on turbulent energy cascading in forced homogeneous isotropic turbulence studied by direct numerical simulations

Direct numerical simulations （DNS） were performed for the forced homogeneous isotropic turbulence （FHIT） with/without polymer additives in order to elaborate the characteristics of the turbulent energy cascading influenced by drag-reducing effects. The finite elastic non-linear extensibility-Peterlin model （FENE-P） was used as the conformation tensor equation for the viscoelastic polymer solution. Detailed analyses of DNS data were carried out in this paper for the turbulence scaling law and the topological dynamics of FHIT as well as the important turbulent parameters, including turbulent kinetic energy spectra, enstrophy and strain, velocity structure function, small-scale intermittency, etc. A natural and straightforward definition for the drag reduction rate was also proposed for the drag-reducing FHIT based on the decrease degree of the turbulent kinetic energy. It was found that the turbulent energy cascading in the FHIT was greatly modified by the drag-reducing polymer additives. The enstrophy and the strain fields in the FH1T of the polymer solution were remarkably weakened as compared with their Newtonian counterparts. The small-scale vortices and the small-scale intermittency were all inhibited by the viscoelastic effects in the FHIT of the polymer solution. However, the scaling law in a fashion of extended self-similarity for the FHIT of the polymer solution, within the presently simulated range of Weissenberg numbers, had no distinct differences compared with that of the Newtonian fluid case.

Syntheses,Structures,Fluorescence and Heterogeneous Catalysis of Coordination Polymers with 4-Benzoimidazol-1-yl-methyl Benzoic Acid and 2,2′-Dipyridine

Two coordination polymers called [Ni（L）2]n（1） and [Ni（2,2？-bpy）22（H2O）]n （2）（HL = 4-benzoimidazol-1-yl-methyl benzoic acid, 2,2？-bpy = 2,2＇-dipyridine） were synthesized by solvothermal reaction simultaneously and characterized by elemental analyses, thermogravimetric analysis, X-ray powder diffraction, IR spectroscopy and single-crystal X-ray diffraction analysis. Complex 1 crystallizes in monoclinic system, space group P21/c with a = 14.673（3）, b = 10.773（2）, c = 16.566（3） ？, V = 2559.2（8） A^3, Z = 4 and F（000） = 1160. 2 also crystallizes in monoclinic system, space group C2/c with a = 15.404（3）, b = 12.652（3）, c = 6.5362（13） ？, V = 1246.2（5） A^3, Z = 4 and F（000） = 712. The bridging L ligand connects the Ni^Ⅱ cations into a 2D network in complex 1, while 2 shows a 1D structure formed through the two O atoms of SO4^（2-） ions connecting the molecule. The catalytic properties indicate that complex 1 shows good catalytic activities for the cyanosilylation of 4-chlorobenzaldehyde. In addition, fluorescence property of complex 1 which quenches the excitation intensity in solid state was investigated at room temperature.

THE INFLUENCE OF SUBSTITUENTS IN METALLOCENE ON PROPYLENE POLYMERIZATION

Two new unbridged zirconocenes, bis(2.4,7-trimethyl indenyl)zirconium dichloride (Met-I) and bis(2-methyl-4,7-diethyl indenyl)zirconium dichloride (Met-II) were prepared in order to investigate the steric effects of substituents on the nature of the catalysts for the: polymerization of propylene. A mixture of methyl aluminoxane (MAO) and triisobutylaluminum [Al(iBu)(3)] was used as cocatalyst to activate these catalysts. The decrease in steric bulkiness of substituents at 4 and 7 positions of the indenyl ring resulted in an increase of both activity and molecular weight as well as the isotacticity.

Synthesis, Crystal Structure and Norbornene Polymerization of a Palladium(Ⅱ) Complex Based on Phenoxyimine Ligand

The title complex N,O-bis{2-[[(2,6-benzhydryl-4-methylphenyl)imino]-methyl]-phenol}-palladium(II)(C_(80)H_(64)N_2O_2 Pd) has been synthesized by the reaction of 2-[[(2,6-benzhydryl-4-methylphenyl)imino]-methyl]-phenol with Pd(CH_3COO)_2, and characterized by IR spectrum and elemental analysis. The spatial structure of the complex has been verified by single-crystal X-ray diffraction analysis. The compound belongs to the monoclinic system, space group P21/n with a = 13.492(3), b = 16.924(3), c = 14.135(3) ?, β = 97.84(3)°, V = 3197.4(11) ?~3, C_(80)H_(64)N_2O_2 Pd, Mr = 1191.73, Z = 2, Dc = 1.238 Mg/m^3, μ = 0.339 mm^(-1), F(000) = 1240, T = 293(2) K, the final R = 0.0593 and wR = 0.1192(I > 2s(I)). The compound showed excellent catalytic activity up to 1.130 × 10~7 g of PNB(mol of Pd)^(-1)h^(-1) for the addition polymerization of norbornene by using methylaluminoxane(MAO) as a cocatalyst.

Rapid Biodiesel Fuel Production Using Novel Fibrous Catalyst Synthesized by Radiation-Induced Graft Polymerization

An efficient fibrous catalyst for the biodiesel fuel production has been synthesized by radiation-induced graft polymerization of 4-chloromethylstyrene onto a nonwoven polyethylene (NWPE) fabric followed by amination with trimethylamine (TMA) and further treatment with NaOH. The degree of grafting of NWPE fabric and TMA group density of fibrous catalyst could easily and reproducibly be controlled within a range of up to 340% and 3.6 mmol-TMA/g-catalyst, respectively. In the transesterification of triglycerides and ethanol using the synthesized fibrous catalyst, the conversion ratio of triglycerides reached 95% after 4 h reaction at 50°C.

Large-eddy simulations of a forced homogeneous isotropic turbulence with polymer additives

Large-eddy simulations （LES） based on the temporal approximate deconvolution model were performed for a forced homogeneous isotropic turbulence （FHIT） with polymer additives at moderate Taylor Reynolds number. Finitely extensible nonlinear elastic in the Peterlin approximation model was adopted as the constitutive equation for the filtered conformation tensor of the polymer molecules. The LES results were verified through comparisons with the direct numerical simulation results. Using the LES database of the FHIT in the Newtonian fluid and the polymer solution flows, the polymer effects on some important parameters such as strain, vorticity, drag reduction, and so forth were studied. By extracting the vortex structures and exploring the flatness factor through a high-order correlation function of velocity derivative and wavelet analysis, it can be found that the small-scale vortex structures and small-scale intermittency in the FHIT are all inhibited due to the existence of the polymers. The extended self-similarity scaling law in the polymer solution flow shows no apparent difference from that in the Newtonian fluid flow at the currently simulated ranges of Reynolds and Weissenberg numbers.

Homogeneously Catalyzed Transesterification of Nigerian <i>Jatropha curcas</i>Oil into Biodiesel: A Kinetic Study

As a follow-up to our previous study on the transesterification of Nigerian Jatropha curcas oil into Biodiesel using homogenous catalysis, kinetic study of the reaction is hereby presented. The kinetic study revealed that the rate of formation of biodiesel can be increased by increasing reaction temperature and oil to alcohol molar ratio. The optimum reaction condition was established to be 60°C (reaction temperature) and 1:6 (oil to alcohol ratio). Accordingly, the highest biodiesel yield obtained from homogeneously catalyzed transesterification of Nigerian Jatropha curcas (JC) oil into Biodiesel was 86.61% w/w at 60°C with oil to alcohol ratio of 1:6. Furthermore, kinetic study also revealed that conversion of triglyceride to diglyceride was the rate determining step (RDS) of the overall reaction because activation energy of its backward reaction is lower than that of the forward reaction, indicating unstable nature and higher potential energy of the diglyceride in comparison to the triglyceride.