铁系亚胺基配合物催化乙烯齐聚表观动力学

考察了4种具有电子效应差异的铁系亚胺基配合物2,6-二[(2-甲基-4-甲氧基-苯胺)乙基]吡啶二氯化铁、2,6-二[(2,4-二甲基-苯胺)乙基]吡啶二氯化铁、2,6-二[(2-甲基苯胺)乙基]吡啶二氯化铁和2,6-二[(2-甲基-4-溴-苯胺)乙基]吡啶二氯化铁,在不同反应温度、乙烯压力和催化剂用量下乙烯齐聚的表观动力学行为。在20～50℃、0 3～1 0MPa条件下,这4种配合物所制备催化剂的反应速率随反应温度升高、乙烯压力增大而提高,而随着催化剂浓度的增大,反应速率反而降低。利用简化的表观动力学方程,求出了催化剂的表观活化能和表观速率方程。

无机/有机复合载体负载乙酰丙酮铁/双亚胺基吡啶催化剂及其乙烯聚合

采用溶胶-凝胶法,将苯乙烯-丙烯酸共聚物(PSA)包覆于955 Davison硅胶上得到无机/有机复合微球载体,并在2,6-二[1-(2-异丙基苯基亚胺基)乙基]吡啶/Fe(acac)3均相催化剂中浸渍后得到负载型双亚胺基吡啶铁催化剂.该催化剂在生产高结晶度(72%)聚乙烯的同时,还能生产一定量的α-烯烃.考察了不同膜材料以及聚合条件(不同助催化剂,压力,温度,Al/Fe摩尔比)对聚合活性以及聚合产物性能的影响,发现温度对聚合产物的α-烯烃与聚乙烯的质量比影响最大,助催化剂类型既影响催化剂的活性,也对最终产物的性质有着很大的影响.氯化镁处理的PSA作为膜材料时,负载2,6-二[1-(2-异丙基苯基亚胺基)乙基]吡啶/Fe(acac)3所得到聚乙烯分子量较低(Mw=11.9×104),结晶度较大(72%),熔融指数MI较高(2.35 g/10min),可作为双峰聚乙烯中的低分子量部分加以利用.

副品红的合成、提纯及生产废水处理

采用两步催化法合成副品红。首先,对硝基甲苯与多硫化钠在无水乙醇为有机溶剂、N,N-二甲基乙酰胺(DMA)为胺基催化剂条件下生成对氨基苯甲醛,得到最佳n(DMA)∶n(对硝基甲苯)=3∶13,其中,对硝基甲苯用量为25 g(0.18 mol),下同。然后,对氨基苯甲醛在聚乙二醇400(PEG-400)催化下与苯胺和盐酸反应生成副品红粗品,考察了物料比、反应温度和反应时间对副品红粗品产率的影响。结果表明,在n(PEG-400)∶n(对硝基甲苯)=2∶300、n(对硝基甲苯)∶n(苯胺)∶n(盐酸)=1∶5.9∶2.8、110℃下反应4 h,副品红粗品产率为85.6%。最后,考察了蒸馏温度和时间对副品红质量分数的影响。发现在130℃下蒸馏3 h,副品红的质量分数达到91.3%。副品红生产废水主要为苯胺,精馏后苯胺回收率达89.3%。

A novel iron-chelating polyimide network as a visible-light-driven catalyst for photoinduced radical polymerization

With the aim of developing a low-cost and efficient visible-light-driven photocatalyst for radical polymerization,iron-chelating polyimide networks(Fe@MPI)was fabricated by firstly synthesizing photoactive melamine-containing polyimide(MPI)networks and then incorporating Fe(III)cations into the polymer networks.Fe@MPI exhibits a wide absorption spectrum ranging from 220 to 1250 nm and 3.5 times higher photocurrent intensity as compared with the pristine MPI.Based on its excellent photo-electric properties,Fe@MPI was employed as a recyclable heterogeneous catalyst,providing sufficient activity for the visible-light driven radical polymerization to synthesize poly(methyl methacrylate)with molecular weight up to 31.×10^4 g mol.Taking advantage of the heterogeneous nature of the catalyst,Fe@MPI could be facilely regenerated from the polymerization solution by filtration without an obvious loss of its activity.This research provides a novel recyclable catalyst for visible-light driven radical polymerization.

Aerobic oxidative coupling of alcohols and amines to imines over iron catalysts supported on mesoporous carbon

Direct oxidative coupling of an alcohol and amine,with air or molecular oxygen as the oxygen source,is an environmentally friendly method for imine synthesis.We developed an Fe catalyst supported on mesoporous carbon（denoted by FeOx/HCMK-3） for this reaction with excellent activity and recyclability.FeOx/HCMK-3 was prepared by impregnating HNO3-treated mesoporous carbon（CMK-3） with iron nitrate solution.The highly dispersed FeOx species give FeOx/HCMK-3 high reducibility and are responsible for the high catalytic performance.Imine synthesis over FeOx/HCMK-3 follows a redox mechanism.The oxygen species in FeOx/HCMK-3 participate in the reaction and are then regenerated by oxidation with molecular O2.The reaction involves two consecutive steps：oxidative dehydrogenation of an alcohol to an aldehyde and coupling of the aldehyde with an amine to give an imine.Oxidative dehydrogenation of the alcohol is the rate-determining step in the reaction.

乙烯/1-辛烯嵌段共聚物的合成

以合成的“软段”吡啶胺基铪配合物和“硬段”水杨醛亚胺锆配合物,在二乙基锌链转移剂作用下制备了窄分子量分布的乙烯/1-辛烯嵌段烯烃共聚物。结果表明,链穿梭聚合的活性(以铪催化剂计)能够达到34.8×10^(6) g/(mol·h),辛烯插入摩尔分数达到了23.5%,烯烃嵌段共聚物的重均分子量可达到225 kg/mol,分子量分布较窄(分子量分布指数2.0~2.3),嵌段共聚物熔点能够达到115℃以上。通过调节吡啶胺基铪催化剂与水杨醛亚胺锆催化剂的比例可以调控共聚物的嵌段长度及分子量。

Catalytic Hydrogenation of Aromatic Compounds in the Liquid Phase

Peculiarities of a liquid phase hydrogenation, namely lower diffusivity of components influencing the reaction rate and deactivation of catalysts by leaching, are discussed. A focus is on hydrogenation of aromatic compounds, whereas the following processes are evaluated： （l） partial hydrogenation of benzene to cyclohexene; （2） hydrogenation of aniline; （3） hydrogenation of diphenylamine; （4） preparation of aniline from nitrobenzene; （5） hydrogenation of chloronitrobenzenes; （6） hydrogenation of 4-nitrosodiphenylamine and 4-nitrodiphenylamine mixture. Processes （1） and （6） are typically carried out in the water-oil system. Generally, this type of system allows reaching a higher selectivity to desired products. In the case of hydrogenation of 4-nitrosodiphenylamine and 4-nitrodiphenylamine mixture, the water phase extracts a water soluble catalyst; which is recycled and used for condensation of aniline and nitrobenzene. Problems of reaction kinetics, as well as catalysts deactivation are here discussed.

Heterogeneous synthesis of dimethylhexane-1,6-dicarbamate from 1,6-hexanediamine and methyl carbonate in methanol over a CeO_2 catalyst

The efficient synthesis of dimethylhexane-1,6-dicarbamate(HDC)from 1,6-hexanediamine(HDA)and methyl carbonate over a series of heterogeneous catalysts(e.g.,Mg O,Fe2O3,Mo2O3,and Ce O2)was investigated.The reaction pathway was confirmed as an alcoholysis reaction through a series of designed experiments.Under optimized conditions,100%HDA conversion with 83.1%HDCtotaland 16.9%polyurea was obtained using a onestep with high temperature procedure with Ce O2as the catalyst.A new two-step with variable temperature technology was developed based on the reaction pathway to reduce the polyurea yield.Using the proposed method,the HDCtotalyield reached 95.2%,whereas the polyurea yield decreased to 4.8%.The Ce O2catalyst showed high stability and did not exhibit any observable decrease in the HDC yield or any structural changes after four recycling periods.

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 theft catalytic activities for hydrophosphonylation of aldehydes and ketones were developed. Reaction of [（Me3Si）2N]3RE（ct- C1）Li（THF）3 with the cyclohexyl-linked bis（13-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）, Sin（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 tool%） at room temperature in a short time.

Effect of polyamide on selectivity of its supported Raney Ni catalyst

A newly-developed polyamide supported Raney Ni catalyst, which is suitable for use in fix-bed reactions with high selectivity, was studied in this paper. Selective hydrogenation of acetone to isopropanol was chosen as a probe reaction. It has been found that clean preparation of isopropanol could be achieved, that is to say, the two main byproducts(isopropyl ether and methyl-iso-butyl carbinol) could be eliminated with the newly-developed polyamide supported Raney Ni catalyst. The elimination of these side reactions was attributed to the adsorption effect of polyamide support and a model was proposed. The proposed model was further proved by hydroamination reaction of acetone. According to this model, catalyst support can play an important role in chemical reactions. Different products could be produced when different catalyst support is used, the main reaction and side reactions can even be reversed sometimes when the chemicals, active component of catalyst and reaction condition are the same. This model could help to improve catalytic selectivity of many Raney metal catalysts used routinely in chemical and oil refining industry, and is also useful for hydrogenation reactions in pharmaceutical and food industry.

Platinum nanowires catalyzed direct amidation of aldehydes and amines

Different from the conventional synthesis methods and substrates, we designed a brand new method for synthesizing amides with platinum nanowires as catalysts and tert-butylhydroperoxide(TBHP) as the oxidant. Influence of factors, such as the catalyst, solvents, and the reaction temperature, were studied to determine the optimal reaction conditions. In addition, we explored the substrate generality and observed excellent yields.