Epoxidation of alkenes with molecular oxygen and isobutyraldehyde catalyzed by immobilized vitamin B12 within Al-MCM-41

Vit-B₁₂/ Al-MCM-41 catalyzed successfully the epoxidation either of cis or trans — stilbene with O₂ as oxidant and isobutyraldehyde as co-reductant with 86–98% reactivity and 97–100% selectivity. Other olefins such as norbornene and styrene undergo epoxidation reaction under similar conditions with good to fair selectivity. Details of the reactions will be presented in this article.     

Efficient catalytic conversion of carbohydrates into 5-ethoxymethylfurfural over MIL-101-based sulfated porous coordination polymers

In this work, a series of MIL-101-SO3H(x) polymeric materials were prepared and further used for the first time as efficient heterogeneous catalysts for the conversion of fructose-based carbohydrates into 5-ethoxymethylfurfural(EMF) in a renewable mixed solvent system consisting of ethanol and tetrahydrofuran(THF). The influence of –SO3H content on the acidity as well as on the catalytic activity of the porous coordination polymers in EMF production was also studied. High EMF yields of 67.7% and 54.2% could be successively obtained from fructose and inulin in the presence of MIL-101-SO_3H(100) at 130 °C for 15 h.The catalyst could be reused for five times without significant loss of its activity and the recovery process was facile and simple. This work provides a new platform by application of porous coordination polymers(PCPs) for the production of the potential liquid fuel molecule EMF from biomass in a sustainable solvent system.     

Dynamic porous properties of coordination polymers inspired by hydrogen bonds

In a decade, many porous coordination polymers have been synthesized, providing a variety of properties ranging from storage, separation, exchange of guests in their cavities, magnetism, conductivity and catalysis by their frameworks. In this tutorial review, we focus on the hydrogen bonding type arrangements for dynamic porous coordination polymers exhibiting elastic guest accommodations, in contrast to rigid three-dimensional (3-D) frameworks. Such dynamic porous properties induce highly-selective guest accommodation and magnetic modulation, and could now be considered a new class of practical materials.     

Fe-MIL-101催化Paal-Knorr反应合成吡咯衍生物

以Fe-MIL-101为非均相催化剂,通过多种伯胺与2,5-二甲氧基四氢呋喃进行Paal-Knorr反应,高效合成相应的吡咯衍生物.在Fe-MIL-101结构中,裸露的Fe(Ⅲ)配位点作为催化活性中心参与吡咯衍生物的催化合成反应.同时Fe-MIL-101的高比表面积和大的孔尺寸确保了底物分子与催化活性中心的充分接触以及产物的自由脱离,从而促进了催化反应的快速进行.Fe-MIL-101在催化反应过程中具有很好的稳定性,多次循环使用后仍能表现出良好的催化性能.此外,该催化剂在伯胺(包括脂肪胺、芳香胺)与2,5-己二酮的Paal-Knorr缩合反应中也具有优异的催化性能.     

Selective oxidation of ethylbenzene catalyzed by fluorinated metalloporphyrins with molecular oxygen

This paper reported the oxidation of ethylbenzene catalyzed by fluorinated metalloporphyrins under mild conditions without any additives.The results showed that the cobalt(Ⅱ)(5,10,15,20-tetrakis(pentafluorophenyl))porphyrin was the best catalyst among the fluorinated metalloporphyrins.The conversion of ethylbenzene reached 38.6%,the selectivity to acetophenone reached 94.0%,and the turnover number is 2719 under the optimal conditions.     

Radical polymerisation of styrene in porous coordination polymers

The first radical polymerisation of styrene in porous coordination polymers has been carried out, providing stable propagating radicals (living radicals), and a specific space effect of the host frameworks on the monomer reactivity is demonstrated.     

Hydroformylation of alkenes with paraformaldehyde catalyzed by rhodium-phosphine complexes

The hydroformylation of medium-chain C6 olefins and of allyl alcohol was achieved with paraformaldehyde in dioxane solution using rhodium catalysts with mono-, bi-, and tri-dentate phosphine ligands. The highest activities with n/i ratios around 2, were obtained for a system derived from [Rh(dppe)₂]⁺, prepared in situ by reaction of Rh(acac)(CO)₂ with 2 eq of dppe.     

The study of cyclooctene oxidation with molecular oxygen catalyzed by VSi2

The catalytic effect of VSi₂ on initial stages of the liquid-phase oxidation of cyclooctene by molecular oxygen was studied. The vanadium disilicide influences on the oxidation process in the presence of hydroperoxide. VSi₂ takes part in a radical formation stage by catalysis of hydroperoxide decomposition reaction. The catalyst was investigated before and after reaction using FTIR spectroscopy. From the data obtained, the kinetic model of the catalytic oxidation process was proposed and the equation for the reaction rate was derived. The equation has described all observed dependences of reaction rate on the concentration of reactants and content of catalyst.      

Flavin catalyzed oxidations of sulfides and amines with molecular oxygen

Novel biomimetic, aerobic oxidation with an organocatalyst was performed. The oxidations of organic substrates such as sulfides, secondary amines, N-hydroxylamines, and tertiary amines with molecular oxygen (1 atm) or even in air in the presence of 5-ethyl-3-methyllumiflavinium perchlorate catalyst and hydrazine monohydrate in 2,2,2-trifluoroethanol occur highly efficiently to give the corresponding oxidized compounds in excellent yields along with water and molecular nitrogen, which are environmentally benign. The TON of the oxidation of sulfides amounts to 19 000.     

Wide control of proton conductivity in porous coordination polymers

The proton conductivities of the porous coordination polymers M(OH)(bdc-R) [H(2)bdc = 1,4-benzenedicarboxylic acid; M = Al, Fe; R = H, NH(2), OH, (COOH)(2)] were investigated under humid conditions. Good correlations among pK(a), proton conductivity, and activation energy were observed. Fe(OH)(bdc-(COOH)(2)), having carboxy group and the lowest pK(a), showed the highest proton conductivity and the lowest activation energy in this system. This is the first example in which proton conductivity has been widely controlled by substitution of ligand functional groups in an isostructural series.     

Hydrosilylation of alkenes catalyzed by Fe powder

A novel iron-catalyzed hydrosilylation of alkenes process under solvent-free conditions has been reported. The influence of the amount of Fe catalyst, reaction temperature and various alkenes and silanes on the hydrosilylation were investigated. High yields of adduct were obtained in the hydrosilylation of octene with MeCl₂H, Me₂ClSiH and Ph₂SiH₂ by using 10?mol% iron powder as a signal catalyst.     

Allylic alkylation of benzoimidazole catalyzed by palladium complexes

Bis(dibenzylidenacetone)palladium is an efficient and highly selective catalyst for the formation ofN-(2,7-dimethylocta-2,7-dienyl)benzoimidazole in the allylation of benzoimidazole withN-(2,7-dimethylocta-2,7-dienyl)-N-methylpiperidinium iodide in the presence of NaH. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 357–360, February, 1999.     

Copper-catalyzed oxidative direct cyclization of N-methylanilines with electron-deficient alkenes using molecular oxygen

The oxidative direct cyclizaion of N-methylanilines with electron-deficient alkenes involving maleimides and benzylidene malononitriles through sp(3) and sp(2) C-H bond cleavage proceeds effectively under a CuCl(2)/O(2) catalysis to provide the corresponding tetrahydroquinolines in good yields.     

Heterogeneous reactions of singlet molecular oxygen with solid polymers

The effect of gas-phase singlet molecular oxygen (¹ΔO₂) upon several solid polymers was investigated by using electron paramagnetic resonance, infrared spectroscopy, and chemical detection techniques. The study was performed by use of ¹ΔO₂ produced by microwave discharge. The application of this method to polymer studies was closely examined. The saturated-chain polymers polystyrene, polyurethane, and polyethylene were found to be inert within the experimental conditions to reaction with ¹ΔO₂, while the unsaturated polymers cis-polybutadiene, trans-polybutadiene, and trans-polyisoprene were found to react quite readily in an apparently surface or near-surface limited reaction to produce hydroperoxide and/or peroxide groups. The introduction by homogeneous mixing of some known metal-chelate ¹ΔO₂ quenchers into the polymer trans-polyisoprene appeared to significantly decrease the rate of oxidation observed.     

Impact of metal-ion dependence on the porous and electronic properties of TCNQ-dianion-based porous coordination polymers

A series of TCNQ-dianion-based porous coordination polymers [M(TCNQ)bpy] (M = Fe, Zn, Mn, Co, Cd) have been synthesized and characterized. The synthesis reactions of these compounds are promoted by the addition of ascorbic acid, which is the key to obtaining a high yield. They form almost identical three-dimensional pillared layer structures with the M-TCNQ two-dimensional layers linked by bpy pillar ligands. The electronic properties of these compounds vary depending on the constitutional metal ions and guest molecules. We found that the electronic interaction between metal ions and TCNQ moieties in the frameworks strongly impacted the electronic properties of the compounds.     

Chelation-assisted hydroesterification of alkenes catalyzed by rhodium complex

[reaction: see text] The hydroesterification of alkenes with 2-pyridylmethanol (1) catalyzed by Rh(4)(CO)(12) is described. The reaction is accelerated by the presence of a pyridine ring in the alcohol 1. The reaction is applicable to various alkenes, both terminal and internal alkenes.