二甲二氧环烷与一些不饱和天然有机化合物反应的选择性

The acetone solution of dimethyldioxirane was prepared with caroate (KHSO5) andacetone.This solution can be kept at low temperature(-20℃) for days. It is much conve-nient to use the oxidant for the epoxidation of carbon carbon double bonds in some unsaturat-ed natural products. Five unsaturated compounds were oxidized to the corresponding epox-ides with dimethyldioxirane and the reaction selectivity was discussed.

二甲二氧环烷的制备和一些碳碳双键的环氧化

通过过一硫酸和丙酮反应,合成了新型高效的氧化剂二甲二氧环烷。其光谱数据和理化性能与文献报道一致,制得的氧化剂应用于一系列天然化合物的碳碳双键环氧化反应,取得较好结果。反应转化率高,副反应很少,产物纯化方便。

二氧环烷及其在有机合成中的应用

介绍了二氧环烷的结构与性质、制备及其在有机合成中的应用。

A New Antioxidant Cyclic Diarylheptanoid from the Rhizomes of Zingiber officinale

The bioassay was directed to the fractionation of the methanol extract of the rhizomes of Zingiber officinale Roscoe leading to the isolation of a new antioxidant cyclic diarylheptanoid. The structure of the new compound was established as 1, 5-epoxy-3-hydroxy-1-(3,4-dihydroxy-5-methoxy-phenyl)-7-(3,4-dihydroxyphenyl) heptane (1) on the basis of MS, 1D and 2D-NMR experiments.

Synthesis and Crystal Structure of t he Complex of Antimony Trichloride and Dioxane

New solid complex of the antimony trichloride and dioxane was obtained th rough a reaction of the dioxane and the absolute methanol solution of the antimony trichloride.The formula of the complex is[SbCl_(3)·{(CH_(2))_(4)O_(2)}_(1.5)].The crystal structure of the comple x belongs to cubic system,space group I-43d,a=17.1417(5)?,Z=16.The trivalent antimony ion not only bonds directly to three chlorine anions,but also is co ordinated by three oxygen atoms of th e dioxane molecules.Two oxygen atoms in a dioxane molecule wi ll coordinate to different antimony ions,respectively.

Clathrate Hydrate Capture of CO2 from Simulated Flue Gas with Cyclopentane/Water Emulsion

Capture of CO2 by hydrate is one of the attractive technologies for reducing greenhouse effect.The primary challenges are the large energy consumption,low hydrate formation rate and separation efficiency.This work presents a new method for capture of CO2 from simulated flue gasCO2(16.60%,by mole) /N2 binary mixture by formation of cyclopentane(CP) hydrates at initial temperature of 8.1°C with the feed pressures from 2.49 to 3.95 MPa.The effect of cyclopentane and cyclopentane/water emulsion on the hydrate formation rate and CO2 separation efficiency was studied in a 1000 ml stirred reactor.The results showed the hydrate formation rate could be increased remarkably with cyclopentane/water emulsion.CO2 could be enriched to 43.97%(by mole) and 35.29%(by mole) from simulated flue gas with cyclopentane and cyclopentane/water(O/W) emulsion,respectively,by one stage hydrate separation under low feed pressure.CO2 separation factor with cyclopentane was 6.18,higher than that with cyclopentane/water emulsion(4.01) ,in the range of the feed pressure.The results demonstrated that cyclopentane/water emulsion is a good additive for efficient hydrate capture of CO2.

Study on Synthesis, Characterization and Catalytic Activity of Polystyrene-supported Mo (VI) Complex in Epoxidation of Cyclohexene

Molybdenum (VI) complex, namely molybdenum dioxobis(2,4-pentanedione) [MoO2(acac)2] used as epoxidation catalyst species, was synthesized and characterized by elemental analysis and infrared spectrum. Polystyrene-supported molybdenum dioxobis(2,4-pentanedione) [MoO2(acac)2] for synthesis of epoxycyclohexane was prepared by phase transfer catalysis method. Effects of various factors in synthesis of epoxycyclohexane by reaction of cyclohexene and t-BuOOH in the atmosphere of nitrogen catalyzed by polystyrene-supported MoO2(acac)2 were also investigated. Under the following conditions, n(cyclohexene):n(t-BuOOH)=3.5:l (based on 0.1 mol of t-BuOOH), volume of solvent -10ml, reaction temperature -80℃, reaction time -60min, and mass of molybdenum in the catalyst -2.30×0^(-3)g, the yield of epoxycyclohexane on the basis of t-BuOOH is over 99.5%, and the purity of epoxycyclohexane is about 99.9% by gas chromatogram(GC) analysis.

Recent advances on controllable and selective catalytic oxidation of cyclohexene

Because of multiple potential reaction sites and variable oxidation depths,oxidation of cyclohexene can lead to a mixture of products with different oxidation states and functional groups,such as 7-oxabicyclo[4.1.0]heptane,trans/cis-cyclohexane-1,2-diol,cyclohex-2-en-1-ol,cyclohex-2-en-1-one,and even adipic acid.These products are broadly and abundantly used intermediates in the chemical industry;therefore,controllable oxidation reactions for cyclohexene that can selectively afford the targeted products are synthetically valuable for applications in both the academy and industry,thus becoming the aim of synthetic and catalytic chemists in the field.Many reports on selective oxidation of cyclohexene have recently appeared in the literature because of its significance.This short review summarizes the recent advances on this subject,and the contents are mainly classified based on the chosen oxidants.We hope that this review can provide a useful guide for controllable and selective catalytic oxidation of cyclohexene for interested readers from both the academy and industry.

Synthesis of propylene glycol ethers from propylene oxide catalyzed by environmentally friendly ionic liquids

A series of acetate ionic liquids were synthesized using a typical two‐step method.The ionic liquids were used as environmentally benign catalysts in the production of propylene glycol ethers from propylene oxide and alcohols under mild conditions.The basic strengths of the ionic liquids were evaluated by determination of their Hammett functions,obtained using ultraviolet‐visible spectroscopy,and the relationship between their catalytic activities and basicities was established.The catalytic efficiencies of the ionic liquids were higher than that of the traditional basic catalyst NaOH.This can be attributed to the involvement of a novel reaction mechanism when these ionic liquids are used.A possible electrophilic‐nucleophilic dual activation mechanism was proposed and confirmed using electrospray ionization quadrupole time‐of‐flight mass spectrometry.In addition,the effects of significant reaction parameters such as concentration of catalyst,molar ratio of alcohol to propylene oxide,reaction temperature,and steric hindrance of the alcohol were investigated in detail.

Degradation of 1,4-Dioxane Using Ozone Oxidation with UV Irradiation （Ozone/UV） Treatment

A method for oxidative degradation of 1,4-dioxane （1,4-D） in waste water using a combination of ozone oxidation with UV irradiation （ozone/UV） treatment was investigated. The results showed that 1,4-D was degraded by ozone/UV treatment up to 90 min. The optimum concentration for the injected ozone gas was about 40 g·m^3 under a constant level of UV irradiation. Furthermore, solid phase extraction and GC-MS analysis showed no specific or reproducible peaks due to by-products of 1,4-D. It was therefore concluded that 1,4-D was completely degraded by ozone/UV treatment. In contrast, the amount of 1,4-D remaining decreased slowly in the presence of HCOf or CI. It was suggested that the degradation of 1,4-D, which results from .OH oxidation, was retarded by the presence of HCO3 or CI, which act as radical scavengers.

Microparticle Formation and Crystallization Rate of HMX with Supercritical CO_2 Antisolvent Recrystallization

Microparticle formation and crystallization rate of 1,3,5,7-tetranitro-l,3,5,7-tetraazacyclooctane (HMX) in acetone solution using supercritical carbon dioxide antisolvent (GAS) recrystallization were studied. Scanning electronic microscopy, X-ray diffraction and infrared radiation were used to examine particle size, crystallinity and chemical structure. The results show that B-HMX microparticle in different average size (2-9.5um) and with narrow size distribution were obtained by controlling the expansibility, expansion speed, initial concentration and temperature during recrystallization of HMX. The formation of nuclei may be a main cause of consumption of solute when the solution is expanded rapidly enough and the equilibrium concentration is lower, in which almost monodisperse microparticle can be obtained.

Synthesis and Structure of a Novel Macrocyclic Ligand( C_(22) H_(29) N_3 O_3 Br_2)

The title compound, 1,12,15 triaza 3,4:9,10 dibenzo 5,8 dioxacyclopentadecane N acetic lactam (C 22 H 29 N 3O 3Br 2, M r =543.29) has been synthesized and characterized by analytical data, IR and 1HNMR spectra. The compound crystallizes in the trigonal system, space group R 3 with a = 35.194(1), c = 10.397(1) , γ=120°, V=11152.6(1) 3, Z=18, D c =1.456 gcm -3 , F(000)=4968, μ =3.3 mm -1 . Mo Kα radiation ( λ = 0.71073), R = 0.0145 for 3094 observed reflections 〔 I>2σ(I )〕 of 3392 independent reflections. The result shows that monofunction reaction for polyaza macrocycle were protonized. 1H NMR spectra of the ligand showed two sets of multiplets due to the two phenyl rings of the ligand in different environments.

Methane Dynamics in Northern Peatlands: A Review

Northern peatlands store a large amount of carbon and play a significant role in the global carbon cycle. Owing to the presence of waterlogged and anaerobic conditions, peatlands are typically a source of methane (CH4), a very potent greenhouse gas. This paper reviews the key mechanisms of peatland CH4 production, consumption and transport and the major environmental and biotic controls on peatland CH4 emissions. The advantages and disadvantages of micrometeorological and chamber methods in measuring CH4 fluxes from northern peatlands are also discussed. The magnitude of CH4 flux varies considerably among peatland types (bogs and fens) and microtopographic locations (hummocks and hollows). Some anthropogenic activities including forestry, peat harvesting and industrial emission of sulphur dioxide can cause a reduction in CH4 release from northern peatlands. Further research should be conducted to investigate the in fluence of plant growth forms on CH4 flux from northern peatlands, determine the water table threshold at which plant production in peatlands enhances CH4 release, and quantify peatland CH4 exchange at plant community level with a higher temporal resolution using automatic chambers.

Measurement and Correlation of Vapor-Liquid Equilibrium of the 1,2-Epoxycyclohexane-Cyclohexanone Binary System at 101.3kPa

Many by-products are generated in the process of oxidizing cyclohexene to produce 1,2-epoxycyclohexane by hydrogen peroxide, including cyclohexanol, cyclohexanone, etc. To obtain high-purity 1,2-epoxycyclohexane, the by-products must be removed through rectification. Refining 1,2-epoxycyclohexane through rectification requires vapor-liquid equilibrium(VLE) data of the related system. Therefore, the VLE data of 1,2-epoxycyclohexane- cyc-lohexanone system were measured at 101.3 kPa using an improved EC-2 VLE still. The thermodynamic consistency of the data was then tested by Herington's method and the rigorous point-to-point method. The results obtained were exemplary. The VLE data were correlated by the Wilson and non-random two-liquid(NRTL) equations, using the error sum squares of the vapor composition as the objective function to obtain the model parameters. The difference between the calculated values and the experimental data is minor, indicating that the VLE data are suitable for engineering design.

Measurement and Correlation of Vapor-Liquid Equilibrium for a Cyclohexene-Cyclohexanol Binary System at 101.3 kPa

Many by-products are generated in the process of oxidizing cyclohexene to produce 1,2-epoxycyclohexane by hydrogen peroxide,including cyclohexanol,cyclohexanone,etc.To obtain high-purity 1,2-epoxycyclohexane, the by-products and unreacted cyclohexene must be removed through rectification,in which the vapor-liquid equilibrium(VLE)data of the system are needed.In this study,the VLE data of cyclohexene-cyclohexanol system were studied at 101.3 kPa using an improved EC-2 VLE still.The thermodynamic consistency of the data was examined by Herington's method.The results obtained were exemplary.The VLE data were correlated by the Wilson equation. The difference between the calculated values and the experimental data is minor,indicating that the VLE data are suitable for engineering design.

Measurement and Correlation of Vapor-Liquid Equilibrium for Binary System 1,2-Epoxycyclohexane ＋ 1,2-Dlchloroethane

Vapor-liquid equilibrium data (T, x, y) of binary system 1,2-epoxycyclohexane + 1,2-dichloroethane were determined experimentally by using a modified ROSE-Williams equilibrium vaporization system at 101.33 kPa. The results show that this binary system does not have azeotropic point. The vapor-liquid equilibrium data are in thermodynamic consistency. The binary interaction parameters in the Wilson equation are presented with the correlation of vapor-liquid equilibrium data. The measurements of liquid phase composition and bubble point temperature are well represented by the Wilson equation. Values of vapor molecular fractions and activity coefficients from the Wilson equation are presented. This work provides important engineering data for the separation of 1,2-dichloroethane and 1,2-epoxycyclohexane .

Studies on Selena-Macrocyclic Amides Synthesis and Structural Characterization of 7-Phenyl-5, 9-dioxo-1-selena-4, 7, 10-triazacyclododecane and 6-(4-Nitrobenzyl )-5, 9-dioxo-1, 4, 7, 10-selenatriazacyclododecane

7-Phenyl-5, 9-dioxo-1-selena-4, 7, 10-triazacyclododecane (1) and 6-(4-Nitrobenzyl)-5, 9-dioxo-1, 4, 7, 10-selenatriazacycloedecane (2) were synthesizedby condensation of bis (2-aminoethyl) selenide and corresponding diethyl esters. Theircrystal structures were determined. Crystal data: C14H19N3O2Se (1), Mr= 340. 28,space group P212121, a=5. 328(5), b= 14. 043(5), c= 18. 569(5) A, V= 1403(1)A3, Z= 4, Dc = 1. 610 g/cm3, μ= 3. 676 mm-1, F(000) = 696, T= 296K, R=0. 0269 for 1577 observed data. C15 H20 N4O4Se (2), Mr = 399. 31, space groupP212121, a=13. 849(5), b=4. 936(5), c=24. 942(5) A, V= 1705(1) A s, Z=4,Dc= 1. 566g/cm3, μ= 3. 230 mm-1 F(000) =816, T= 296K, R=0. 0856 for 3442observed data.

Hot water as a mild Brφnsted acid catalyst in ring opening reactions of epoxides

Ring opening of extremely hydrophobic epoxides with water, amines, sodium azide and thiophenol was realized in the mixture solvent of water and 1, 4-dioxane under reflux condition. Hot water was believed to act as a mild Bronsted acid catalyst in the epoxide-opening reactions.

Cloning and characterization of an oxiranedicarboxylate hydrolase from Labrys sp. WH-1

Objective:This study aimed to clone and characterize the oxiranedicarboxylate hydrolase(ORCH) from Labrys sp.WH-1.Methods:Purification by column chromatography,characterization of enzymatic properties,gene cloning by protein terminal sequencing and polymerase chain reaction(PCR),and sequence analysis by secondary structure prediction and multiple sequence alignment were performed.Results:The ORCH from Labrys sp.WH-1 was purified 26-fold with a yield of 12.7%.It is a monomer with an isoelectric point(pl) of 8.57 and molecular mass of 30.2 kDa.It was stable up to 55℃with temperature at which the activity of the enzyme decreased by 50% in 15 min(T5015) of 61℃and the half-life at 50℃(t1/2,50℃) of 51 min and was also stable from pH 4 to 10,with maximum activity at 55℃and pH 8.5.It is a metal-independent enzyme and strongly inhibited by Cu2+,Ag+,and anionic surfactants.Its kinetic parameters(Km,kcat,and kcat/Km) were 18.7 mmol/L,222.3 s-1,and 11.9 mmol/(L s),respectively.The ORCH gene,which contained an open reading frame(ORF) of 825 bp encoding 274 amino acid residues,was overexpressed in Escherichia coli and the enzyme activity was 33 times higher than that of the wild strain.Conclusions The catalytic efficiency and thermal stability of the ORCH from Labrys sp.WH-1 were the best among the reported ORCHs,and it provides an alternative catalyst for preparation of L(+)-2,3-dihydrobutanedioic acid.