In searching for effective anticonvulsant agents,fourteen 6-aryl-4.5-di- hydro-3(2H)pyridazinones.fifteen 6-aryl-3(2H)pyridazinones,and seventeen 3-GABA derivatives of 6-aryIpyridazines have been synthesized,and evalu...In searching for effective anticonvulsant agents,fourteen 6-aryl-4.5-di- hydro-3(2H)pyridazinones.fifteen 6-aryl-3(2H)pyridazinones,and seventeen 3-GABA derivatives of 6-aryIpyridazines have been synthesized,and evaluated in mice for the ability to antagonize maximal electroshock seizure(MES).The ED_(50) values showed that 6-(2′,4′- dichlorophenyt)-3(2H)pyridazinone was the most potent anticonvulsant among these corn- pounds(ED_(50)=10.15 mg/kg).The structure-activity relationships of the aryl pyridazinones were studied.The result showed that:(1)the higher the value of the hydrophobic parameter л of the substituent on the phenyl ring.the more potent the anticonvulsant activity of the corn- pound.and(2)only the compounds with an electron withdrawing substituent on the phenyl ring exhibited appreciable anticonvulsant activity.展开更多
An efficient Cu catalyzed selective arylation/annulation cascade reaction of 2-alkynylanilines with diaryliodonium salts was developed.This reaction was selective to N-arylation instead of C-arylation,which provides a...An efficient Cu catalyzed selective arylation/annulation cascade reaction of 2-alkynylanilines with diaryliodonium salts was developed.This reaction was selective to N-arylation instead of C-arylation,which provides a simple synthetic method for N-aryl indoles.展开更多
Lubricating mineral base oils are normally extracted from lube-oil cuts with furfural solvent.Aromatic content in the raffinate phase from extraction process is an essential parameter that affects the quality of the l...Lubricating mineral base oils are normally extracted from lube-oil cuts with furfural solvent.Aromatic content in the raffinate phase from extraction process is an essential parameter that affects the quality of the lubricating base-oils.For determination of aromatic content by the usual ASTM D3238 method,density,refractive index and molecular weight of the raffinate are required.In this work,a new generalized correlation is developed for de-termination the aromatic content by using only the measured viscosity of lubricating oil.With a mole fraction of aromatic compounds,the kinematic viscosity may be obtained at any temperature between 60-100°C along with their molecular weight and refractive index.展开更多
Objective:The coal-fired pollution in Xuanwei area has been considered to be local main reason for high incidence of female lung cancers.The aim of the study was to investigate the expression of PAH-DNA adducts in lun...Objective:The coal-fired pollution in Xuanwei area has been considered to be local main reason for high incidence of female lung cancers.The aim of the study was to investigate the expression of PAH-DNA adducts in lung tissues of Xuanwei female lung cancer patients, and to explore the relationship between the large number of coal-fired pollution PAHs materials and the high incidence of Xuanwei female lung cancers.Methods:We totally collected each 20 cases of Xuanwei female lung cancer patients, Xuanwei male lung cancer patients, non-Xuanwei female lung cancer patients and collected each 10 cases of Xuanwei, non-Xuanwei female patients with benign lung lesions.The cancer tissues, adjacent cancer tissues and normal lung tissues were collected in lung cancer patients and only the normal tissues were collected in benign lung lesion patients.There were total 80 cases and 200 tissues.Using immunofluorescence, we detected the expression of PAH-DNA adducts in each group.Image pro-plus 6.0 software was used to analyze the images and did part quantified analysis.SPSS 13.0 statistical software was used to analyze the data.Results:The positive expressions of PAH-DNA adducts in lung cancer tissues, adjacent cancer tissues and normal lung tissues of Xuanwei female lung cancer patients were 90%, 80% and 65%, respectively.They were higher than the positive expressions of PAH-DNA adducts in Xuanwei male lung cancer patients (35%, 30% and 30%) and non-Xuanwei female lung cancer patients (20%, 15% and 10%; P<0.01).The expression of PAH-DNA adducts in lung tissues of Xuanwei female benign lung lesion patients (70%) was higher than that in non-Xuanwei female benign lung lesion patients (10%).With the direction changing from cancer tissues, adjacent cancer tissues to normal lung tissues, the expression of PAH-DNA adducts was decreased but had no statistical difference (P>0.05).Conclusion:The expression of PAH-DNA adducts in lung tissues of Xuanwei females was higher than that in Xuanwei males and non-Xuanwei females.展开更多
Separation and analysis of aromatic hydrocarbons (AHs) from coals is of considerable significance for both fuel and non-fuel use of the coals. In present work two Chinese bituminous coals were selected for separation ...Separation and analysis of aromatic hydrocarbons (AHs) from coals is of considerable significance for both fuel and non-fuel use of the coals. In present work two Chinese bituminous coals were selected for separation of AHs by ultrasonic extrac-tion with CS2 followed by column chromatography using hexane as eluent. A series of AHs were separated from the two coals and analyzed by GC/MS. FTIR was employed to characterize the raw coals and the extracted residues. The results of GC/MS analysis show that the separated AHs are mono- to tetracyclic arenes, among which the principle AHs are alkyl naphthalenes and phenan-threnes. Obvious differences in the composition and the structure of AHs exist between the two coals, i.e., the AHs from Tongting coal tend to be higher rings compared to those from Pingshuo coal both from the variety and from the abundance of the AHs. FTIR analysis shows that the raw and extracted coals are similar in terms of functional groups, suggesting that the composition and structure of CS2 extract, especially the AHs, from coals can be used to interpret the coal structure to some extent.展开更多
Organoboron compounds are widely used in synthetic chemistry,pharmaceutical chemistry and material chemistry.Among various organoboron compounds,benzylboronic esters are unique and highly reactive,making them suitable...Organoboron compounds are widely used in synthetic chemistry,pharmaceutical chemistry and material chemistry.Among various organoboron compounds,benzylboronic esters are unique and highly reactive,making them suitable benzylation reagents.At present,the synthetic methods for the syntheses of benzylboronic esters are still insufficient to meet their demands.It is necessary to develop novel and practical methods for their preparation.In this work,a novel copper‐catalyzed deoxygenative gem‐hydroborylation of aromatic aldehydes and ketones has been developed.This direct and operationally simple protocol provides an effective approach for the synthesis of a variety of primary and secondary benzylboronates,in which broad functional group tolerance was presented.Widely available B2pin2(pin=pinacol)was used as the boron source and alcoholic proton was applied as the hydride source.展开更多
A Cu2O/SiC heterogeneous catalyst was prepared via a two‐step liquid‐phase method using diethyleneglycol as both the solvent and the reducing agent.The catalyst was characterized using X‐raydiffraction,X‐ray photo...A Cu2O/SiC heterogeneous catalyst was prepared via a two‐step liquid‐phase method using diethyleneglycol as both the solvent and the reducing agent.The catalyst was characterized using X‐raydiffraction,X‐ray photoelectron spectroscopy,scanning electron microscopy(SEM),transmissionelectron microscopy(TEM),and H2temperature‐programmed reduction.All the results indicatethat Cu is present on the SiC support primarily as Cu2O.The SEM and TEM results show that cubicCu2O nanoparticles are uniformly dispersed on theβ‐SiC surface.The reaction conditions,namelythe temperature,reaction time,and amounts of base and catalyst used,for the Ullmann‐type C–Ocross‐coupling reaction were optimized.A model reaction was performed using iodobenzene(14.0mmol)and phenol(14.0mmol)with Cu2O/SiC(5wt%Cu)as the catalyst,Cs2CO3(1.0equiv.)as thebase,and tetrahydrofuran as the solvent at150°C for3h;a yield of97%was obtained and theturnover frequency(TOF)was1136h?1.The Cu2O/SiC catalyst has a broad substrate scope and canbe used in Ullmann‐type C–O cross‐coupling reactions of aryl halides and phenols bearing a varietyof different substituents.The catalyst also showed high activity in the Ullmann‐type C–Scross‐coupling of thiophenol with iodobenzene and substituted iodobenzenes;a TOF of1186h?1was achieved.The recyclability of the Cu2O/SiC catalyst in the O‐arylation of phenol with iodobenzenewas investigated under the optimum conditions.The yield decreased from97%to64%afterfive cycles.The main reason for the decrease in the catalyst activity is loss of the active component,i.e.,Cu2O.展开更多
The solvent-free reactions of aromatic ketones and aldehydes in the presence of Zn-ZnCl2 were performed with the aid of high-speed vibration mill, Retsch MM200 mixer mill and Retsch RM100 mortar grinder to give pinaco...The solvent-free reactions of aromatic ketones and aldehydes in the presence of Zn-ZnCl2 were performed with the aid of high-speed vibration mill, Retsch MM200 mixer mill and Retsch RM100 mortar grinder to give pinacol coupling and reduction products in varying yields.展开更多
Coal seam pyrolysis occurs during coal seam fires and during underground coal gasification. This is an important source of polycyclic aromatic hydrocarbon (PAH) emission in China. Pyrolysis in a coal seam was simula...Coal seam pyrolysis occurs during coal seam fires and during underground coal gasification. This is an important source of polycyclic aromatic hydrocarbon (PAH) emission in China. Pyrolysis in a coal seam was simulated in a tubular furnace. The 16 US Environmental Protection Agency priority controlled PAHs were analyzed by HPLC. The effects of temperature, heating rate, pyrolysis atmosphere, and coal size were investigated. The results indicate that the 3-ring PAHs AcP and AcPy are the main species in the pyrolysis gas. The 2-ring NaP and the 4-ring Pyr are also of concern. Increasing temperature caused the total PAH yield to go through a minimum. The lowest value was obtained at the temperature of 600℃. Higher heating rates promote PAH formation, especially formation of the lower molecular weight PAHs. The typical heating rate in a coal seam, 5 ℃/min, results in intermediate yields of PAHs. The total PAHs yield in an atmosphere of N2 is about 1.81 times that seen without added N2, which indicates that an air flow through the coal seam accelerates the formation of PAHs. An increase in coal particle size reduces the total PAHs emission but promotes the formation of 5- and f-ring PAHs.展开更多
Although many aroma components have been identified in green tea leaves, the aroma compounds contributing to green tea's characteristic odor have not yet been reported. The authors recently reported that aroma compon...Although many aroma components have been identified in green tea leaves, the aroma compounds contributing to green tea's characteristic odor have not yet been reported. The authors recently reported that aroma components with a matcha-like odor are present in both green tea and black tea prepared from the Sayamakaori tea cuttivar. This matcha-like odor is similar to the odor of commercial available matcha (high-quality powdered green tea), and is a specific odor feature of green tea leaves. At present, the green-tea odor is thought to arise from the combination of a large number of constituents. Recent reports indicate that a complex interaction between olfactory receptors and odorants is important for the evaluation of the odors. Taking into consideration these findings, the authors investigated the aroma profile of green tea, focusing on the characteristic molecular structures of the constituents that give matcha-like odor. Using a combination of organic synthesis and gas chromatography-mass spectrometry plus gas chromatography-olfactometry, the authors identified aroma components with matcha-like odors in five other tea cultivars. This investigation also revealed that several compounds with a formyl group were important constituents of the aroma of green tea leaves, although the odor of each constituent was not individually similar to the tea's overall aroma. The authors found for the first time a group of key components that have the matcha-like odor.展开更多
The present study was used freshwater Crab (Sesarma boulengeri Caiman) as bioindicator to measured the PAHs levels in AI-Hilla River, Iraq, during the period from March 2010 to February 2011. Crab samples were colle...The present study was used freshwater Crab (Sesarma boulengeri Caiman) as bioindicator to measured the PAHs levels in AI-Hilla River, Iraq, during the period from March 2010 to February 2011. Crab samples were collected from two sites on the AI-Hilla River. Sixteen of PAils compounds were identified seasonally in these samples. High mean value was (72.06 μg/g), recorded by Dibenzo (a, h) anthracene (DbA) in Site 1 and low mean value was (0.36 μg/g) recorded by Anthracene (Ant) in Site 2. The study showed a clear variation in PAHs concentration independent from the seasons and locations. Site 1 recorded high value of HMW (high molecular weight) and LMW (low molecular weight) more than Site 2. The present study revealed that all PAHs compounds were from Pyrogenic Origin. Seven carcinogenic PAHs (cPAHs) were recorded in crab tissues that were collected from the AI-Hilla River. The TEF (toxicity equivalency factor) was calculated to toxicity equivalent crab concentration. From the results, the fresh water Crab Sesarma boulengeri is a good bioindicator to water pollution by PAHs.展开更多
Dearomative carboxylation of aromatic compounds with carbon dioxide(CO_(2))could be utilized for the synthesis of cyclic carboxylative frameworks.The dearomative carboxylation exhibits advantages such as reconstitutio...Dearomative carboxylation of aromatic compounds with carbon dioxide(CO_(2))could be utilized for the synthesis of cyclic carboxylative frameworks.The dearomative carboxylation exhibits advantages such as reconstitution molecular spatial structure,environmental friendliness,mild conditions,high yield,and high selectivity,and is of significant importance in pharmaceutical synthesis and natural product chemistry.The recent advancements in the dearomative carboxylation of aromatics with CO_(2) are summarized,including elucidation of the reaction characteristics and the scope of substrates via transition-metal catalysis,photoredox catalysis,and electropromoted chemistry.展开更多
Aromatic hydrocarbons are generally main distillation of crude oil and organic extract of source rocks. Bicyclic and tricyclic aromatic hydrocarbons can be purified by two-step method of chromatography on alumina. Car...Aromatic hydrocarbons are generally main distillation of crude oil and organic extract of source rocks. Bicyclic and tricyclic aromatic hydrocarbons can be purified by two-step method of chromatography on alumina. Carbon isotopic composition of in- dividual aromatic hydrocarbons is affected not only by thermal maturity, but also by organic matter input, depositional envi- ronment, and hydrocarbon generation process based on the GC-IRMS analysis of Upper Ordovician, Lower Ordovician, and Cambrian source rocks in different areas in the Tarim Basin, western China. The subgroups of aromatic hydrocarbons as well as individual aromatic compound, such as 1-MP, 9-MP, and 2,6-DMP from Cambrian-Lower Ordovician section show more depleted 13C distribution. The δ13C value difference between Cambrian-Lower Ordovician section and Upper Ordovician source rocks is up to 16.1%o for subgroups and 14%o for individual compounds. It can provide strong evidence for oil source correlation by combing the δ13C value and biomarker distribution of different oil and source rocks from different strata in the Tarim Basin. Most oils from Tazhong area have geochemical characteristics such as more negative δI3Cg_Mp value, poor gam macerane, and abundant homohopanes, which indicate that Upper Ordovician source rock is the main source rock. In contrast, oils from Tadong area and some oils from Tazhong area have geochemical characteristics such as high 613C9-MP, value, abun dant gammacerane, and poor homohopanes, which suggest that the major contributor is Cambrian-Lower Ordovician source rock.展开更多
Synthesis of organosilanes from alkenes is a very important topic owing to their wide applications.A Ni/Cu dual metal-catalyzed arylsilylation of terminal alkenes,featuring migratory selectivity,has been developed.A w...Synthesis of organosilanes from alkenes is a very important topic owing to their wide applications.A Ni/Cu dual metal-catalyzed arylsilylation of terminal alkenes,featuring migratory selectivity,has been developed.A wide diversity of aliphatic silanes have been prepared from terminal alkenes,aryl halides and Suginome’s reagent.This protocol is highlighted by excellent regioselectivity,mild reaction conditions and good functional group tolerance.In addition to benzylic positions,carbon–carbon bonds can also be constructed at allylic positions.Preliminary mechanistic studies suggest that the copper cocatalyst promotes the transmetalation of Suginome’s reagent,and the addition of a Pyr Ox ligand inhibits the formation of side-products from the carbon-Heck pathway.Moreover,studies toward the nature of the Pyr Ox ligand revealed that the steric hindrance of the oxazoline moiety greatly affects the chain–walking process,but not the arylation step.展开更多
An efficient approach for the synthesis of N-arylated amides was developed via copper(Ⅱ) triflate-catalyzed direct oxidation of(aryl)methylamines to primary arylamides by air and subsequent N-arylation by diaryliodon...An efficient approach for the synthesis of N-arylated amides was developed via copper(Ⅱ) triflate-catalyzed direct oxidation of(aryl)methylamines to primary arylamides by air and subsequent N-arylation by diaryliodonium salts. Various substituted benzylamines could be applied in the reaction, providing a series of N-arylated amides in moderate to good yields. This method showed convenient, practical, and environment friendly advantages.展开更多
A domino [4+2]/retro [4+2] cycloaddition process of cyclohexadienes with arylethynes or benzyne providing access to biaryls and polycyclic aromatics has been studied theoretically using density functional theory calcu...A domino [4+2]/retro [4+2] cycloaddition process of cyclohexadienes with arylethynes or benzyne providing access to biaryls and polycyclic aromatics has been studied theoretically using density functional theory calculations. It has been found that the initial Diels-Alder (D-A) reaction acts as the rate-determining step and the consequent [4+2] cycloreversion reaction is feasible under the conditions used. Furthermore, the D-A reaction affects the regioselectivity, the origin of which is essentially derived from the good match of orbital coefficients between dienes and dienophiles as shown by using frontier molecular orbital (FMO) theory. Further investigation of the reactivity reveals that the reactions are predicted to fail to occur if an electron-donor group in the diene or an electron-acceptor group in the dienophile is lacking, as a consequence of the increased FMO energy gap. By further exploring the scope of substrates computationally, benzyne as an active dienophile was predicted to react with a variety of dienes in a cascade reaction under mild conditions with a low energy barrier, with the rate-determining step being the retro [4+2] cycloaddition.展开更多
文摘In searching for effective anticonvulsant agents,fourteen 6-aryl-4.5-di- hydro-3(2H)pyridazinones.fifteen 6-aryl-3(2H)pyridazinones,and seventeen 3-GABA derivatives of 6-aryIpyridazines have been synthesized,and evaluated in mice for the ability to antagonize maximal electroshock seizure(MES).The ED_(50) values showed that 6-(2′,4′- dichlorophenyt)-3(2H)pyridazinone was the most potent anticonvulsant among these corn- pounds(ED_(50)=10.15 mg/kg).The structure-activity relationships of the aryl pyridazinones were studied.The result showed that:(1)the higher the value of the hydrophobic parameter л of the substituent on the phenyl ring.the more potent the anticonvulsant activity of the corn- pound.and(2)only the compounds with an electron withdrawing substituent on the phenyl ring exhibited appreciable anticonvulsant activity.
基金supported by the Intercollegiate Key Scientific Research Projects of Henan Province(15A150018)~~
文摘An efficient Cu catalyzed selective arylation/annulation cascade reaction of 2-alkynylanilines with diaryliodonium salts was developed.This reaction was selective to N-arylation instead of C-arylation,which provides a simple synthetic method for N-aryl indoles.
文摘Lubricating mineral base oils are normally extracted from lube-oil cuts with furfural solvent.Aromatic content in the raffinate phase from extraction process is an essential parameter that affects the quality of the lubricating base-oils.For determination of aromatic content by the usual ASTM D3238 method,density,refractive index and molecular weight of the raffinate are required.In this work,a new generalized correlation is developed for de-termination the aromatic content by using only the measured viscosity of lubricating oil.With a mole fraction of aromatic compounds,the kinematic viscosity may be obtained at any temperature between 60-100°C along with their molecular weight and refractive index.
基金Supported by grants from Yunnan Province Science and Technology Foundation (No.2007C009Z)Yunnan Province Science and Technology International Cooperation Foundation (No.2008CA030)
文摘Objective:The coal-fired pollution in Xuanwei area has been considered to be local main reason for high incidence of female lung cancers.The aim of the study was to investigate the expression of PAH-DNA adducts in lung tissues of Xuanwei female lung cancer patients, and to explore the relationship between the large number of coal-fired pollution PAHs materials and the high incidence of Xuanwei female lung cancers.Methods:We totally collected each 20 cases of Xuanwei female lung cancer patients, Xuanwei male lung cancer patients, non-Xuanwei female lung cancer patients and collected each 10 cases of Xuanwei, non-Xuanwei female patients with benign lung lesions.The cancer tissues, adjacent cancer tissues and normal lung tissues were collected in lung cancer patients and only the normal tissues were collected in benign lung lesion patients.There were total 80 cases and 200 tissues.Using immunofluorescence, we detected the expression of PAH-DNA adducts in each group.Image pro-plus 6.0 software was used to analyze the images and did part quantified analysis.SPSS 13.0 statistical software was used to analyze the data.Results:The positive expressions of PAH-DNA adducts in lung cancer tissues, adjacent cancer tissues and normal lung tissues of Xuanwei female lung cancer patients were 90%, 80% and 65%, respectively.They were higher than the positive expressions of PAH-DNA adducts in Xuanwei male lung cancer patients (35%, 30% and 30%) and non-Xuanwei female lung cancer patients (20%, 15% and 10%; P<0.01).The expression of PAH-DNA adducts in lung tissues of Xuanwei female benign lung lesion patients (70%) was higher than that in non-Xuanwei female benign lung lesion patients (10%).With the direction changing from cancer tissues, adjacent cancer tissues to normal lung tissues, the expression of PAH-DNA adducts was decreased but had no statistical difference (P>0.05).Conclusion:The expression of PAH-DNA adducts in lung tissues of Xuanwei females was higher than that in Xuanwei males and non-Xuanwei females.
基金Projects 90410018 and 20676142 supported by the National Natural Science Foundation of China2004CB217601 by the Special Fund for Major State Basic ResearchJHB05-33 by the Program of the Universities in Jiangsu Province for the Development of High-Tech Industries
文摘Separation and analysis of aromatic hydrocarbons (AHs) from coals is of considerable significance for both fuel and non-fuel use of the coals. In present work two Chinese bituminous coals were selected for separation of AHs by ultrasonic extrac-tion with CS2 followed by column chromatography using hexane as eluent. A series of AHs were separated from the two coals and analyzed by GC/MS. FTIR was employed to characterize the raw coals and the extracted residues. The results of GC/MS analysis show that the separated AHs are mono- to tetracyclic arenes, among which the principle AHs are alkyl naphthalenes and phenan-threnes. Obvious differences in the composition and the structure of AHs exist between the two coals, i.e., the AHs from Tongting coal tend to be higher rings compared to those from Pingshuo coal both from the variety and from the abundance of the AHs. FTIR analysis shows that the raw and extracted coals are similar in terms of functional groups, suggesting that the composition and structure of CS2 extract, especially the AHs, from coals can be used to interpret the coal structure to some extent.
文摘Organoboron compounds are widely used in synthetic chemistry,pharmaceutical chemistry and material chemistry.Among various organoboron compounds,benzylboronic esters are unique and highly reactive,making them suitable benzylation reagents.At present,the synthetic methods for the syntheses of benzylboronic esters are still insufficient to meet their demands.It is necessary to develop novel and practical methods for their preparation.In this work,a novel copper‐catalyzed deoxygenative gem‐hydroborylation of aromatic aldehydes and ketones has been developed.This direct and operationally simple protocol provides an effective approach for the synthesis of a variety of primary and secondary benzylboronates,in which broad functional group tolerance was presented.Widely available B2pin2(pin=pinacol)was used as the boron source and alcoholic proton was applied as the hydride source.
基金supported by the National Natural Science Foundation of China (21203233,21473232,21403270)Youth Innovation Promotion Association,CAS (2013115)~~
文摘A Cu2O/SiC heterogeneous catalyst was prepared via a two‐step liquid‐phase method using diethyleneglycol as both the solvent and the reducing agent.The catalyst was characterized using X‐raydiffraction,X‐ray photoelectron spectroscopy,scanning electron microscopy(SEM),transmissionelectron microscopy(TEM),and H2temperature‐programmed reduction.All the results indicatethat Cu is present on the SiC support primarily as Cu2O.The SEM and TEM results show that cubicCu2O nanoparticles are uniformly dispersed on theβ‐SiC surface.The reaction conditions,namelythe temperature,reaction time,and amounts of base and catalyst used,for the Ullmann‐type C–Ocross‐coupling reaction were optimized.A model reaction was performed using iodobenzene(14.0mmol)and phenol(14.0mmol)with Cu2O/SiC(5wt%Cu)as the catalyst,Cs2CO3(1.0equiv.)as thebase,and tetrahydrofuran as the solvent at150°C for3h;a yield of97%was obtained and theturnover frequency(TOF)was1136h?1.The Cu2O/SiC catalyst has a broad substrate scope and canbe used in Ullmann‐type C–O cross‐coupling reactions of aryl halides and phenols bearing a varietyof different substituents.The catalyst also showed high activity in the Ullmann‐type C–Scross‐coupling of thiophenol with iodobenzene and substituted iodobenzenes;a TOF of1186h?1was achieved.The recyclability of the Cu2O/SiC catalyst in the O‐arylation of phenol with iodobenzenewas investigated under the optimum conditions.The yield decreased from97%to64%afterfive cycles.The main reason for the decrease in the catalyst activity is loss of the active component,i.e.,Cu2O.
文摘The solvent-free reactions of aromatic ketones and aldehydes in the presence of Zn-ZnCl2 were performed with the aid of high-speed vibration mill, Retsch MM200 mixer mill and Retsch RM100 mortar grinder to give pinacol coupling and reduction products in varying yields.
基金provided by the National Natural Science Foundation of China (No. 50876112)the Fundamental Research Funds for the Central Universities (No. 2009QH13)the International Scientific and Technological Cooperation Project(No. 2010DFR60610)
文摘Coal seam pyrolysis occurs during coal seam fires and during underground coal gasification. This is an important source of polycyclic aromatic hydrocarbon (PAH) emission in China. Pyrolysis in a coal seam was simulated in a tubular furnace. The 16 US Environmental Protection Agency priority controlled PAHs were analyzed by HPLC. The effects of temperature, heating rate, pyrolysis atmosphere, and coal size were investigated. The results indicate that the 3-ring PAHs AcP and AcPy are the main species in the pyrolysis gas. The 2-ring NaP and the 4-ring Pyr are also of concern. Increasing temperature caused the total PAH yield to go through a minimum. The lowest value was obtained at the temperature of 600℃. Higher heating rates promote PAH formation, especially formation of the lower molecular weight PAHs. The typical heating rate in a coal seam, 5 ℃/min, results in intermediate yields of PAHs. The total PAHs yield in an atmosphere of N2 is about 1.81 times that seen without added N2, which indicates that an air flow through the coal seam accelerates the formation of PAHs. An increase in coal particle size reduces the total PAHs emission but promotes the formation of 5- and f-ring PAHs.
文摘Although many aroma components have been identified in green tea leaves, the aroma compounds contributing to green tea's characteristic odor have not yet been reported. The authors recently reported that aroma components with a matcha-like odor are present in both green tea and black tea prepared from the Sayamakaori tea cuttivar. This matcha-like odor is similar to the odor of commercial available matcha (high-quality powdered green tea), and is a specific odor feature of green tea leaves. At present, the green-tea odor is thought to arise from the combination of a large number of constituents. Recent reports indicate that a complex interaction between olfactory receptors and odorants is important for the evaluation of the odors. Taking into consideration these findings, the authors investigated the aroma profile of green tea, focusing on the characteristic molecular structures of the constituents that give matcha-like odor. Using a combination of organic synthesis and gas chromatography-mass spectrometry plus gas chromatography-olfactometry, the authors identified aroma components with matcha-like odors in five other tea cultivars. This investigation also revealed that several compounds with a formyl group were important constituents of the aroma of green tea leaves, although the odor of each constituent was not individually similar to the tea's overall aroma. The authors found for the first time a group of key components that have the matcha-like odor.
文摘The present study was used freshwater Crab (Sesarma boulengeri Caiman) as bioindicator to measured the PAHs levels in AI-Hilla River, Iraq, during the period from March 2010 to February 2011. Crab samples were collected from two sites on the AI-Hilla River. Sixteen of PAils compounds were identified seasonally in these samples. High mean value was (72.06 μg/g), recorded by Dibenzo (a, h) anthracene (DbA) in Site 1 and low mean value was (0.36 μg/g) recorded by Anthracene (Ant) in Site 2. The study showed a clear variation in PAHs concentration independent from the seasons and locations. Site 1 recorded high value of HMW (high molecular weight) and LMW (low molecular weight) more than Site 2. The present study revealed that all PAHs compounds were from Pyrogenic Origin. Seven carcinogenic PAHs (cPAHs) were recorded in crab tissues that were collected from the AI-Hilla River. The TEF (toxicity equivalency factor) was calculated to toxicity equivalent crab concentration. From the results, the fresh water Crab Sesarma boulengeri is a good bioindicator to water pollution by PAHs.
文摘Dearomative carboxylation of aromatic compounds with carbon dioxide(CO_(2))could be utilized for the synthesis of cyclic carboxylative frameworks.The dearomative carboxylation exhibits advantages such as reconstitution molecular spatial structure,environmental friendliness,mild conditions,high yield,and high selectivity,and is of significant importance in pharmaceutical synthesis and natural product chemistry.The recent advancements in the dearomative carboxylation of aromatics with CO_(2) are summarized,including elucidation of the reaction characteristics and the scope of substrates via transition-metal catalysis,photoredox catalysis,and electropromoted chemistry.
基金supported by National Natural Science Foundation of China(Grant No.40973041)College Fund for the Doctoral Project(Grant No.20104220110001)Natural Science Foundation of Hubei Province(Grant No.2009CDB205)
文摘Aromatic hydrocarbons are generally main distillation of crude oil and organic extract of source rocks. Bicyclic and tricyclic aromatic hydrocarbons can be purified by two-step method of chromatography on alumina. Carbon isotopic composition of in- dividual aromatic hydrocarbons is affected not only by thermal maturity, but also by organic matter input, depositional envi- ronment, and hydrocarbon generation process based on the GC-IRMS analysis of Upper Ordovician, Lower Ordovician, and Cambrian source rocks in different areas in the Tarim Basin, western China. The subgroups of aromatic hydrocarbons as well as individual aromatic compound, such as 1-MP, 9-MP, and 2,6-DMP from Cambrian-Lower Ordovician section show more depleted 13C distribution. The δ13C value difference between Cambrian-Lower Ordovician section and Upper Ordovician source rocks is up to 16.1%o for subgroups and 14%o for individual compounds. It can provide strong evidence for oil source correlation by combing the δ13C value and biomarker distribution of different oil and source rocks from different strata in the Tarim Basin. Most oils from Tazhong area have geochemical characteristics such as more negative δI3Cg_Mp value, poor gam macerane, and abundant homohopanes, which indicate that Upper Ordovician source rock is the main source rock. In contrast, oils from Tadong area and some oils from Tazhong area have geochemical characteristics such as high 613C9-MP, value, abun dant gammacerane, and poor homohopanes, which suggest that the major contributor is Cambrian-Lower Ordovician source rock.
基金supported by the National Natural Science Foundation of China(21702151,21774029,and 21871211)the Fundamental Research Funds for Central Universities(2042019kf0208)。
文摘Synthesis of organosilanes from alkenes is a very important topic owing to their wide applications.A Ni/Cu dual metal-catalyzed arylsilylation of terminal alkenes,featuring migratory selectivity,has been developed.A wide diversity of aliphatic silanes have been prepared from terminal alkenes,aryl halides and Suginome’s reagent.This protocol is highlighted by excellent regioselectivity,mild reaction conditions and good functional group tolerance.In addition to benzylic positions,carbon–carbon bonds can also be constructed at allylic positions.Preliminary mechanistic studies suggest that the copper cocatalyst promotes the transmetalation of Suginome’s reagent,and the addition of a Pyr Ox ligand inhibits the formation of side-products from the carbon-Heck pathway.Moreover,studies toward the nature of the Pyr Ox ligand revealed that the steric hindrance of the oxazoline moiety greatly affects the chain–walking process,but not the arylation step.
基金This work was financially supported by the National Nature Science Foundation of China(21272069,20672035)the Fundamental Reearch Funds for the Central Universities and Key Laboratory of Organofluorine Chemistry,Shanghai Institute of Organic Chemistry,Chinese Academy of Sciences.
文摘An efficient approach for the synthesis of N-arylated amides was developed via copper(Ⅱ) triflate-catalyzed direct oxidation of(aryl)methylamines to primary arylamides by air and subsequent N-arylation by diaryliodonium salts. Various substituted benzylamines could be applied in the reaction, providing a series of N-arylated amides in moderate to good yields. This method showed convenient, practical, and environment friendly advantages.
基金supported by the National Natural Science Foundation of China (21172017, 20972013 and 20772005)the specialized Research Fund for the Doctoral Program of Higher Education, Ministry of Education of China (20110010110011)"CHEMCLOUD COMPUTING " of Beijing University of Chemical Technology
文摘A domino [4+2]/retro [4+2] cycloaddition process of cyclohexadienes with arylethynes or benzyne providing access to biaryls and polycyclic aromatics has been studied theoretically using density functional theory calculations. It has been found that the initial Diels-Alder (D-A) reaction acts as the rate-determining step and the consequent [4+2] cycloreversion reaction is feasible under the conditions used. Furthermore, the D-A reaction affects the regioselectivity, the origin of which is essentially derived from the good match of orbital coefficients between dienes and dienophiles as shown by using frontier molecular orbital (FMO) theory. Further investigation of the reactivity reveals that the reactions are predicted to fail to occur if an electron-donor group in the diene or an electron-acceptor group in the dienophile is lacking, as a consequence of the increased FMO energy gap. By further exploring the scope of substrates computationally, benzyne as an active dienophile was predicted to react with a variety of dienes in a cascade reaction under mild conditions with a low energy barrier, with the rate-determining step being the retro [4+2] cycloaddition.