bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of 4‐fluoroalkyl‐2H‐pyrido [1, 2‐a] pyrimidin‐2‐ones from 2, 2‐dihydropolyfluoroalkanoic acids
Authors: Lu He‐Jun , Liu Jin‐Tao 
Published: September 2010

AbstractIn the presence of N, N′‐dicyclohexylcarbodiimide, 2‐aminopyridine and its derivatives (2) condensed with 2, 2‐di‐hydropolyfluoroalkanoic adds (1) to give the corresponding amides. Subsequent intramolecular Micheal addition‐elimination reactions of the fluorine‐containing amides under basic conditions gave 4‐fluoroalkyl‐2H‐pyrido[1,2‐a]pyrimidin‐2‐ones (3) in good yields.
Reaction of HCFC‐133a (CF3CH2C1) or HFC‐134a (CF3CH2F) with alcohols or phenols in DMSO in the presence of KOH
Authors: Wu Kai , Chen Qing‐Yun 
Published: September 2010

AbstractIn an open glassware, heating a gas HCFC‐133a (CF3CH2C1) or HFC‐134a (CF3CH2F), KOH and a phenol (or an alcohol) in DMSO at 80°C gave ethers ROCF2CH2X and (E/Z)‐ROCF = CHX (X = Cl, F) in moderate yields.
Effect of Different Salts on the Solubilities of Benzene and Diphenyl in t‐Butyl Alcohol‐Water Mixture and Hydrophobic Interaction
Authors: Zou Li‐Zhuang , Wang Xiao‐Ling , Zhu Shu‐Quan , Han Bu‐Xing , Liu Rui‐Lin , Yna Hai‐Ke 
Published: September 2010

AbstractThe solubilities of benzene and diphenyl in mixed solvents of t‐butyl alcohol (TBA) and water with different salts have been determined at T = 298.15, 303.15, 308.15 and 313.15 K. The molar fraction of TBA [x(TBA)] in mixed solvent is 0.045, and the molality of the salts (m2) in mixed solvents are 0.000, 0.250, 0.500, 0.750 and 1.000 mol/kg, respectively. The standard Gibbs energies of solution of benzene and diphenyl in the mixed solvents have also been calculated based on the solubility data. The effects of different salts on the hydrophobic interaction (HI) for benzene‐benzene pair in the systems were discussed.
Synthesis of TiO2 Nanoparticles via a Ti(IV) Complex with Stearic Acid and the Photocatalytic Activity for Organic Oxidation
Authors: Xu Yi‐Ming , Yu Xiao‐Han , Liu Hni‐Jun 
Published: September 2010

AbstractThe nano‐sized particles of TiO2 were prepared by thermal decomposition of titanium(IV) tetrabutanoxide complex with stearic acid at 450 °C in the air. It was observed that the amount of stearic acid, used initially for the complex synthesis in 2‐propano) at 25 °C, had great influence on the physical properties of the prepared TiO2 including crystal structure, the particle size, surface area and the adsorption capacity for organic substrate of a textile dye X3B in water, and thereafter the photocatalytic activity for the dye oxidation. Some samples displayed lower adsorption capacity for the organic substrate in water than a TiO2 of Degussa p25, but higher photocatalytic activity for the organic oxidation. Possible reason for the observed difference was discussed in the text.
Thermokinetics of the Formation Reaction of Zinc Histidine Complex
Authors: Gao Sheng‐Li , Chen San‐Ping , Hu Rong‐Zu , Shi Qi‐Zhen 
Published: September 2010

AbstractThe enthalpy change of reaction of zinc chloride with L‐α‐histidine in the temperature range of 25‐50 °C has been determined by a microcalorimeter. On the basis of experimental and calculated results, three thermodynamics parameters (the activation enthalpy, the activation entropy, the activation free energy), the rate constant and three kinetic parameters (the activation energy, the pre‐exponential constant and the reaction order) of the reaction, and the standard enthalpy of formation of Zn(His)2+ (aq.) are obtained. The results showed that the title reaction easily took place at the studied temperature.
Hydrothermal Synthesis and Structural Characterization of a Novel Organic‐Inorganic Hybrid Compound {[Cu (2, 2′‐bpy)2]2‐Mo8O26}
Authors: Wang Yong‐Hui , Li‐Dong Chen, , Hu Chang‐Wen , En‐Bo Wang, , Jia Heng‐Qing , Hu Ning‐Hai 
Published: September 2010

AbstractA novel organic‐inorganic hybrid compound {[Cu(2, 2′‐bpy)2]2Mo8O26 } has been hydrothermally synthesized and structurally characterized by single‐crystal X‐ray diffraction. The compound crystallizes in the orthorhombic space group, Pna21 with a = 2.4164(5), b = 1.8281(4), c= 1.1877(2) nm, V = 5.247(2) nm3, Z = 4, and final R1, =0.0331, wR2, = 0.0727. The structure consists of discrete { [ Cu (2, 2′‐bpy)2]2Mo8O26} dusters, constructed from a β‐octamolybdate subunit [Mo8O26]4‐ covalently bonded to two [Cu(2, 2′‐bpy)2]2+ coordination complex cations via bridging oxo groups. In addition, the spectroscopic properties and thermal behavior of this compound have been investigated by spectroscopic techniques (UV‐vis, IR, Raman and EPR spectra) and TG analysis.
Structural and Spectroscopic Studies on [Cu(DACH)2(H2O)]‐Cl2 (DACH = 1,4‐Diazacycloheptane)
Authors: Guo Ya‐Mei , Du Miao , Bu Xian‐He 
Published: September 2010

AbstractA penta‐coordinated Cu(II) complex with 1,4‐diazacydoheptane(DACH), [Cu(DACH)2(H2O)]Cl2(1), has been synthesized and characterized by X‐ray diffraction, IR spectra, elemental analyses, thermal analyses, UV‐Vis and ESR techniques. Complex 1 crystallizes in orthorhombic crystal system, Pbcn space group with a = 1.6075(4), b = 1.0539(3), c = 0.9195(3) nm, V=l.5578(7) nm3, Mr = 352.79, Z = 4, Dc= 1.487 g/cm3, final R = 0.0451 and wR = 0.1294. The structure of 1 indicates that the central Cu(II) atom is penta‐coordinated by four nitrogen atoms of two DACH moieties at the equatorial positions and a water molecule at the axis position. The coordination geometry of Cu(II) could be considered as an approximately ideal square‐pyramidal environment. Both DACH rings arrange in cis‐form and are predominantly in the boat‐boat conformation (80%) with some disorder to the chair‐chair conformation (20%). The Cl− anions are hydrogen bonded with the nitrogen donors of the DACH rings and the oxygen donor of the coordinated H2O molecule to form a one‐dimensional zigzag linear structure. The solution behaviors of 1 are also discussed in detail by Uv‐vis and ESR technique.
[Co(H2O)(HPO4)]·H2O: The Layered Divalent Metal Mono‐hydrogenphosphate Structure
Authors: Shan Yong‐Kui , Dai Li‐Yi , Yu Shu‐Yuan , Ye Sheng‐Rong , He Ming‐Yuan 
Published: September 2010

AbstractA new layered divalent metal monohydrogenphosphate [Co(H2O) (HPO4)] · H2O (1) was hydrothermally synthesized from the reaction of CoCl2·6H2O with H3PO4 in the presence of cis‐Pt(NH3)2Cl2 and ethylenediamine. The structure features extensive intra‐ and inter‐layer hydrogen bonding among the hydrogenphosphate anion, the coordinated water and the crystallization water. X‐ray crystallographic parameters for 1 are orthorhombic Pnma (#62), a = 1.7528(2), b=0.56158(7), c = 0.47867(6) nm, V = 0.47116(9) nm3, Z=4.
Boron Separation by the Two‐step Ion‐Exchange for the Isotopic Measurement of Boron
Authors: Wang Qing‐Zhong , Xiao Ying‐Kai , Wang Yun‐Hui , Zhang Chong‐Geng , Wei Hai‐Zhen 
Published: September 2010

AbstractAn improved procedure for extraction and purification of boron from natural samples is presented. The separation and purification of boron was carried out using a boron‐specific resin, Amberlite IRA743, and a mixed ion exchange resin, Dowex 50W × 8 and Ion Exchanger II resin. Using the mixed ion exchange resin which adsorbs all cations and anions except boron, the HCl and other cations and anions left in eluant from the Amberlite IRA 743 were removed effectively. In this case, boron loss can be avoided because the boron‐bearing solution does not have to be evaporated to reach dryness to dislodge HCl. The boron recovery ranged from 97.6% to 102% in this study. The isotopic fractionation of boron can be negligible within the precision of the isotopic measurement. The results show that boron separation for the isotopic measurement by using both Amberlite IRA 743 resin and the mixed resin is more effective than that using Amberlite IRA 743 resin alone. The boron in samples of brine, seawater, rock, coral and foraminifer were separated by this procedure. Boron isotopic compositions of these samples were measured by thermal ionization mass spectrometry in this study.
Derivatization Reaction of Carbohydrates with Urea as the Reagent and Fluorimetric Determination of Carbohydrates
Authors: Yang Jing‐He , Cao Xi‐Hui , Wang Min , Wu Xia , Sun Chang‐Xia 
Published: September 2010

AbstractIt is found that in the presence of sulfuric add carbohydrates condense with urea to afford the condensation products, which emit fluorescence. Under optimum conditions, the fluorescence intensities of system are proportional to the concentrations of carbohydrates. Based on this linear relationship, quantitative determination of kinds of carbohydrates has been made. Among all the carbohydrates tested, the sensitivity of α‐rhamnose is the highest and its limits of detection reaches 3.5 × 10−8 mol/L. So α‐rhamnose can be selectively determined in the presence of other carbohydrates. A interaction mechanism is also discussed.
Spectroscopic and Spectroelectrochemical Studies of Interaction of Nile Blue with DNA
Authors: Zhao Guang‐Chao , Zhu Jun‐Jie , Chen Hong‐Yuan , Wang Xue‐Mei , Lu Zu‐Hong 
Published: September 2010

AbstractNile Blue can strongly bind to DNA and its affinity for DNA has been investigated by spectroscopy and spectroelectrochemistry. At low DNA concentrations, Nile Blue can bind to DNA(per nucleotide phosphate) to form a 1:1 association complex with the binding constant of 4.7 × 104 L/mol and the major binding model of Nile Blue to DNA is “electrostatic binding”. However, the major binding model changes into “intercalative binding” at high DNA concentrations. In order to confirm which part of Nile Blue intercalating into DNA, the inclusion action of β‐cydodextrin (β‐CD) has been used to study the interaction. Nile Blue can be included into the hydrophobic cavity of β‐CD to form an inclusion complex with a stability constant of 1.9 × 103 L/mol. The experimental results indicate that the naphthalene ring part of Nile Blue is included into β‐CD's hydrophobic cavity and the inclusion complex decomposes at high DNA concentrations. It may be deduced reasonably that the naphthalene ring part of Nile Blue molecule intercalates into DNA helix Strand.
Determination of Methanol Increment in Mobile Phase Consisting of Methanol and Water by On‐line UV Spectrometry in Reversed Phase Liquid Chromatography
Authors: Geng Xin‐Du , Regnier Fred E. 
Published: September 2010

AbstractAn on‐line UV spectrometric method for the quantitative determination of methanol increment of methanol‐water in the mobile phase (i.e., of greater concentration than that of the mobile phase) by frontal analysis (FA) of insulin in reversed phase liquid chromatography (RPLC) was presented. When the methanol increment concentration ranged from 0.05% to 0.50%, V(CH3OH)/V(H2O), a set of elution curves could be obtained at 198 nm by a diode‐array detector in the presence of 47% methanol, V(CH3OH)/V(H2O) containing 0.03% hydrochloric add, V(CH3OH‐H2O)/V(HCl) in the mobile phase. The plateau height of the elution curves of the methanol increment was found to be proportional to the methanol increment in the mobile phase. The methanol increment could be determined on a quantitative basis. When the method was used to investigate the elution curve of insulin by FA in RPLC, a small plateau, being the methanol increment, was detected before the usual insulin plateau of each elution curve. In this case the methanol increment was found to vary with insulin concentration in the mobile phase. When that concentration was between 0.025 mg/mL and 0.30 mg/mL, the methanol increment could be determined in the range from 0.03% to 0.19% with a deviation of ± 0.02% and a relative deviation of ± 10%. A nuclear magnetic resonance spectrometer (NMR) was also employed to confirm the obtained result. A methodology with a very rigorous experimental procedure for obtaining results of such accuracy is also included. The presented result may be used to prove that a displacement process definitely occurs as insulin is adsorbed by the RPLC stationary phase inFA.
Synthesis of a New Class of Chiral β‐Mercaptoalcohols from Amino Acids
Authors: Ge Jian‐Feng , Shen Zong‐Xuan , Zhang Li‐Fen , Zhang Ya‐Wen 
Published: September 2010

AbstractThe syntheses of three new optically active β‐mercaptoalcohols, (R)‐1,1‐diphenyl‐2‐mercapto‐3‐methyl‐1‐butanol, (R)‐1,1‐diphenyl‐2‐mercapto‐4‐methyl‐1‐pentanol, and (R)‐1,1‐diphenyl‐2‐mercapto‐l‐benzenepropanol from the corresponding amino adds are described. The enantiomeric excesses of these β‐mercaptoalcohols were determined by 1H NMR as their (S)‐mandeloyl derivatives.
Synthesis of Chiral 2,5‐Bis(oxazolinyl)thiophenes and Their Application as Chiral Shift Reagents for 1,1′‐Bi‐2‐naphthol
Authors: Gao Ming‐Zhang , Wang Bo , Liu Han‐Biao , Xu Zun‐Le 
Published: September 2010

AbstractA series of C2‐symmetrical chiral 2,5‐bis(4′‐alkyloxazolin‐2‐yl) thiophenes (thiobox) have been synthesized from thiophene‐2, 5‐dicarboxylic acid by sequential amidation with a chiral ethanolamine, conversion of hydroxyl to chloro group, and base‐promoted oxazoline ring formation. As demonstrated by ( ‐ )‐2, 5‐Ws[4′‐( S)‐isopropyloxazolin‐2′‐yl] thiophene, these thiobox systems exhibited remarkable chirality recognition of 1, 1′‐bi‐2‐naphthol giving rise to pronounced shifts in the lH NMR signals of the latter axial chiral compound at the positions of C‐3, C‐4, C‐5, and C‐8.
Selective Transport of Alkali‐Metal Cations through Liquid Membranes by Non‐Cyclic Carriers
Authors: Xu Ming , Song Kai , Wu Li‐Zhu , Zhang Li‐Ping , Tung Chen‐Ho 
Published: September 2010

AbstractThe emission spectra of a series of naphthalene end‐labeled oligo‐oxyethylene (N‐Pn‐N) and their facilitated transport of cations across liquid membranes have been investigated. Alkali‐metal cations enhance or inhibit the intramolecular excimer formation of N‐Pn‐N remarkably, suggesting that the polyether chain of N‐Pn‐N in solution complexes with the cations, and the orientation of the terminal chromophores depends on the cation size and the length of the polyether chain. These compounds are able to act as carriers to facilitate transport of alkali‐metal cations through organic liquid membranes. The transport efficiencies are comparable with those of cyclic carriers such as crown ethers, and show remarkable selectivity.
Regioselective Synthesis and Base Catalyzed Transacylation of Substituted 1H‐Pyrazole‐4‐carboxamides
Authors: Ren Jim , Zhang Xiao‐Hong , Liu Ying , Chen Wei‐Qiang , Jin Gui‐Yu 
Published: September 2010

AbstractNew type of substituted 1H‐pyrazole‐4‐carboxamides were obtained by regioselective synthesis under the catalysis of different bases. The structures of the title compounds were confirmed by elemental analysis, 1H NMR, IR, MS and X‐ray crystallography. Compounds 1 were transacylated into their corresponding amides 3 in the presence of sodium hydride. Preliminary bioassays indicated that some compounds showed fungicidal activities against Rhizoctonia solani and Sclerotinia sclerotiorum.
Synthesis of Ordered Biosilica Materials
Authors: Wang Li‐Jun , Wang Yun‐Hua , Li Min , Fan Ming‐Sheng , Zhang Fu‐Suo , Wu Xue‐Min , Yang Wen‐Sheng , Li Tie‐Jin 
Published: September 2010

AbstractBiogenic silica with amazing diversity of nanostructure shells, fibers and granules in diatoms and sponges is radiated by proteins and polysaccharides and forms at ambient pressure and temperatures. Chemical synthetic methods, in contrast, have to rely on extreme pH and/or surfactants to induce the condensation of silica precursors into specific patterns. One kind of benign synthesis method through plant cell wall template‐directed ordered biosilica materials under ambient conditions is intriguing in this context. Organized silica materials in intercellular spaces of epidermal cells of tall fescue leaves were synthesized through molecular recognition between Si‐OH and polysaccharide‐OH or glycoprotein‐OH of main components of plant cell walls and cellular processing as well when Si(OEt)4 was supplied rather than monosilicic acid. The biosynthesis of structural silica in tall fescue plant was correlated with the Si species applied, reflecting the slower condensation from tetraethoxysilane (TEOS) and thus providing greater opportunities for structural control by the underlying matrix of cell walls. The composition was estimated by energy dispersive X‐ray (EDX) spectra on a scanning electron microscope. All organized structures showed carbon, oxygen and silicon peaks, indicating that their formations differ from natural siliceous process.
Sm/BiCl3System Mediated Reformatsky Type Reactions of α‐Bromoacetophenone with Aldehydes in THF‐H2O Solvent
Authors: Zhang Ji‐Ming , Zhang Yong‐Min 
Published: September 2010

AbstractIn the presence of samarium‐bismuth(III) chloride, inter‐molecular aldol type reactions of α‐bromoacetophenone with various aldehydes in tetrahydrofuran‐water mixed solvent afford β‐hydroxy ketones in moderate to good yields under mild and neutral conditions.
Sol‐Gel Derived Carbon Ceramic Electrode Bulk‐Modified with Tris (1, 10‐phenanthroline‐5, 6‐dione) iron (II) Hexafluorophosphate and Its Use as an Amperometric Iodate Sensor
Authors: Wang Peng , Zhu Guo‐Yi 
Published: September 2010

AbstractA surface‐renewable tris(1, 10‐phenanthroline‐5, 6‐dione) iron (D) hexafluorophosphate (FePD) modified carbon ceramic electrode was constructed by dispersing FePD and graphite powder in methyltrimethoxysilane (MTMOS) based gels. The FePD‐modified electrode presented pH‐dependent voltammetric behavior, and its peak currents were diffusion‐controlled in 0.1 mol/L Na2SO4 + H2SO4 solution (pH = 0.4). In the presence of iodate, dear electrocatalytic reduction waves were observed and thus the chemically modified electrode was used as an amperometric sensor for iodate in common salt. The linear range, sensitivity, detection limit and response time of the iodate sensor were 5 × 10−6–1 × 10−2 mol/L, 7.448 μA·L/ mmol, 1.2 × 10−6 mol/L and 5 s, respectively. A distinct advantage of this sensor is its good reproducibility of surface‐renewal by simple mechanical polishing.
Facile Formation of Ytterbium Diiodide and Its Use in the Synthesis of Allyl Selenides
Authors: Su Wei‐Ke , Li Yong‐Shu , Zhang Yong‐Min , Zheng Yun‐Fa 
Published: September 2010

AbstractYtterbium metal reacts with iodine to generate ytterbium diiodide directly, which can react with diselenides to form ytterbium selenolates (RSeYbI2). These species reacted smoothly with allyl bromide to give allyselenides in moderate to good yields under neutral conditions.
Synthesis of Thiourea Derivatives on Soluble Polymeric Support
Authors: Yang Gui‐Chun , Chen Zu‐Xing , Zhang Zhao‐Jun 
Published: September 2010

AbstractA modified poly (ethylene glycol) (PEG) has been developed as the soluble polymeric supports for liquid phase synthesis of novel thiourea derivatives. In each step of the sequence, the PEG‐bound products were precipitated in cold Et2O and the unreacted materials and by‐products were removed by simple filtration. The progress of reaction, purity of the isolation and the structure of the PEG‐bound products were easily monitored by TLC, IR and 1H NMR spectra. Representative thiourea derivatives were obtained in moderate yields with excellent purity from this modified PEG‐bound product by the cleavage with 50% TFA/H2O.
Bis (ortho‐) chelated Monoanionic Bisphosphinoaryl Ruthenium (II) Complexes: Synthesis, Characterization and Reactivity†
Authors: Klink Gerard P. M. , Dani Paulo , Koten Gerard 
Published: September 2010

AbstractBisphosphinoaryl ruthenium (II) compounds are synthesized using two distinct synthetic routes. One route, direct cycloruthenation, consists of the reaction of the parent arene compound R‐PCHP with [RuCl2 (PPh3)3] in chlorinated solvents. However, this route suffers from major drawbacks because HCl is formed as well as free triphenylphoshine. The other route, the transcyclometalation reaction, involves the interconversion of one cyclometalated ligand metal complex, [RuCl (NCN) (PPh3)], into another complex, [RuCl (R‐PCP) (PPh3)], with concomitant consumption and formation of the corresponding arenes R‐PCHP and NCHN, respectively.
Ab initio Calculation and Kinetic Study for the Abstraction Reaction of H with SiHCl3
Authors: Zhang Qing‐Zhu , Wang Shao‐Kun , Gu Yue‐Shu 
Published: September 2010

AbstractThe mechanism of the reaction of H with SiHCl3 has been investigated at high level of ab initio molecular orbital theory. Theoretical analysis provides a conclusive evidence that the main process occurring in this reaction is the hydrogen abstraction from the Si‐H bond, the abstraction of Cl has higher barrier and is difficult to react. The kinetics has been studied using canonical variational transition‐state theory (CVT) with small curvature tunneling effect (SCT) correction. The rate constants have been calculated over a wide temperature range of 200‐3000 K. The CVT/SCT rate constants exhibit typical non‐Arrhenius behavior, a three‐parameter rate‐temperature formula is fitted as follows:k (T) = (3.24 × 10−19) T2.30 exp (‐250/T) [in unit of mL/ (molecule · s). The calculated CVT/SCT rate constants match well with the experimental values.
Substituent Effects on the Blue‐Shifting Hydrogen Bonds between X ‐ C  C ‐ CF2 ‐ H and Water
Authors: Fan Jian‐Miao , Zhang Ke‐Chun , Liu Lei , Li Xiao‐Song , Guo Qing‐Xiang 
Published: September 2010

AbstractMP2/6‐31 + g (d) calculations were performed verifying the existences of blue‐shifting X ‐ C  C ‐ CF2 ‐ HḋOH2 hydrogen bonds. Detailed analyses revealed that the interaction energy and donor‐acceptor distance had good correlations with the substituent Hammett constants. However, the extent of C‐H bond contraction and the blue shift of the C‐H stretching vibration did not show any good correlation with the traditional substituent constants, indicating that certain more complicated mechanisms might be involved in the present systems. Nevertheless, it was found that highly electron‐withdrawing substituents were not favorable to the C‐H bond contraction, and it was suggested that the attractive interaction between water and the carbon of ‐ CF2H probably played an important role in the blue shift.
Xanthine Biosensor Based on Didodecyldimethylammonium Bromide Modified Pyrolytic Graphite Electrode
Authors: Tang Ji‐Lin , Han Xiao‐Jun , Huang Wei‐Min , Wang Er‐Kuq 
Published: September 2010

AbstractThe vesicle of didodecyldimethylammonium bromide (DDAB) which contained tetrathiafulvalene (TTF) was mixed with xanthine oxidase, and the mixture was cast on the pyrolytic graphite electrode. The lipid films were used to supply a biological environment resembling biomembrane on the surface of the electrode. TTF was used as a mediator because of its high electron‐transfer efficiency. A novel xanthine biosensor based on cast DDAB film was developed. The effects of pH and operating potential were explored for optimum analytical performance by using the amperometric method. The response time of the biosensor was less than 10 s. The detection limit of the biosensor was 3.2 × 10−7 mol/L and the liner range was from 4 × 10−7 mol/L to 2.4 × 10−6 mol/L.