摘要:

AbstractThe ability to monitor a broad range of chemical species in the atmosphere, geosphere, and hydrosphere is a key technology for addressing global environmental issues. This report surveys several high sensitivity spectroscopic techniques for this purpose, including Frequency‐Modulation‐Enhanced Remote Sensing, Intra Cavity Laser Absorption Spectroscopy, Cavity Ring Down Spectroscopy, and Raman Spectrosc

ISSN:1001-604X    

DOI:10.1002/cjoc.19990170302

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1999

数据来源: WILEY

摘要:

AbstractSupercritical fluids are becoming increasingly attractive as environmentally acceptable replacement for organic solvents in chemical reactions and material processing. This paper highlights some of the properties of supercritical fluids, especially supercritical CO2, which offer particular advantages for the handling of polymers, metal complexes and the environmentally more friendly synthesis and manufacture of chemicals. The paper includes same of the researches in University of Nottingham and a number of recent reviews which together provide a comprehensive introduction.

ISSN:1001-604X    

DOI:10.1002/cjoc.19990170303

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1999

数据来源: WILEY

摘要:

AbstractFTIR spectroscopy was used to study the hydrogen bonding of stearic acid with ethanol, dimethyl sulfoxide (DMSO), and acetonitrile in supercritical CO2at 318. 15 K, and 12.5 and 16.5 MPa. The concentration of the cosolvents range from 0–0.6 mol·L−1. The area percentage of absorption bands for hydrogen‐bonded and nonhydrogen‐bonded species was Obtained from the IR spectra. The acid and the cosolvents can form hydrogen bond even when their concentrations a very low. At fixed solute concentration, the extent of hydrogen bonding increases with cosolvent concentration. At higher ethanol concentrations, it seems that one stearic acid molecule can hydrogen bond with more than one ethanol molecules simultaneously. It is seen that the strength of the hydrogen bond formed by the acid and the cosolvents is in the order: DMSO ethanol acet

ISSN:1001-604X    

DOI:10.1002/cjoc.19990170304

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1999

数据来源: WILEY

摘要:

AbstractThe solubility of stearic acid in supercritical CO2with acetonitrile (CH3CN) cosolvent was measured at 318. 15 K in the pressure range hm 9.5 to 16.5 MPa, and the cosolvent concentration ranges from 0. 0 to 5.5 mol%. The solubility increases with acetonitrile concentration and pressure, and it also increases with the apparent density of CO2d1(moles of CO2in per liter of fluid) at higher co solvent concentrations. At lower d1, however, the solubility of the acid at lower acetonitrile concentrations is lower than that in pure CO2provided that d1is fixed, which is discussed qualitatively based on the clustering of the components in the system.

ISSN:1001-604X    

DOI:10.1002/cjoc.19990170305

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1999

数据来源: WILEY

摘要:

AbstractBased on the concept of Green Chemistry, a new procedure of finding bioactive compounds and their synthetic routes by computer‐aided techniques was proposed. The procedure consists of pharmacopoeia search against a 3D structural database of natural products for lead discovery and computer‐aided synthesis design for avoiding un useful synthetic experiments. This work demonstrated that computer aided drug design and synthesis design would help us to make the consideration of environmental concerns systematically, rather than having to deal later with the unnecessary waste chemicals. Thus, it is shown that chemical computer‐aided design (CAD) is an indispensable part of Green Chem

ISSN:1001-604X    

DOI:10.1002/cjoc.19990170306

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1999

数据来源: WILEY

摘要:

AbstractA fluorocarbon‐modified ply(N‐isopropylacrylamide) has been synthesized by copolymerization ofN‐isopropyl acrylamide with a small amount of acrylate or methacrylate containing a perfluoroalkyl group. It was found that the hydrophilicity of macromolecular backbone is an important factor to the solution properties of the copolymers and that hydrophobic association between fluorocarbon group is stronger than that between the corresponding hydrocarbon analogies. The viscosity of some of the copolymer solutions was very sensitive to temperature. It was dilatant at higher fluorocarbon comonomer content ( 0. 20–1.0 mol%) and was Newtonian at very low fluorocarbon comonomer content (0.03–0.2 mol%). Evidence for hydrophobic association of the fluorocarbon groups was obtained from the effects of adding NaCl and surfactants on the solution viscosity. The LC‐ST properties of these copolymers were studied by DSC method and this was also found to be consistent with hydrophobic association between the fl

ISSN:1001-604X    

DOI:10.1002/cjoc.19990170307

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1999

数据来源: WILEY

摘要:

AbstractResearch topics and methods of green chemistry in chromate production are introduced in this paper. New original green chemical process of the heterogeneous reaction and separation system of liquid phase oxidation of chromite in molten salt of sodium hydroxide—one way separation in high concentration medium—metastable phase separation—carbonate recycle conversion has been developed. The green commercial process for comprehensive utilization of mineral resources—reactant recycle inside the process—zero emission was es

ISSN:1001-604X    

DOI:10.1002/cjoc.19990170308

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1999

数据来源: WILEY

摘要:

AbstractA differential approach for self‐optimizing diffusion Monte Carlo calculation was proposed in this paper, which is a new algorithm combining three techniques such as optimizing, diffusion and correlation sampling. This method can be used to directly compute the energy differential between two system in the diffusion process, making the statistical error of calculation be reduced to Order of 10−‐5hartree, and recover about more than 80% of the correlation. We employed this approach to set up a potential energy surface of a molecule, used a “rigid move” model, and utilized Jacobi transformation to make energy calculation for two configurations of a molecule having good positive correlation. So, an accurate energy differential could be obtained, and the potential energy surface with good quality can be depicted. In calculation, a technique called “post‐equilibrium remaining sample” was set up firstly, which can save about 50% of computation expense. This novel algorithm was used to study the potential as molecular spectroscopy and the energy variation in che

ISSN:1001-604X    

DOI:10.1002/cjoc.19990170309

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1999

数据来源: WILEY

摘要:

AbstractThe title compound is formed by controlled hydrolytic polymerization in nonaqueous solution of simple oxo‐bridged binuclear ferric salts under the presence of carboxylate ligands. The rhombohedral crystalline form of the cluster with six imidazole molecules, which has crystallographically required C3ysymmetry, will be reported. The largest Fe—Fe distance in the undecairon oxo‐hydroxo cluster is about 0.68 nm and the cluster has a diameter near 2 nm, which implies that this cluster reach‐ a nanometer‐sized

ISSN:1001-604X    

DOI:10.1002/cjoc.19990170310

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1999

数据来源: WILEY

摘要:

AbstractThe novel trinuclear copper(I) complex [Cu3(μ3,‐Br)2(dppm)3]Br has been obtained by reaction of bis(diphenyl‐phosphino)methane (dppm) with cupric bromide. The title complex was characterized by single‐crystal X‐ray analysis, elemental analysis, molecular weight determination,31P NMR and its conductivity was also measured. The [ Cu3(dppm)3Br2]+cation consists of a triangular array of copper atoms, with dppm ligands (Ph2PCH2PPh2) bridging each edge of the triangle and two triply bridging Br groups bound to the two faces of the Cu3unit. Crystallographic data: monoclinic, space groupP21/c, a= 1.4739(4),b= l.7708(5),c= 2.8395(8) nm, β= 97.16(3)°,V= 7.353nm3, Z = 4,F(000)= 3296,Dcalc, = 1.472 g/cm3, μ = 26.478 cm−1,R=0.06,RW= 0.08, 4654 reflections observ

ISSN:1001-604X    

DOI:10.1002/cjoc.19990170311

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1999

数据来源: WILEY