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Different Reaction Conditions (different + reaction_condition)
Selected AbstractsRapid Method of Converting Primary Amides to Nitriles and Nitriles to Primary Amides by ZnCl2 Using Microwaves under Different Reaction Conditions.CHEMINFORM, Issue 41 2007Krishnappa Manjula Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Crystal Structures of Extended Europium Cyanamide,Carbodiimide Compounds Derived from Different Reaction Conditions: Temperature-Controlled Syntheses of In0.08Eu4(NCN)3I3, Eu8I9(CN)(NCN)3, and In0.28Eu12(NCN)5I14.91.CHEMINFORM, Issue 31 2006Wuping Liao Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] A Facile Reduction of Azoxyarenes with Hydrazine Hydrate/Magnesium: Formation of Different Products under Different Reaction Conditions.CHEMINFORM, Issue 14 2006Hemmaragala M. Nanjundaswamy Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Preparation of shuttle-like Sb2S3 nanorod-bundles via a solvothermal approach under alkaline conditionCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2010Ling Zhang Abstract Uniform shuttle-like Sb2S3 nanorod-bundles were synthesized via a polyvinylpyrrolidone (PVP) assisted solvothermal approach under alkaline condition, using antimony chloride (SbCl3) and thiourea (CH4N2S, Tu) as the starting materials in ethanol. The phase structure, composition and morphology of the product were characterized by means of X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). XRD and EDS results confirm that the synthesized Sb2S3 nanorod-bundles have an orthorhombic structure and an atomic ratio of 3:2 for S:Sb. TEM and HRTEM results show that the shuttle-like Sb2S3 bundles are composed of nanorods with a size distribution of 20-40 nm and growing along c-axis. Furthermore, experiments under different reaction conditions were carried out and the mechanism for the growth of nanorod-bundles was discussed (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nucleophilic Addition of Water and Alcohols to Dicyanonitrosomethanide: Ligands with Diverse Bonding Modes in Magnetically Coupled d-Block ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2010Anthony S. R. Chesman Abstract Ligands resulting from the transition-metal-promoted nucleophilic addition of water or an alcohol to dicyanonitrosomethanide ions (dcnm) have been utilised in the formation of a large series of polynuclear complexes. Addition of water to dcnm results in formation of carbamoylcyanonitrosomethanide (ccnm); deprotonation of this ligand gives amidocarbonyl(cyano)nitrosomethanide (acnm), which has been incorporated into the trinuclear complex [Cu3(acnm)2(dmae)2(H2O)2] [dmae = 2-(dimethylamino)ethoxide] (1) which shows strong antiferromagnetic coupling with an exchange coupling constant, J = ,500 cm,1. [Cu(acnm)(NH3)2], (2) marks the first instance of acnm facilitating the formation of a coordination polymer, namely a 1D chain with intramolecular hydrogen bonding. Attempts to synthesise 2 through different reaction conditions instead resulted in the mononuclear [Cu(acnm)(NH3)2(py)] (py = pyridine) (3). The addition of ethanol to dcnm results in cyano[imino(ethoxy)methyl]nitrosomethanide (cenm) which features in the mononuclear [Cu(cenm)2(H2O)2] (4) and polymeric {[Cu(cenm)2]2·H2O}, (5). The latter is the first example of the cenm ligand in a coordination polymer and has a highly unusual coordination mode through the nitrile groups and extremely weak antiferromagnetic coupling. {[Mn3(ccnm)2(EtOH)2(OAc)4]·2EtOH}, (6) and (Et4N)2[Cu(ccnm)4] (7) contain previously unobserved coordination modes of the ccnm ligand while the complex [Mn(cmnm)3Mn(bipy)(MeOH)](ClO4) (8) {cmnm = cyano[imino(methoxy)methyl]nitrosomethanide, bipy = 2,2,-bipyridine} displays weak antiferromagnetic coupling between manganese atoms with J = ,1.44 cm,1. A change in the solvent systems used in the synthesis of 7 results in the formation of the mononuclear complexes [Mn(bipy)2(dcnm)2] (9) or [Mn(bipy)2(H2O)(dcnm)](dcnm)·H2O (10) and [Mn(bipy)2(dcnm)(H2O)](dcnm) (11). The addition of ethlyene glycol monomethyl ether to dcnm gives cyano[imino(2-methoxyethoxy)methyl]nitrosomethanide (cgnm) and the formation of [Cu(cgnm)2(H2O)2] (12). [source] Colorimetric investigation of the reaction between p -phenylendiamine and meta -substituted derivatives of benzene on a model supportINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 3 2010M. Scalzo J. Cosmet. Sci., 60, 429,436 (July/August 2009) Synopsis The aim of this work was the employment of colorimetric techniques in the analysis of the color formed, on a proteic substrate, by the reaction between p -phenylendiamine and some meta -substituted benzene derivatives in the presence of hydrogen peroxide and in media at different pH values. In particular we investigated the chromatic variations that take place on the substrate in dependence on different reaction conditions. The obtained results show that for each couple of reagents the colorimetric data, namely the reflectance of the formed color, change considerably with the pH of the reaction medium and demonstrate how this parameter can be considered a good descriptor of the composition of the formed pigment. [source] Ferric Chloride Hexahydrate-Catalyzed Highly Regio- and Stereoselective Conjugate Addition Reaction of 2,3-Allenoates with Grignard Reagents: An Efficient Synthesis of ,,,-AlkenoatesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Guobi Chai Abstract Ferric chloride hexahydrate was shown to be an efficient catalyst for the conjugate addition of 2,3-allenoates with alkyl-, aryl-, or vinyl-Grignard reagents to synthesize polysubstituted ,,,-unsaturated alkenoates with high regio- and stereoselectivity. The in situ formed magnesium dienolate may readily react with different electrophilic reagents under different reaction conditions with or without a catalyst to construct an allylic quaternary carbon at the ,-position of the ester group and a stereocontrollable retention of the carbon-carbon double bond. [source] Comparison of the surface and catalytic properties of rare earth-promoted CaO catalysts in the oxidative coupling of methaneJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2006Vilas H Rane Abstract Rare earth (viz. La, Ce, Sm, Nd and Yb) promoted CaO catalysts have been investigated, comparing their surface properties (viz. surface area and basicity/base strength distribution) and catalytic activity/selectivity in the oxidative coupling of methane at different reaction conditions (temperatures, 650,800 °C, CH4/O2 ratios, 2.0,8.0 and space velocity, 51 360 cm3 g,1 h,1). The surface properties and catalytic activity/selectivity are strongly influenced by the rare earth promoter and its concentration. Apart from the Sm-promoted CaO catalyst, both the total and strong basic sites (measured in terms of CO2 chemisorbed at 50° and 500 °C respectively) are decreased due to the promotion of CaO by rare earth metals (viz. La, Ce, Nd and Yb). The catalytic activity/selectivity is strongly influenced by the temperature, particularly below ,700 °C, whereas at higher temperature no further effect is seen. The La2O3CaO, Nd2O3CaO and Yb2O3CaO catalysts showed high activity and selectivity, and also their results are comparable. Among the catalysts, Nd-promoted CaO (with Nd/Ca = 0.05) showed the best performance (19.5% CH4 conversion with 70.8% C2+ selectivity) in the oxidative coupling of methane. A close relationship between the surface density of total and strong basic sites (measured in terms of CO2 chemisorbed at 50° and 500 °C respectively) and the C2+ selectivity and/or C2+ yield has been observed. Copyright © 2005 Society of Chemical Industry [source] Investigation on the reactions of o -hydroxybenzyl alcohols with vinyl ethers under acidic and/or thermal conditionsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 2009Volkan Kumbaraci The reaction of vinyl ethers with o -hydroxybenzyl alcohols under different reaction conditions was investigated. The aim of this attempt was to find out whether the protection reactions or the hetero Diels,Alder reaction of quinone methide in situ generated from o -hydroxybenzyl alcohol is more likely to occur. o -hydroxybenzyl alcohols can give hetero Diels,Alder reactions with dihydro-2H -pyran at high temperatures but only when used with acid catalysts. At room temperature, even in the presence of acid catalyst, reactions yielded regular protection products. However, butyl vinyl ether and 4-methoxy-3-butenone could not give intermolecular cycloaddition reactions under the acidic conditions, because both decomposed to the new products with acids. Hetero-Diels,Alder products obtained only under thermal conditions but in low yields. J. Heterocyclic Chem., 46, 226 (2009). [source] On the reaction of 3,4-dihydropyrimidones with nitric acid.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2001Preparation, x-ray structure analysis of a stable nitrolic acid A series of substituted 3,4-dihydro-2-pyrimidones (DHPMs) was reacted with nitric acid under different reaction conditions. Treatment of DHPMs with 50-65% nitric acid at 0 °C led to the formation of the corresponding dehydrogenated 2-pyrimidones in moderate to good yields. In contrast, reaction of one representative DHPM with 60% nitric acid at 50 °C led to an unusually stable nitrolic acid, involving a formal nitration, nitrosation, and dehydrogenation step. The molecular structure of this product was determined by X-ray crystallographic analysis [source] Improvement in radiolabelling proteins with the 99mTc-tricarbonyl-core [99mTc(CO)3]+, by thiol-derivatization with iminothiolane: application to ,-globulins and annexin VJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 12 2005Marie-Laure Biechlin Abstract The aim of this study was to improve the radiolabelling of proteins with the 99mTc-tricarbonyl-[Tc(I)(CO)3]+ core by introducing thiol groups to their structure. To achieve this goal, ,-globulins and annexin V were derivatized with mercaptobutyrimidyl groups (MBG) after reaction with 2-iminothiolane. The optimal conditions permitted attachment of an average of 3.3 thiol groups on ,-globulins and 1.0 to annexin V. The radiolabelling assays were carried out by incubating 3.2 nmol of either ,-globulin-SH or unmodified ,-globulin with 60 MBq 99mTc-tricarbonyl produced from an Isolink® kit (Mallinckrodt) under different reaction conditions. Results clearly showed that the introduction of three MBG could double the radiolabelling yields to more than 90% in a short time (30 mn, 37°C). Such results would never have been reached with unmodified ,-globulins alone. Under the same conditions when using 1,2 nmol derivatized annexin V, the average radiolabelling yield was 55% against 19% with the unmodified protein. The 99mTc-tricarbonyl-conjugates were challenged with cysteine or histidine and showed good stability. Copyright © 2005 John Wiley & Sons, Ltd. [source] Phthalide as an activating group for the synthesis of poly(aryl ether phthalide)s by nucleophilic aromatic substitutionJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2002Daniel M. Knauss Abstract The phthalide ring was examined as an activating group for nucleophilic aromatic substitution. The proposed mechanism by which activation occurs is through a ring opening of the phthalide ring to form a Meisenheimer-like , complex. 3,3-Bis(4-fluorophenyl)phthalide was synthesized and examined under different reaction conditions to determine its suitability for polymer formation. Semiempirical calculations at the PM3 level suggested that 3,3-bis(4-fluorophenyl)phthalide is only moderately activated, whereas 1H, 13C, and 19F NMR spectroscopy suggested that the monomer was not sufficiently activated for nucleophilic aromatic substitution. However, low-molecular-weight polymers (number-average molecular weight < 7000 g/mol) were produced from bisphenol A, hydroquinone, and phenolphthalein. The polymers were characterized by gel permeation chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, NMR spectroscopy, and differential scanning calorimetry. The polymers displayed relatively high glass-transition temperatures. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3046,3054, 2002 [source] Coagulation of Carboxylic Acid-Functionalized LatexesMACROMOLECULAR SYMPOSIA, Issue 1 2008Adélia Santos Abstract In the present work, the stability of particles produced by emulsion polymerization and stabilized by carboxylic acid groups was studied from turbidity measurements. To achieve this, a number of copolymerization runs was carried out under different reaction conditions, including the use of different carboxylic monomers. Partitioning analyses using conductimetric and potentiometric titrations were performed in order to assess the distribution of carboxylic monomers among the main phases of the produced latexes. Additionally, the stability and coalescence of particles were measured by turbidimetry in a diluted latex considering either the presence or not of the anionic surfactant sodium lauryl sulfate. Coalescence of particles was provoked in the latex samples at different temperatures by addition of an aliquot of a concentrated solution of electrolyte. The influence of surfactant, temperature and type of carboxylic acid group on the particle stability was investigated. [source] Production of leather-like composites using short leather fibers.POLYMER COMPOSITES, Issue 6 2002Leather-like composites were prepared by addition of chemically modified short leather fibers (SLF) into a plasticized polyvinyl chloride (pPVC) matrix. The fibers were subjected to chemical modification by emulsion polymerization to achieve good interfacial adhesion between SLF and the pPVC matrix. The SLF with chemical modification were obtained from three different reaction conditions where these SLF have different percentages of grafted and deposited PMMA polymer onto the fiber surface. The incorporation of the SLF into the thermoplastic matrix was carried out using a torque-rheometer and the composites obtained were molded by compression. Tensile and tear mechanical tests were performed on composite samples, and the morphology of the fractured surfaces was analyzed using scanning electron microscopy (SEM). The results show that the incorporation by grafting of polymethyl metacrylate (PMMA) onto the fibers produced a significant improvement of their interfacial adhesion to pPVC, promoting the compatibilization between the fiber surface and matrix. The findings are discussed and interpreted in terms of enhanced adhesion at phase boundaries. Overall, the results confirm that it is possible to produce modified leather composites based on a pPVC matrix, which exhibit relatively high tensile strength, tear resistance and flexibility. These composites are very suitable candidate materials for applications in the footwear industry. [source] Measurement of critical concentration for mesophase formation of chitosan derivatives in both aqueous and organic solutionsPOLYMER INTERNATIONAL, Issue 12 2006Yan-ming Dong Abstract A novel chitosan derivative, acryloyl chitosan (AcCs), and two N -maleoyl chitosans, MaCs-1 and MaCs-2, with different degrees of substitution were synthesized using completely deacetylated chitosan as raw material under different reaction conditions. AcCs is an amphiphilic chitosan derivative, but MaCs-1 and MaCs-2 are soluble in water and organic solvents respectively. The concentrated solutions of AcCs, MaCs-1 and MaCs-2 all demonstrated mesophases and were investigated using polarizing optical microscopy (POM). Circular dichroism (CD) was also employed for determining the critical concentration for mesophase formation. A broad peak in the visible light region of CD spectra had its origin in the appearance of the mesophase, and arose from the selective reflection of cholesteric helix pitches. The results of CD measurements agreed with those of POM. The critical concentration values for aqueous solutions were much lower than those for organic solutions, which was explained by the strong interactions between the chitosan derivatives and water. Copyright © 2006 Society of Chemical Industry [source] Implications of enzymatic, acidic and thermal hydrolysis of DNA on the occurrence of cross-linked melphalan DNA adductsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 4 2005Bart Van den Driessche Calf thymus DNA was treated with melphalan, a nitrogen mustard, and the formation of melphalan cross-linked DNA adducts was investigated. These cross-linked adducts could not be detected either in the enzymatically or in the thermally generated DNA hydrolysates. However, a search for DNA cross-linked adducts in the hydrolysates obtained under acidic conditions revealed the presence of different types of cross-links, mainly containing an adenine moiety. These results are very important because they show that the detection of cross-links is dependent on the hydrolytic procedure used and that these cross-linked adducts are formed under totally different reaction conditions from those in in vivo situations. This can explain the very low abundance or even the absence of cross-linked adducts in nitrogen mustard treated animals. The generally accepted theory that the anti-cancer activity of bifunctional mustards such as melphalan is due to cross-linking of DNA strands remains therefore from our point of view questionable. Copyright © 2005 John Wiley & Sons, Ltd. [source] Methylation of tin(II) by methyl iodide: influences of different environmental factors on the efficiency and reaction kineticsAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2006Chen Baowei Abstract The methylation reaction of Sn(II) with methyl iodide (MeI) in water has been studied using sensitive GC-QSIL-FPD technology. The pH value, amount of MeI and salinity (S) are the three important factors that influence the methylation reaction in an aquatic environment. In all experiments, monomethyltin (MMT) is the only methylation product of the tin(II) reacting with MeI observed. At the 95% confidence level, the pH, MeI and S are significant for the MMT yield. The concentration of MMT in the reactor increases with increase in pH within the selected pH range of 4,9 because four different species of Sn(II),Sn2+, SnOH+, Sn(OH)20 and Sn(OH)3,,have different reaction activities with MeI. The methylation activity of Sn(II) was found to be highest at a salinity of 0.1 M at three different pH levels: 5, 7 and 9. Higher concentration of Cl, (as a relatively weak nucleophilic ion) will obstruct nucleophilic attack of Sn(II) on MeI. MMT production also increases with rising volume of MeI. Moreover, first-order reaction rates have been calculated at different pH, salinity and MeI, and found to be in the range 0.0018,0.0199 h,1. The reaction rate also varies largely under different reaction conditions. One probable mechanism for the methylation reaction of Sn(II) with MeI is a SN2 nucleophilic attack on the methyl group of MeI by Sn(II), via a process of oxidative methyl-transfer. Copyright © 2006 John Wiley & Sons, Ltd. [source] Assembly synthesis of sheet-like calcite array and stable-vaterite by supported liquid membraneCHINESE JOURNAL OF CHEMISTRY, Issue 10 2004Dong-Mei Sun Abstract Sheet-like calcite array and stable vaterite were synthesized by bio-mimetic supported liquid membrane system under different reaction conditions. Both of the FTIR spectra of products showed narrower peak at 1418 cm,1 than that of bulk CaCO3, and that of vaterite has a split in this peak. [source] | |||||||||||||