Journal of the Chemical Society, Faraday Transactions最新文献_第9页

Spatiotemporal chaos in a differential flow reactor 差动反应器的时空混沌

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A709156G

J. Merkin, R. Satnoianu, S. Scott

引用次数: 8

Free radical mechanism of the Cl2 addition to acetylene Cl2加成乙炔的自由基机理

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A803923B

S. M. Resende, J. R. Pliego, W. B. Almeida

{"title":"Free radical mechanism of the Cl2 addition to acetylene","authors":"S. M. Resende, J. R. Pliego, W. B. Almeida","doi":"10.1039/A803923B","DOIUrl":"https://doi.org/10.1039/A803923B","url":null,"abstract":"The free radical mechanism for the addition of Cl2 to acetylene in the gas phase has been studied. The structures and energies of reactants, transition states and products were determined through abinitio calculations of the stationary points on the potential-energy surface (PES) for the interaction of these two molecules. Using BD(T)/6-311+G(2df,2p)//CASSCF(6,6)/6-31G(d,p) level of theory, the reaction rate for the initiation step (Cl2+C2H2→Cl+C2H2Cl) was estimated as 10-18 l mol-1 s-1 (at 298.15 K). This leads to the formation of a small quantity of Cl and C2H2Cl radicals, the chain propagators, and the following steps will only occur to an appreciable extent after an induction period, which generates a measurable amount of these radicals. The following steps were studied at the UCCSD(T)/6-311+G(2df,2p)//UMP2/6-31G(d,p) level of theory. The propagation reaction C2H2+Cl→C2H2Cl occurs with an activation energy of -1.22 kcal mol-1, and produces a radical C2H2Cl, where the two hydrogens are on opposite sides of the molecule (trans-isomer). This reaction has a rate constant 2.85×1010 l mol-1 s-1 at 298.15 K. The interconversion of the two isomers of the C2H2Cl radical (cis–trans) is very fast, with a rate constant 4.75×1010 s-1 and so these species can be considered to be in equilibrium. The rate constants for the reaction C2H2Cl+Cl2→C2H2Cl2+Cl, where the products trans- and cis-1,2-dichloroethylenes are formed, are 1.95×1010 and 3.63×109 l mol-1 s-1, respectively, and those for the two polymerization reactions C2H2+C2H2Cl→C2H2C2H2Cl are ca. 102 l mol-1 s-1. Hence, the latter reactions will not compete with the formation of C2H2Cl2, and the polymerization products will not be produced in meaningful amounts. Analysis of the kinetics data gives 97.3% of the trans-1,2-dichloroethylene and 2.7% of the cis-1,2-dichloroethylene products.","PeriodicalId":17286,"journal":{"name":"Journal of the Chemical Society, Faraday Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80446234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

THE ADSORPTION PROPERTIES OF NAY ZEOLITE FOR SEPARATION OF AROMATIC TRIAZOLES nay沸石对芳香三唑的吸附性能研究

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A806370B

Nicola L. Singleton, K. Huddersman, M. Needham

引用次数: 8

Characterisation of a basal-plane-oriented graphite 基底平面取向石墨的表征

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A801303I

E. Gilbert, P. A. Reynolds, J. White

{"title":"Characterisation of a basal-plane-oriented graphite","authors":"E. Gilbert, P. A. Reynolds, J. White","doi":"10.1039/A801303I","DOIUrl":"https://doi.org/10.1039/A801303I","url":null,"abstract":"We have employed scanning electron microscopy (SEM), scanning tunnelling microscopy (STM), wide-angle X-ray scattering (WAXS), small-angle neutron scattering (SANS) and adsorption isotherms to characterise the recompressed, exfoliated graphite ‘Papyex’. The substrate is found to consist of ca. 60% void space, most of which is associated with galleries with a thickness of ca. 300 A. The substrate contains ca. 70% rhombohedral and 30% hexagonal graphite crystallites with dimensions of the order of several hundred angstroms. We confirm that Papyex has preferentially oriented graphite (0001) planes whose surfaces mainly contribute to the total available surface area. Using the theory of Debye etal., the substrate may be classed as a random two-phase structure. SANS experiments employing contrast variation show that the voids in Papyex are connected and fillable. A Guinier analysis is inappropriate to apply to the present system owing to the large scale and interconnected nature of the void space of the galleries. BET analysis shows Papyex is a non-porous or macroporous material giving a Type II isotherm with a surface area of ca. 20 g−1 and negligible micropores. This suggests that the substrate consists of voids and macroscopic cracks and fissures with dimensions of the order of ca. 500 A or more. Porod analysis of the SANS data gives a surface dimension of 2.5 and a surface area comparable to that obtained from the BET analysis. However, the limited range in which power-law behaviour is observed makes conclusions about fractal dimensions and polydispersity questionable.","PeriodicalId":17286,"journal":{"name":"Journal of the Chemical Society, Faraday Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82934575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 36

Numerical simulation of temperature-programmed reaction data: an application in surface chemical kinetics 程控温度反应数据的数值模拟:在表面化学动力学中的应用

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A803766C

G. Ellis, J. Sidaway, M. McCoustra

引用次数: 5

Interaction of Triton X-100 with cyclodextrins. A fluorescence study Triton X-100与环糊精的相互作用。荧光研究

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A806868B

A. Datta, D. Mandal, S. Pal, Swati Das, K. Bhattacharyya

引用次数: 33

FTIR study of defects produced in ZrO2 samples by thermal treatment 热处理ZrO2试样中缺陷的FTIR研究

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A708208H

M. Daturi, C. Binet, S. Bernal, J. A. P. Omil, J. Lavalley

{"title":"FTIR study of defects produced in ZrO2 samples by thermal treatment","authors":"M. Daturi, C. Binet, S. Bernal, J. A. P. Omil, J. Lavalley","doi":"10.1039/A708208H","DOIUrl":"https://doi.org/10.1039/A708208H","url":null,"abstract":"The effect of two different thermal/chemical pretreatments on a high surface area zirconia sample has been studied using FTIR spectroscopy. As revealed by high resolution electron microscopy (HREM), the sample exhibits a significant concentration of small pores and cavities with size ranging from 1 to 2 nm. When pretreatment 1 was applied, (step-by-step heating under O2 followed by evacuation at increasing temperatures up to 873 K), the oxide appeared clean, and free from impurities detectable by IR spectroscopy. Likewise, no O2− species resulting from further O2 chemisorption at 298 K were observed. In contrast, the IR spectrum for the oxide exposed to pretreatment 2 (heating under O2 at 873 K, followed by fast evacuation at 873 K), shows a number of features that can be interpreted as due to oxalate-like species, as well as adsorbed CO. Additionally, superoxide species could be identified upon O2 chemisorption at room temperature. Further reoxidation treatment at 673 K induces the disappearance of CO features and the transformation of the oxalate-like species. The initial spectrum can be recovered by subsequent evacuation at 873 K, thus indicating the reversible nature of the chemical processes involved. In accordance with the HREM images, we propose that a redox interconversion reaction of chemisorbed species trapped in the oxide cavities is responsible for what we observe on the zirconia sample exposed to pretreatment 2.","PeriodicalId":17286,"journal":{"name":"Journal of the Chemical Society, Faraday Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83353522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 26

Surface-enhanced Raman spectroscopy of ClO4- and SO42- anions adsorbed at a Cu electrode Cu电极吸附ClO4-和SO42-阴离子的表面增强拉曼光谱

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A800574E

G. Niaura, A. Malinauskas

引用次数: 32

Solvation dynamics of Coumarin 503 in the liquid-crystal mixture ZLI 1167 香豆素503在液晶混合物ZLI 1167中的溶剂化动力学

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A703999I

G. Saielli, A. Polimeno, P. Nordio, P. Bartolini, M. Ricci, R. Righini

{"title":"Solvation dynamics of Coumarin 503 in the liquid-crystal mixture ZLI 1167","authors":"G. Saielli, A. Polimeno, P. Nordio, P. Bartolini, M. Ricci, R. Righini","doi":"10.1039/A703999I","DOIUrl":"https://doi.org/10.1039/A703999I","url":null,"abstract":"The solvation dynamics of the dye Coumarin 503 in the nematic mixture ZLI 1167 has been investigated by means of time-resolved fluorescence spectroscopy, both in the nematic and isotropic phases of the sample. No alignment was imposed on the micro-domains of the nematic phase, so that a complete depolarization of the emitted light was obtained. For the isotropic phase the usual set-up with vertically polarized excitation light and magic-angle detection was used. A time-dependent frequency shift of the maximum of the fluorescence band, caused by solvent reorganization after pulse excitation of the fluorescent probe, was observed. The analysis of the transient Stokes shift correlation function clearly shows biexponential behavior in the nematic phase, the slowest time constant varying from 1670 ps at 311.5 K to 230 ps at 373 K. The decay of the correlation function appears to be largely unaffected by the nematic–isotropic transition, suggesting that the local environment, rather than long-range ordering, determines Stokes shift dynamics. A theoretical model, which takes into account probe reorientations in the presence of a nematic field, and fluctuation of the local solvent polarization, has been developed to interpret the experimental findings.","PeriodicalId":17286,"journal":{"name":"Journal of the Chemical Society, Faraday Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89234538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Thermodynamics of ion solvation in dipolar solvent using Monte Carlo mean reaction field simulation 用蒙特卡罗平均反应场模拟离子在偶极溶剂中的溶剂化热力学

Journal of the Chemical Society, Faraday Transactions Pub Date : 1998-01-01 DOI: 10.1039/A706091B

A. Bandura, S. Lvov, D. Macdonald

{"title":"Thermodynamics of ion solvation in dipolar solvent using Monte Carlo mean reaction field simulation","authors":"A. Bandura, S. Lvov, D. Macdonald","doi":"10.1039/A706091B","DOIUrl":"https://doi.org/10.1039/A706091B","url":null,"abstract":"The mean reaction field approximation has been developed for Monte Carlo simulation of ion solvation thermodynamics and structure in ion–dipolar systems. Calculations have been carried out for systems having one hard-sphere ion and N-1 hard-sphere dipoles of equal diameter, 256⩽N⩽1372, where N is the number of particles. The reduced charge on the ion, q*, was varied from 0 to 14.15, and two values of the reduced dipole moment, µ*, (1.14 and 1.50) were used for the simulations. The mean reaction field corrections were introduced to take into account the changes in long-range dipole–dipole interactions due to the presence of the ion. The corrections were performed for molecules both inside and outside the truncation sphere, which has an ion at the center, resulting in a small dependence of solvation energy on simulation cell size. Expressions have been developed within the framework of thermodynamic integration and perturbation techniques for calculating the free-energy change on ion charging. The applicability of this approach for simulating the solvation internal energy has been investigated and compared with other methods. The influence of system size and cut-off radius on the thermodynamic solvation parameters and the radial distribution functions were studied. It has been shown that for N500, variation of the simulated system size and cut-off radius does not drastically affect the calculated thermodynamic quantities and radial distribution functions when the mean reaction field corrections were applied. The simulated thermodynamic solvation properties were compared with results found in the literature for various molecular statistical approaches [mean spherical approximation (MSA), linearized hypernetted-chain (LHNC), etc.].","PeriodicalId":17286,"journal":{"name":"Journal of the Chemical Society, Faraday Transactions","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89821600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4