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1986 Volume 2 Issue 2
1986, 2(02): 97-102
doi: 10.3866/PKU.WHXB19860201
Abstract:
The complex of Co(C_(13)H_(14)N_2)Cl_2 was prepared and crystal structures of the Iigand and the complex were determined by X-Ray diffraction. The crystallogr- aphic data and atomic coordinates with equivalent isotropic of the two structures are listed in Table 1 and Table 2 respectively. The tetrahedral coordination is found in the complex of Co(C_(13)H_(14)N_2)Cl_2. The torsion angle between pyridine ring and benzene ring is 5.0° in C_(13)H_(14)N_2 and 73.7° in Co(C_(13)H_(14)N_2)Cl_2. The confor- mations of the ligand in two crystal structures are very different (see Fig.2). The differences of the torsion angles of τ_1, τ_2, τ_3 and τ_4 between conformation 1 (conformation of C_(13)H_(14)N_2 in crystal state) and conformation 2 (conformation of C_(13)H_(14)N_2 in Co(C_(13)H_(14)N_2)Cl_2 crystal state) are 22.5°, 79.1°, -113.2° and 63.3° respectively. EHMO and DPCILO calculations were applied to describe the change of ligand conformations.
The complex of Co(C_(13)H_(14)N_2)Cl_2 was prepared and crystal structures of the Iigand and the complex were determined by X-Ray diffraction. The crystallogr- aphic data and atomic coordinates with equivalent isotropic of the two structures are listed in Table 1 and Table 2 respectively. The tetrahedral coordination is found in the complex of Co(C_(13)H_(14)N_2)Cl_2. The torsion angle between pyridine ring and benzene ring is 5.0° in C_(13)H_(14)N_2 and 73.7° in Co(C_(13)H_(14)N_2)Cl_2. The confor- mations of the ligand in two crystal structures are very different (see Fig.2). The differences of the torsion angles of τ_1, τ_2, τ_3 and τ_4 between conformation 1 (conformation of C_(13)H_(14)N_2 in crystal state) and conformation 2 (conformation of C_(13)H_(14)N_2 in Co(C_(13)H_(14)N_2)Cl_2 crystal state) are 22.5°, 79.1°, -113.2° and 63.3° respectively. EHMO and DPCILO calculations were applied to describe the change of ligand conformations.
1986, 2(02): 103-109
doi: 10.3866/PKU.WHXB19860202
Abstract:
The rheological properties of benzene and heptane solutions of cobalt monooleate soap have been investigated. The solution viscosity increased up to a steady equi- librium value with aging time. A remarkable non-Newtonian behavior was observed even with dilute soap solutions. The thickening ability of cobalt monosoap in non- polar media may be ascribed to the formation of polymer chains through the coo- rdination bonding between soap molecules. The high solution viscosity decreased to the same level as the solvent alone in the presence of small amounts of additives containing groups with strong coordinating ability with cobalt atom.
The rheological properties of benzene and heptane solutions of cobalt monooleate soap have been investigated. The solution viscosity increased up to a steady equi- librium value with aging time. A remarkable non-Newtonian behavior was observed even with dilute soap solutions. The thickening ability of cobalt monosoap in non- polar media may be ascribed to the formation of polymer chains through the coo- rdination bonding between soap molecules. The high solution viscosity decreased to the same level as the solvent alone in the presence of small amounts of additives containing groups with strong coordinating ability with cobalt atom.
1986, 2(02): 110-118
doi: 10.3866/PKU.WHXB19860203
Abstract:
An approach of theoretical calculation of Cibbs Free Energy of ionic solvation has been proposed. A new treatment of electrostatic interaction between ion and solvent molecules located in the first solvation layer has been shown. Contribution of solute-solvent interaction to energy calcuiation has been considered. Born equation was used in the calculation of electrostatic energy out of the first solva- tion layer. Scaled particle theory was used for non-electrostatic interactions. Re- pulsion energy was estimated by the formula given by F. H. Lee and Y. K. Tai. Calculations of various kinds of ions in H_2O, DMF and PC are in od agreement with experimental values.
An approach of theoretical calculation of Cibbs Free Energy of ionic solvation has been proposed. A new treatment of electrostatic interaction between ion and solvent molecules located in the first solvation layer has been shown. Contribution of solute-solvent interaction to energy calcuiation has been considered. Born equation was used in the calculation of electrostatic energy out of the first solva- tion layer. Scaled particle theory was used for non-electrostatic interactions. Re- pulsion energy was estimated by the formula given by F. H. Lee and Y. K. Tai. Calculations of various kinds of ions in H_2O, DMF and PC are in od agreement with experimental values.
1986, 2(02): 119-124
doi: 10.3866/PKU.WHXB19860204
Abstract:
Using N_2 laser as an excited source, the fluorescence spectra of ethanol solu- tions of rhodamine 6G(Rh6G) and N,N′-dimethyl-carbothiocyanine iodide(DMTC) mixed at various concentrations have been studied. The results show that Rh6G and DMTC compose donor-accepter pair and exist intermolecular energy transfer effect. By means of measuring the relation between DMTC fluorescence intensity and Rh6G concentration, we have discussed the mechanism of Rh6G-DMTC energy transfer and have deduced the relative expressions of accepter fluorescence intensity and donor concentraton for both radiative transfer and Förster transfer processes.
Using N_2 laser as an excited source, the fluorescence spectra of ethanol solu- tions of rhodamine 6G(Rh6G) and N,N′-dimethyl-carbothiocyanine iodide(DMTC) mixed at various concentrations have been studied. The results show that Rh6G and DMTC compose donor-accepter pair and exist intermolecular energy transfer effect. By means of measuring the relation between DMTC fluorescence intensity and Rh6G concentration, we have discussed the mechanism of Rh6G-DMTC energy transfer and have deduced the relative expressions of accepter fluorescence intensity and donor concentraton for both radiative transfer and Förster transfer processes.
1986, 2(02): 125-132
doi: 10.3866/PKU.WHXB19860205
Abstract:
A Flow-DTA adsorptive calorimetric system constructed by the combination of Differential Thermal Analysis (DTA) and Gas Chromatograph is described in this paper. Through the column thermotank designed specially the DTA cell and the Katharometer are combined. A system for the inputting of sample taking the form of a rectangular pulse is assembled. The higher sensitivity and lower noise level and synchronism of DTA and Katharometer response make it possible to determine the heat effects in various adsorption processes. The reliability of this method has been verified by the fact that the results obtained in this paper are consistent with those determined by the adsorption microcalorimeter and the fact that the experimental data of adsorption equilibrium and of calorimetric adsorption heat are in agreement with each other. The system is available to investigate the adsorption and catalysis in the conditions which are approximate to those in the industrial reactions.
A Flow-DTA adsorptive calorimetric system constructed by the combination of Differential Thermal Analysis (DTA) and Gas Chromatograph is described in this paper. Through the column thermotank designed specially the DTA cell and the Katharometer are combined. A system for the inputting of sample taking the form of a rectangular pulse is assembled. The higher sensitivity and lower noise level and synchronism of DTA and Katharometer response make it possible to determine the heat effects in various adsorption processes. The reliability of this method has been verified by the fact that the results obtained in this paper are consistent with those determined by the adsorption microcalorimeter and the fact that the experimental data of adsorption equilibrium and of calorimetric adsorption heat are in agreement with each other. The system is available to investigate the adsorption and catalysis in the conditions which are approximate to those in the industrial reactions.
1986, 2(02): 133-140
doi: 10.3866/PKU.WHXB19860206
Abstract:
~(23)Na~+ chemical shift of NaClO_4 in mixed solvents of water-acetone,water- acetonitrile, and water-ethanol and of NaBPh_4 in methanol-DMF, methanol-benzene, and methanol-dioxane were measured. By means of iso-solvation point the sol- rating abilities were compared as water>acetone≥acetonitile≥ethanol and DMF> methanol. The preferential solvation free energies of Na~+ for the pairs solvenst, methanol-DMF and water-acetone, were evaluated as -2.7 kJmol~(-1) for DMF to methanol and 4.6 kJmol~(-1) for acetone to water.
~(23)Na~+ chmical shift in methanol-benzene is independent of the content of benzene. It verified the simple solvation modle for ion in methanol-inert solvent mixture. However the chemical shift of ~(23)Na~+ in methanol-dioxane mixture varies with the composition of solvent. The linewidth of Na-23 resonance peak increases dramtically with the increasing of dioxane. It seems that the dioxane molecules disturb the primary solvation shell of Na~+ in methanol and result a unsymmetrical immediate surrounding for Na~+ cation.
~(23)Na~+ chemical shift of NaClO_4 in mixed solvents of water-acetone,water- acetonitrile, and water-ethanol and of NaBPh_4 in methanol-DMF, methanol-benzene, and methanol-dioxane were measured. By means of iso-solvation point the sol- rating abilities were compared as water>acetone≥acetonitile≥ethanol and DMF> methanol. The preferential solvation free energies of Na~+ for the pairs solvenst, methanol-DMF and water-acetone, were evaluated as -2.7 kJmol~(-1) for DMF to methanol and 4.6 kJmol~(-1) for acetone to water.
~(23)Na~+ chmical shift in methanol-benzene is independent of the content of benzene. It verified the simple solvation modle for ion in methanol-inert solvent mixture. However the chemical shift of ~(23)Na~+ in methanol-dioxane mixture varies with the composition of solvent. The linewidth of Na-23 resonance peak increases dramtically with the increasing of dioxane. It seems that the dioxane molecules disturb the primary solvation shell of Na~+ in methanol and result a unsymmetrical immediate surrounding for Na~+ cation.
1986, 2(02): 141-145
doi: 10.3866/PKU.WHXB19860207
Abstract:
The binary systems composed of alcohols and other organic solvents, both in theory and in practice, are important to us. Researches for the thermodynamic properties of these systems can not only provide reliable data and empirical rules for science and technology, but also help to investigate the states, structures of the solutes and sol- vent in solution as well as their interactions. In this series, by measuring the excess thermodynamic functions (such as the heats of mixing, volume changes on mixing and excess free energies) for the systems of C_1 to C_(10) alcohls with various organic solvents we will explore the influence of the size and structure of the molecules present in mixtures on excess termodynamic functions, and further discuss these effects from theories of solution.
In the first part, molar excess enthalpies of methanol+, ethanol+, n-propanol+, n-butanol+and n-amyl alcohol+benzene at 298.15 K and under normal pressure have been measured with a Picker flow microcalorimeter. The results obtained was slightly higher than those of the available literature data. Maximum values of H~E for these systems are situated on 0.30—0.33 mole fraction of alcohols. Molar excess enthalpies of the titled systems increase with chain length of the alcohols, whereas the difference between two neighbouring alcohols decrease with increasing of the number of carbon atoms in alcohol.
The binary systems composed of alcohols and other organic solvents, both in theory and in practice, are important to us. Researches for the thermodynamic properties of these systems can not only provide reliable data and empirical rules for science and technology, but also help to investigate the states, structures of the solutes and sol- vent in solution as well as their interactions. In this series, by measuring the excess thermodynamic functions (such as the heats of mixing, volume changes on mixing and excess free energies) for the systems of C_1 to C_(10) alcohls with various organic solvents we will explore the influence of the size and structure of the molecules present in mixtures on excess termodynamic functions, and further discuss these effects from theories of solution.
In the first part, molar excess enthalpies of methanol+, ethanol+, n-propanol+, n-butanol+and n-amyl alcohol+benzene at 298.15 K and under normal pressure have been measured with a Picker flow microcalorimeter. The results obtained was slightly higher than those of the available literature data. Maximum values of H~E for these systems are situated on 0.30—0.33 mole fraction of alcohols. Molar excess enthalpies of the titled systems increase with chain length of the alcohols, whereas the difference between two neighbouring alcohols decrease with increasing of the number of carbon atoms in alcohol.
1986, 2(02): 146-152
doi: 10.3866/PKU.WHXB19860208
Abstract:
An experimental study of the chemiluminescent reaction of Sn with N_2O and O_2 is first performed in a supersonic flow apparatus by using the electric-arc plasma technique to generate atomic Sn vapor. The temperature and pressure in the reacton zone are 900 K and 1-10 torr, respectively. The emission spectra of SnO (a~3Σ~+-X~1Σ~+) are recorded using an optical multichannel analyzer (OMA) at different reaction pressures and the dependence of the relative vibrational population of the product SnO(a~3Σ~+), on the pressure has been presented. The vibraitional relaxation rates of the SnO (a~3Σ~+) by Ar and Ar+N_2 had been calculated as ～10~4 torr~(-1) s~(-1) by the leastsquare fit of the experimental data. The emissions from the electronically excited states, b~3Π and a~3Σ~+, in the reaction of Sn+O_2 can be explained in terms of the reactions of Sn_2+O_2 and Sn_2+O. An unusually high population of a~3Σ~+v′=1 in the reaction of Sn+O_2 is also found. The results are compared with those obtained in high-temperature-fast-flow reactor (HTFFR) and the reaction mechanism is discussed.
An experimental study of the chemiluminescent reaction of Sn with N_2O and O_2 is first performed in a supersonic flow apparatus by using the electric-arc plasma technique to generate atomic Sn vapor. The temperature and pressure in the reacton zone are 900 K and 1-10 torr, respectively. The emission spectra of SnO (a~3Σ~+-X~1Σ~+) are recorded using an optical multichannel analyzer (OMA) at different reaction pressures and the dependence of the relative vibrational population of the product SnO(a~3Σ~+), on the pressure has been presented. The vibraitional relaxation rates of the SnO (a~3Σ~+) by Ar and Ar+N_2 had been calculated as ～10~4 torr~(-1) s~(-1) by the leastsquare fit of the experimental data. The emissions from the electronically excited states, b~3Π and a~3Σ~+, in the reaction of Sn+O_2 can be explained in terms of the reactions of Sn_2+O_2 and Sn_2+O. An unusually high population of a~3Σ~+v′=1 in the reaction of Sn+O_2 is also found. The results are compared with those obtained in high-temperature-fast-flow reactor (HTFFR) and the reaction mechanism is discussed.
1986, 2(02): 153-159
doi: 10.3866/PKU.WHXB19860209
Abstract:
In this paper, the scaled particle theory (SPT) is improved by considering various interactions among particles in solution and then is applied to ternary sys- tems with a polar organic compound.
The salting effect constants of di(2-ethyl-hexyl) phoshoric acid (D2EHPA) in alkali chloride solutions were determined by tracer technique. By comparing the results calculated by the improved SPT formulas with the experimental values, it seems that the improved SPT formulas are much better than the previous if the parameters are chosen properly.
It is found that the calculated results are sensitive to the ionic radii and the hardcore diameter of the non-electrolyte. A method, based on the packing factor, is also suggested to estimate the hardcore diameter of the non-electrolyte.
In this paper, the scaled particle theory (SPT) is improved by considering various interactions among particles in solution and then is applied to ternary sys- tems with a polar organic compound.
The salting effect constants of di(2-ethyl-hexyl) phoshoric acid (D2EHPA) in alkali chloride solutions were determined by tracer technique. By comparing the results calculated by the improved SPT formulas with the experimental values, it seems that the improved SPT formulas are much better than the previous if the parameters are chosen properly.
It is found that the calculated results are sensitive to the ionic radii and the hardcore diameter of the non-electrolyte. A method, based on the packing factor, is also suggested to estimate the hardcore diameter of the non-electrolyte.
1986, 2(02): 160-165
doi: 10.3866/PKU.WHXB19860210
Abstract:
Based on the results of phase plane analysis in paper I and using the technique of linear stability analysis and numerical simulation, the dynamic be- haviour of Schlögl model in CSTR is further analysed. It is shown that, with in- creasing the input concentration x° of species X but fixing the values of other parameters, the system may under the bifurcation from one steady state to three steady states and in turn to one steady state again, shown as in Fig.2.
Linear stability analysis shows that only one of the three branches of steady states for A<x°<B is stable. This stability feature may endow the system such an interesting behaviour that when the value of x° passes through point B, the transition from steady state on branch (1) to oscillatory state around branch (2) is discontinuous and abrupt, that is, the system transits abruptly from a steady stase to an oscillatory state with finite amplitude. On the other hand, the transition from oscillatory state to steady one (or inverse transition) is smooth and continuous when the value of x° passes through point C.
From the point of view of bifurcation theory, above discontinuous transiton belongs the saddle-node transition, that is, the saddle point and node approach each other, merge into one compliated multiple singular point, and finally disappear and a limit cycle apears. This result would be helpful for explaination of some abrupt transition phenomena between steady state and oscillatory stte observed in some physical-chemical systems, such as B-Z reaction system.
Based on the results of phase plane analysis in paper I and using the technique of linear stability analysis and numerical simulation, the dynamic be- haviour of Schlögl model in CSTR is further analysed. It is shown that, with in- creasing the input concentration x° of species X but fixing the values of other parameters, the system may under the bifurcation from one steady state to three steady states and in turn to one steady state again, shown as in Fig.2.
Linear stability analysis shows that only one of the three branches of steady states for A<x°<B is stable. This stability feature may endow the system such an interesting behaviour that when the value of x° passes through point B, the transition from steady state on branch (1) to oscillatory state around branch (2) is discontinuous and abrupt, that is, the system transits abruptly from a steady stase to an oscillatory state with finite amplitude. On the other hand, the transition from oscillatory state to steady one (or inverse transition) is smooth and continuous when the value of x° passes through point C.
From the point of view of bifurcation theory, above discontinuous transiton belongs the saddle-node transition, that is, the saddle point and node approach each other, merge into one compliated multiple singular point, and finally disappear and a limit cycle apears. This result would be helpful for explaination of some abrupt transition phenomena between steady state and oscillatory stte observed in some physical-chemical systems, such as B-Z reaction system.
1986, 2(02): 166-172
doi: 10.3866/PKU.WHXB19860211
Abstract:
In this paper, ZnO/γ-Al_2O_3 system has been studied by XRD and XPS. Ex- perimental results show that ZnO reacts with γ-Al_2O_3 in solid state extremely readily, and it can be observed after heating at 240 ℃.
The structure and state of samples depond on the conditions of calcination and the composition of samples. The samples with less ZnO are made up of zinc-defi- cient zinc aluminate (Zn_xAl_2O_(3+x), 0<x<1), whose composition in surface phase depends on the conditions of calcination and the composition of precursors. There are two situations for the samples with more ZnO: The samples calcined at lower temperature consist of Zn_xAl_2O_(3+x) and crystalline ZnO. However calcined at high temperature, they can form the stoichiometric zinc aluminate ZnAl_2O_4 with a monolayer zinc oxide on it. When the ZnO content in ZnO/ZnAl_2O_4 is above the monolayer capacity, crystaalline ZnO begins to appear.It was estimated that most samples except those calcined at high temperature have not reached the equilibrium states. So, their structure and character should be closely related to the conditions of preparation and operation.
In this paper, ZnO/γ-Al_2O_3 system has been studied by XRD and XPS. Ex- perimental results show that ZnO reacts with γ-Al_2O_3 in solid state extremely readily, and it can be observed after heating at 240 ℃.
The structure and state of samples depond on the conditions of calcination and the composition of samples. The samples with less ZnO are made up of zinc-defi- cient zinc aluminate (Zn_xAl_2O_(3+x), 0<x<1), whose composition in surface phase depends on the conditions of calcination and the composition of precursors. There are two situations for the samples with more ZnO: The samples calcined at lower temperature consist of Zn_xAl_2O_(3+x) and crystalline ZnO. However calcined at high temperature, they can form the stoichiometric zinc aluminate ZnAl_2O_4 with a monolayer zinc oxide on it. When the ZnO content in ZnO/ZnAl_2O_4 is above the monolayer capacity, crystaalline ZnO begins to appear.
1986, 2(02): 173-182
doi: 10.3866/PKU.WHXB19860212
Abstract:
In this artical, a new concept of local symmetry for chemical reaction is used to produce the correlation diagrams and the curves of total energe of elec- trons for various cheletropic reactions, i.e. the odd-even selection rules for eheletropie reactions are obtained.
In this artical, a new concept of local symmetry for chemical reaction is used to produce the correlation diagrams and the curves of total energe of elec- trons for various cheletropic reactions, i.e. the odd-even selection rules for eheletropie reactions are obtained.
1986, 2(02): 183-189
doi: 10.3866/PKU.WHXB19860213
Abstract:
This investigation is related to solubilisation process of aqueous micellar solu- tion containing nonpolar m-xylene or moderately polar benzyl alcohol and surfac- tant sodium dodecyl sulfate (SDS) by high resolution proton nuclear magnetic resonance spectroscopy (~1H-NMR).
The examined results indicate that the long chain methylene in SDS shows a singlet signal for m-xylene/SDS/H_2O system,while it is split into an up-field signal and a down-field signal for benzyl alcohol/SDS/H_2O system. From the de- pendence of chemical shifts of SDS on solubilisate concentration, it is ascertained that at low solubilisate contents m-xylene or benzyl alcohol is solubilised by adsorption at the micelle-water “interface”. With further addition of m-xylene, it is solubilised and uniformly distributed along the hybrocarbon chain of surfactant. When mole fraction of m-xylene in surfactant is about 0.34, m-xylene es predominantly the hydrocarbon chain of hte surfactant molecules. Whereas, benzyl alcohol solubilisation is probably localized in the palisade layer. It is orientated in such a manner ring is directed towarde the micellar interior. When a benzyl alcohol content approximates to 0.77 mole fraction, benzyl alcohol may predominantly to the centre of the micellar interior core.
The above-mentioned results are also discussed theoretically in this paper.
This investigation is related to solubilisation process of aqueous micellar solu- tion containing nonpolar m-xylene or moderately polar benzyl alcohol and surfac- tant sodium dodecyl sulfate (SDS) by high resolution proton nuclear magnetic resonance spectroscopy (~1H-NMR).
The examined results indicate that the long chain methylene in SDS shows a singlet signal for m-xylene/SDS/H_2O system,while it is split into an up-field signal and a down-field signal for benzyl alcohol/SDS/H_2O system. From the de- pendence of chemical shifts of SDS on solubilisate concentration, it is ascertained that at low solubilisate contents m-xylene or benzyl alcohol is solubilised by adsorption at the micelle-water “interface”. With further addition of m-xylene, it is solubilised and uniformly distributed along the hybrocarbon chain of surfactant. When mole fraction of m-xylene in surfactant is about 0.34, m-xylene es predominantly the hydrocarbon chain of hte surfactant molecules. Whereas, benzyl alcohol solubilisation is probably localized in the palisade layer. It is orientated in such a manner ring is directed towarde the micellar interior. When a benzyl alcohol content approximates to 0.77 mole fraction, benzyl alcohol may predominantly to the centre of the micellar interior core.
The above-mentioned results are also discussed theoretically in this paper.
1986, 2(02): 190-191
doi: 10.3866/PKU.WHXB19860214
Abstract:
The non-ortho nal localized molecular orbitals (NOLMO) and Fock energies of σ_(C-H) and σ_(C-C) bonding orbitals, and inner shell orbitals of carbon atoms in various hybridized molecules were evaluated. It was shown that NOLMO and the Fock energies are transferable among various hybridized molecules. It is possible, therefore, to calculate certain chemical and physical properties of big molecules by means of NOLMO of small molecules.
The non-ortho nal localized molecular orbitals (NOLMO) and Fock energies of σ_(C-H) and σ_(C-C) bonding orbitals, and inner shell orbitals of carbon atoms in various hybridized molecules were evaluated. It was shown that NOLMO and the Fock energies are transferable among various hybridized molecules. It is possible, therefore, to calculate certain chemical and physical properties of big molecules by means of NOLMO of small molecules.
