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1990 Volume 6 Issue 2
1990, 6(02): 129-131
doi: 10.3866/PKU.WHXB19900201
Abstract:
The low temperature infrared spectroscopy was applied to investigate the adsorp-tion of NO and CO on CuO/γ-Al_2O_3. The measured infrared bands were asigned. The results of alternate adsorption and coadsorption of NO and CO exhibited that Cu~(2+) and Cu~+ sites coexist on the surface of oxidized CuO/γ-Al_2O_3 and the selective ad-sorption of CO/Cu~+ and NO/Cu~(2+) was observed.
The low temperature infrared spectroscopy was applied to investigate the adsorp-tion of NO and CO on CuO/γ-Al_2O_3. The measured infrared bands were asigned. The results of alternate adsorption and coadsorption of NO and CO exhibited that Cu~(2+) and Cu~+ sites coexist on the surface of oxidized CuO/γ-Al_2O_3 and the selective ad-sorption of CO/Cu~+ and NO/Cu~(2+) was observed.
1990, 6(02): 132-133
doi: 10.3866/PKU.WHXB19900202
Abstract:
In this paper we defined regidly the microscopic hole existing in molten salt and established the embedding method for locating the hole and calculating the size of the hole. To describe the statistical distribution of the microscopic holes better we introduce the RDF of the microscopic hole. In molten 900 K LiCl we finded that there were about 20 microscopic holes with the radius larger than 0.10 nm, the largest is 0.18 nm. The RDF of the microscopic holes shewed us that both g_(h-Li~+) (r) and g_(h-Cl~-)(r) have two peaks. The maximal values of the two peaks are about 0.5. The coordinated number of Li~+ ion with microscopic hole is about one and that of Cl~- ion is about 1.5. Using this method we can study the distributional character of different radius of the microscopic holes.
In this paper we defined regidly the microscopic hole existing in molten salt and established the embedding method for locating the hole and calculating the size of the hole. To describe the statistical distribution of the microscopic holes better we introduce the RDF of the microscopic hole. In molten 900 K LiCl we finded that there were about 20 microscopic holes with the radius larger than 0.10 nm, the largest is 0.18 nm. The RDF of the microscopic holes shewed us that both g_(h-Li~+) (r) and g_(h-Cl~-)(r) have two peaks. The maximal values of the two peaks are about 0.5. The coordinated number of Li~+ ion with microscopic hole is about one and that of Cl~- ion is about 1.5. Using this method we can study the distributional character of different radius of the microscopic holes.
1990, 6(02): 134-138
doi: 10.3866/PKU.WHXB19900203
Abstract:
The kinetics of anodic O_2 evolution on Ti/RuO_2+TiO_2 anodes was studied in acid solutions, by with two Tafel regions have been confirmed. At low current densities i.e. the first Tafel region ?φ/lgi=2.303RT/((1+β)F, whereas at high cds i. e. second Tafel region it is 2.303RT/βF. In the low current densities region, the reaction order with respect to α_w is 4. For the second Tafel region the reaction order is 2.
The kinetic data obtained show that the rate determining step of the anodic evo-lution of oxygen on Ti/RuO_2+TiO_2 anodes in acid solutions is
...
The kinetics of anodic O_2 evolution on Ti/RuO_2+TiO_2 anodes was studied in acid solutions, by with two Tafel regions have been confirmed. At low current densities i.e. the first Tafel region ?φ/lgi=2.303RT/((1+β)F, whereas at high cds i. e. second Tafel region it is 2.303RT/βF. In the low current densities region, the reaction order with respect to α_w is 4. For the second Tafel region the reaction order is 2.
The kinetic data obtained show that the rate determining step of the anodic evo-lution of oxygen on Ti/RuO_2+TiO_2 anodes in acid solutions is
...
1990, 6(02): 139-145
doi: 10.3866/PKU.WHXB19900204
Abstract:
The bi-exponential decay of the luminescence of electronically excited uranyl ions in perchloric acid has been investigated with detailed study of the time resolved lu-minescence spectra and Raman spectra of uranium. While the U(Ⅵ) concentration is in the range of 0.01-0. 1 molL~(-1) and the pH is≤1.5, the luminescence decay is sin-gle exponential and the luminescence spectra are independent on the delay time and the U(Ⅵ) concentration with peaks at 488.0, 510.0, and 533.0 nm, which belong toaquo-uranyl ions. While the pH of the solution is increased to higher than 2.8, the luminescence under es bi-exponential decay and the luminescence spectra with 0.2 μs delay time change dramatically with increasing the pH and the U(VI) concentration, and are different from the spectra with 20 μs time delay, which consist of three peaks at 500.0, 518.0, and 538.0 nm. From the thermodynamic data of the hydrolysis of uranyl ions and the dependence of the Raman spectra of U(VI) on the pH and the uranium concentration the later spectra can be identified as the spectra of the dinuclear hydrolysis product of UO~(2+)_2 and (UO_2)_2(OH)~(2+)_2. All the measured time resolved spectra can be fitted to the linear combination of the spectra of aquo-uranyl ions and (UO_2)~(2+)_2(OH)~(2+)_2 satisfatorily. The conclusion that the bi-exponential decay is attributed to UO_2(H_2O)~(2+)_x and (UO_2)_2(OH)~(2+)_2 ions has been withdrawn.
The bi-exponential decay of the luminescence of electronically excited uranyl ions in perchloric acid has been investigated with detailed study of the time resolved lu-minescence spectra and Raman spectra of uranium. While the U(Ⅵ) concentration is in the range of 0.01-0. 1 molL~(-1) and the pH is≤1.5, the luminescence decay is sin-gle exponential and the luminescence spectra are independent on the delay time and the U(Ⅵ) concentration with peaks at 488.0, 510.0, and 533.0 nm, which belong toaquo-uranyl ions. While the pH of the solution is increased to higher than 2.8, the luminescence under es bi-exponential decay and the luminescence spectra with 0.2 μs delay time change dramatically with increasing the pH and the U(VI) concentration, and are different from the spectra with 20 μs time delay, which consist of three peaks at 500.0, 518.0, and 538.0 nm. From the thermodynamic data of the hydrolysis of uranyl ions and the dependence of the Raman spectra of U(VI) on the pH and the uranium concentration the later spectra can be identified as the spectra of the dinuclear hydrolysis product of UO~(2+)_2 and (UO_2)_2(OH)~(2+)_2. All the measured time resolved spectra can be fitted to the linear combination of the spectra of aquo-uranyl ions and (UO_2)~(2+)_2(OH)~(2+)_2 satisfatorily. The conclusion that the bi-exponential decay is attributed to UO_2(H_2O)~(2+)_x and (UO_2)_2(OH)~(2+)_2 ions has been withdrawn.
1990, 6(02): 146-150
doi: 10.3866/PKU.WHXB19900205
Abstract:
The nature and mechanism of solubilization of the block copolymer of polyoxye-thylene-polyoxypropylene glycols-Pluronic were investigated and the results showed that only the samples with appropriate HLB value were valid for solubilization. In aqueous solution of L64 the aromatic hydrocarbon could be solubilized, while the alkanes almost could not. The lowest concentration of L64 for solubilization decreased with the increase of the temperature.
Water could also be solubilizated in the xylene solution of L64. The size of the inverse micelles of solubilized water was much bigger than that of the micelles of solubilized xylene.
Ultraviolet and NMR spectroscopic studies showed that the xylene and toluene were included into the polyoxypropylene chains at the interior of the micelles for the PPO-PEO block copolymer.
The nature and mechanism of solubilization of the block copolymer of polyoxye-thylene-polyoxypropylene glycols-Pluronic were investigated and the results showed that only the samples with appropriate HLB value were valid for solubilization. In aqueous solution of L64 the aromatic hydrocarbon could be solubilized, while the alkanes almost could not. The lowest concentration of L64 for solubilization decreased with the increase of the temperature.
Water could also be solubilizated in the xylene solution of L64. The size of the inverse micelles of solubilized water was much bigger than that of the micelles of solubilized xylene.
Ultraviolet and NMR spectroscopic studies showed that the xylene and toluene were included into the polyoxypropylene chains at the interior of the micelles for the PPO-PEO block copolymer.
1990, 6(02): 151-158
doi: 10.3866/PKU.WHXB19900206
Abstract:
In this paper the bonded tableau method for many-electron systems, which was recently proposed by authors, is exploited to study the chemical interactions of sub-systems. Two approaches are given for constructing symmetry adapted states of par-tition system, namely the method based on the non-standard basis projector of the permutation group and the coupling method of bonded tableaux. Based on the par-tition states, the interaction energy between two subsystems is investigated. The present method can be easily used, in valence bond (VB) structure interaction or configuration interaction (GI) level, to handle with the general problems of partition system, such as the problems of inter- or intra-molecule interaction.
In this paper the bonded tableau method for many-electron systems, which was recently proposed by authors, is exploited to study the chemical interactions of sub-systems. Two approaches are given for constructing symmetry adapted states of par-tition system, namely the method based on the non-standard basis projector of the permutation group and the coupling method of bonded tableaux. Based on the par-tition states, the interaction energy between two subsystems is investigated. The present method can be easily used, in valence bond (VB) structure interaction or configuration interaction (GI) level, to handle with the general problems of partition system, such as the problems of inter- or intra-molecule interaction.
1990, 6(02): 159-162
doi: 10.3866/PKU.WHXB19900207
Abstract:
The voltammetric characteristics of RuO_2 electrode has been studied by means of cyclic voltammetry and pulse polarography. In the potential range of 0.2-0.8 V, there are two redox reactions as follows:
RuOOH<+>RuO_2+H~++e
RuO_2+H_2O<=>RuO_3+2H~++2e
but not one redox reaction to turn Ru~(3+) into Ru~(4+).
The oxygen-deficient structures are the active sites whose disappearance results in the deactivation of the electrode.
The voltammetric characteristics of RuO_2 electrode has been studied by means of cyclic voltammetry and pulse polarography. In the potential range of 0.2-0.8 V, there are two redox reactions as follows:
RuOOH<+>RuO_2+H~++e
RuO_2+H_2O<=>RuO_3+2H~++2e
but not one redox reaction to turn Ru~(3+) into Ru~(4+).
The oxygen-deficient structures are the active sites whose disappearance results in the deactivation of the electrode.
1990, 6(02): 163-168
doi: 10.3866/PKU.WHXB19900208
Abstract:
In this paper, we have studied the mechanism of intermolecular energy transfer of Rh6G and Cresyl Violet which form a donor-acceptor pair in mixture solution. The relationship between the fluorescence intensity of Cresyl Violet and its concentration has been emphatically studied. The effect of self-absorption of Cresyl Violet upon the fluorescence intensity is appreciable and can not be ignored, as the concentration of Cresyl Violet being high. Considering the effect of self-absorption, we have mo-dified the theoretical formula obtained by Birks, and deduced the relative expressions of acceptor fluorescence intensity and acceptor concentration for both radiative transfer and Forster transfer processes.
In this paper, we have studied the mechanism of intermolecular energy transfer of Rh6G and Cresyl Violet which form a donor-acceptor pair in mixture solution. The relationship between the fluorescence intensity of Cresyl Violet and its concentration has been emphatically studied. The effect of self-absorption of Cresyl Violet upon the fluorescence intensity is appreciable and can not be ignored, as the concentration of Cresyl Violet being high. Considering the effect of self-absorption, we have mo-dified the theoretical formula obtained by Birks, and deduced the relative expressions of acceptor fluorescence intensity and acceptor concentration for both radiative transfer and Forster transfer processes.
1990, 6(02): 169-176
doi: 10.3866/PKU.WHXB19900209
Abstract:
Relationships between the activity of a certain component and the product of ac-tivities of three components, Φ, which may be the activity of the compound, on boundaries of two-phase region in ternary systems have been studied. An important formula expressing above mentioned relationships has been derived. It is a common expression which involves various kinds of formulae for two-phase region in ternary systems. At the same time, we analyzed in detail the influence of the direction of tie-line on relationships between the activities. A parameter θ is empolyed in order to overcome the difficulties encountered in integration in the two-phase region. In addition, we consummated Krivsky and Schuhmann's rule on the basis of certain results in the paper.
Relationships between the activity of a certain component and the product of ac-tivities of three components, Φ, which may be the activity of the compound, on boundaries of two-phase region in ternary systems have been studied. An important formula expressing above mentioned relationships has been derived. It is a common expression which involves various kinds of formulae for two-phase region in ternary systems. At the same time, we analyzed in detail the influence of the direction of tie-line on relationships between the activities. A parameter θ is empolyed in order to overcome the difficulties encountered in integration in the two-phase region. In addition, we consummated Krivsky and Schuhmann's rule on the basis of certain results in the paper.
1990, 6(02): 177-182
doi: 10.3866/PKU.WHXB19900210
Abstract:
The mechanism of the thermolysis of oxetane to form ethylene and formaldehyde has been studied in detail by semiempirical molecular orbital theory. The calculations have been carried out using a new general purpose quantum mechanical molecular model AM_1 presented by M. J. S. Dewar et al in 1985,and performed with GAUSSIAN 86 program. The various critical points in the region of the reaction have been fully optimized with Berny gradients and transition structures (TS) have been confirmed by frequency analysis. By calculations, we concluded that: 1) concerted supra-supra reaction path doesn't exist and the critical point involved is a second-order asddle point with two negative eigenvalues; 2) concerted supra-antara approach is found to proceed via a very high energy transition state; 3) the favoured reaction pathway is found to proceed via a stepwise approach characterized by diradical intermediates. The stepwise approach has two different pathways, one of them is to cleava carbon-car-bon bond firstly and then carbon-oxygen bond, it involves gauche intermediate and corresponding transition states. Another stepwise pathway is to break carbon-oxygen bond at first and then carbon-carbon bond, it proceeds vis a gauche or a trans intermediate and corresponding transition states. The two stepwise pathways coexist and compete each other.
The mechanism of the thermolysis of oxetane to form ethylene and formaldehyde has been studied in detail by semiempirical molecular orbital theory. The calculations have been carried out using a new general purpose quantum mechanical molecular model AM_1 presented by M. J. S. Dewar et al in 1985,and performed with GAUSSIAN 86 program. The various critical points in the region of the reaction have been fully optimized with Berny gradients and transition structures (TS) have been confirmed by frequency analysis. By calculations, we concluded that: 1) concerted supra-supra reaction path doesn't exist and the critical point involved is a second-order asddle point with two negative eigenvalues; 2) concerted supra-antara approach is found to proceed via a very high energy transition state; 3) the favoured reaction pathway is found to proceed via a stepwise approach characterized by diradical intermediates. The stepwise approach has two different pathways, one of them is to cleava carbon-car-bon bond firstly and then carbon-oxygen bond, it involves gauche intermediate and corresponding transition states. Another stepwise pathway is to break carbon-oxygen bond at first and then carbon-carbon bond, it proceeds vis a gauche or a trans intermediate and corresponding transition states. The two stepwise pathways coexist and compete each other.
1990, 6(02): 183-189
doi: 10.3866/PKU.WHXB19900211
Abstract:
Acidity of La~(3+)-exchanged HY zeolite has been studied by the measurements of adsorption on the in-situ IR system and MAS-NMR method. The results show that:
1.The IR bands at 3631 and 3556 cm~(-1) are all assigned to hydroxyl group of strong acidic sites. The band at 3531 cm~(-1) is assigned to nonacidic hydroxyl group, since it has no interaction with ammonia. It is possible that two hydroxyl groups coor-dinate with one La~(3+) directly; the band at 3520 cm~(-1) is assigned to weak acidic hy-droxyl group, because it has weak interaction with ammonia, and one hydroxyl group may coordinate with one La~(3+) directly.
2. The hydroxyl group at 3638 cm~(-1), which is in supercage of HY Zeolite, is of heterogeneity of actidity resulting from silicon atoms with different numbers of coordinated Aluminium.
Acidity of La~(3+)-exchanged HY zeolite has been studied by the measurements of adsorption on the in-situ IR system and MAS-NMR method. The results show that:
1.The IR bands at 3631 and 3556 cm~(-1) are all assigned to hydroxyl group of strong acidic sites. The band at 3531 cm~(-1) is assigned to nonacidic hydroxyl group, since it has no interaction with ammonia. It is possible that two hydroxyl groups coor-dinate with one La~(3+) directly; the band at 3520 cm~(-1) is assigned to weak acidic hy-droxyl group, because it has weak interaction with ammonia, and one hydroxyl group may coordinate with one La~(3+) directly.
2. The hydroxyl group at 3638 cm~(-1), which is in supercage of HY Zeolite, is of heterogeneity of actidity resulting from silicon atoms with different numbers of coordinated Aluminium.
1990, 6(02): 190-195
doi: 10.3866/PKU.WHXB19900212
Abstract:
The impedance plane plots for four ISEs, two liquid membrane bile salt ISEs and two PVC membrane Ca ISEs based on ETH 1001 and phosphate, were measured from 65 kHz to 0.01 Hz. All the impedance spectra obtained showed two semicircles and a Warburg impedance (Fig.1). The bulk resistance of membrane, R_b, and the charge-transfer resistance, R_(ct), were estimated from the high frequency and the low fre-quency semicircles respectively. The activation energy for ion transport in membrane, E_a, and the apparent standard exchange current density, i°_0, were calculaed from the R_b varied with temperature and the R_(ct) varied with the ion concentration in bathing the R_b values are not, and the E_a values and R_b values for two liquid membrane ISEs are also the case, The E_a values for the former are three times larger than the than in liquid membrane. The ETH 1001-based Ca ISE is a very od Nernstain sensor. The i°_0 value of it bathing in Ca~(2+) solution is 1.9×10~(-4) A·cm~(-2). The potentionetric responses of the two liquid membrane ISEs are near Nernstain. The i°_0 of them bathing in the potential-determining ion solution are in 1×10~(-6)-6×10~(-5) A·cm~(-2) range. The Warburg impedance was eliminated by the strong anion surfactant added in bathing solution. It was shown that the diffusion of the potential-determining ion near the membrane/solution interface is inhibited, then the potentialmetric response for the potential-determining ion is disturbed.
The impedance plane plots for four ISEs, two liquid membrane bile salt ISEs and two PVC membrane Ca ISEs based on ETH 1001 and phosphate, were measured from 65 kHz to 0.01 Hz. All the impedance spectra obtained showed two semicircles and a Warburg impedance (Fig.1). The bulk resistance of membrane, R_b, and the charge-transfer resistance, R_(ct), were estimated from the high frequency and the low fre-quency semicircles respectively. The activation energy for ion transport in membrane, E_a, and the apparent standard exchange current density, i°_0, were calculaed from the R_b varied with temperature and the R_(ct) varied with the ion concentration in bathing the R_b values are not, and the E_a values and R_b values for two liquid membrane ISEs are also the case, The E_a values for the former are three times larger than the than in liquid membrane. The ETH 1001-based Ca ISE is a very od Nernstain sensor. The i°_0 value of it bathing in Ca~(2+) solution is 1.9×10~(-4) A·cm~(-2). The potentionetric responses of the two liquid membrane ISEs are near Nernstain. The i°_0 of them bathing in the potential-determining ion solution are in 1×10~(-6)-6×10~(-5) A·cm~(-2) range. The Warburg impedance was eliminated by the strong anion surfactant added in bathing solution. It was shown that the diffusion of the potential-determining ion near the membrane/solution interface is inhibited, then the potentialmetric response for the potential-determining ion is disturbed.
1990, 6(02): 196-202
doi: 10.3866/PKU.WHXB19900213
Abstract:
The rate constant of very fast chemical reaction generally can be measured by electrochemical methods, but can not by the thin layer electrochemical methods because of the influence of diffussion effect. Long optical path length thin layer cell (LOPTLC) with large ratio of electrode area to solution volume can be used to monitor the fast chemical reaction in situ with high sensitivity and accuracy. It enables the absorption spectra to be measured without the influence of diffussion effect.
In the present paper, a fast chemical reaction of Alizain Red S (ARS) with its oxidative state ha been studied. The reaction equilibrium constant (K) under different potentials can be determined by single step potential-absorption spectra in LOPTLC. An equilibrium constant of 7.94×10~5 l·mol~(-1) for the chemical reaction has been obtained from the plot of lgK vs. (E-E~0′_1). Rate constant (k) under different potentials can be measured by single step potential-chronoabsorptionmetry. At rate constant of 426.6 l·mol~(-1)·s~(-1) for the chemical reaction has been obtained from the plot of lgK vs. (E_E~0′_1) with (E-E~0′_1)=0.
The rate constant of very fast chemical reaction generally can be measured by electrochemical methods, but can not by the thin layer electrochemical methods because of the influence of diffussion effect. Long optical path length thin layer cell (LOPTLC) with large ratio of electrode area to solution volume can be used to monitor the fast chemical reaction in situ with high sensitivity and accuracy. It enables the absorption spectra to be measured without the influence of diffussion effect.
In the present paper, a fast chemical reaction of Alizain Red S (ARS) with its oxidative state ha been studied. The reaction equilibrium constant (K) under different potentials can be determined by single step potential-absorption spectra in LOPTLC. An equilibrium constant of 7.94×10~5 l·mol~(-1) for the chemical reaction has been obtained from the plot of lgK vs. (E-E~0′_1). Rate constant (k) under different potentials can be measured by single step potential-chronoabsorptionmetry. At rate constant of 426.6 l·mol~(-1)·s~(-1) for the chemical reaction has been obtained from the plot of lgK vs. (E_E~0′_1) with (E-E~0′_1)=0.
1990, 6(02): 203-208
doi: 10.3866/PKU.WHXB19900214
Abstract:
The densities of the mixtures of N,N-Dimethylformamide (DMF) and water(w) have been measured at ten temperatures from 278.15 K to 318.15 K with the vibra-tingtube density meter(Anton Paar Model DMA602). Then the excess molal volumes V~E of solutions and apparent and partial molal volumes of DMF over the range of mole fraction 0-1 have been determined. Comparing these quantities as functions of mole fraction of mixtures with the standard entropies of transfer for NaCl from water to DMF-H_2O mixtures as function of mole fraction of mixed solvent we found out there is a correspondence between the V_(DMF) varied with x and the standard entropies of transfer of NaCl. Both have the extremes at x=0.075. Therefore the structure of solution have been discussed. It might be considered that monomeric DMF molecules have been trapped in a quasi-clathrate "cage" made up of 12 water molecules at x=0.075 forming the possible closest packing of particles.
The densities of the mixtures of N,N-Dimethylformamide (DMF) and water(w) have been measured at ten temperatures from 278.15 K to 318.15 K with the vibra-tingtube density meter(Anton Paar Model DMA602). Then the excess molal volumes V~E of solutions and apparent and partial molal volumes of DMF over the range of mole fraction 0-1 have been determined. Comparing these quantities as functions of mole fraction of mixtures with the standard entropies of transfer for NaCl from water to DMF-H_2O mixtures as function of mole fraction of mixed solvent we found out there is a correspondence between the V_(DMF) varied with x and the standard entropies of transfer of NaCl. Both have the extremes at x=0.075. Therefore the structure of solution have been discussed. It might be considered that monomeric DMF molecules have been trapped in a quasi-clathrate "cage" made up of 12 water molecules at x=0.075 forming the possible closest packing of particles.
1990, 6(02): 209-214
doi: 10.3866/PKU.WHXB19900215
Abstract:
A dynamic algebraic h_(15) is formed by using the semiclassical potential surface for AB+CD. The V-V energy transfer and the expectation of the potential are calculated; the selection rules are discussed under the first-order approximation of the group parameters.
A dynamic algebraic h_(15) is formed by using the semiclassical potential surface for AB+CD. The V-V energy transfer and the expectation of the potential are calculated; the selection rules are discussed under the first-order approximation of the group parameters.
1990, 6(02): 215-219
doi: 10.3866/PKU.WHXB19900216
Abstract:
The interaction of water with solvents in H_2O-TBP-CCl_4 system and H_2O-p-dio-xan-CCl_4 system is studied with IR method. The absorbances of free water, 1:1 and 1:2 complex are observed and the absorbance frequencies of each species are assigned. In H_2O-TBP-CCl_4 system, there exists not only symmetric 1:2 complex but also unsymmetric one. The water molecule in unsymmetric 1:2 complex is considered to be hydrogen bonded with two kinds of oxygen atom in TBP. And the hydrogen bonds are different in strenghth. Because of diffeent spatial configurations of solvent molecules around water, more than one kind of 1:2 complex exist in H_2O-p-dioxan-CCl_4 system.
The interaction of water with solvents in H_2O-TBP-CCl_4 system and H_2O-p-dio-xan-CCl_4 system is studied with IR method. The absorbances of free water, 1:1 and 1:2 complex are observed and the absorbance frequencies of each species are assigned. In H_2O-TBP-CCl_4 system, there exists not only symmetric 1:2 complex but also unsymmetric one. The water molecule in unsymmetric 1:2 complex is considered to be hydrogen bonded with two kinds of oxygen atom in TBP. And the hydrogen bonds are different in strenghth. Because of diffeent spatial configurations of solvent molecules around water, more than one kind of 1:2 complex exist in H_2O-p-dioxan-CCl_4 system.
1990, 6(02): 220-223
doi: 10.3866/PKU.WHXB19900217
Abstract:
The process of glass transition on the non-crystal SeTe_8Sb_1 has been researched using low temperature differential scanning calorimetry (DSC). The following conclusions are deduced: this process is a second-order phase transformation, the stronger endotherm displayed in it is imputed to hysteresis of the transition. The temperature of glass transition in heating process decrease with reduction of the cooling rate while forming glass. The activation energy of glass transition quickly increases from 174 kJ·mol. (at quenching rate ~10~4 K·min~(-1)) to 399 kJ·mol~(-1). (at cooling rate ~10 K·min~(-1)) So that the glass obtained at lower cooling rate is more stable than that obtained at higher rate.
The process of glass transition on the non-crystal SeTe_8Sb_1 has been researched using low temperature differential scanning calorimetry (DSC). The following conclusions are deduced: this process is a second-order phase transformation, the stronger endotherm displayed in it is imputed to hysteresis of the transition. The temperature of glass transition in heating process decrease with reduction of the cooling rate while forming glass. The activation energy of glass transition quickly increases from 174 kJ·mol. (at quenching rate ~10~4 K·min~(-1)) to 399 kJ·mol~(-1). (at cooling rate ~10 K·min~(-1)) So that the glass obtained at lower cooling rate is more stable than that obtained at higher rate.
1990, 6(02): 224-228
doi: 10.3866/PKU.WHXB19900218
Abstract:
The crystal structures of the title compound (Ⅰ) and (Ⅱ) have been determined by X-ray diffraction. Crystal data are: C_(17)H_(15)NO_3(Ⅰ), triclinic, α=0.7308(2) nm, b=0.8845(3) nm, c=1.1323(3) nm, α=100.03(2)°, β=104.81(2)°, γ=97.20(2)°, V=0.6856(3) nm, Z=2, R=0.047 and C_(18)H_(17)NO_3(Ⅱ), monoclinic, a=1.1006(3) nm, b=1.1172(2) nm, c=1.4046(3) nm, β=102.78(2)°, V=1.5337(6) nm, Z=4, R=0.055. The molecular conformation is cis form for compound Ⅰ and trans form for compound(Ⅱ).
The crystal structures of the title compound (Ⅰ) and (Ⅱ) have been determined by X-ray diffraction. Crystal data are: C_(17)H_(15)NO_3(Ⅰ), triclinic, α=0.7308(2) nm, b=0.8845(3) nm, c=1.1323(3) nm, α=100.03(2)°, β=104.81(2)°, γ=97.20(2)°, V=0.6856(3) nm, Z=2, R=0.047 and C_(18)H_(17)NO_3(Ⅱ), monoclinic, a=1.1006(3) nm, b=1.1172(2) nm, c=1.4046(3) nm, β=102.78(2)°, V=1.5337(6) nm, Z=4, R=0.055. The molecular conformation is cis form for compound Ⅰ and trans form for compound(Ⅱ).
1990, 6(02): 229-232
doi: 10.3866/PKU.WHXB19900219
Abstract:
In this paper, two different kinds of B-Z type oscillating reactions have been described. One is the couple catalyzed oscillating reaction with vanillin(OA) as the organic substrate. Another is the uncatalyzed oscillating reaction with 2,7-dihydroxynaphthalene (DN) as the organic substrate. Effects of many factors on the oscillations have been examined. According to the FKN mechanism, a simple model for the catalyzed oscillation has been proposed. Each of experimental results can be explained with this model. It is found thad the model can also be employed in the uncatalyzed oscillating reaction supposing that the organic substrate DN can play the role of catalyst as the metal ion in the catalyzed oscillating reaction.
In this paper, two different kinds of B-Z type oscillating reactions have been described. One is the couple catalyzed oscillating reaction with vanillin(OA) as the organic substrate. Another is the uncatalyzed oscillating reaction with 2,7-dihydroxynaphthalene (DN) as the organic substrate. Effects of many factors on the oscillations have been examined. According to the FKN mechanism, a simple model for the catalyzed oscillation has been proposed. Each of experimental results can be explained with this model. It is found thad the model can also be employed in the uncatalyzed oscillating reaction supposing that the organic substrate DN can play the role of catalyst as the metal ion in the catalyzed oscillating reaction.
1990, 6(02): 233-238
doi: 10.3866/PKU.WHXB19900220
Abstract:
The crystal structures of 2,3,7,8-tetrachlorodibenzo-p-dioxin(2, 3, 7, 8-TCDD) and its analogues have been determined. And the semiempirical INDO calculations for this type of compounds have been undertaken. Their characteristics of electronic structures were discussed. The possible active centers which can interact with biological receptor were also proposed.
The crystal structures of 2,3,7,8-tetrachlorodibenzo-p-dioxin(2, 3, 7, 8-TCDD) and its analogues have been determined. And the semiempirical INDO calculations for this type of compounds have been undertaken. Their characteristics of electronic structures were discussed. The possible active centers which can interact with biological receptor were also proposed.
1990, 6(02): 239-245
doi: 10.3866/PKU.WHXB19900221
Abstract:
In this paper, B-02 catalyst, developed by Yanshan Synthetic Rubber Factory and used in two large production plants, was investigated by means of pulse technique and temperature-programmed techniques, as well as XRD and FT-IR techniques. Three related iron compound, magnesium ferrite, hematite, and maghemite, were also studied.
XRD showed the presence of two crystallographic phases, viz., magnesium ferrite and hematite, in the B-02 catalyst.
A combination study of the reduction behavior of B-02 was established, comp...
In this paper, B-02 catalyst, developed by Yanshan Synthetic Rubber Factory and used in two large production plants, was investigated by means of pulse technique and temperature-programmed techniques, as well as XRD and FT-IR techniques. Three related iron compound, magnesium ferrite, hematite, and maghemite, were also studied.
XRD showed the presence of two crystallographic phases, viz., magnesium ferrite and hematite, in the B-02 catalyst.
A combination study of the reduction behavior of B-02 was established, comp...
1990, 6(02): 246-251
doi: 10.3866/PKU.WHXB19900222
Abstract:
The linear equation of salt effect on phase transformation in the mixtures of nonpolar-nonpolar system and nonpolar-polar system can be proved with the aid of perturbation expansion. The cause of linear equation has been discussed from ther-modynamics. By introducing the expanding boundary function, we calculated phase transformation temperatures for a number of systems in which the phenomenon of seperating phase has been observed and compared with experiments.
The linear equation of salt effect on phase transformation in the mixtures of nonpolar-nonpolar system and nonpolar-polar system can be proved with the aid of perturbation expansion. The cause of linear equation has been discussed from ther-modynamics. By introducing the expanding boundary function, we calculated phase transformation temperatures for a number of systems in which the phenomenon of seperating phase has been observed and compared with experiments.
1990, 6(02): 252-256
doi: 10.3866/PKU.WHXB19900223
Abstract:
In tbe present paper, the adsorption heats of CO on copper (powder) have been determined by impulsive method with Rigaku TG-DTA-DSC thermal analyzer, Ar as the carrier gas. The sample Cu is prepared by precipitation of copper nitrate. The weight of adsorbed CO is designated by TG curves and heat by peak area of DSC. The instrument constant is determined by means of standard substances, such as In Sn and Pb.
Relationship between instrument constant K and temperature T can be represented as following equation:
K=9.464-23.33×10~(-3) T+25.74×10~(-6) T~2
It is found that the temperature has influence on the adsorption heat of CO. The...
In tbe present paper, the adsorption heats of CO on copper (powder) have been determined by impulsive method with Rigaku TG-DTA-DSC thermal analyzer, Ar as the carrier gas. The sample Cu is prepared by precipitation of copper nitrate. The weight of adsorbed CO is designated by TG curves and heat by peak area of DSC. The instrument constant is determined by means of standard substances, such as In Sn and Pb.
Relationship between instrument constant K and temperature T can be represented as following equation:
K=9.464-23.33×10~(-3) T+25.74×10~(-6) T~2
It is found that the temperature has influence on the adsorption heat of CO. The...
