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1985 Volume 1 Issue 4
1985, 1(04): 301-303
doi: 10.3866/PKU.WHXB19850401
Abstract:
The molar excess enthalpies of cyclohexane+methanol were systematically measured with a Picker flow microcalorimeter operated in discontinuous mode at 298.15 303.15, 308.15, 313.15, 318.15 and 323.15 K. Our values are higher than the literature data. This work shows that the molar excess enthalpies increase with tem- perature, and the straight segments of the excess enthalpy curves in the mid become shorter with the increasing of temperature. At 323.15 K the sample becomes one of a miscible liquid system, and the position of themaximum value of molar excess enthalpies is at x=0.6. In addition, the calorimetric measurement can be used to determine the compositions of two immiscible phases for the binary mixture.
1985, 1(04): 304-307
doi: 10.3866/PKU.WHXB19850402
Abstract:
Some assumptions were made for the modified equation of the internal pressure theory originally suggested by McDevit and Long~[2].
κ_s={V~0_n(V_s-V~0_s)}/(2.303RTβ_0)·a/(a+b) (1)
When the distance between ion and nonelectrolyte molecule in aqueous salt solution is calculated, the ionic hydration should be considered for the larger nonelectrolyte molecules; and the nonelectrolyte molecule must be excluded from the primary solvation shell of the ion. For 1-1 electrolytes, we assume that: (a) Latimer's radii are used instead of the radii of ions, i.e., r_L~+=r_P~+_P+0.085 (nm), r~-_L=r~-_P+0.010 (nm), where r_P is the Pauling′s radius; (b) a in equation (1) is the average of the radii of cation and anion, i.e., a=1/2(R~-_L+r~-_L); (c) b is the radius of the nonelectroiyte molecule, i.e., b=1/2(V_n/N)~1/3, in which V_n is the molar volume of the nonelectrolyte, N is the Avogadro′s number. In order to test these assumptions, it has been calculated for the salting-out constant of five benzene derivatives and four fatty acids in the solution of alkaline halides by the theories of (I) Debye-McAulay, (II) Conway-Desnoyers-Smith, (III) McDevit-Long and (IV) modified McDevit-Long. For larger nonelectrolyte molecules equation (1) of the modifited McDevit-Long. theory (IV) gives results in better agreement with the experiment than those of (I), (II) and (III).
1985, 1(04): 308-317
doi: 10.3866/PKU.WHXB19850403
Abstract:
Sprengel pycnometers were used for density measurements. The volume of the pycnometers is about 25 ml. The precision of density data is within ±0.015 kgm~(-3). All measurements have been performed at 25.000±0.001 ℃. Partial molal volumes of salts in H_2O、 DMF and PC at 25 ℃ have been reported (Table 1).
A method to get ionic partial molal volumes from salt data based on thermodynamic and statistical approximation has been given. Ionic partial molal volumes in H_2O、DMF and PC have been obtained (Table 3). According to one layer structure model, a formula of solvation number related to partial molal volume is reported:
m_i=m_α+m_β
...
Sprengel pycnometers were used for density measurements. The volume of the pycnometers is about 25 ml. The precision of density data is within ±0.015 kgm~(-3). All measurements have been performed at 25.000±0.001 ℃. Partial molal volumes of salts in H_2O、 DMF and PC at 25 ℃ have been reported (Table 1).
A method to get ionic partial molal volumes from salt data based on thermodynamic and statistical approximation has been given. Ionic partial molal volumes in H_2O、DMF and PC have been obtained (Table 3). According to one layer structure model, a formula of solvation number related to partial molal volume is reported:
m_i=m_α+m_β
...
1985, 1(04): 318-323
doi: 10.3866/PKU.WHXB19850404
Abstract:
The variational method calculating the Hückel energy of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) in alternant hydrocarbon species has been modified and extended to one including nonalternant hydrocarbons shown as the following:
A~(-1)y~(ν)=y~(ν+1)
λ~(ν)=(y~(ν)]~Hy~(ν))/([y~(ν)]~HA~(-1)y~(ν)) } ν=0, 1
The zero iterate vector is selected as following: a_(kj) is the element in A~(-1); A~(-1) is the inverse of adjacency matrix; y~((ν)) is the νth iterate vector; [y~((ν))]~H is the transpose of y~((ν)). ν taken the value of 0,1 indicates ...
The variational method calculating the Hückel energy of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) in alternant hydrocarbon species has been modified and extended to one including nonalternant hydrocarbons shown as the following:
A~(-1)y~(ν)=y~(ν+1)
λ~(ν)=(y~(ν)]~Hy~(ν))/([y~(ν)]~HA~(-1)y~(ν)) } ν=0, 1
The zero iterate vector is selected as following: a_(kj) is the element in A~(-1); A~(-1) is the inverse of adjacency matrix; y~((ν)) is the νth iterate vector; [y~((ν))]~H is the transpose of y~((ν)). ν taken the value of 0,1 indicates ...
1985, 1(04): 324-328
doi: 10.3866/PKU.WHXB19850405
Abstract:
The [2_s+n_a] system can have C_2 symmetry (Fig.1) rather than local C_2 and local σ as described in Ref.4. For the [m_s +n_a] cycloaddition with m>2, the reaction system is no doubt unsymmetrical, the special symmetry of the MOs obtained by the HMO model is due to oversimplification. Bond angles are not concerned in the HMO method. Thus, if the m_s component is regarded as a straight carbon skeleton, the system will be of C_2 symmetry, which is shown in Fig.1 with the m_s in place of the ethylene. Correlation diagrams of [m_s+n_a] canbe constructed from the MO energies and special symmetries of the initial and the final states. For [m_s+m_a] reaction, the eigenvalue problem is equivalent to that of two identical systems with straight carbon chains (Fig.3). Therefore, double degeneracy holds for all MOs throughout the reaction (Fig.4).
The [2_s+n_a] system can have C_2 symmetry (Fig.1) rather than local C_2 and local σ as described in Ref.4. For the [m_s +n_a] cycloaddition with m>2, the reaction system is no doubt unsymmetrical, the special symmetry of the MOs obtained by the HMO model is due to oversimplification. Bond angles are not concerned in the HMO method. Thus, if the m_s component is regarded as a straight carbon skeleton, the system will be of C_2 symmetry, which is shown in Fig.1 with the m_s in place of the ethylene. Correlation diagrams of [m_s+n_a] canbe constructed from the MO energies and special symmetries of the initial and the final states. For [m_s+m_a] reaction, the eigenvalue problem is equivalent to that of two identical systems with straight carbon chains (Fig.3). Therefore, double degeneracy holds for all MOs throughout the reaction (Fig.4).
1985, 1(04): 329-334
doi: 10.3866/PKU.WHXB19850406
Abstract:
Free radicals produced by the photolysis processes of arenediazonium salts and their crown ether complexes have been investigated by combination of spin trapping technique and ESR spectrometry. The results show that the active radicals R-C_6H_4 are produced during the course of photolysis of these compounds and can be trapped by spirt trapping reagents phenyl tert-butyl nitrone (PBN) and nitrosodurene (ND) to form spin adduets Ⅰ, Ⅱ, Ⅲ, Ⅳ and Ⅴ.
In the cases of Ⅰ, Ⅱ, Ⅲ, and Ⅳ the effects of different substitue R at the same ring position on a_N are in the order of
o—R OCH_3>H>Br≥Cl
m—R H>Br≥Cl
p—R OCH_3>H>I≥Br≥Cl>NO_2
and the effects of same substituent at different ring position on a_N are in the order of
o—R≥p—R>m—R
The role of crown ether is favourable to the trapping of active radicals.
Free radicals produced by the photolysis processes of arenediazonium salts and their crown ether complexes have been investigated by combination of spin trapping technique and ESR spectrometry. The results show that the active radicals R-C_6H_4 are produced during the course of photolysis of these compounds and can be trapped by spirt trapping reagents phenyl tert-butyl nitrone (PBN) and nitrosodurene (ND) to form spin adduets Ⅰ, Ⅱ, Ⅲ, Ⅳ and Ⅴ.
In the cases of Ⅰ, Ⅱ, Ⅲ, and Ⅳ the effects of different substitue R at the same ring position on a_N are in the order of
o—R OCH_3>H>Br≥Cl
m—R H>Br≥Cl
p—R OCH_3>H>I≥Br≥Cl>NO_2
and the effects of same substituent at different ring position on a_N are in the order of
o—R≥p—R>m—R
The role of crown ether is favourable to the trapping of active radicals.
1985, 1(04): 335-339
doi: 10.3866/PKU.WHXB19850407
Abstract:
The title complex has been synthesized by reaction of TiCl_3·3THF with salenNa_2 in THF. The solution of this compound, which is very air-sensitive, is able to exist for a long time when free from air. Single crystals were obtained in ether and THF mixed solvents. Crystal structure of the complex has been determined by the direct method from diffractometer data and refined by the least-square method to final R=0.086 and R_W=0.066. The crystals are orthorhombic, space group D_(2h)~(16)-Pbnm with a=0.7458(2), b=1.4075(6), c=1.8752(2) nm, V=1.968(2) nm, z=4. Discrete molecule of Ti(salen)Cl·THF which has mirror symetry in itself sits on crystallography mirror. The co-ordinating geometry of titanium is pseudooctahedral. The reason why the reaction of TiCl·3THF with salen-H_2 only gives oxidized prnduct has been found out. The reactions between the complex and CO_2 or ALR_3 were also studied.
The title complex has been synthesized by reaction of TiCl_3·3THF with salenNa_2 in THF. The solution of this compound, which is very air-sensitive, is able to exist for a long time when free from air. Single crystals were obtained in ether and THF mixed solvents. Crystal structure of the complex has been determined by the direct method from diffractometer data and refined by the least-square method to final R=0.086 and R_W=0.066. The crystals are orthorhombic, space group D_(2h)~(16)-Pbnm with a=0.7458(2), b=1.4075(6), c=1.8752(2) nm, V=1.968(2) nm, z=4. Discrete molecule of Ti(salen)Cl·THF which has mirror symetry in itself sits on crystallography mirror. The co-ordinating geometry of titanium is pseudooctahedral. The reason why the reaction of TiCl·3THF with salen-H_2 only gives oxidized prnduct has been found out. The reactions between the complex and CO_2 or ALR_3 were also studied.
1985, 1(04): 340-348
doi: 10.3866/PKU.WHXB19850408
Abstract:
Viscosity measurements of aqueous tetradecylpyridinium bromide solutions using a capillary viscometer have been made to determine the intrinsic viscosity of the micellar solutions as a function of salt concentration (0.5—2.0 mol L~(-1)NaBr), temperature (20—40 ℃), and amphiphile concentration (3—25 g/l). From the intrinsie viscosity values several basic micellar parameters including the thermodynamic parameter K, verning the sphere-to-rod transition in the micelle growth process, and the weight average aggregation number of polydisperse micelles, n_w, were calculated based on a thermodynamic model for micellization developed dy Missel et al. In both 0.5 and 1.0 mol L~(-1) NaBr solutions the parameter Kealuaed at various temperatures as well as the parameter n_w calculated as a function of amphiphile concentrtion at 30 ℃ are in od agreement with those obtained in our previous studies on TPB micellar properties by static and dynamic light scattering techniques. In addition, a constancy of K deduced from viscometric data over a suitable range of amphiphile concentrations, as required by the model, was observed at various temperatures. However, the parameter K becomes remarkably concentration-dependent and an obvious discrepancy in the determined parameters K and m_w between the two methods is observed under conditions of higher NaBr concentration (2 mol L~(-1)) which demostrates the invalidity of the model. It is therefore concluded that for amphiphile systems which display the sphere-to-rod transition behavior, the viscometric technique provides a simple, reliable approach to study micelle growth, extracting extensive information on amphiphile aggregation from a quantitative analysis of concentration-dependent intrinsic viscosities.
Viscosity measurements of aqueous tetradecylpyridinium bromide solutions using a capillary viscometer have been made to determine the intrinsic viscosity of the micellar solutions as a function of salt concentration (0.5—2.0 mol L~(-1)NaBr), temperature (20—40 ℃), and amphiphile concentration (3—25 g/l). From the intrinsie viscosity values several basic micellar parameters including the thermodynamic parameter K, verning the sphere-to-rod transition in the micelle growth process, and the weight average aggregation number of polydisperse micelles, n_w, were calculated based on a thermodynamic model for micellization developed dy Missel et al. In both 0.5 and 1.0 mol L~(-1) NaBr solutions the parameter Kealuaed at various temperatures as well as the parameter n_w calculated as a function of amphiphile concentrtion at 30 ℃ are in od agreement with those obtained in our previous studies on TPB micellar properties by static and dynamic light scattering techniques. In addition, a constancy of K deduced from viscometric data over a suitable range of amphiphile concentrations, as required by the model, was observed at various temperatures. However, the parameter K becomes remarkably concentration-dependent and an obvious discrepancy in the determined parameters K and m_w between the two methods is observed under conditions of higher NaBr concentration (2 mol L~(-1)) which demostrates the invalidity of the model. It is therefore concluded that for amphiphile systems which display the sphere-to-rod transition behavior, the viscometric technique provides a simple, reliable approach to study micelle growth, extracting extensive information on amphiphile aggregation from a quantitative analysis of concentration-dependent intrinsic viscosities.
1985, 1(04): 349-356
doi: 10.3866/PKU.WHXB19850409
Abstract:
In this paper oscillating phenomena of the Belousov-Zhabotinskii(BZ) reaction between malonic acid, ferrous o-phenanthroline and bromate ion have been studied. The effects of different atmospheres and the dissociation of ferrous o-phenanthroline ion in acid solution on the oscillation behavior of the reaction are investigated. Experiment results are interpreted in terms of the familiar reaction mechanism. The major results of this work are as follows:
(1) In order to investigate the effect of flow rate of gases on time of initiation (t_(in)), time period (t_p) and life time (t_l) of the oscillation, nitrogen and hydrogen were bubbled into the reaction system. The effect of stirring rate on t_(in), t_p and t_l in the same atmospheres was also studied. The experiment results are shown in Fig.1 These results show that in nitrogen or hydrogen atmosphere, flow rate and stirring rate do not obviously affect t_(in), t_p and t_l at fixed initial concentrations of various reagents. So it can be concluded that nitrogen and hydrogen are inert for the oscillation behavior of the BZ reaction.
(2) ...
In this paper oscillating phenomena of the Belousov-Zhabotinskii(BZ) reaction between malonic acid, ferrous o-phenanthroline and bromate ion have been studied. The effects of different atmospheres and the dissociation of ferrous o-phenanthroline ion in acid solution on the oscillation behavior of the reaction are investigated. Experiment results are interpreted in terms of the familiar reaction mechanism. The major results of this work are as follows:
(1) In order to investigate the effect of flow rate of gases on time of initiation (t_(in)), time period (t_p) and life time (t_l) of the oscillation, nitrogen and hydrogen were bubbled into the reaction system. The effect of stirring rate on t_(in), t_p and t_l in the same atmospheres was also studied. The experiment results are shown in Fig.1 These results show that in nitrogen or hydrogen atmosphere, flow rate and stirring rate do not obviously affect t_(in), t_p and t_l at fixed initial concentrations of various reagents. So it can be concluded that nitrogen and hydrogen are inert for the oscillation behavior of the BZ reaction.
(2) ...
1985, 1(04): 357-364
doi: 10.3866/PKU.WHXB19850410
Abstract:
The initial stages of the electrocrystallization of zinc onto vitreous carbon from chloride zinc-plating solutions were investigated using linear sweep voltammetry and potential step method. It was observed that the deposition of zinc on the substrate did not under the UPD process before its overpotential deposition occurred. In the experimental conditions, the growth of the mature nuclei is controlled by the diffusion of the depositing ions to the electrode. The mechanism of nucleation evidently depends on the presence of the additives used, i.e., 3D progressive in the solutions with the additives, instead, 3D instantaneous without them.
By analyzing of the potentiostatic transients, the D value of the depositing zinc ions was estimated, and the nucleation rate constants A at different overpotentials η were obtained. lgA was found to be in direct proportion to η rather than η~(-2), which means that the so-called atomistic model is better than the classical model of nucleation in the present system.
Nuclear ...
The initial stages of the electrocrystallization of zinc onto vitreous carbon from chloride zinc-plating solutions were investigated using linear sweep voltammetry and potential step method. It was observed that the deposition of zinc on the substrate did not under the UPD process before its overpotential deposition occurred. In the experimental conditions, the growth of the mature nuclei is controlled by the diffusion of the depositing ions to the electrode. The mechanism of nucleation evidently depends on the presence of the additives used, i.e., 3D progressive in the solutions with the additives, instead, 3D instantaneous without them.
By analyzing of the potentiostatic transients, the D value of the depositing zinc ions was estimated, and the nucleation rate constants A at different overpotentials η were obtained. lgA was found to be in direct proportion to η rather than η~(-2), which means that the so-called atomistic model is better than the classical model of nucleation in the present system.
Nuclear ...
1985, 1(04): 365-369
doi: 10.3866/PKU.WHXB19850411
Abstract:
Activity coefficient ν_1 of HCl in quaternary system of HCl-KCl-BaCl_2-H_2O was investigated by means of a reversible cell.
H_2|HCl(I_1), KCl(I_2), BaCl_2(I_3)|AgCl-Ag
It has been shown by the experiments that logγ_1 varied linearly with I_2 at the constant total ionic strength I and I_3, but its value is only a little different from that of logγ_1 calculated from the data by Harned for the corresponding ternary system. The logγ_1 of HCl in quaternary system may be expressed by
logγ_1=logγ_(1(0))-α_(12)I_2...
Activity coefficient ν_1 of HCl in quaternary system of HCl-KCl-BaCl_2-H_2O was investigated by means of a reversible cell.
H_2|HCl(I_1), KCl(I_2), BaCl_2(I_3)|AgCl-Ag
It has been shown by the experiments that logγ_1 varied linearly with I_2 at the constant total ionic strength I and I_3, but its value is only a little different from that of logγ_1 calculated from the data by Harned for the corresponding ternary system. The logγ_1 of HCl in quaternary system may be expressed by
logγ_1=logγ_(1(0))-α_(12)I_2...
1985, 1(04): 370-377
doi: 10.3866/PKU.WHXB19850412
Abstract:
CF_3I is an important molecule in the field of infrared laser chemistry, but its rotational structure of vibrational bands remained unresolved so far because of its small rotational constants. The diode laser infrared spectroscopy of ν_4 band under the resolution of 0.002 cm~(-1) is reported here. About ten Q sub-braches, and some thousands of ~PP, ~RR lines were observed, two hot bands ν_4+ν_6←ν_6 and ν_4+ν_3←ν_3 were also investigated. Possible vibration-rotation interactions in ν_4 band were studied. Some of ~RR lines were assigned and least-squares fitted to get the molecular constants, some are improved and others are reported for the first time.
CF_3I is an important molecule in the field of infrared laser chemistry, but its rotational structure of vibrational bands remained unresolved so far because of its small rotational constants. The diode laser infrared spectroscopy of ν_4 band under the resolution of 0.002 cm~(-1) is reported here. About ten Q sub-braches, and some thousands of ~PP, ~RR lines were observed, two hot bands ν_4+ν_6←ν_6 and ν_4+ν_3←ν_3 were also investigated. Possible vibration-rotation interactions in ν_4 band were studied. Some of ~RR lines were assigned and least-squares fitted to get the molecular constants, some are improved and others are reported for the first time.
1985, 1(04): 378-383
doi: 10.3866/PKU.WHXB19850413
Abstract:
The crystal structures of the title compounds have been determined from threedimensional intensity measured on a R3m/E four circle diffractometer. The crystallographic data are listed in Table 1.
The structure of [N(C_4H_9)_4]_2[Cu(S_5C_3)_2] was solved by trial and error using isomophous [N(C_4H_9)_4]_2[Pd(S_5C_3)_2] crystal data. The structure of [N(C_4H_9)_4]_2[Zn(S_5C_3)_2] was solved by direct method using SHELXTL program system. The H atom coordinates were calculated geometrically. The refinement of coordinates and anisotropic thermal parameters was performed by “blocked cascade” least squares to R=0.044 for Cu(II) compound and R=0.057 for Zn(II) compound calculated on the basis of 2424 and 1219 independent reflections respectively. All the numerical calculations were carried out on a Eclipse/S_(140) computer with programs of R3m/E system.
...
The crystal structures of the title compounds have been determined from threedimensional intensity measured on a R3m/E four circle diffractometer. The crystallographic data are listed in Table 1.
The structure of [N(C_4H_9)_4]_2[Cu(S_5C_3)_2] was solved by trial and error using isomophous [N(C_4H_9)_4]_2[Pd(S_5C_3)_2] crystal data. The structure of [N(C_4H_9)_4]_2[Zn(S_5C_3)_2] was solved by direct method using SHELXTL program system. The H atom coordinates were calculated geometrically. The refinement of coordinates and anisotropic thermal parameters was performed by “blocked cascade” least squares to R=0.044 for Cu(II) compound and R=0.057 for Zn(II) compound calculated on the basis of 2424 and 1219 independent reflections respectively. All the numerical calculations were carried out on a Eclipse/S_(140) computer with programs of R3m/E system.
...
1985, 1(04): 384-388
doi: 10.3866/PKU.WHXB19850414
Abstract:
Mean activity coefficients of perchloric acid in system of HCl-HClO_4-H_2O at a constant total ionic strengths (I=0.7, 0.5, 0.3 and 0.1) have been measured by E.M.F. method from a cell without liquid junctions. The cell consists of a perchloric ion sensitive electode and a glass electrode. Results obtained show that the relationships between the logarithm of the mean activity coefficients of perchloric acid and the concentration of each of the two acids in the above mixtures obey Harned's rule. The respective Harned's coefficients a_(21) have been computed by the least square method.
Mean activity coefficients of perchloric acid in system of HCl-HClO_4-H_2O at a constant total ionic strengths (I=0.7, 0.5, 0.3 and 0.1) have been measured by E.M.F. method from a cell without liquid junctions. The cell consists of a perchloric ion sensitive electode and a glass electrode. Results obtained show that the relationships between the logarithm of the mean activity coefficients of perchloric acid and the concentration of each of the two acids in the above mixtures obey Harned's rule. The respective Harned's coefficients a_(21) have been computed by the least square method.
1985, 1(04): 389-395
doi: 10.3866/PKU.WHXB19850415
Abstract:
