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1988 Volume 5 Issue 1
1988, 5(1): 1-14
Abstract:
Some important applications of the palladium complexes in the past decade are reviewed covering the synthesis of cyclic compounds, formation of the carbon-carbon bond and preparation of aldehydes, ketoues, carboxylic acids and their derivatives.
Some important applications of the palladium complexes in the past decade are reviewed covering the synthesis of cyclic compounds, formation of the carbon-carbon bond and preparation of aldehydes, ketoues, carboxylic acids and their derivatives.
1988, 5(1): 15-20
Abstract:
In order to investigate their effects on the polymerization of butadiene and the microstructure of polymers, three series of nitrogen-containing compounds were added into the catalyst system of FeCl3-(i-C4H9)3Al i.e.1), pyridine, quinoline, 2,2'-bipyridine, 2,2',2″-terpyri-dine, 2,2',2″,2'''-tetrapyridine; 2), pyridine, 2-cyanopyridine, 2,6-dicyanopyridine; 3),triethylamine, N,N,N',N″-tetramethylethylenediamine, diethylenetriamine. The effects of concentration of ligands as well as alkylaluminum on both catalytic activity and the [η] of polymers were investigated. It was observed that the larger the number of nitrogen atomsin the ligand, the more the 1,2-structural content of polybutadieneo It is considered that the ligand coordinated to active center would occupy the empty orbitals, increasing the opportunity of trans-configuration of butadiene on the active center as well as the content of 1,2-units in polymer. The mechanism is also used to explain the difference in catalytic activities caused by various ligands.
In order to investigate their effects on the polymerization of butadiene and the microstructure of polymers, three series of nitrogen-containing compounds were added into the catalyst system of FeCl3-(i-C4H9)3Al i.e.1), pyridine, quinoline, 2,2'-bipyridine, 2,2',2″-terpyri-dine, 2,2',2″,2'''-tetrapyridine; 2), pyridine, 2-cyanopyridine, 2,6-dicyanopyridine; 3),triethylamine, N,N,N',N″-tetramethylethylenediamine, diethylenetriamine. The effects of concentration of ligands as well as alkylaluminum on both catalytic activity and the [η] of polymers were investigated. It was observed that the larger the number of nitrogen atomsin the ligand, the more the 1,2-structural content of polybutadieneo It is considered that the ligand coordinated to active center would occupy the empty orbitals, increasing the opportunity of trans-configuration of butadiene on the active center as well as the content of 1,2-units in polymer. The mechanism is also used to explain the difference in catalytic activities caused by various ligands.
1988, 5(1): 21-26
Abstract:
This paper reports the kinetic study of butadiene polymerization in toluene with n-butyl lithium and potassium butoxide as catalyst and with or without the addition of polar modifiers. It is found that,when K/Li=0,at 0℃, the reaction order of initiator concentration with respect to polymerization rate was 1; apparent rate constant kap of polymerization was independent of the initiator concentration. When K/Li=0.5 and 1.1, A/Li=0, k'=2/100, kap differed significantly, but the apparent energy of activation Eap in both cases gave the same value:45.2kJ/mol. When K/Li<1.0, the polymerization rate increased with increase of K/Li; when K/Li>1.0, the polymerization rate became constant. Addition of polar modifiers greatly increased the rate of polymerization.
This paper reports the kinetic study of butadiene polymerization in toluene with n-butyl lithium and potassium butoxide as catalyst and with or without the addition of polar modifiers. It is found that,when K/Li=0,at 0℃, the reaction order of initiator concentration with respect to polymerization rate was 1; apparent rate constant kap of polymerization was independent of the initiator concentration. When K/Li=0.5 and 1.1, A/Li=0, k'=2/100, kap differed significantly, but the apparent energy of activation Eap in both cases gave the same value:45.2kJ/mol. When K/Li<1.0, the polymerization rate increased with increase of K/Li; when K/Li>1.0, the polymerization rate became constant. Addition of polar modifiers greatly increased the rate of polymerization.
1988, 5(1): 27-31
Abstract:
The mechanism of extraction of silver(I) from thiosulphate solution by N1923 nitrate has been Studied. The effects of acidity, concentration of NO3- and S2O32- in aqueous phase on the diStribution ratio (D) of Ag(I) have been investigated. It is found that the D value decreases with increase of concentration of NO3- and S2O32-, and pH value as well. The results show that the extraction process is an anion exchange and the extracted species are a mixture of AgS2O3- and Ag(S2O3)23-. The IR spectra of the extracted complexes were measured, which support the mechanism proposed.
The mechanism of extraction of silver(I) from thiosulphate solution by N1923 nitrate has been Studied. The effects of acidity, concentration of NO3- and S2O32- in aqueous phase on the diStribution ratio (D) of Ag(I) have been investigated. It is found that the D value decreases with increase of concentration of NO3- and S2O32-, and pH value as well. The results show that the extraction process is an anion exchange and the extracted species are a mixture of AgS2O3- and Ag(S2O3)23-. The IR spectra of the extracted complexes were measured, which support the mechanism proposed.
1988, 5(1): 32-37
Abstract:
A theoretical and experimental investigation of quasi-reversible electrode processes using square wave voltammetry, especially with cyclic voltammetry, is described. The mathematical expressions of current functions have been deduced. It is shown that the difference between the peak potentials for forward sweep and for reverse sweep, ΔEp, is not equal to zero, but increases with decrease of the degree of the reversibility and strongly depends on the standard rate constant, Ks, of the electrode reaction and the voltage scan rate, and it is also independent of the square wave amplitude. With a new parameter proposed, Kc, which is related to Ks and ΔE/τ, one can get the theoretical plot of Kc against ΔEp. Thus, the value of Ks can be estimated from ΔEp measured by cyclic square wave voltammetry and Kc obtained from the theoretical curve. The method has been used to determine the Ks of [Fe(CN)6]-3-H2SO4 system at glassy carton electrode. The Ks obtained then has a value of 2.5×10-3cm/s, whichis in fair agreement with 2.1×10-3cm/s obtained by staircase scan technique and 2.2×10-3 cm/s as repoprted in literature.
A theoretical and experimental investigation of quasi-reversible electrode processes using square wave voltammetry, especially with cyclic voltammetry, is described. The mathematical expressions of current functions have been deduced. It is shown that the difference between the peak potentials for forward sweep and for reverse sweep, ΔEp, is not equal to zero, but increases with decrease of the degree of the reversibility and strongly depends on the standard rate constant, Ks, of the electrode reaction and the voltage scan rate, and it is also independent of the square wave amplitude. With a new parameter proposed, Kc, which is related to Ks and ΔE/τ, one can get the theoretical plot of Kc against ΔEp. Thus, the value of Ks can be estimated from ΔEp measured by cyclic square wave voltammetry and Kc obtained from the theoretical curve. The method has been used to determine the Ks of [Fe(CN)6]-3-H2SO4 system at glassy carton electrode. The Ks obtained then has a value of 2.5×10-3cm/s, whichis in fair agreement with 2.1×10-3cm/s obtained by staircase scan technique and 2.2×10-3 cm/s as repoprted in literature.
1988, 5(1): 38-41
Abstract:
Anhydrous metal iodides of Sc, Dy, Er and Tm were prepared by the reaction of metallic rare earths with mercuric iodide at elevated temperature. Phase diagrams of the binary systems NaI-REI3 (RE= Sc, Dy, Er and Tin) were obtained by DTA technique. All they are simple binary eutectic system. For RE=Dy, Er and Tm, the phase transition of the corresponding systems occured below eutectic temperature, indicating the possible existence of some unstable compounds. Metal halide lamps filled with the mixture of sodium iodide and rare earth iodides have been made and compared with the mercury arc lamp. It was shown that addition of sodium iodide and rare earth iodides improves the color temperature, color rendering indices and efficacy of the lamps.
Anhydrous metal iodides of Sc, Dy, Er and Tm were prepared by the reaction of metallic rare earths with mercuric iodide at elevated temperature. Phase diagrams of the binary systems NaI-REI3 (RE= Sc, Dy, Er and Tin) were obtained by DTA technique. All they are simple binary eutectic system. For RE=Dy, Er and Tm, the phase transition of the corresponding systems occured below eutectic temperature, indicating the possible existence of some unstable compounds. Metal halide lamps filled with the mixture of sodium iodide and rare earth iodides have been made and compared with the mercury arc lamp. It was shown that addition of sodium iodide and rare earth iodides improves the color temperature, color rendering indices and efficacy of the lamps.
1988, 5(1): 42-46
Abstract:
The crystal structure of the CHCl3-soluble fraction (low molecular weight) of chemically prepared polytbiophene(PT1) has been investigated using WAXD and TGA techniques. Ruland's method has been used to calculate its crystallinity. Heat treatment for 30 min. at 150℃ in N2 leads to a significant increase in crystallinity and crystallite size of polymer. From the crystal-lographic data although incomplete at present time, a preliminary model of the polymer structure has been proposed. The results are in consistence with those devised from an orthorhombic or a monoclinic unit cell. In either case the polymer chain axes are found to be along the c-axis. The calculated density is approximately 1.55g/cm3 assuming two chains per unit cell. The preliminary density value of the sample is 1.18g/cm3 in satisfactory agreement with the calculated value since the density of the partially amorphous material is expected to be less than that of the full crystalline polymer. An individual chain structure for PT1 in which the thiophene units alternate on both sides results in straight chain conformation. FTIR spectra of unannealed and annealed PT1 powder have been assigned.
The crystal structure of the CHCl3-soluble fraction (low molecular weight) of chemically prepared polytbiophene(PT1) has been investigated using WAXD and TGA techniques. Ruland's method has been used to calculate its crystallinity. Heat treatment for 30 min. at 150℃ in N2 leads to a significant increase in crystallinity and crystallite size of polymer. From the crystal-lographic data although incomplete at present time, a preliminary model of the polymer structure has been proposed. The results are in consistence with those devised from an orthorhombic or a monoclinic unit cell. In either case the polymer chain axes are found to be along the c-axis. The calculated density is approximately 1.55g/cm3 assuming two chains per unit cell. The preliminary density value of the sample is 1.18g/cm3 in satisfactory agreement with the calculated value since the density of the partially amorphous material is expected to be less than that of the full crystalline polymer. An individual chain structure for PT1 in which the thiophene units alternate on both sides results in straight chain conformation. FTIR spectra of unannealed and annealed PT1 powder have been assigned.
1988, 5(1): 47-51
Abstract:
Kinetic studies of consecutive hydrogenation of acetylene on Pd/Al2O3 (fiber) catalyst were carried out in a flow type integral reactor combined with chromatography analysis. Model discrimination was made and the surface reaction controlled Langmuir-Hinshelwood mechanism model was shown to be preferred. The rate parameters were evaluated by the combination of integral and differential methods. The following expressions for rate constants k1(for acetylene hydrogenation) and k2 (for ethylene hydrogenation) as a function of reaction temperature were obtained: k1=4.46×106exp(-10400/RT) k2=2.83×108exp(-12200/RT) A brief discussion about the hydrogenation of single ethylene was also given.
Kinetic studies of consecutive hydrogenation of acetylene on Pd/Al2O3 (fiber) catalyst were carried out in a flow type integral reactor combined with chromatography analysis. Model discrimination was made and the surface reaction controlled Langmuir-Hinshelwood mechanism model was shown to be preferred. The rate parameters were evaluated by the combination of integral and differential methods. The following expressions for rate constants k1(for acetylene hydrogenation) and k2 (for ethylene hydrogenation) as a function of reaction temperature were obtained: k1=4.46×106exp(-10400/RT) k2=2.83×108exp(-12200/RT) A brief discussion about the hydrogenation of single ethylene was also given.
1988, 5(1): 52-56
Abstract:
The crystal structure of [Nd(DMSO)5(H2O)3]Cl3·H2O was determined on an ENRAFNONIUS CAD4 diffractometer with X-ray intensity data collected in 0° < 2θ < 50°. The space group is P1 with a=9.800(1), b=10.153(1), c=14.757(2)Å; α=93.07(1), β=100.21(1),γ=99.71(1)°, Z=2. The structure was solved by Patterson method and refined with a fullmatrix least-squares procedure to R=0.036. Nd(Ⅲ) ions are coordinated by eight oxygen atoms forming a distorted dodecahedron. The crystal is stabilized through ionic bonds and hydrogen bonds as well.
The crystal structure of [Nd(DMSO)5(H2O)3]Cl3·H2O was determined on an ENRAFNONIUS CAD4 diffractometer with X-ray intensity data collected in 0° < 2θ < 50°. The space group is P1 with a=9.800(1), b=10.153(1), c=14.757(2)Å; α=93.07(1), β=100.21(1),γ=99.71(1)°, Z=2. The structure was solved by Patterson method and refined with a fullmatrix least-squares procedure to R=0.036. Nd(Ⅲ) ions are coordinated by eight oxygen atoms forming a distorted dodecahedron. The crystal is stabilized through ionic bonds and hydrogen bonds as well.
1988, 5(1): 57-61
Abstract:
In this paper, the values of g factor, ΔHpp, line shape and spin concentration of 2,4-di-(α-imino acetic acid ethyl) bcuteroporphyrin Ⅸ and 2,4-di-(α-mcrcaptoethyl) deutcroporphyrin Ⅸ on X-band were determined. The relationships of the ESR line intensity to saturation effect of microwave power, as well as the temperature were also determined. It is postulated that the ESR spectra registcd under the UV-irradiation at various temperatures were originated from single delocalized electron of porphyrin ring and oxygen dependent radical; the dependence of ESR line intensity on the saturation effect of microwave power is related to isoelectric point (pH value), but the effect of temperature is more complicated. The photochemical reaction is of zero order with respect to oxygen dependent radical and is controlled by the diffusion of the triplet oxygen to the around site of cxcited state of porphyrin.
In this paper, the values of g factor, ΔHpp, line shape and spin concentration of 2,4-di-(α-imino acetic acid ethyl) bcuteroporphyrin Ⅸ and 2,4-di-(α-mcrcaptoethyl) deutcroporphyrin Ⅸ on X-band were determined. The relationships of the ESR line intensity to saturation effect of microwave power, as well as the temperature were also determined. It is postulated that the ESR spectra registcd under the UV-irradiation at various temperatures were originated from single delocalized electron of porphyrin ring and oxygen dependent radical; the dependence of ESR line intensity on the saturation effect of microwave power is related to isoelectric point (pH value), but the effect of temperature is more complicated. The photochemical reaction is of zero order with respect to oxygen dependent radical and is controlled by the diffusion of the triplet oxygen to the around site of cxcited state of porphyrin.
1988, 5(1): 62-66
Abstract:
The results in this paper show that the activation energy of themolysis of PPHFP film is 101.6 kJ·mol-1 and its half-decomposition temperature is 322℃. The plasma polymerization rate has been investigated under different plasma gas, plasma power and gas pressure in plasma tube. On the experimental results the plot of polymerization rate vs. gas pressure in any position of the reactor was obtained. By elemental analysis and ESCA measurements of the film obtained it is confirmed that N atoms have get into the film through chemical bonding when nitrogen is used as plasma gas.
The results in this paper show that the activation energy of themolysis of PPHFP film is 101.6 kJ·mol-1 and its half-decomposition temperature is 322℃. The plasma polymerization rate has been investigated under different plasma gas, plasma power and gas pressure in plasma tube. On the experimental results the plot of polymerization rate vs. gas pressure in any position of the reactor was obtained. By elemental analysis and ESCA measurements of the film obtained it is confirmed that N atoms have get into the film through chemical bonding when nitrogen is used as plasma gas.
1988, 5(1): 67-70
Abstract:
A series of hitherto unknown isomeric monobutyl esters of octylphosphonates was investigated for the structure-reactivity relationship in cobalt and nickel extraction. Linear regression analyses of the apparent extraction equilibrium constants with σp constants and Charton's steric parameters v of substituents directly linked to the coordinating moiety of the acidic phosphonates P(O) OH gave, as a rule, excellent results. Since the σp values of sudstituents of the compounds under investigation are similar, the correlation analysis between extraction constant and Charton's parameter v also gave satisfactory results. Based on these observation, it was suggested that in the serics of acidic mono-alkyl alkylphosphonates, steric effect plays a predominating rule in the extractive separation of cobalt and nickel.
A series of hitherto unknown isomeric monobutyl esters of octylphosphonates was investigated for the structure-reactivity relationship in cobalt and nickel extraction. Linear regression analyses of the apparent extraction equilibrium constants with σp constants and Charton's steric parameters v of substituents directly linked to the coordinating moiety of the acidic phosphonates P(O) OH gave, as a rule, excellent results. Since the σp values of sudstituents of the compounds under investigation are similar, the correlation analysis between extraction constant and Charton's parameter v also gave satisfactory results. Based on these observation, it was suggested that in the serics of acidic mono-alkyl alkylphosphonates, steric effect plays a predominating rule in the extractive separation of cobalt and nickel.
1988, 5(1): 71-73
Abstract:
The total synthesis of an ether-type pyrethroid, Chloproxyfen, is reported in this paper. Starting from chlorobenzene, the Chloproxyfen was synthesized through the Friedel-Crafts alkylation, free radical chlorination and improved Williamson etherification. High yields were achieved in each reaction process with the overall yield of 57.6%. The method is proved to be feasible for the industrial preparation.
The total synthesis of an ether-type pyrethroid, Chloproxyfen, is reported in this paper. Starting from chlorobenzene, the Chloproxyfen was synthesized through the Friedel-Crafts alkylation, free radical chlorination and improved Williamson etherification. High yields were achieved in each reaction process with the overall yield of 57.6%. The method is proved to be feasible for the industrial preparation.
1988, 5(1): 74-77
Abstract:
The oxygen and nitrogen transport rate of methylsilicone rubber, poly (4-methylpentene-1), ethylene-propylene rubber, high-pressure polyethylene and natural rubber membranes were measured at different temperature. The results exhibited that the dependence of gas transport rate of polymer membranes on temperature is relative only to the materials the membranes made. The oxygen and nitrogen permeation activation energy and the temperature coefficient of the gas transport rate were calculated. The relationship of permeation activation energy with the molecular structure of membrane materials was discussed.
The oxygen and nitrogen transport rate of methylsilicone rubber, poly (4-methylpentene-1), ethylene-propylene rubber, high-pressure polyethylene and natural rubber membranes were measured at different temperature. The results exhibited that the dependence of gas transport rate of polymer membranes on temperature is relative only to the materials the membranes made. The oxygen and nitrogen permeation activation energy and the temperature coefficient of the gas transport rate were calculated. The relationship of permeation activation energy with the molecular structure of membrane materials was discussed.
1988, 5(1): 78-81
Abstract:
The effects of normal aliphatie alcohols (C2-C7) on the demulsifibility of five demulsifiers (block eopolymers of polyoxyethylene and polyoxypropylene) for O/W type emulsion have been studied. The results show that the addition of alcohols (2.5vol.%) greatly enhances the demulsification, and n-butyl and n-amyl alcohols are found to be the most effective.
The effects of normal aliphatie alcohols (C2-C7) on the demulsifibility of five demulsifiers (block eopolymers of polyoxyethylene and polyoxypropylene) for O/W type emulsion have been studied. The results show that the addition of alcohols (2.5vol.%) greatly enhances the demulsification, and n-butyl and n-amyl alcohols are found to be the most effective.
1988, 5(1): 82-84
Abstract:
In this paper, the solubility of ternary system Li2SO4-C2H5OH-H2O has been determined at -20℃, 0℃, 30℃ and 50℃ respectively; It has been found that the equilibrium solid phase in the range of studied concentration and temperature is Li2SO4·H2O, which decreases its solubility in water with increase of temperature, but dissolves a little in ethanol. The isothermal solubility data have been correlated by experimental formulae.
In this paper, the solubility of ternary system Li2SO4-C2H5OH-H2O has been determined at -20℃, 0℃, 30℃ and 50℃ respectively; It has been found that the equilibrium solid phase in the range of studied concentration and temperature is Li2SO4·H2O, which decreases its solubility in water with increase of temperature, but dissolves a little in ethanol. The isothermal solubility data have been correlated by experimental formulae.
1988, 5(1): 85-87
Abstract:
By analysing the relationship between the density of oxygen vacancies and the surface potential barrier of SnO2 grain, the effects of the oxygen vacancy density on the electrical conductivity of tin oxide gas sensors, as well as the process of production and recombination of the oxygen vacancies, an oxygen vacancy domination model for electrical conductivity of polyerystalline tin oxide is established. The model explaines the changes in electrical conductivity of the sensors under different sintering conditions. It has been verified by X-ray photoemission spectroscopy measurements.
By analysing the relationship between the density of oxygen vacancies and the surface potential barrier of SnO2 grain, the effects of the oxygen vacancy density on the electrical conductivity of tin oxide gas sensors, as well as the process of production and recombination of the oxygen vacancies, an oxygen vacancy domination model for electrical conductivity of polyerystalline tin oxide is established. The model explaines the changes in electrical conductivity of the sensors under different sintering conditions. It has been verified by X-ray photoemission spectroscopy measurements.
1988, 5(1): 88-90
Abstract:
A simultaneous electrochemical-electron spin resonance(SEESR) cell has been designed. It is easily fabricated and operated and can be used for either aqueous or nonaqueous determation.Using this aparatus, the ESR signals were observed for nitrobenzcne anion radicals, produced by constant potential electrolysis of nitrobenzene in acetonitrile media with 0.1M TBAP as electrolyte and in 0.5M KCl aqueous solution respectively. The hyperfine coupling constants of the nitrobenzene anion radical have been estimated which are in accordance with the literature values.
A simultaneous electrochemical-electron spin resonance(SEESR) cell has been designed. It is easily fabricated and operated and can be used for either aqueous or nonaqueous determation.Using this aparatus, the ESR signals were observed for nitrobenzcne anion radicals, produced by constant potential electrolysis of nitrobenzene in acetonitrile media with 0.1M TBAP as electrolyte and in 0.5M KCl aqueous solution respectively. The hyperfine coupling constants of the nitrobenzene anion radical have been estimated which are in accordance with the literature values.
1988, 5(1): 91-92
Abstract:
A new and convenient synthetic method for aromatic and saturated aliphatic aldehydes with moderate yield via the oxidation of corresponding alcohols by dimethyl sulfoxide in the presence of thiophenol is described.
A new and convenient synthetic method for aromatic and saturated aliphatic aldehydes with moderate yield via the oxidation of corresponding alcohols by dimethyl sulfoxide in the presence of thiophenol is described.
1988, 5(1): 93-96
Abstract:
The polarographie wave of Co(Ⅱ)-5-Br-PADAP complex has been studied in hydroxylamine-NaOH solution in the presence of 0.05-0.2MNaOH, 0.37-0.7% hydroxylamine and 1.2×10-6-2.1×10-6M 5-Br-PADAP. Co(Ⅱ) can be determined in the concentration from 1.7×10-9 to 3.4×10-7M. This method has been used for determining micro amount of cobalt in steel samples with a coefficient of variation of 6%. The property of the peak current and the composition of the complex have also been discussed.
The polarographie wave of Co(Ⅱ)-5-Br-PADAP complex has been studied in hydroxylamine-NaOH solution in the presence of 0.05-0.2MNaOH, 0.37-0.7% hydroxylamine and 1.2×10-6-2.1×10-6M 5-Br-PADAP. Co(Ⅱ) can be determined in the concentration from 1.7×10-9 to 3.4×10-7M. This method has been used for determining micro amount of cobalt in steel samples with a coefficient of variation of 6%. The property of the peak current and the composition of the complex have also been discussed.
