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1988 Volume 5 Issue 4
1988, 5(4): 1-6
Abstract:
In this work, the crystal morphology and the crystallization process of butadiene-isoprene copolymers (BIC) have been observed by electron microscopy. The crystallinities and the crystallization rates were obtained quantitatively using a linear dilatometer. It was found that at the same temperature, the crystallization rate and the crystallinity decreased with the increase of isoprene content, and for the same sample BIC crystallized most rapidly at the temperature of -65℃- -45℃, According to the experimental results about the crystallization of BIC, the Avrami equation has been revised
In this work, the crystal morphology and the crystallization process of butadiene-isoprene copolymers (BIC) have been observed by electron microscopy. The crystallinities and the crystallization rates were obtained quantitatively using a linear dilatometer. It was found that at the same temperature, the crystallization rate and the crystallinity decreased with the increase of isoprene content, and for the same sample BIC crystallized most rapidly at the temperature of -65℃- -45℃, According to the experimental results about the crystallization of BIC, the Avrami equation has been revised
1988, 5(4): 7-11
Abstract:
Bimetallic catalysts were prepared from a zinc salt, triethylaluminum, and an active proton containing compound.The catalysts were studied for the alternating copolymerization of carbon dioxide with propylene oxide giving poly (propylene carbonate). As a cocatalyst, polymer containing carboxyl groups was superior to water.The catalytic activities of the systems depended on the type of zinc salts,the molar ratio of catalyst's components, and the mixing procedure of the components. It is considered that there exists certain cooperative effect from two metals and a possible structure of the active center was proposed.
Bimetallic catalysts were prepared from a zinc salt, triethylaluminum, and an active proton containing compound.The catalysts were studied for the alternating copolymerization of carbon dioxide with propylene oxide giving poly (propylene carbonate). As a cocatalyst, polymer containing carboxyl groups was superior to water.The catalytic activities of the systems depended on the type of zinc salts,the molar ratio of catalyst's components, and the mixing procedure of the components. It is considered that there exists certain cooperative effect from two metals and a possible structure of the active center was proposed.
1988, 5(4): 12-16
Abstract:
The effects of kinds of oxidants and the concentration of oxidant (NH4)2S2O8, HC1 and monomer on aniline polymerization have been investigated. The products were characterized by FTIR,elemental analysis and conductivity measurements. The results show that the polymerization conditions affect not only the polymer yield, but also its conductivity and molecular structure. The experimental conditions to obtain the polyaniline with higher conductivity is outlined.
The effects of kinds of oxidants and the concentration of oxidant (NH4)2S2O8, HC1 and monomer on aniline polymerization have been investigated. The products were characterized by FTIR,elemental analysis and conductivity measurements. The results show that the polymerization conditions affect not only the polymer yield, but also its conductivity and molecular structure. The experimental conditions to obtain the polyaniline with higher conductivity is outlined.
1988, 5(4): 17-23
Abstract:
Eleven antibiotics quinoxaline-1, 4-dioxides (2α-k) were synthesi/ed according to direct oxidation and Beirut reaction.Detailed UV,IR, NMR data were reported and relevant spectroscopic properties were discussed. EPR studies showed that stable paramagnetic species were formed in the photolytic process of these N-oxides in solution.Well-resolved EPR spectrum was obtained from the photolytic solution of 2,3-cyclobutylenequinoxaline-l,4-dioxide(2g). in chloroform, and the hyperfire splittings of 9.69G(1N), 3.59G(2H), 1.25G(2H) and 0.76G(1H) were determined from the spectrum. This radical was assigned as l-hydroxy-2,3-cyclobutylenequinoxalinyl-4-oxyl(4).The similarities between naphthaquinones and quinoxaline-l,4-dioxides in molecular structure and in properties were also pointed out.
Eleven antibiotics quinoxaline-1, 4-dioxides (2α-k) were synthesi/ed according to direct oxidation and Beirut reaction.Detailed UV,IR, NMR data were reported and relevant spectroscopic properties were discussed. EPR studies showed that stable paramagnetic species were formed in the photolytic process of these N-oxides in solution.Well-resolved EPR spectrum was obtained from the photolytic solution of 2,3-cyclobutylenequinoxaline-l,4-dioxide(2g). in chloroform, and the hyperfire splittings of 9.69G(1N), 3.59G(2H), 1.25G(2H) and 0.76G(1H) were determined from the spectrum. This radical was assigned as l-hydroxy-2,3-cyclobutylenequinoxalinyl-4-oxyl(4).The similarities between naphthaquinones and quinoxaline-l,4-dioxides in molecular structure and in properties were also pointed out.
1988, 5(4): 24-28
Abstract:
This paper describes the preparation of macroreticular polymethylmethacrylate beads by means of suspension polymerization, which is then loaded with mono-2-ethylhexyl 2-ethylhexylphosphonic acid(designated as P 507).The effects of degree of cross-linking, composition and amount of pore-produring agent added upon the pore structure of the resin beads are discussed. It is found that, good and poor solvents in various proportions may produce resins with different pore structures.By increasing the amount of pore-producing agent, the apparent specific gravity, ρa, decreases, while specific surface area, S, pore volume, PV, and average pore diameter,D, increase. Both ρ. and S increase, and PV and D decrease, when the degree of cross-linking increases from 10 to 35%.Increasing the proportion of good solvent in pore-producing agent, increase ρa and S, decrease PV and D.A series of macroreticular resin beads with different pore structure has been prepared, and compared for their effectiveness in the separation of lanthanum, cerium, praseodymium and neodymium mixture under identical conditions.Experimental results show that pore structure of the P 507 loaded polymethylmethacrylate beads plays an important role in the separation of rare earths. With polymethylmethacrylate beads of appropriate pore structure, the separation of rare earths by means of extractive chromatograchy can be achieved satisfactorily.
This paper describes the preparation of macroreticular polymethylmethacrylate beads by means of suspension polymerization, which is then loaded with mono-2-ethylhexyl 2-ethylhexylphosphonic acid(designated as P 507).The effects of degree of cross-linking, composition and amount of pore-produring agent added upon the pore structure of the resin beads are discussed. It is found that, good and poor solvents in various proportions may produce resins with different pore structures.By increasing the amount of pore-producing agent, the apparent specific gravity, ρa, decreases, while specific surface area, S, pore volume, PV, and average pore diameter,D, increase. Both ρ. and S increase, and PV and D decrease, when the degree of cross-linking increases from 10 to 35%.Increasing the proportion of good solvent in pore-producing agent, increase ρa and S, decrease PV and D.A series of macroreticular resin beads with different pore structure has been prepared, and compared for their effectiveness in the separation of lanthanum, cerium, praseodymium and neodymium mixture under identical conditions.Experimental results show that pore structure of the P 507 loaded polymethylmethacrylate beads plays an important role in the separation of rare earths. With polymethylmethacrylate beads of appropriate pore structure, the separation of rare earths by means of extractive chromatograchy can be achieved satisfactorily.
1988, 5(4): 29-32
Abstract:
The photooxidation of Tb3+ in KIO4-KOH solution is reported in this paper.The soluble complex formed in this system was irradiated by high pressure mercury lamp (366nm). The influences of the concentration of KIO4,KOH and Tb3+,the time and area of exposure and the light intensity on the amount of Tb4+ formed were investigated. The preferable concentration of KOH is>0.3M,and that of KIO4 is two orders higher than the initial concentration of Tb3+. The soluble complex ion of Tb4+ formed is red-brown and fairly stable. The maximum of its absorption band is at about 420nm.
The photooxidation of Tb3+ in KIO4-KOH solution is reported in this paper.The soluble complex formed in this system was irradiated by high pressure mercury lamp (366nm). The influences of the concentration of KIO4,KOH and Tb3+,the time and area of exposure and the light intensity on the amount of Tb4+ formed were investigated. The preferable concentration of KOH is>0.3M,and that of KIO4 is two orders higher than the initial concentration of Tb3+. The soluble complex ion of Tb4+ formed is red-brown and fairly stable. The maximum of its absorption band is at about 420nm.
1988, 5(4): 33-36
Abstract:
A solid complex of manganous chloride with benzo-15-crown-5 ether was prepared from absolute alcohol and acetone in a wide range of mole ratio of salt to crown ether. The unique stoichiometric complex formed has been characterized as 3MnCl2·2B15C5·4H2O by elemental analysis, gas chromatography,IR-spectra, UV-spectra, x-ray diffraction, thermo gravimetric and differential thermal analysis.Its solubilities in some organic solvents are reported in the paper.
A solid complex of manganous chloride with benzo-15-crown-5 ether was prepared from absolute alcohol and acetone in a wide range of mole ratio of salt to crown ether. The unique stoichiometric complex formed has been characterized as 3MnCl2·2B15C5·4H2O by elemental analysis, gas chromatography,IR-spectra, UV-spectra, x-ray diffraction, thermo gravimetric and differential thermal analysis.Its solubilities in some organic solvents are reported in the paper.
1988, 5(4): 37-41
Abstract:
In this paper, the effect of chain structure, molecular weight and its distribution on the processibility and vulcanizate's properties of 1,2-polybutadiene (1,2-PB) synthesized with molybdenum based catalyst was studied.It is shown that its yield strength (σy) increases, plasticity decreases but millibility, extrudability and stock adhesion become poorer with increase of the molecular weight of 1,2-PB.When [η] was over 3, processing oil had to be added during mixing, otherwise, the mixed stock was too crumbly to be sheeted out. In addition, the cord adhesion for 1,2-PB vulcanizate decreases with increase of molecular weight of polymer. Results indicate that the Wet-skid resistance of 1,2-PB vulcanizate is enhanced as its 1,2 unit content increases. Raising syndyotactic content would lead to strain induced crystallization.When syndyotactic content was 20%, the critical intrinsic viscosity [η]c was 4, above which strain ind uced crystallization could appear.The stock adhesion,as well as the resilience of 1,2-PB vulcanizates would obviously decrease with raised syndyotactic content.
In this paper, the effect of chain structure, molecular weight and its distribution on the processibility and vulcanizate's properties of 1,2-polybutadiene (1,2-PB) synthesized with molybdenum based catalyst was studied.It is shown that its yield strength (σy) increases, plasticity decreases but millibility, extrudability and stock adhesion become poorer with increase of the molecular weight of 1,2-PB.When [η] was over 3, processing oil had to be added during mixing, otherwise, the mixed stock was too crumbly to be sheeted out. In addition, the cord adhesion for 1,2-PB vulcanizate decreases with increase of molecular weight of polymer. Results indicate that the Wet-skid resistance of 1,2-PB vulcanizate is enhanced as its 1,2 unit content increases. Raising syndyotactic content would lead to strain induced crystallization.When syndyotactic content was 20%, the critical intrinsic viscosity [η]c was 4, above which strain ind uced crystallization could appear.The stock adhesion,as well as the resilience of 1,2-PB vulcanizates would obviously decrease with raised syndyotactic content.
1988, 5(4): 42-45
Abstract:
The crystal structures of the title compounds were determined by single crystal X-ray diffraction. The complexes all crystallize in the monoclinic space group P21/c, with Z=4. Lattice parameters are, a=12.160(4)[12.153(4), 12.122(4)]**,b=8.549(3)[8.562(2), 8.550(4)], c=15.425(2)[l5.376(3), 15.293(6)]Å, β=92.55(2)[92.22(2), 91.77 (3)]°. The structures were solved by Patterson and Fourier techniques and refined by leastsquares to R=0.032 [0.067, 0.067]. The Ln (Ⅲ) ions (Ln=Pr, Nb, Sm) are 10-coordinated, being bonded to three bidentate nitrate groups and to the four oxygen atoms of the crown ether. The Ln-O distances are in the range 2.49-2.62[2.47-2.62,2.44-2.58]Å(average:2.54[2.53, 2.51]Å).
The crystal structures of the title compounds were determined by single crystal X-ray diffraction. The complexes all crystallize in the monoclinic space group P21/c, with Z=4. Lattice parameters are, a=12.160(4)[12.153(4), 12.122(4)]**,b=8.549(3)[8.562(2), 8.550(4)], c=15.425(2)[l5.376(3), 15.293(6)]Å, β=92.55(2)[92.22(2), 91.77 (3)]°. The structures were solved by Patterson and Fourier techniques and refined by leastsquares to R=0.032 [0.067, 0.067]. The Ln (Ⅲ) ions (Ln=Pr, Nb, Sm) are 10-coordinated, being bonded to three bidentate nitrate groups and to the four oxygen atoms of the crown ether. The Ln-O distances are in the range 2.49-2.62[2.47-2.62,2.44-2.58]Å(average:2.54[2.53, 2.51]Å).
1988, 5(4): 46-49
Abstract:
The self-condensation of crotonaldehyde was studied in the presence of tripyridyl π-allyl iron chloride.The product was confirmed as 6-methyl 1,3-cyclohexadiene-1-carboxaldehyde by Gc-MS, IR and ~1H NMR.It was suggested that the possible mechanism of the reaction might be the initial ligand exchange of crotonaldehyde with tripyridyl π-allyl iron chloride followed by addition and cyclization with another molecule of crotonaldehyde.The selectivity of reaction was increased greatly by orientation effect of ligand in the complex without side reaction.
The self-condensation of crotonaldehyde was studied in the presence of tripyridyl π-allyl iron chloride.The product was confirmed as 6-methyl 1,3-cyclohexadiene-1-carboxaldehyde by Gc-MS, IR and ~1H NMR.It was suggested that the possible mechanism of the reaction might be the initial ligand exchange of crotonaldehyde with tripyridyl π-allyl iron chloride followed by addition and cyclization with another molecule of crotonaldehyde.The selectivity of reaction was increased greatly by orientation effect of ligand in the complex without side reaction.
1988, 5(4): 50-53
Abstract:
The crystals of the title compound are orthorhombic with space group Pbca and a=23.3973(6)Å,b=22.5524(7)Å, c=15.1043(2)Å V=7970.02Å3, for Z=8.Diffracted intensities were collected on a Nicolet XRD R3 four-circle diffractometer using MoKα radiation.The scanning technique was employed with a scan range 3° < 2θ < 45°.All independent reflections were 5200 among which 2859 reflections were observable (Ⅰ>3σ(Ⅰ)).The structure was determined by the heavy atom method and refined by block-diagonal matric least-square method.The average Mn-N bond length is 2.005Å and Mn-Cl bond length is 2.370(3)Å.
The crystals of the title compound are orthorhombic with space group Pbca and a=23.3973(6)Å,b=22.5524(7)Å, c=15.1043(2)Å V=7970.02Å3, for Z=8.Diffracted intensities were collected on a Nicolet XRD R3 four-circle diffractometer using MoKα radiation.The scanning technique was employed with a scan range 3° < 2θ < 45°.All independent reflections were 5200 among which 2859 reflections were observable (Ⅰ>3σ(Ⅰ)).The structure was determined by the heavy atom method and refined by block-diagonal matric least-square method.The average Mn-N bond length is 2.005Å and Mn-Cl bond length is 2.370(3)Å.
1988, 5(4): 54-57
Abstract:
The synthesis of 11 novel compounds of 5-substituted 2-amino-l,3,4-thiadiazole and 2-substituted amino-l,3,4-thiadiazoles are described.The bactericidal activity against Xanthomonas campestris pv oryzae in vivo of about 30 ATDA analogues is observed.2-Amino-5-car-boxyl-l,3,4-thiadiazole exhibites an excellent bactericidal activity.It is postulated that the acive compound which can serve as the competitor of nicotinamide in metabolite.system in bacteria cell seems to be 2-amino-5-carboxyl-l,3,4-thiadiazole rather than ATDA itself.
The synthesis of 11 novel compounds of 5-substituted 2-amino-l,3,4-thiadiazole and 2-substituted amino-l,3,4-thiadiazoles are described.The bactericidal activity against Xanthomonas campestris pv oryzae in vivo of about 30 ATDA analogues is observed.2-Amino-5-car-boxyl-l,3,4-thiadiazole exhibites an excellent bactericidal activity.It is postulated that the acive compound which can serve as the competitor of nicotinamide in metabolite.system in bacteria cell seems to be 2-amino-5-carboxyl-l,3,4-thiadiazole rather than ATDA itself.
1988, 5(4): 58-60
Abstract:
p-CulnSe2 thin film on titaniun or nickel substrate was obtained by electro deposition from a solution of 0.08M InCl3+0.02M CuCl+0.052M SeO2(pH=1.3) with current density of about 6mA/cm2 and under potential of -0.7-0.75V(vs.SCE).The effects of the deposition conditions and the annealing treatment on the film appearance were discussed.The photoelectrochemical currents of the cells based on P-CuInSe2 thin film in a mixture of Na2S, S,and NaOH were measured.
p-CulnSe2 thin film on titaniun or nickel substrate was obtained by electro deposition from a solution of 0.08M InCl3+0.02M CuCl+0.052M SeO2(pH=1.3) with current density of about 6mA/cm2 and under potential of -0.7-0.75V(vs.SCE).The effects of the deposition conditions and the annealing treatment on the film appearance were discussed.The photoelectrochemical currents of the cells based on P-CuInSe2 thin film in a mixture of Na2S, S,and NaOH were measured.
1988, 5(4): 61-63
Abstract:
The reactions of YbCl2, SmCl2, NdCl2 with C8H8 have been studied.It is found that SmCl2, NdCl2 can react with C8H8 in THF at room temperature directly, forming SmCl3(Sm(C8H8) Cl·2THF); NdCl3, and (Nd(C8H8)Cl·2THF) respectively, which were characterized by elemental analysis and IR spectra.However, YbCl2 does not react with C8H8 under the same conditions.The mechanism of the reaction is proposed: 2RECl2+C8H8???19880414???(Cl2REC8H8RECl2)→RECl3+REC8H8Cl The reactive activities of LnCl2 in the reaction were found to be in the order: NdCl2>SmCl2>>YbCl2., The reactions of YbCl2, SmCl2, NdCl2 with C8H8 have been studied.It is found that SmCl2, NdCl2 can react with C8H8 in THF at room temperature directly, forming SmCl3(Sm(C8H8) Cl·2THF); NdCl3, and (Nd(C8H8)Cl·2THF) respectively, which were characterized by elemental analysis and IR spectra.However, YbCl2 does not react with C8H8 under the same conditions.The mechanism of the reaction is proposed: 2RECl2+C8H8
(Cl2REC8H8RECl2)→RECl3+REC8H8Cl The reactive activities of LnCl2 in the reaction were found to be in the order: NdCl2>SmCl2>>YbCl2.
The reactions of YbCl2, SmCl2, NdCl2 with C8H8 have been studied.It is found that SmCl2, NdCl2 can react with C8H8 in THF at room temperature directly, forming SmCl3(Sm(C8H8) Cl·2THF); NdCl3, and (Nd(C8H8)Cl·2THF) respectively, which were characterized by elemental analysis and IR spectra.However, YbCl2 does not react with C8H8 under the same conditions.The mechanism of the reaction is proposed: 2RECl2+C8H8???19880414???(Cl2REC8H8RECl2)→RECl3+REC8H8Cl The reactive activities of LnCl2 in the reaction were found to be in the order: NdCl2>SmCl2>>YbCl2., The reactions of YbCl2, SmCl2, NdCl2 with C8H8 have been studied.It is found that SmCl2, NdCl2 can react with C8H8 in THF at room temperature directly, forming SmCl3(Sm(C8H8) Cl·2THF); NdCl3, and (Nd(C8H8)Cl·2THF) respectively, which were characterized by elemental analysis and IR spectra.However, YbCl2 does not react with C8H8 under the same conditions.The mechanism of the reaction is proposed: 2RECl2+C8H8
(Cl2REC8H8RECl2)→RECl3+REC8H8Cl The reactive activities of LnCl2 in the reaction were found to be in the order: NdCl2>SmCl2>>YbCl2.
1988, 5(4): 64-66
Abstract:
The extraction mechanism of molybdenum from sulfate system by trialkyl benzyl ammonium sulfate (TABAS) has been studied.The results showed that the extraction rate of molybdenum has a maximum value at pH=2-3.The composition of the extracted complex is [R3NCH2-C6H5]3HMo7O23 as determined by the saturation method and slope method.The extraction mechanism based on UV-VIS spectra and IR-spectra was proved to be an anion exchange reaction as follows: 3[R3NCH2-C6H5]2SO4(o)+2HMo7O23(z)2-⇌2[R3NCH2-C6H5]3HMo7O23(o)+
The extraction mechanism of molybdenum from sulfate system by trialkyl benzyl ammonium sulfate (TABAS) has been studied.The results showed that the extraction rate of molybdenum has a maximum value at pH=2-3.The composition of the extracted complex is [R3NCH2-C6H5]3HMo7O23 as determined by the saturation method and slope method.The extraction mechanism based on UV-VIS spectra and IR-spectra was proved to be an anion exchange reaction as follows: 3[R3NCH2-C6H5]2SO4(o)+2HMo7O23(z)2-⇌2[R3NCH2-C6H5]3HMo7O23(o)+
1988, 5(4): 67-69
Abstract:
The crystal of K3Dy(PO4)2 has been grown from KCl-KF melt.A single crystal in size of 1.5×1.2×0.5mm3 was obtained under certain ratio of rare-earths to flux and by proper controlling the quantity of volatilization.The composition K3Dy(PO4)2 was identified by chemical analysis.X-ray diffractometry proved that the crystal belongs to monoclinic system with space group P21/m.The lattice parameters of the crystal were calculated. It is found that the cell volume of crystal reduces as the atomic number of rare earth in K3Ln(Po4)2 increases, ion radius of Ln3+ decreaces and the complex ability increases. The infrared,absorption,excition,and fluorescene spectra of K3Dy(PO4)2 are also reported.
The crystal of K3Dy(PO4)2 has been grown from KCl-KF melt.A single crystal in size of 1.5×1.2×0.5mm3 was obtained under certain ratio of rare-earths to flux and by proper controlling the quantity of volatilization.The composition K3Dy(PO4)2 was identified by chemical analysis.X-ray diffractometry proved that the crystal belongs to monoclinic system with space group P21/m.The lattice parameters of the crystal were calculated. It is found that the cell volume of crystal reduces as the atomic number of rare earth in K3Ln(Po4)2 increases, ion radius of Ln3+ decreaces and the complex ability increases. The infrared,absorption,excition,and fluorescene spectra of K3Dy(PO4)2 are also reported.
1988, 5(4): 70-72
Abstract:
The kinetics and mechanism of extraction of HNO3, HC1 and HClO4 with trioctylamine have been studied in a stirred cell with stationary interface.The extraction rate is proved to be controlled by two interface reactions (5) and (6).
The kinetics and mechanism of extraction of HNO3, HC1 and HClO4 with trioctylamine have been studied in a stirred cell with stationary interface.The extraction rate is proved to be controlled by two interface reactions (5) and (6).
1988, 5(4): 73-75
Abstract:
The redox electric charges of polyaniline synthesized by potentiostatic electrolysis in varius acids were mearsured,they were much higher than that of polyaniline synthesized by chemical method.The redox peaks of polyaniline synthesized at high anodic potential are decreased markedly.It might be caused by an irreversible degradation of polyaniline and/or a certain type of destruction of the polymer structure.A.C.impedance measurements at different potential show that the resistance of the polyaniline electrode varies with the electrode potential.
The redox electric charges of polyaniline synthesized by potentiostatic electrolysis in varius acids were mearsured,they were much higher than that of polyaniline synthesized by chemical method.The redox peaks of polyaniline synthesized at high anodic potential are decreased markedly.It might be caused by an irreversible degradation of polyaniline and/or a certain type of destruction of the polymer structure.A.C.impedance measurements at different potential show that the resistance of the polyaniline electrode varies with the electrode potential.
1988, 5(4): 76-78
Abstract:
A solid superacid SO42-/TiO2 has been synthesied according to Hino's method.Its catalytic properties in esterifications were examined.The yields of esters are 95% for HAc with C2H9OH and 88% for phthalic anhydride with CH3(CH2)3 CH(C2H5)CH2OH.
A solid superacid SO42-/TiO2 has been synthesied according to Hino's method.Its catalytic properties in esterifications were examined.The yields of esters are 95% for HAc with C2H9OH and 88% for phthalic anhydride with CH3(CH2)3 CH(C2H5)CH2OH.
1988, 5(4): 79-80
Abstract:
A new compound l,2-bis(2,4,6-tribromo-3-methylphenoxy) ethane was synthesized from m-cresol in an autoclave.Methanol and Na2CO3 were used as solvent and base respectively.The yield was 79%.
A new compound l,2-bis(2,4,6-tribromo-3-methylphenoxy) ethane was synthesized from m-cresol in an autoclave.Methanol and Na2CO3 were used as solvent and base respectively.The yield was 79%.
1988, 5(4): 81-83
Abstract:
Hydroquinone monomethyl ether was synthesized from hydroquinone and methanol using heteropolyacid as catalyst and an autocatalysis mechanism was proposed by which quinonc is considered to be a promotor during the reaction.It is suggested that the high activity and selectivity of the heteropolyacid are due to the strong acidity and redox property of the acid.
Hydroquinone monomethyl ether was synthesized from hydroquinone and methanol using heteropolyacid as catalyst and an autocatalysis mechanism was proposed by which quinonc is considered to be a promotor during the reaction.It is suggested that the high activity and selectivity of the heteropolyacid are due to the strong acidity and redox property of the acid.
1988, 5(4): 84-86
Abstract:
Basic carbonate of Pr(Ⅳ) being dissolved in aqueous solution of acetic acid gives an yellow Pr(Ⅳ)-Ac- complex which shows a broad characteristic absorption band at 266nm.The ratio of Pr(Ⅳ): Ac- in complex as determined by equilibrium shifting method is 1:4.It is found that the reduction of Pr(Ⅳ)-Ac- complex in aqueous acetic acid solution is a pseudo first order reaction.
Basic carbonate of Pr(Ⅳ) being dissolved in aqueous solution of acetic acid gives an yellow Pr(Ⅳ)-Ac- complex which shows a broad characteristic absorption band at 266nm.The ratio of Pr(Ⅳ): Ac- in complex as determined by equilibrium shifting method is 1:4.It is found that the reduction of Pr(Ⅳ)-Ac- complex in aqueous acetic acid solution is a pseudo first order reaction.
1988, 5(4): 87-90
Abstract:
In order to restrain the electrochemical aging of viologens, a polyionccmplex based on poly (m-xylyl viologen dibromide) (m-PXV-Br2) and polymethacrylic acid (PMAA) was synthesised.Cyclic voltammogram and potential-step tests show that the redox.active sites in the polyion complex have a very good electrochemical stability, that is, no any decrease in peak current was observed even the potential scan lasting 500 Cycles.It was also observed that the electrochemical activity of the film decreases with increase of the film thickness and is in relation with the ionic-strength of supporting electrolyte.The response speed of the film coated on a graghite electrode was 0.18 second with the thickness being 0.875μm.
In order to restrain the electrochemical aging of viologens, a polyionccmplex based on poly (m-xylyl viologen dibromide) (m-PXV-Br2) and polymethacrylic acid (PMAA) was synthesised.Cyclic voltammogram and potential-step tests show that the redox.active sites in the polyion complex have a very good electrochemical stability, that is, no any decrease in peak current was observed even the potential scan lasting 500 Cycles.It was also observed that the electrochemical activity of the film decreases with increase of the film thickness and is in relation with the ionic-strength of supporting electrolyte.The response speed of the film coated on a graghite electrode was 0.18 second with the thickness being 0.875μm.
