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2002 Volume 19 Issue 11
2002, 19(11): 1021-1026
Abstract:
An optical chemical sensor for molybdate based on reversible fluorescence quenching property of 2,2,7,7,12,12,17,17-octamethyl-21,22,23,24-tetraoxaquaterene(TOE) immobilized in poly(vinyl chloride)(PVC) membrane has been developed. The optimum membrane sensor consists of 2.6 mg TOE, 50 mg PVC and 100 mg diisooctyl sebacate(DOS). The maximum response of the membrane sensor for molybdate was obtained in Tris/HCl buffer solution (pH=8.0). The sensor responds linearly in range of 1.43×10-7 to 5.0×10-4 mol/L molybdate, with detection limit of 4.73×10-8 mol/L, response time less than 30 s. In addition to high reproducibility and reversibility, the sensor also exhibits good selectivity over some common anions and cations. It has been applied in the determination of molybdenum as molybdate in a Scheelite sample, with satisfactory results.
An optical chemical sensor for molybdate based on reversible fluorescence quenching property of 2,2,7,7,12,12,17,17-octamethyl-21,22,23,24-tetraoxaquaterene(TOE) immobilized in poly(vinyl chloride)(PVC) membrane has been developed. The optimum membrane sensor consists of 2.6 mg TOE, 50 mg PVC and 100 mg diisooctyl sebacate(DOS). The maximum response of the membrane sensor for molybdate was obtained in Tris/HCl buffer solution (pH=8.0). The sensor responds linearly in range of 1.43×10-7 to 5.0×10-4 mol/L molybdate, with detection limit of 4.73×10-8 mol/L, response time less than 30 s. In addition to high reproducibility and reversibility, the sensor also exhibits good selectivity over some common anions and cations. It has been applied in the determination of molybdenum as molybdate in a Scheelite sample, with satisfactory results.
2002, 19(11): 1027-1031
Abstract:
Blends of maleic anhydride endcapped poly(propylene carbonate)(MAPPC) with ethylcellulose(EC) in different mass fraction composition were prepared by solution casting. DSC, TGA, WAXD and SEM were used to investigate the miscibility, thermal stability, aggregation structure and morphology of the blends. A single glass transition temperature of the blend revealed the miscibility of MAPPC with EC in the noncrystalline region. The solid phase-mesophase phase transition temperature, the mesophase-isotropic phase transition temperature and the transition enthalpy of the blends were found increased gradually with the increase of EC content in the EC-rich blend. Upon blending EC into MAPPC, the thermal decomposition temperatures were elevated, especially for MAPPC/EC blend with mass ratio of 90:10. Dilution of MAPPC with cholesteric liquid crystalline EC caused the shift of two peaks of EC to greater Bragg angles and the decrease of the distances between layers of ordered polymer chains and the distances between polymer chains, and resulted in the increase of crystallite dimensions of mesophase region and the decrease of sizes of non-crystalline region. Blends appeared to pack more compactly.
Blends of maleic anhydride endcapped poly(propylene carbonate)(MAPPC) with ethylcellulose(EC) in different mass fraction composition were prepared by solution casting. DSC, TGA, WAXD and SEM were used to investigate the miscibility, thermal stability, aggregation structure and morphology of the blends. A single glass transition temperature of the blend revealed the miscibility of MAPPC with EC in the noncrystalline region. The solid phase-mesophase phase transition temperature, the mesophase-isotropic phase transition temperature and the transition enthalpy of the blends were found increased gradually with the increase of EC content in the EC-rich blend. Upon blending EC into MAPPC, the thermal decomposition temperatures were elevated, especially for MAPPC/EC blend with mass ratio of 90:10. Dilution of MAPPC with cholesteric liquid crystalline EC caused the shift of two peaks of EC to greater Bragg angles and the decrease of the distances between layers of ordered polymer chains and the distances between polymer chains, and resulted in the increase of crystallite dimensions of mesophase region and the decrease of sizes of non-crystalline region. Blends appeared to pack more compactly.
2002, 19(11): 1032-1036
Abstract:
Alumina with particle size of ca. 15 nm was synthesized by a frothing method. Effects of frothing reagents, ratio of frothing reagent to Al3+, frothing evaporat temperature and evaporation temperature on the particle size of product were investigated. The thermal stability and complexing ability of the frothing reagents were found to be the determined factors in synthesis of nanosized alumina. Citric acid appeared the best one among the frothing reagents tested to give the product with the smallest size, probably due to its medium complexizing ability and thermal stability. The optimum evaporation and frothing temperatures were 70~90℃ and 120~150℃, respectively. XRD, IR, DTG-DSC, TEM and NMR were used in monitoring the synthetic process.
Alumina with particle size of ca. 15 nm was synthesized by a frothing method. Effects of frothing reagents, ratio of frothing reagent to Al3+, frothing evaporat temperature and evaporation temperature on the particle size of product were investigated. The thermal stability and complexing ability of the frothing reagents were found to be the determined factors in synthesis of nanosized alumina. Citric acid appeared the best one among the frothing reagents tested to give the product with the smallest size, probably due to its medium complexizing ability and thermal stability. The optimum evaporation and frothing temperatures were 70~90℃ and 120~150℃, respectively. XRD, IR, DTG-DSC, TEM and NMR were used in monitoring the synthetic process.
2002, 19(11): 1037-1042
Abstract:
A novel autocorrelation topological index (tG) for twenty four substituted aromatic compounds (with substituents Cl, Br, OH, NH2, NO2 and alkyl) has been derived based on the gi, a characteristic value of bioactivity for bonding atom i. The quantitative structure-activity relationships(QSAR) studies are performed in relation to the acute toxicities and 1G, 0G, L of the compounds. The linear regression equations between 1G, 0G, L and acute toxicity of the substituted aromatic compounds to the aquatic organisms are obtained as follows: -lg EC50=2.19633+0.018901G+0.01780L, r= 0.9632 -lg EC'50=2.28712+0.018411G+0.01080L, r= 0.9683 -lg LC50=1.78688+0.034411G-0.01201L-0.03278 0G, r= 0.936 6 The values calculated by the models are basically true as the experiment values.
A novel autocorrelation topological index (tG) for twenty four substituted aromatic compounds (with substituents Cl, Br, OH, NH2, NO2 and alkyl) has been derived based on the gi, a characteristic value of bioactivity for bonding atom i. The quantitative structure-activity relationships(QSAR) studies are performed in relation to the acute toxicities and 1G, 0G, L of the compounds. The linear regression equations between 1G, 0G, L and acute toxicity of the substituted aromatic compounds to the aquatic organisms are obtained as follows: -lg EC50=2.19633+0.018901G+0.01780L, r= 0.9632 -lg EC'50=2.28712+0.018411G+0.01080L, r= 0.9683 -lg LC50=1.78688+0.034411G-0.01201L-0.03278 0G, r= 0.936 6 The values calculated by the models are basically true as the experiment values.
2002, 19(11): 1043-1048
Abstract:
The precursors Nax[Li1/6Mn5/6]O2 having P2 structure were synthesized by solid-state reaction at high temperature followed by calcination. The layered Liy[Li1/6Mn5/6]O2 was then obtained by refluxing precursor with an excess of LiBr in n-hexanol. Li+ was confirmed to be in the host layers by virtue of its slow rate of exchange with molten magnesium nitrate. XRD showed that the Liy[Li1/6Mn5/6]O2 has a layered O2 structure with hexagonal space group P3ml. Laser particle size analysis of Na0.06 Li0.65[Li0.10Mn0.88]O2 gives a uniform particle size distribution with a maximum at 2.88 μm. BET surface area was 4.68 m2/g. The crystals of products possess a defected hexagonal plate-like morphology with stacking faults. XRD and elemental analysis confirmed that the n(Na)/n(Mn) ratio of the reagents shows a direct effect on the crystal structure and chemical composition of both the precusor and final product.
The precursors Nax[Li1/6Mn5/6]O2 having P2 structure were synthesized by solid-state reaction at high temperature followed by calcination. The layered Liy[Li1/6Mn5/6]O2 was then obtained by refluxing precursor with an excess of LiBr in n-hexanol. Li+ was confirmed to be in the host layers by virtue of its slow rate of exchange with molten magnesium nitrate. XRD showed that the Liy[Li1/6Mn5/6]O2 has a layered O2 structure with hexagonal space group P3ml. Laser particle size analysis of Na0.06 Li0.65[Li0.10Mn0.88]O2 gives a uniform particle size distribution with a maximum at 2.88 μm. BET surface area was 4.68 m2/g. The crystals of products possess a defected hexagonal plate-like morphology with stacking faults. XRD and elemental analysis confirmed that the n(Na)/n(Mn) ratio of the reagents shows a direct effect on the crystal structure and chemical composition of both the precusor and final product.
2002, 19(11): 1049-1053
Abstract:
The influences of preparation technology and composition of Cu-Ce mixed oxide catalysts as well as the reaction condition of hydrogenation of nitrobenzene over (Cu)CeO2 have been investigated. Among the four preparation regimes studied the best appeared the coprecipitation method which comprises coprecipitation of Ce(NO3)3 and Cu(NO3)2 solution with aq. NaOH, followed by calcination of the precipitate at 650℃ for 4 h. The catalyst exhibited a satisfactory working life, with both conversion of nitrobenzene and selectivity of aniline being achieved almost quantitatively in hydrogenation reaction at the structure threshold of the catalyst near 9% Cu content. The optimum reaction conditions was as follows: 190℃, PH2 0.5 MPa, n(H2)/n(C6H5NO2)>4, LHSV<6 h-1.
The influences of preparation technology and composition of Cu-Ce mixed oxide catalysts as well as the reaction condition of hydrogenation of nitrobenzene over (Cu)CeO2 have been investigated. Among the four preparation regimes studied the best appeared the coprecipitation method which comprises coprecipitation of Ce(NO3)3 and Cu(NO3)2 solution with aq. NaOH, followed by calcination of the precipitate at 650℃ for 4 h. The catalyst exhibited a satisfactory working life, with both conversion of nitrobenzene and selectivity of aniline being achieved almost quantitatively in hydrogenation reaction at the structure threshold of the catalyst near 9% Cu content. The optimum reaction conditions was as follows: 190℃, PH2 0.5 MPa, n(H2)/n(C6H5NO2)>4, LHSV<6 h-1.
2002, 19(11): 1054-1058
Abstract:
The quantum-chemical descriptors were used on the study of structures of benzoic acid derivatives and their pKa values, and the algorithms of multiple linear regression(MLR) and artificial neural network(ANN) were applied for 2D-QSPR. The comparative molecular field analysis(CoMFA) method was used for 3D-QSPR. Better results have been obtained. The influences of steric and electrostatic effects were discussed.
The quantum-chemical descriptors were used on the study of structures of benzoic acid derivatives and their pKa values, and the algorithms of multiple linear regression(MLR) and artificial neural network(ANN) were applied for 2D-QSPR. The comparative molecular field analysis(CoMFA) method was used for 3D-QSPR. Better results have been obtained. The influences of steric and electrostatic effects were discussed.
2002, 19(11): 1059-1063
Abstract:
The complex CuZnTS·CH3OH, where TS denotes the binuclear ligand derived from the Schiff base N,N'-bis(3-carboxylsalicyl aldehyde)trimethylenediamine, was synthesized and its crystal structure was determined by the single-crystal X-ray diffraction method at room temperature. The complex crystallizes in triclinic system with space group P1. The lattice parameters are a=0.94403(19) nm, b=1.1591(2) nm, c=0.91322(18) nm, and T=91.09(3)°, U=97.06(3)°, V=75.06(3)°, Z=2 with R1=0.0499, wR2=0.0318. The structure is consisted of heterobinuclear units, where the copper atom is fivefold coordinated by two nitrogens, two phenolic oxygens, and one oxygen of a methanol molecule in a distorted square pyramid, and the zinc atom is also in a distorted square pyramid manner, coordinated by two phenolic oxygen atoms, two equatorial carboxyl oxygen atoms and one oxygen of the adjacent molecular. The cyclic voltametric behavior of the complex is briefly examined.
The complex CuZnTS·CH3OH, where TS denotes the binuclear ligand derived from the Schiff base N,N'-bis(3-carboxylsalicyl aldehyde)trimethylenediamine, was synthesized and its crystal structure was determined by the single-crystal X-ray diffraction method at room temperature. The complex crystallizes in triclinic system with space group P1. The lattice parameters are a=0.94403(19) nm, b=1.1591(2) nm, c=0.91322(18) nm, and T=91.09(3)°, U=97.06(3)°, V=75.06(3)°, Z=2 with R1=0.0499, wR2=0.0318. The structure is consisted of heterobinuclear units, where the copper atom is fivefold coordinated by two nitrogens, two phenolic oxygens, and one oxygen of a methanol molecule in a distorted square pyramid, and the zinc atom is also in a distorted square pyramid manner, coordinated by two phenolic oxygen atoms, two equatorial carboxyl oxygen atoms and one oxygen of the adjacent molecular. The cyclic voltametric behavior of the complex is briefly examined.
2002, 19(11): 1064-1067
Abstract:
The suitabale ratio material and reaction conditions were selected, saturated acid such as m-phthalic acid, o-phthalic acid and their mixing acid(m/o-phthalic acid mol ratio 4:1), mix disalcohol(propanediol/diethylene glycol mol ratio 4:1) were used, respectively. Three kinds of resins(they are m-UPR, o-UPR and mix-UPR, respectively) have been prepared. They can be cured when 1% mass fraction Benzoin ethyl ether is added in the resins, and UV illumination for 30 min. In cured resins, the property of m-UPR is the best in acid-restant, base-restant, dissolvent-restant and surface luster of the UV-cured resins. Their UV-curing process has been investigated by FTIR spectra. The hermostability of the cured resins are studied by TG/DTA technique, it is found that loss gravity of o-UPR begins at 100℃ but m-UPR do not happen at 300℃. In addition, UV-cured resins have better themostability than resins cured by peroxide.
The suitabale ratio material and reaction conditions were selected, saturated acid such as m-phthalic acid, o-phthalic acid and their mixing acid(m/o-phthalic acid mol ratio 4:1), mix disalcohol(propanediol/diethylene glycol mol ratio 4:1) were used, respectively. Three kinds of resins(they are m-UPR, o-UPR and mix-UPR, respectively) have been prepared. They can be cured when 1% mass fraction Benzoin ethyl ether is added in the resins, and UV illumination for 30 min. In cured resins, the property of m-UPR is the best in acid-restant, base-restant, dissolvent-restant and surface luster of the UV-cured resins. Their UV-curing process has been investigated by FTIR spectra. The hermostability of the cured resins are studied by TG/DTA technique, it is found that loss gravity of o-UPR begins at 100℃ but m-UPR do not happen at 300℃. In addition, UV-cured resins have better themostability than resins cured by peroxide.
2002, 19(11): 1068-1071
Abstract:
The surface of the thermoplastic starch(TPS) material made from native starch and glycerol(3:1 by mass) has been hydrophobizated with reactive prepolymer of toluene diisocyanate(TDI)/castor oil (n(-NCO):n(-OH) from 2:1 to 8:1). The reactions between prepolymer and TPS, the hydrophobicity and the appearance of different coatings are studied and confirmed by IR. The change rate of contact angles of the materials with water decreased from 3.90°/min(uncoated) to 0.3~0.4°/min for TPS coated, resulting in great improvement of the surface hydrophobicity of TPS, have the viscosity and n(-NCO)/n(-OH) ratio of the prepolymer appeared the important factors. The sample surface coated with prepolymer of n(-NCO):n(-OH)=2:1 was smooth and transparent, while that coated with prepolymer of n(-NCO):n(-OH)=4:1 and 8:1 were rough and brittle. The coating thickness could be controlled by the viscosity of the prepolymer.
The surface of the thermoplastic starch(TPS) material made from native starch and glycerol(3:1 by mass) has been hydrophobizated with reactive prepolymer of toluene diisocyanate(TDI)/castor oil (n(-NCO):n(-OH) from 2:1 to 8:1). The reactions between prepolymer and TPS, the hydrophobicity and the appearance of different coatings are studied and confirmed by IR. The change rate of contact angles of the materials with water decreased from 3.90°/min(uncoated) to 0.3~0.4°/min for TPS coated, resulting in great improvement of the surface hydrophobicity of TPS, have the viscosity and n(-NCO)/n(-OH) ratio of the prepolymer appeared the important factors. The sample surface coated with prepolymer of n(-NCO):n(-OH)=2:1 was smooth and transparent, while that coated with prepolymer of n(-NCO):n(-OH)=4:1 and 8:1 were rough and brittle. The coating thickness could be controlled by the viscosity of the prepolymer.
2002, 19(11): 1072-1075
Abstract:
The cyclization process was carried out by double reflux instead of conventional single reflux and at the cyclization stage a solvent was added to the reaction mixture during the synthesis of trimethoprim(TMP) from 3,4,5-trimethoxy benzaldehyde. Cyclization yield was raised to 90% based on condensation product consisting of 80% T-(3,4,5-trimethoxy-benzal)-U-alkoxy-propionitrile and 20% T-(3,4,5-trimethoxy-benzyl)-U-alkoxy-acrylonitrile. The cyclization conditions were obtained by orthogonal factors and single factors experiments. When the mass of condensation product was 10 g, the temperature/time of the first and 2nd reflux were 80℃/2h, and 84~86℃/3h respectively, the amount of ethylene glycol monomethylether was 30 mL, the mass of guanidine nitrate was 11 g, at 100℃ for 4 h, TMP yield could be reached 90%.
The cyclization process was carried out by double reflux instead of conventional single reflux and at the cyclization stage a solvent was added to the reaction mixture during the synthesis of trimethoprim(TMP) from 3,4,5-trimethoxy benzaldehyde. Cyclization yield was raised to 90% based on condensation product consisting of 80% T-(3,4,5-trimethoxy-benzal)-U-alkoxy-propionitrile and 20% T-(3,4,5-trimethoxy-benzyl)-U-alkoxy-acrylonitrile. The cyclization conditions were obtained by orthogonal factors and single factors experiments. When the mass of condensation product was 10 g, the temperature/time of the first and 2nd reflux were 80℃/2h, and 84~86℃/3h respectively, the amount of ethylene glycol monomethylether was 30 mL, the mass of guanidine nitrate was 11 g, at 100℃ for 4 h, TMP yield could be reached 90%.
2002, 19(11): 1076-1079
Abstract:
The mixed micelles were formed from alkylene-T,k-bis(dodecyldimethylammonium bromide) surfactants, C12-s-C12·2Br(s=2,3,4,6), and the nonionic surfactant Triton X-100 in aqueous solution. The values of the total critical micelle concentration(cmcт) were found to be between cmc10 and cmc20, i.e. the critical micelle concentrations for individual surfactant 1 and surfactant 2, respectively. Addition of nonionic surfactant in 0.1 molar fraction(T2) in the bulk solution results in the molar fraction of Triton X-100 in the mixed micelle≥0.4. With further increase of T2, Triton X-100 composition in the mixed micelles became predominant.
The mixed micelles were formed from alkylene-T,k-bis(dodecyldimethylammonium bromide) surfactants, C12-s-C12·2Br(s=2,3,4,6), and the nonionic surfactant Triton X-100 in aqueous solution. The values of the total critical micelle concentration(cmcт) were found to be between cmc10 and cmc20, i.e. the critical micelle concentrations for individual surfactant 1 and surfactant 2, respectively. Addition of nonionic surfactant in 0.1 molar fraction(T2) in the bulk solution results in the molar fraction of Triton X-100 in the mixed micelle≥0.4. With further increase of T2, Triton X-100 composition in the mixed micelles became predominant.
2002, 19(11): 1080-1083
Abstract:
The phosphoric ester of potato starch(PEPS) has been compared with corn starch and potato starch in viscosity, paste stability in hot and cold conditions, and paste gel strength in the presence of electrolyte(NaCl) and non-electrolyte(sucrose). The results indicate the PEPS paste is more stable than corn starch and potato starch pastes. The presence of electrolyte(NaCl) and non-electrolyte(sucrose) scarcely affects the stability of the paste, moreover, the PEPS paste has a greater gel strength and anti-freezing property, particularly under acid condition.
The phosphoric ester of potato starch(PEPS) has been compared with corn starch and potato starch in viscosity, paste stability in hot and cold conditions, and paste gel strength in the presence of electrolyte(NaCl) and non-electrolyte(sucrose). The results indicate the PEPS paste is more stable than corn starch and potato starch pastes. The presence of electrolyte(NaCl) and non-electrolyte(sucrose) scarcely affects the stability of the paste, moreover, the PEPS paste has a greater gel strength and anti-freezing property, particularly under acid condition.
2002, 19(11): 1084-1087
Abstract:
Gadolinium doped ceria Ce0.8Gd0.2O1.9(GDC) powders were synthesized by a gel-casting method. The phase composition, morphology, and particle size of the powders were characterized. The GDC powder obtained was of a single fluorite phase with particle size from 30 to 100 nm after calcining the dried gel at 500~900℃. The green GDC tapes with thickness of 50~200 μm were obtained by tape casting. The cast GDC tapes have a density more than 95% of theoretical after sintering at 1 450℃. An ionic conductivity of about 4.6 S/m was measured for the sintered tapes calcined at 700℃ in air.
Gadolinium doped ceria Ce0.8Gd0.2O1.9(GDC) powders were synthesized by a gel-casting method. The phase composition, morphology, and particle size of the powders were characterized. The GDC powder obtained was of a single fluorite phase with particle size from 30 to 100 nm after calcining the dried gel at 500~900℃. The green GDC tapes with thickness of 50~200 μm were obtained by tape casting. The cast GDC tapes have a density more than 95% of theoretical after sintering at 1 450℃. An ionic conductivity of about 4.6 S/m was measured for the sintered tapes calcined at 700℃ in air.
2002, 19(11): 1088-1090
Abstract:
Four complexes K8[P2W17MO62]·5H2O, K8[P2W17MO61]·9H2O,K8[P2W17MO62]·7H2O and K8[P2W17MO61]·4H2O were synthesized by the cubic selective method and characterized by IR and UV spectroscopy, polarography, cyclic voltammetry and 183W NMR methods. The results indicate that they all have Dawson structure with high catalytic activity in the epoxidation of maleic acid by H2O2. Peroxotitanium mono-substituted tungstophosphate, K8[P2W17MO61]·9H2O, has the highest catalytic activity to give sodium epoxy-maleate in yield of 86.21%.
Four complexes K8[P2W17MO62]·5H2O, K8[P2W17MO61]·9H2O,K8[P2W17MO62]·7H2O and K8[P2W17MO61]·4H2O were synthesized by the cubic selective method and characterized by IR and UV spectroscopy, polarography, cyclic voltammetry and 183W NMR methods. The results indicate that they all have Dawson structure with high catalytic activity in the epoxidation of maleic acid by H2O2. Peroxotitanium mono-substituted tungstophosphate, K8[P2W17MO61]·9H2O, has the highest catalytic activity to give sodium epoxy-maleate in yield of 86.21%.
2002, 19(11): 1091-1093
Abstract:
Water-soluble N-carboxybutyl-chitosan was synthesized by reacting chitosan with levulinic acid and sodium borohydride. The moisture-absorption and moisture-retention capacity of chitosans with different degree of deacetylation and different molecular weight and N-carboxybutyl-chitosan were studied. The results indicated that chitosan with degree of deacetylation 50% had the best ability of moisture-absorption and retention and N-carboxybutyl-chitosan showed a quite same moisture-absorption capacity to that of hyaluronic acid when their molecular mass was at 5.0×105 level.
Water-soluble N-carboxybutyl-chitosan was synthesized by reacting chitosan with levulinic acid and sodium borohydride. The moisture-absorption and moisture-retention capacity of chitosans with different degree of deacetylation and different molecular weight and N-carboxybutyl-chitosan were studied. The results indicated that chitosan with degree of deacetylation 50% had the best ability of moisture-absorption and retention and N-carboxybutyl-chitosan showed a quite same moisture-absorption capacity to that of hyaluronic acid when their molecular mass was at 5.0×105 level.
2002, 19(11): 1094-1096
Abstract:
The pale green powder of nickel L-threonate Ni(C4H7O5)2·2H2O was prepared from excess nickelous dihydroxycarbonate and L-threonic acid obtained by double decomposition reaction of calcium L-threonate with oxalic acid at 80℃ for 2 h. The IR spectra indicated that Ni2+ was in coordination with oxygen atom of the carboxyl group of L-threonic acid with coordination number of 4. The TG-DTG results showed the compound discomposes into NiO at 380℃ in nitrogen atmosphere. The constant volume combustion energy of the compound, ΔcE, determined by a precise rotating-bomb combustion calorimeter at 298.15 K, was (-3 515.22±1.97) kJ/mol. The standard enthalpy of combustion, ΔcHm0, and standard enthalpy of formation, ΔfHm0, were calculated to be -3 512.74±1.97 kJ/mol and -2 447.51±2.26 kJ/mol, respectively.
The pale green powder of nickel L-threonate Ni(C4H7O5)2·2H2O was prepared from excess nickelous dihydroxycarbonate and L-threonic acid obtained by double decomposition reaction of calcium L-threonate with oxalic acid at 80℃ for 2 h. The IR spectra indicated that Ni2+ was in coordination with oxygen atom of the carboxyl group of L-threonic acid with coordination number of 4. The TG-DTG results showed the compound discomposes into NiO at 380℃ in nitrogen atmosphere. The constant volume combustion energy of the compound, ΔcE, determined by a precise rotating-bomb combustion calorimeter at 298.15 K, was (-3 515.22±1.97) kJ/mol. The standard enthalpy of combustion, ΔcHm0, and standard enthalpy of formation, ΔfHm0, were calculated to be -3 512.74±1.97 kJ/mol and -2 447.51±2.26 kJ/mol, respectively.
2002, 19(11): 1097-1099
Abstract:
The adsorption mechanism of Cd2+ onto cellulose pyrrolidinedithiocarboxylic ammomium(CC-APDC) has been studied. The results show that the coordination could increase the thermal stability of the cellulose and the adsorption occurs through a chelating reaction between Cd2+ and O of OH from cellulose and S from pyrrolidine thiocarboxylic acid.
The adsorption mechanism of Cd2+ onto cellulose pyrrolidinedithiocarboxylic ammomium(CC-APDC) has been studied. The results show that the coordination could increase the thermal stability of the cellulose and the adsorption occurs through a chelating reaction between Cd2+ and O of OH from cellulose and S from pyrrolidine thiocarboxylic acid.
2002, 19(11): 1100-1102
Abstract:
The mixture of some sugars has been separated and analysed by capillary electrophoresis combined with indirect conductance detection. The factors significantly affecting the separation and determination have been investigated in borate buffer in the presence of a little glycerol. The mechanism of the separation was discussed. The method has been used to determine fructose, glucose and sucrose in apple juice samples with satisfactory results. Recoveries of fructose, glucose and sucrose were 101.7%, 100.4% and 97.4% respectively, in 5 determinations.
The mixture of some sugars has been separated and analysed by capillary electrophoresis combined with indirect conductance detection. The factors significantly affecting the separation and determination have been investigated in borate buffer in the presence of a little glycerol. The mechanism of the separation was discussed. The method has been used to determine fructose, glucose and sucrose in apple juice samples with satisfactory results. Recoveries of fructose, glucose and sucrose were 101.7%, 100.4% and 97.4% respectively, in 5 determinations.
2002, 19(11): 1103-1105
Abstract:
Nano-pore array structure of alumina films formed on different aluminum substrate in acid electrolyte by electrochemical anodization has been studied. It is found that dislocation as one of the important parameters in self-assembling process not only affects the current density occuring in anodization, but also the nano-pore order. Dislocation leads to the differences of the energy of Al and the speed of Al3+ forming in dislocation and non-dislocation. Dislocation was also in close relation with the acidity of the electrolyte used. The stronger the acidity of the electrolyte, the greater the influence of the dislocation.
Nano-pore array structure of alumina films formed on different aluminum substrate in acid electrolyte by electrochemical anodization has been studied. It is found that dislocation as one of the important parameters in self-assembling process not only affects the current density occuring in anodization, but also the nano-pore order. Dislocation leads to the differences of the energy of Al and the speed of Al3+ forming in dislocation and non-dislocation. Dislocation was also in close relation with the acidity of the electrolyte used. The stronger the acidity of the electrolyte, the greater the influence of the dislocation.
2002, 19(11): 1106-1108
Abstract:
Three kinds of new type solid strong acid catalysts S2O82-/ZrO2-Al2O3-M2O3(M=Cr,Ce,La) were prepared. Their crystal structure, surface area, acid strength and sulfur content were determined by means of XRD, BET, flow Hammett indicator method and chemical analysis. Their catalytic activities in esterification reaction of acetic acid with n-butanol were studied. The results showed that ZrO2 in the catalysts mainly in tetragonal phase and few in monoclinic phase. The tetragonal phase of ZrO2 and S2O82- are the key factors that guarantee the catalytic activity. Incorporation of appropriate amounts of metallic oxides(Cr2O3,Ce2O3,La2O3) into the catalyst favors the stabilization of sulfur species and surface area, which increase the activity sites on the catalyst. The experimental results showed that three catalysts S2O82-/ZrO2-Al2O3(2%)-M2O3(1%)(M=Cr,Ce,La) had higher catalytic activity in mentioned esterification, with the conversion of acetic acid reached 96.8%, 95.7% and 96.1%, respectively. The preparation condition of the catalysts showed great influence on the catalytic activity.
Three kinds of new type solid strong acid catalysts S2O82-/ZrO2-Al2O3-M2O3(M=Cr,Ce,La) were prepared. Their crystal structure, surface area, acid strength and sulfur content were determined by means of XRD, BET, flow Hammett indicator method and chemical analysis. Their catalytic activities in esterification reaction of acetic acid with n-butanol were studied. The results showed that ZrO2 in the catalysts mainly in tetragonal phase and few in monoclinic phase. The tetragonal phase of ZrO2 and S2O82- are the key factors that guarantee the catalytic activity. Incorporation of appropriate amounts of metallic oxides(Cr2O3,Ce2O3,La2O3) into the catalyst favors the stabilization of sulfur species and surface area, which increase the activity sites on the catalyst. The experimental results showed that three catalysts S2O82-/ZrO2-Al2O3(2%)-M2O3(1%)(M=Cr,Ce,La) had higher catalytic activity in mentioned esterification, with the conversion of acetic acid reached 96.8%, 95.7% and 96.1%, respectively. The preparation condition of the catalysts showed great influence on the catalytic activity.
2002, 19(11): 1109-1111
Abstract:
The crystal and molecular structure of the title complex, Cu(ada)2(py)2(H2O)(ada=adamantanecarboxylic group, py=pyridine), C32H42CuN2O5, were determined by XRD. It belongs to monoclinic system with space group P21/n and crystal cell parameters:a=1.6199(3), b=0.6805(1), c=2.8028(6) nm, U=94.15(3)°; V=3.082(1) nm3, Z=4, Dc=1.289 g/cm3, Mr=589.22, _(MoKT)=0.750 mm-1, F(000)=1 268. The structure was refined to R=0.0578 and wR=0.1581 for 4 447 observed reflections with I≥2e(I). The aquo complex is mononuclear with distorted square-pyramidal coordination.
The crystal and molecular structure of the title complex, Cu(ada)2(py)2(H2O)(ada=adamantanecarboxylic group, py=pyridine), C32H42CuN2O5, were determined by XRD. It belongs to monoclinic system with space group P21/n and crystal cell parameters:a=1.6199(3), b=0.6805(1), c=2.8028(6) nm, U=94.15(3)°; V=3.082(1) nm3, Z=4, Dc=1.289 g/cm3, Mr=589.22, _(MoKT)=0.750 mm-1, F(000)=1 268. The structure was refined to R=0.0578 and wR=0.1581 for 4 447 observed reflections with I≥2e(I). The aquo complex is mononuclear with distorted square-pyramidal coordination.
2002, 19(11): 1112-1114
Abstract:
mono-Nitro-, 1,3-bis-nitro-, tetra-nitro- and 1,2-bis-nitro-calix [4]arenes were obtained separately by treating calix [4]arene tetraethers with 65% HNO3 and HOAc in the yields of 70%, 62%, 15% and 50%, respectively. The reaction mechanism has been discussed.
mono-Nitro-, 1,3-bis-nitro-, tetra-nitro- and 1,2-bis-nitro-calix [4]arenes were obtained separately by treating calix [4]arene tetraethers with 65% HNO3 and HOAc in the yields of 70%, 62%, 15% and 50%, respectively. The reaction mechanism has been discussed.
2002, 19(11): 1115-1117
Abstract:
Two k-mercaptoalkoxy quinoline compounds:6-(k-mercaptodecoxy)-quinoline and 2-(k-mercaptodecoxy)-4-methyl-quinoline were succesfully synthesized by reacting quinoline with 1,10-dibromodecane and thiourea in alkaline solution. The intermediates and products were characterized by IR, 1H NMR and MS.
Two k-mercaptoalkoxy quinoline compounds:6-(k-mercaptodecoxy)-quinoline and 2-(k-mercaptodecoxy)-4-methyl-quinoline were succesfully synthesized by reacting quinoline with 1,10-dibromodecane and thiourea in alkaline solution. The intermediates and products were characterized by IR, 1H NMR and MS.
2002, 19(11): 1118-1119
Abstract:
Sodium m-nitrobenzene sulfonate was reduced by formal solution to give disulfo azoxybenzene. The latter was reduced by an alkali solution of glucose at 94~96℃ for 5 hours to give hydrazobenzene disulfonic sodium (2). The title compound was obtained by rearrangement of (2) by hydrochloric acid in yield of 81.5%. The method has the advantages of cheapness and high yield.
Sodium m-nitrobenzene sulfonate was reduced by formal solution to give disulfo azoxybenzene. The latter was reduced by an alkali solution of glucose at 94~96℃ for 5 hours to give hydrazobenzene disulfonic sodium (2). The title compound was obtained by rearrangement of (2) by hydrochloric acid in yield of 81.5%. The method has the advantages of cheapness and high yield.
2002, 19(11): 1120-1122
Abstract:
Seven novel N-(5-tetrazolyl)-N'-(aryloxyacetyl)ureas have been synthesized by the additive reaction of 5-amino-1H-1,2,3,4-tetrazole with aryloxyacetyl isocyanate. Their structures were confirmed by IR, 1H NMR and elemental analysis. The biological activity tests show the target compounds have a good activity as plant growth regulator, and N-(5-tetrazolyl)-N'-(3-chlorophenyloxyacetyl)-urea and N-(5-tetrazolyl)-N'-(1-naphthyloxyacetyl)-urea have a activity close to cytokinin.
Seven novel N-(5-tetrazolyl)-N'-(aryloxyacetyl)ureas have been synthesized by the additive reaction of 5-amino-1H-1,2,3,4-tetrazole with aryloxyacetyl isocyanate. Their structures were confirmed by IR, 1H NMR and elemental analysis. The biological activity tests show the target compounds have a good activity as plant growth regulator, and N-(5-tetrazolyl)-N'-(3-chlorophenyloxyacetyl)-urea and N-(5-tetrazolyl)-N'-(1-naphthyloxyacetyl)-urea have a activity close to cytokinin.
