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2008 Volume 25 Issue 8
2008, 25(8): 877-881
Abstract:
Some basic constants of p-tert-butylcalixarene acetic acid tBu[4]CH2COOH and tBu[6]CH2COOH including solubility(S) in water, dissociation constant(Ka) in aqueous solution, dimerization constant(K2) and distribution constant(KD) between water and chloroform were determined at 25℃ by two-phase titration method. The results are as follows: tBu[4]CH2COOH: S4=(2.03±0.04)×10-4 mol/L, Ka,4=(1.50±0.02)×10-5, KD,4=1.55×102 and K2,4=3.73×102. tBu[6]CH2COOH: S6=(1.25±0.05)×10-4 mol/L, Ka,4=(8.71±0.05)×10-6, KD,6=1.28×102 and K2,6=3.88×102.
Some basic constants of p-tert-butylcalixarene acetic acid tBu[4]CH2COOH and tBu[6]CH2COOH including solubility(S) in water, dissociation constant(Ka) in aqueous solution, dimerization constant(K2) and distribution constant(KD) between water and chloroform were determined at 25℃ by two-phase titration method. The results are as follows: tBu[4]CH2COOH: S4=(2.03±0.04)×10-4 mol/L, Ka,4=(1.50±0.02)×10-5, KD,4=1.55×102 and K2,4=3.73×102. tBu[6]CH2COOH: S6=(1.25±0.05)×10-4 mol/L, Ka,4=(8.71±0.05)×10-6, KD,6=1.28×102 and K2,6=3.88×102.
2008, 25(8): 882-885
Abstract:
Mg-Al hydrotalcite-like compound(HTlc) was synthesized by the co-precipitation method, and the effects of temperature(T), aging time (t), total metal ion concentration(c) and mixing method on the size and size distribution of HTlc were investigated by orthogonal design method. It was found that the primary factor affecting the size of Mg-Al HTlc was aging time, while that affecting the size distribution of Mg-Al HTlc was mixing method. The optimal synthesis method and conditions for Mg-Al HTlc with small uniform size were obtained: decreasing pH method, T=25℃, c=0.50 mol/L and t=0.75 h.
Mg-Al hydrotalcite-like compound(HTlc) was synthesized by the co-precipitation method, and the effects of temperature(T), aging time (t), total metal ion concentration(c) and mixing method on the size and size distribution of HTlc were investigated by orthogonal design method. It was found that the primary factor affecting the size of Mg-Al HTlc was aging time, while that affecting the size distribution of Mg-Al HTlc was mixing method. The optimal synthesis method and conditions for Mg-Al HTlc with small uniform size were obtained: decreasing pH method, T=25℃, c=0.50 mol/L and t=0.75 h.
2008, 25(8): 886-889
Abstract:
Cobalt(Ⅱ) polyamidomine dendrimer was synthesized by glyoxal with cobalt chloride and polyamidomine dendrimer 5.0G. A gold electrode was modified with self-assembly of 3-mercaptopropionic acid, which was then reacted with cobalt(Ⅱ) polyamidomine dendrimer modified by the covalent interactions between the carboxyl groups on the modified electrode surface and amino terminals of the dendrimer to yield an electrode modified by the dendrimer. The sensor was used to study the electrocatalytic oxidation of guanine. The effects of pH value, scanning rate and guanine concentration were discussed. The assembled electrode had an obvious electrocatalytic activity on guanine and decreased the oxidation potential of the guanine. In an acetate buffer solution(pH=5.8), the oxidation peak current of guanine and its concentration had a linear relationship in a range of 1.32×10-6 mol/L to 46.3×10-6 mol/L at the modified electrode. The regression equation was Ip(μA)=0.294 3c+0.802 9, R2=0.995 9, and the detection limit was 0.66×10-6 mol/L. The modified electrode is suitable for the detection of guanine.
Cobalt(Ⅱ) polyamidomine dendrimer was synthesized by glyoxal with cobalt chloride and polyamidomine dendrimer 5.0G. A gold electrode was modified with self-assembly of 3-mercaptopropionic acid, which was then reacted with cobalt(Ⅱ) polyamidomine dendrimer modified by the covalent interactions between the carboxyl groups on the modified electrode surface and amino terminals of the dendrimer to yield an electrode modified by the dendrimer. The sensor was used to study the electrocatalytic oxidation of guanine. The effects of pH value, scanning rate and guanine concentration were discussed. The assembled electrode had an obvious electrocatalytic activity on guanine and decreased the oxidation potential of the guanine. In an acetate buffer solution(pH=5.8), the oxidation peak current of guanine and its concentration had a linear relationship in a range of 1.32×10-6 mol/L to 46.3×10-6 mol/L at the modified electrode. The regression equation was Ip(μA)=0.294 3c+0.802 9, R2=0.995 9, and the detection limit was 0.66×10-6 mol/L. The modified electrode is suitable for the detection of guanine.
2008, 25(8): 890-894
Abstract:
The critical micelle concentration(CMC) and surface tension of several different types of surfactants and their mixtures were measured in the system with water as continuous medium and cyclohexanone as solvent. Their effects on phase behavior and physical stability of 2.5% bifenthrin microemulsion were investigated in detail. Among several pure surfactants, the CMC of triphenylphenoxy polyoxyethylenyl polyoxypro-pylene(EPE type) with block nonion surfactant stucture is the lowest, γcmc=28.18 mN/m. The CMC of a mixture of EPE and SDBS [m(EPE):m(SDBS)=2:1] is 27.60 mN/m, which is further lower than that of pure EPE. This is very helpful to form O/W type microemulsion. When the dosage of the mixture was about 10%, the heat storage decomposition rate of 2.5% bifenthrin microemulsion was 2.35%.
The critical micelle concentration(CMC) and surface tension of several different types of surfactants and their mixtures were measured in the system with water as continuous medium and cyclohexanone as solvent. Their effects on phase behavior and physical stability of 2.5% bifenthrin microemulsion were investigated in detail. Among several pure surfactants, the CMC of triphenylphenoxy polyoxyethylenyl polyoxypro-pylene(EPE type) with block nonion surfactant stucture is the lowest, γcmc=28.18 mN/m. The CMC of a mixture of EPE and SDBS [m(EPE):m(SDBS)=2:1] is 27.60 mN/m, which is further lower than that of pure EPE. This is very helpful to form O/W type microemulsion. When the dosage of the mixture was about 10%, the heat storage decomposition rate of 2.5% bifenthrin microemulsion was 2.35%.
2008, 25(8): 895-898
Abstract:
We studied the effect of water on the palladium acetate-catalyzed coupling reaction of aryl boronic acid with aryl bromide or acyl chloride in ionic liquid or PEG, and found that water had a remarkable rate accelerating effect on the Suzuki reaction and Suzuki-Type reaction when other reaction conditions were uniform. The ratio of water to IL or PEG was pivotal to the reaction, and the optimal ratio of water to IL or PEG was different to the Suzuki and Suzuki-Type reactions. When the ratio of [bmim][PF6] and water was 3:1, the best yield of 99% of Suzuki reaction was achieved, while the optimal ratio of [bmim][BF4] to water was 3:3(93%). The Suzuki-Type reaction delivered the good yield of 82% in the [bmim][PF6]-H2O system when the mass ratio of [bmim][PF6] to water was 3:2.5, while in the PEG-H2O system, the optimal ratio of PEG to water was 3:3(yield was 94%). The possible mechanism of water influence on the cross-coupling reaction was discussed.
We studied the effect of water on the palladium acetate-catalyzed coupling reaction of aryl boronic acid with aryl bromide or acyl chloride in ionic liquid or PEG, and found that water had a remarkable rate accelerating effect on the Suzuki reaction and Suzuki-Type reaction when other reaction conditions were uniform. The ratio of water to IL or PEG was pivotal to the reaction, and the optimal ratio of water to IL or PEG was different to the Suzuki and Suzuki-Type reactions. When the ratio of [bmim][PF6] and water was 3:1, the best yield of 99% of Suzuki reaction was achieved, while the optimal ratio of [bmim][BF4] to water was 3:3(93%). The Suzuki-Type reaction delivered the good yield of 82% in the [bmim][PF6]-H2O system when the mass ratio of [bmim][PF6] to water was 3:2.5, while in the PEG-H2O system, the optimal ratio of PEG to water was 3:3(yield was 94%). The possible mechanism of water influence on the cross-coupling reaction was discussed.
2008, 25(8): 899-903
Abstract:
An ionic liquid modified carbon paste electrode(IL/CPE) was fabricated with hydrophilic ionic liquid 1-amyl-3-methylimidazolium chloride([AMIM]Cl) as a modifier. The electrochemical behavior of baicalin at the modified electrode and bare carbon paste electrode(CPE) was investigated in a Britton-Robinson(B-R) buffer solution(pH=3.53) by cyclic voltammetry(CV) and square wave voltammetry(SWV), and a novel method for the determination of baicalin in urine and serum samples was thus established. At CPE, the peak-to-peak potential separation(ΔEp) of baicalin was 0.204 V, while at IL/CPE, the Ep decreased to 0.103 V. Furthermore, the current response of baicalin at IL/CPE was 7.1 times of that at CPE. These indicated the IL/CPE possessed an excellent electrocatalytic activity for the redox of baicalin. The electron transfer coefficient and standard rate constant of baicalin at IL/CPE were calculated. In the SWV curves, a linear dependence of oxidation current on baicalin concentration was obtained in the range of 1.0×10-8~2.0×10-6 mol/L(r=0.999 8), with a detection limit of 3.0×10-9 mol/L(S/N=3). The relative standard deviation of 4.0×10-7 mol/L baicalin was 1.3% for 6 consective measurements.
An ionic liquid modified carbon paste electrode(IL/CPE) was fabricated with hydrophilic ionic liquid 1-amyl-3-methylimidazolium chloride([AMIM]Cl) as a modifier. The electrochemical behavior of baicalin at the modified electrode and bare carbon paste electrode(CPE) was investigated in a Britton-Robinson(B-R) buffer solution(pH=3.53) by cyclic voltammetry(CV) and square wave voltammetry(SWV), and a novel method for the determination of baicalin in urine and serum samples was thus established. At CPE, the peak-to-peak potential separation(ΔEp) of baicalin was 0.204 V, while at IL/CPE, the Ep decreased to 0.103 V. Furthermore, the current response of baicalin at IL/CPE was 7.1 times of that at CPE. These indicated the IL/CPE possessed an excellent electrocatalytic activity for the redox of baicalin. The electron transfer coefficient and standard rate constant of baicalin at IL/CPE were calculated. In the SWV curves, a linear dependence of oxidation current on baicalin concentration was obtained in the range of 1.0×10-8~2.0×10-6 mol/L(r=0.999 8), with a detection limit of 3.0×10-9 mol/L(S/N=3). The relative standard deviation of 4.0×10-7 mol/L baicalin was 1.3% for 6 consective measurements.
2008, 25(8): 904-908
Abstract:
Alkali/surfactant/polymer(ASP) flooding was taken as an example, and the synergistic effect of interfacial and rheologic property(SEIRP) of displacing fluid on enhancing oil recovery has been studied experimentally and theoretically. The results show that the higher the visco-elasticity of the displacing fluid, the stronger the flow disturbance towards bypassed area in pores, and the higher the oil recovery efficiency. Visco-elasticity is beneficial for displacing residual oil. In experiments on natural cores, when the equivalent viscosity of the displacing fluid decreased to a certain value(Critical Viscosity), decreasing the interfacial tension of water/oil cannot improve significantly the displacement efficiency, and the idea of SEIRP was presente. In artificial heterogeneous cores, the effect of the interfacial and rheologic property of the ASP solution on the oil recovery efficiency was non-monotonic, and exhibited a maximum value. When the equivalent viscosity was lower than the critical viscosity, even the interfacial tension of the displacing fluid was reduced greatly, the oil recovery efficiency also decreased with the decrease of the equivalent viscosity. Under the experiment conditions, the critical viscosity was about 20 mPa·s. The oil displacement ability of the chemical displacing fluid depend on the SEIRP. Therefore, under a certain reservoir condition, it is more important to optimize the SEIRP than to make excessive demand for the ultra low interfacial tension. The results are helpful for optimizing the composition of displacing fluids.
Alkali/surfactant/polymer(ASP) flooding was taken as an example, and the synergistic effect of interfacial and rheologic property(SEIRP) of displacing fluid on enhancing oil recovery has been studied experimentally and theoretically. The results show that the higher the visco-elasticity of the displacing fluid, the stronger the flow disturbance towards bypassed area in pores, and the higher the oil recovery efficiency. Visco-elasticity is beneficial for displacing residual oil. In experiments on natural cores, when the equivalent viscosity of the displacing fluid decreased to a certain value(Critical Viscosity), decreasing the interfacial tension of water/oil cannot improve significantly the displacement efficiency, and the idea of SEIRP was presente. In artificial heterogeneous cores, the effect of the interfacial and rheologic property of the ASP solution on the oil recovery efficiency was non-monotonic, and exhibited a maximum value. When the equivalent viscosity was lower than the critical viscosity, even the interfacial tension of the displacing fluid was reduced greatly, the oil recovery efficiency also decreased with the decrease of the equivalent viscosity. Under the experiment conditions, the critical viscosity was about 20 mPa·s. The oil displacement ability of the chemical displacing fluid depend on the SEIRP. Therefore, under a certain reservoir condition, it is more important to optimize the SEIRP than to make excessive demand for the ultra low interfacial tension. The results are helpful for optimizing the composition of displacing fluids.
2008, 25(8): 909-912
Abstract:
A modified carbon paste electrode modified by multi-walled carbon nanotube and α-(2,4-Di-tert-butylphenoxy) phthalocyaninatocobalt towards the electrocatalytic oxidation of L-cysteine was studied. The α-(2,4-Di-tert-butylphenoxy) phthalocyaninatocobalt modified carbon paste electrode showed an excellent electrocatalytic activity to L-cysteine and lowered the anodic oxidation potential. The current signal and the sensitivity were enhanced after multi-walled carbon nanotube was added to the modified electrode. A mixture of graphite powder with 10% of multi-walled carbon nanotube was applied to the preparation of carbon paste. The modified carbon paste electrode had a maximum sensitivity to current signal for L-cysteine. Amperometric response was detected in the stiring solution. The steady-state current quickly reached a stable value in less than 5 s. The sensitivity of the electrode was 84.4 nA·cm-2/(μmol·L-1), and the limit of detection was 5.0×10-6 mol/L.
A modified carbon paste electrode modified by multi-walled carbon nanotube and α-(2,4-Di-tert-butylphenoxy) phthalocyaninatocobalt towards the electrocatalytic oxidation of L-cysteine was studied. The α-(2,4-Di-tert-butylphenoxy) phthalocyaninatocobalt modified carbon paste electrode showed an excellent electrocatalytic activity to L-cysteine and lowered the anodic oxidation potential. The current signal and the sensitivity were enhanced after multi-walled carbon nanotube was added to the modified electrode. A mixture of graphite powder with 10% of multi-walled carbon nanotube was applied to the preparation of carbon paste. The modified carbon paste electrode had a maximum sensitivity to current signal for L-cysteine. Amperometric response was detected in the stiring solution. The steady-state current quickly reached a stable value in less than 5 s. The sensitivity of the electrode was 84.4 nA·cm-2/(μmol·L-1), and the limit of detection was 5.0×10-6 mol/L.
2008, 25(8): 913-917
Abstract:
Poly(L-argenine)-modified glassy carbon electrode was prepared by cyclic voltammetry. The electrochemical behavior of uric acid at it was studied, and a novel method was proposed for the determination of uric acid. In a phosphate buffer solution of pH=7.0, a sensitive oxidation peak and a weak reduction peak were observed at Epa=0.398 V and Epc=0.302 V(vs Ag/AgCl) at a scan rate of 200 mV/s. The oxidation peak current was well proportional to the concentration of uric acid, and the linear ranges for the determination of uric acid were 3.0×10-6~8.0×10-5 mol/L and 8.0×10-5~2.5×10-4 mol/L by linear sweep volta-mmetry. The detection limit was 1.0×10-6 mol/L. The method was applied to the determination of uric acid in urine with satisfactory results.
Poly(L-argenine)-modified glassy carbon electrode was prepared by cyclic voltammetry. The electrochemical behavior of uric acid at it was studied, and a novel method was proposed for the determination of uric acid. In a phosphate buffer solution of pH=7.0, a sensitive oxidation peak and a weak reduction peak were observed at Epa=0.398 V and Epc=0.302 V(vs Ag/AgCl) at a scan rate of 200 mV/s. The oxidation peak current was well proportional to the concentration of uric acid, and the linear ranges for the determination of uric acid were 3.0×10-6~8.0×10-5 mol/L and 8.0×10-5~2.5×10-4 mol/L by linear sweep volta-mmetry. The detection limit was 1.0×10-6 mol/L. The method was applied to the determination of uric acid in urine with satisfactory results.
2008, 25(8): 918-921
Abstract:
Characterization of α-olefin polymer DRA(drag reduction agent) prepared by solution polymerization under different conditions was carried out by loop system. The results showed Drag reduction was affected greatly by the solvent used in the synthesis. When the solvent was Cyclohexane, drag reduction rate was up to 62.3%, but 50.33% when the solvent was Hexane; DR% of three samples droped rapidly with increasing shearing time. On those bases, the effects of the polymer characteristics on drag reduction were studied further. Particle density and concentration were obtained through viscosimetry. The results showed when characteristic viscosity was smaller, the density was higher, the concentration was lower, and the molecular mass was higher, the drag reduction result was better. Otherwise, drag reduction result was worse.
Characterization of α-olefin polymer DRA(drag reduction agent) prepared by solution polymerization under different conditions was carried out by loop system. The results showed Drag reduction was affected greatly by the solvent used in the synthesis. When the solvent was Cyclohexane, drag reduction rate was up to 62.3%, but 50.33% when the solvent was Hexane; DR% of three samples droped rapidly with increasing shearing time. On those bases, the effects of the polymer characteristics on drag reduction were studied further. Particle density and concentration were obtained through viscosimetry. The results showed when characteristic viscosity was smaller, the density was higher, the concentration was lower, and the molecular mass was higher, the drag reduction result was better. Otherwise, drag reduction result was worse.
2008, 25(8): 922-925
Abstract:
Synthesis of DO3A derivatives(H3L) modified by linear alkyl groups, N-hexyl-DO3A(2), N-decyl-DO3A(3), N-hexadecyl-DO3A(4), and their Gd(Ⅲ) chelates(GdL) is described. The protonation constants of compounds 2, 3 and 4, the stability constants and the water proton relaxivity of GdL were determined. The first protonation constants(lg K1H) of compounds 2, 3 and 4 were respectively 10.72, 10.68 and 10.52, the stability constants of the corresponing GdL chelates were respectively 20.50, 19.60 and 19.25, and the water proton relaxivitives(r1) of the corresponding GdL chelates were respectively 4.88, 4.96 and 5.12 L/(mmol·S). The results obtained showed that the basicities of the ligands were all slightly altered, but the ligands still maintained strong chelating property and the water proton relaxivity of the parent DO3A after the introduction of a linear alkyl group at the cyclen backbone of DO3A.
Synthesis of DO3A derivatives(H3L) modified by linear alkyl groups, N-hexyl-DO3A(2), N-decyl-DO3A(3), N-hexadecyl-DO3A(4), and their Gd(Ⅲ) chelates(GdL) is described. The protonation constants of compounds 2, 3 and 4, the stability constants and the water proton relaxivity of GdL were determined. The first protonation constants(lg K1H) of compounds 2, 3 and 4 were respectively 10.72, 10.68 and 10.52, the stability constants of the corresponing GdL chelates were respectively 20.50, 19.60 and 19.25, and the water proton relaxivitives(r1) of the corresponding GdL chelates were respectively 4.88, 4.96 and 5.12 L/(mmol·S). The results obtained showed that the basicities of the ligands were all slightly altered, but the ligands still maintained strong chelating property and the water proton relaxivity of the parent DO3A after the introduction of a linear alkyl group at the cyclen backbone of DO3A.
2008, 25(8): 926-930
Abstract:
Cross-linking humic acid(CL-HA) was synthesized readily with epichlorohydrine as cross-linking reagent. The product was analyzed and confirmed by IR spectrum and solvent experiment. The catalysts of CL-HA-Pd and CL-HA-Pd/Ni were prepared via supporting PdCl2 and NiCl2 on cross-linking humic acid, respectively. The two catalysts were reduced with NaBH4. The catalytic performances of the four catalysts, CL-HA-Pd, CL-HA-Pd/Ni and their reducing products were studied via the Heck reaction of aryl halide with vinyl compounds. The results show that the catalyst could catalyze the Heck reaction of substituted aryl halide with crylic acid, the yields were above 80%.
Cross-linking humic acid(CL-HA) was synthesized readily with epichlorohydrine as cross-linking reagent. The product was analyzed and confirmed by IR spectrum and solvent experiment. The catalysts of CL-HA-Pd and CL-HA-Pd/Ni were prepared via supporting PdCl2 and NiCl2 on cross-linking humic acid, respectively. The two catalysts were reduced with NaBH4. The catalytic performances of the four catalysts, CL-HA-Pd, CL-HA-Pd/Ni and their reducing products were studied via the Heck reaction of aryl halide with vinyl compounds. The results show that the catalyst could catalyze the Heck reaction of substituted aryl halide with crylic acid, the yields were above 80%.
2008, 25(8): 931-936
Abstract:
Fourteen novel 5-aryl-3a,6a-dihydro-4,6-dioxo-pyrrolino[3',4'-d] isoxazole-3-carboxy-lic acid derivatives(3a~3g) and ethyl 5-aryl-3a,6a-dihydro-4,6-dioxo-pyrrolino[3',4'-d] isoxazole-3-carboxylate derivatives(4a~4g) were synthesized by 1,3-dipolar cycloaddition reaction of N-arylmaleimides with isonitrosochloroacetic acid or ethyl chloro oximino acetate. The structures of compounds 3 and 4 were confirmed by 1H NMR, IR and elemental analysis. Preliminary bioassay was tested for the target compounds. The bioassay indicates that compounds 3a, 3b, 3c showed 100% antitumor activity at the test concentration(10 μmol/L). Compounds 3d, 3e and compounds 4a, 4d, 4e showed different inhibiting effects(61.47%, 66.23%, 18.92%, 22.49%, 56.43%) on cell division cycle 25A at the test concentration(2×10-5 g/mL) and the structure-activity relationship of the compounds was investigated.
Fourteen novel 5-aryl-3a,6a-dihydro-4,6-dioxo-pyrrolino[3',4'-d] isoxazole-3-carboxy-lic acid derivatives(3a~3g) and ethyl 5-aryl-3a,6a-dihydro-4,6-dioxo-pyrrolino[3',4'-d] isoxazole-3-carboxylate derivatives(4a~4g) were synthesized by 1,3-dipolar cycloaddition reaction of N-arylmaleimides with isonitrosochloroacetic acid or ethyl chloro oximino acetate. The structures of compounds 3 and 4 were confirmed by 1H NMR, IR and elemental analysis. Preliminary bioassay was tested for the target compounds. The bioassay indicates that compounds 3a, 3b, 3c showed 100% antitumor activity at the test concentration(10 μmol/L). Compounds 3d, 3e and compounds 4a, 4d, 4e showed different inhibiting effects(61.47%, 66.23%, 18.92%, 22.49%, 56.43%) on cell division cycle 25A at the test concentration(2×10-5 g/mL) and the structure-activity relationship of the compounds was investigated.
2008, 25(8): 937-942
Abstract:
Adsorption kinetics of Gemini surfactant C12-2-C12·2Br at the water-air interface was studied by maxium bubble pressure technique. The diffusion rate was enhanced when the bulk concentration increased, and the diffusion coefficient D increased accordingly. The diffusion coefficient D of C12-s-C12·2Br was almost 100 times larger than that for its monomer, dodecyltrimethyl-ammonium bromide(DTAB), due to its higher hydrophobicity resulting from different structures of the two surfactants. The adsorption at long period of time followed a kinetic-diffusion adsorption mechanism, and the adsorption barrier Ea was obtained. The Ea values of C12-2-C12·2Br and DTAB were 17.29 and 9.13 kJ/mol, respectively. The C12-2-C12·2Br exhibited greater surface pressure, fraction of coverage at the air-water interface, and molecular head group area than DTAB, which led to the larger Ea of C12-2-C12·2Br.
Adsorption kinetics of Gemini surfactant C12-2-C12·2Br at the water-air interface was studied by maxium bubble pressure technique. The diffusion rate was enhanced when the bulk concentration increased, and the diffusion coefficient D increased accordingly. The diffusion coefficient D of C12-s-C12·2Br was almost 100 times larger than that for its monomer, dodecyltrimethyl-ammonium bromide(DTAB), due to its higher hydrophobicity resulting from different structures of the two surfactants. The adsorption at long period of time followed a kinetic-diffusion adsorption mechanism, and the adsorption barrier Ea was obtained. The Ea values of C12-2-C12·2Br and DTAB were 17.29 and 9.13 kJ/mol, respectively. The C12-2-C12·2Br exhibited greater surface pressure, fraction of coverage at the air-water interface, and molecular head group area than DTAB, which led to the larger Ea of C12-2-C12·2Br.
2008, 25(8): 943-947
Abstract:
Polymer-supported CuI catalyst was prepared and its catalytic activity was investigated for the 1,3-dipolar cycloaddition reaction. 1,2,3-Triazoles were produced. The influences of reaction conditions, such as solvent, base, amount of catalyst, reaction atmosphere, were studied and optimal conditions were determined. The results showed that the reaction went smoothly to produce 1,4-disubstituted-1,2,3-triazoles at room temperature using PEG/H2O as solvent. Meanwhile, effect of different substrates were explored. Benzyl and allyl halides were active, and the products were obtained with yields of 72%~94% in 8h; alkyl halides were less active and moderate yields were obtained. The cycloaddition of aromatic halides were difficult. Aromatic iodides gave products with moderate yields at 85℃ in 24 h, while aromatic bromides didn't give any product. The catalyst could be recycled by simple filtration and washing and reused for four times without significant decrease in its activity.
Polymer-supported CuI catalyst was prepared and its catalytic activity was investigated for the 1,3-dipolar cycloaddition reaction. 1,2,3-Triazoles were produced. The influences of reaction conditions, such as solvent, base, amount of catalyst, reaction atmosphere, were studied and optimal conditions were determined. The results showed that the reaction went smoothly to produce 1,4-disubstituted-1,2,3-triazoles at room temperature using PEG/H2O as solvent. Meanwhile, effect of different substrates were explored. Benzyl and allyl halides were active, and the products were obtained with yields of 72%~94% in 8h; alkyl halides were less active and moderate yields were obtained. The cycloaddition of aromatic halides were difficult. Aromatic iodides gave products with moderate yields at 85℃ in 24 h, while aromatic bromides didn't give any product. The catalyst could be recycled by simple filtration and washing and reused for four times without significant decrease in its activity.
2008, 25(8): 948-951
Abstract:
Esterification of adipic acid with 1,4-butanediol was carried out in the presence of scandium trifluoromethanesulfonate [Sc(OTf)3] as a Lewis acid catalyst under mild conditions. The effects of reaction temperature, catalyst dosage, and synthesis method on the esterification and the polycondensation were investigated. The product was characterized by FT-IR, 1H NMR and GPC. Under the optimum conditions of 90℃, Sc(OTf)3 0.1%, molar ratio of 1,4-butanediol to adipic acid 1.1:1, reflux time 11 h, the percent of esterification was 93% without removing water, over 99% with water removed. The esterification and the polycondensation were both slow without removing water. With water removed, the reaction rate was improved greatly. The molecular mass also increased, and the molecular mass distribution became narrow. FT-IR and 1H NMR indicated that there was no by-product.
Esterification of adipic acid with 1,4-butanediol was carried out in the presence of scandium trifluoromethanesulfonate [Sc(OTf)3] as a Lewis acid catalyst under mild conditions. The effects of reaction temperature, catalyst dosage, and synthesis method on the esterification and the polycondensation were investigated. The product was characterized by FT-IR, 1H NMR and GPC. Under the optimum conditions of 90℃, Sc(OTf)3 0.1%, molar ratio of 1,4-butanediol to adipic acid 1.1:1, reflux time 11 h, the percent of esterification was 93% without removing water, over 99% with water removed. The esterification and the polycondensation were both slow without removing water. With water removed, the reaction rate was improved greatly. The molecular mass also increased, and the molecular mass distribution became narrow. FT-IR and 1H NMR indicated that there was no by-product.
2008, 25(8): 952-956
Abstract:
An electromagnetic shielding material was made by electroplating amorphous nickel-phosphorous alloy on a fabric, and the preparation process was studied. Stable bright amorphous nickel-phosphorous alloy coating was obtained by electroplating on copper-coated terylene. The effects of electrolyte composition, temperature, time, and pH on the K/S value and resistance of the deposit were studied by orthogonal test, and the process parameters for optimum K/S value and Resistance were determined, which were as follows:NiSO4 250 g/L, NiCl2 55 g/L, NaHPO2 70 g/L, H3BO3 45 g/L, 10 min, 65℃, pH=2.0. The experiments showed that this soft electromagnetic shielding fabric had a fine corrosion and abrasion resistance property.
An electromagnetic shielding material was made by electroplating amorphous nickel-phosphorous alloy on a fabric, and the preparation process was studied. Stable bright amorphous nickel-phosphorous alloy coating was obtained by electroplating on copper-coated terylene. The effects of electrolyte composition, temperature, time, and pH on the K/S value and resistance of the deposit were studied by orthogonal test, and the process parameters for optimum K/S value and Resistance were determined, which were as follows:NiSO4 250 g/L, NiCl2 55 g/L, NaHPO2 70 g/L, H3BO3 45 g/L, 10 min, 65℃, pH=2.0. The experiments showed that this soft electromagnetic shielding fabric had a fine corrosion and abrasion resistance property.
2008, 25(8): 957-960
Abstract:
A high performance liquid chromatography(HPLC) method has been developed for the simul-taneous determination of residues of eleven triazine herbicides in vegetable. Triazine herbicides were extracted from vegetable with water/methanol and cleaned up with solid-phase extraction cartridges. Then triazine herbicides extracted were analyzed by HPLC with ultraviolet and mass spectrometric detection. The pre-treatment method of sample and chromatographic conditions of analysis were critically examined in this work. The linear ranges for the 11 triazine herbicides were 0.02×10-6~1.0×10-6 g/mL, with correlation coefficients of 0.998 7~0.999 9. The average recoveries for the eleven triazine herbicides in spiked vegetable were in the range of 72.1% to 101.0%, and the relative standard deviations were between 1.2% and 5.1%. The method developed is easy and fast, and has a better purification effect. It can meet the requirement for simultaneous determination of many herbicides in vegetable.
A high performance liquid chromatography(HPLC) method has been developed for the simul-taneous determination of residues of eleven triazine herbicides in vegetable. Triazine herbicides were extracted from vegetable with water/methanol and cleaned up with solid-phase extraction cartridges. Then triazine herbicides extracted were analyzed by HPLC with ultraviolet and mass spectrometric detection. The pre-treatment method of sample and chromatographic conditions of analysis were critically examined in this work. The linear ranges for the 11 triazine herbicides were 0.02×10-6~1.0×10-6 g/mL, with correlation coefficients of 0.998 7~0.999 9. The average recoveries for the eleven triazine herbicides in spiked vegetable were in the range of 72.1% to 101.0%, and the relative standard deviations were between 1.2% and 5.1%. The method developed is easy and fast, and has a better purification effect. It can meet the requirement for simultaneous determination of many herbicides in vegetable.
2008, 25(8): 961-965
Abstract:
The hydration properties of a synthesized water soluble phenol-formaldehyde resin, and the influences of reaction parameters on the properties of it were investigated with dynamic light scattering technology, and by means of viscosity and critical coagulating concentration(CCC) determination. The results show that the resin prepared with sodium hydroxide as catalyst at a phenol/formaldehyde mole ratio of 3:1 can be dissolved in distilled water to form a transparent solution. The viscosity of a 10% resin solution ranges from 1.529 1 mPa·s to 6.064 7 mPa·s, and the dispersed unit in a 50 mg/L resin solution exhibits a hydrodynamics diameter between 2.1 nm and 21.1 nm and a Zeta potential varying from -54.38 mV to -10.07 mV. NaCl can weaken the resin hydration and make the resin flocculate, the CCC for different resin product solution is from 0.014 mol/L to 0.099 mol/L. The hydration properties of the resin under different reaction conditions show that along with the prepolymer mass fraction, the polymerization degree of the resin product is increased as the reaction time and reaction temperature increase, causing the viscosity of 10% resin solution and the hydrodynamics diameter of resin aggregate in dilute solution to increase. On the contrary, the CCC of the resin dilute solution and the Zeta potential of the rein aggregate are decreased. Furthermore, the change of the resin caused by the prepolymer mass fraction difference is comparatively insignificant. Otherwise, reaction time can intensively affect the product. In addition, the polycondensation below 90℃ is difficult to take place.
The hydration properties of a synthesized water soluble phenol-formaldehyde resin, and the influences of reaction parameters on the properties of it were investigated with dynamic light scattering technology, and by means of viscosity and critical coagulating concentration(CCC) determination. The results show that the resin prepared with sodium hydroxide as catalyst at a phenol/formaldehyde mole ratio of 3:1 can be dissolved in distilled water to form a transparent solution. The viscosity of a 10% resin solution ranges from 1.529 1 mPa·s to 6.064 7 mPa·s, and the dispersed unit in a 50 mg/L resin solution exhibits a hydrodynamics diameter between 2.1 nm and 21.1 nm and a Zeta potential varying from -54.38 mV to -10.07 mV. NaCl can weaken the resin hydration and make the resin flocculate, the CCC for different resin product solution is from 0.014 mol/L to 0.099 mol/L. The hydration properties of the resin under different reaction conditions show that along with the prepolymer mass fraction, the polymerization degree of the resin product is increased as the reaction time and reaction temperature increase, causing the viscosity of 10% resin solution and the hydrodynamics diameter of resin aggregate in dilute solution to increase. On the contrary, the CCC of the resin dilute solution and the Zeta potential of the rein aggregate are decreased. Furthermore, the change of the resin caused by the prepolymer mass fraction difference is comparatively insignificant. Otherwise, reaction time can intensively affect the product. In addition, the polycondensation below 90℃ is difficult to take place.
2008, 25(8): 966-970
Abstract:
4-(6-Methoxynaphthalen-2-yl)thiazol-2-amine was first prepared from 2-bromo-1-(6-methoxy-naphthalen-2-yl)alkyl-1-one and thiourea. 4-(6-Methoxynaphthalen-2-yl)-2-benzylimino-thiazole was then synthesized via the reaction of 4-(6-methoxynaphthalen-2-yl)thiazol-2-amine with salicylal with yields of 72.1%~94.8%. The structures of the compounds were determined by 1H NMR, IR and elemental analysis. Proton assiqnment of naphthyl was performed by analyzing coupling constants of the protons on the naphthyl of target compound and intermediate.
4-(6-Methoxynaphthalen-2-yl)thiazol-2-amine was first prepared from 2-bromo-1-(6-methoxy-naphthalen-2-yl)alkyl-1-one and thiourea. 4-(6-Methoxynaphthalen-2-yl)-2-benzylimino-thiazole was then synthesized via the reaction of 4-(6-methoxynaphthalen-2-yl)thiazol-2-amine with salicylal with yields of 72.1%~94.8%. The structures of the compounds were determined by 1H NMR, IR and elemental analysis. Proton assiqnment of naphthyl was performed by analyzing coupling constants of the protons on the naphthyl of target compound and intermediate.
2008, 25(8): 971-973
Abstract:
Two novel compounds, 1,4,5,8-tetra-(4-n-butoxy-carbonyl)-naphthalene and 1,4,5,8-tetra-(8-n-octoxy-carbonyl)-naphthalene, were prepared from 1,4,5,8-naphthalene tetracarboxylic acid(NTA) with tetraoctane-ammonium bromide as a phase transfer catalyst. Their UV-Vis and fluorescent spectra suggested that the two compounds formed excimer complex in CH2Cl2, respectively. Their liquid crystalline behavior was investigated by DSC and polarized optical microscopy and their thermotropic liquid crystalline behavior was observed.
Two novel compounds, 1,4,5,8-tetra-(4-n-butoxy-carbonyl)-naphthalene and 1,4,5,8-tetra-(8-n-octoxy-carbonyl)-naphthalene, were prepared from 1,4,5,8-naphthalene tetracarboxylic acid(NTA) with tetraoctane-ammonium bromide as a phase transfer catalyst. Their UV-Vis and fluorescent spectra suggested that the two compounds formed excimer complex in CH2Cl2, respectively. Their liquid crystalline behavior was investigated by DSC and polarized optical microscopy and their thermotropic liquid crystalline behavior was observed.
2008, 25(8): 974-976
Abstract:
The influence of pH value on the viscosity of cationic starch(CS) solution, the mass ratio(R) of Mg-Al-hydrotalcite-like compound(Mg-Al-HTlc) to CS and the pH value on the viscosity of CS/HTlc suspension were studied. The results showed that the viscosity of CS solution had a maximum when the solution pH was in a range of 3~4. The viscosity of CS/Mg-Al-HTlc suspension increased at first and then decreased with the increase of the R value at pH 8.68~8.80. The pH at which the viscosity of CS/Mg-Al-HTlc suspension had a maximum increased with the R increasing. At a low pH, the CS/Mg-Al-HTlc suspension with a low R value had the highest viscosity, and at a high pH value, the CS/Mg-Al-HTlc suspension with a high R value had the highest viscosity.
The influence of pH value on the viscosity of cationic starch(CS) solution, the mass ratio(R) of Mg-Al-hydrotalcite-like compound(Mg-Al-HTlc) to CS and the pH value on the viscosity of CS/HTlc suspension were studied. The results showed that the viscosity of CS solution had a maximum when the solution pH was in a range of 3~4. The viscosity of CS/Mg-Al-HTlc suspension increased at first and then decreased with the increase of the R value at pH 8.68~8.80. The pH at which the viscosity of CS/Mg-Al-HTlc suspension had a maximum increased with the R increasing. At a low pH, the CS/Mg-Al-HTlc suspension with a low R value had the highest viscosity, and at a high pH value, the CS/Mg-Al-HTlc suspension with a high R value had the highest viscosity.
2008, 25(8): 977-979
Abstract:
PEEKK/PEI blends were prepared via melting extrusion at 380℃. The compatibility, crystallization behavior and mechanical properties of the blends were investigated by DSC, WAXD and UTM. The results show that the blends of PEEKK/PEI were compatible completely, all the blends exhibited a single glass transition temperature, and could be described by Fox equation. With increasing the content of PEI, the cold crystallization temperatures of the blends increased from 208℃ to 280℃, the melting crystallization temperatures decreased from 315℃ to 260℃, the melting points also decreased from 363℃ to 322℃, and melting enthalpy varied between -31.5 J/g and -2.2 J/g. The blends show good mechanical properties. With increasing the content of PEI, the elongation of blends at break increased from 25% to 60%, illuminating that PEI could improve the toughness of PEEKK.
PEEKK/PEI blends were prepared via melting extrusion at 380℃. The compatibility, crystallization behavior and mechanical properties of the blends were investigated by DSC, WAXD and UTM. The results show that the blends of PEEKK/PEI were compatible completely, all the blends exhibited a single glass transition temperature, and could be described by Fox equation. With increasing the content of PEI, the cold crystallization temperatures of the blends increased from 208℃ to 280℃, the melting crystallization temperatures decreased from 315℃ to 260℃, the melting points also decreased from 363℃ to 322℃, and melting enthalpy varied between -31.5 J/g and -2.2 J/g. The blends show good mechanical properties. With increasing the content of PEI, the elongation of blends at break increased from 25% to 60%, illuminating that PEI could improve the toughness of PEEKK.
2008, 25(8): 980-982
Abstract:
2-Aminofluorene was synthesized via the nitration and reduction of fluorene. The condensations of 2-aminofluorene with a series of aldehyde gave the corresponding schiff bases(a~h), and their structures were confirmed by IR, 1H NMR, MS and elemental analysis. The antibacterial activity was preliminarily evaluated, the results demonstrate that most of the compounds prepared displayed potential antibacterial activity.
2-Aminofluorene was synthesized via the nitration and reduction of fluorene. The condensations of 2-aminofluorene with a series of aldehyde gave the corresponding schiff bases(a~h), and their structures were confirmed by IR, 1H NMR, MS and elemental analysis. The antibacterial activity was preliminarily evaluated, the results demonstrate that most of the compounds prepared displayed potential antibacterial activity.
2008, 25(8): 983-985
Abstract:
A novel bimetallic complex PrBi(edta)(NO3)2·6.5H2O was synthesized by the reaction of NH4Bi(edta)·2H2O with praseodymium nitrate at a stoichiometric ratio of 1:1 in distilled water. The yield was about 45%. The complex is stable at room temperature and nonhydroscopic. The composition and structure of the complex was characterized by elemental analyses, FT-IR, TG-DSC and XRD. The crystal of the complex belongs to monoclinic system with cell parameters: a=0.988 5 nm, b=2.347 2 nm, c=1.375 6 nm, β=93.375°. IR spectrum and thermal analysis indicate that the thermal decomposition of the complex proceeded in several stages, the dehydration, pyrolysis of ligand, and finally the decomposition of the metallic salt, and the residue is an oxide with formula BiPrO3 at 600℃.
A novel bimetallic complex PrBi(edta)(NO3)2·6.5H2O was synthesized by the reaction of NH4Bi(edta)·2H2O with praseodymium nitrate at a stoichiometric ratio of 1:1 in distilled water. The yield was about 45%. The complex is stable at room temperature and nonhydroscopic. The composition and structure of the complex was characterized by elemental analyses, FT-IR, TG-DSC and XRD. The crystal of the complex belongs to monoclinic system with cell parameters: a=0.988 5 nm, b=2.347 2 nm, c=1.375 6 nm, β=93.375°. IR spectrum and thermal analysis indicate that the thermal decomposition of the complex proceeded in several stages, the dehydration, pyrolysis of ligand, and finally the decomposition of the metallic salt, and the residue is an oxide with formula BiPrO3 at 600℃.
2008, 25(8): 986-988
Abstract:
The red-emitting Y0.95Eu0.05(P1-xVx)O4(x:0, 0.8) phosphor powders were prepared by co-precipitation route. Their phase compositions, morphologies, and luminescent properties were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM) and vacuum ultraviolet emission spectroscopy(VUV), respectively. The results show that the particles in the two phosphor samples are overall spherical-shaped with a mean size of ~300 nm, and their main emission peaks under 147 nm VUV excitation are located at 619 nm. In comparison with Y0.95Eu0.05PO4 phosphor, Y0.95Eu0.05(P0.2V0.8)O4 phosphor is a more promising candidate for red-emitting PDP phosphor application due to its higher homochromy and its chroma-ticity coordinates closer to flammulated chromaticity coordinates (0.67, 0.33) regulated by National Television Standard Committee.
The red-emitting Y0.95Eu0.05(P1-xVx)O4(x:0, 0.8) phosphor powders were prepared by co-precipitation route. Their phase compositions, morphologies, and luminescent properties were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM) and vacuum ultraviolet emission spectroscopy(VUV), respectively. The results show that the particles in the two phosphor samples are overall spherical-shaped with a mean size of ~300 nm, and their main emission peaks under 147 nm VUV excitation are located at 619 nm. In comparison with Y0.95Eu0.05PO4 phosphor, Y0.95Eu0.05(P0.2V0.8)O4 phosphor is a more promising candidate for red-emitting PDP phosphor application due to its higher homochromy and its chroma-ticity coordinates closer to flammulated chromaticity coordinates (0.67, 0.33) regulated by National Television Standard Committee.
2008, 25(8): 989-991
Abstract:
With Cu(Ⅱ) ions as the template, molecular imprinted polymer membranes with supporting membranes were synthesized by UV irradiation. The surface features of the membranes were analyzed by scanning electron microscopy. The imprinted membranes exhibited selective permeation for Cu(Ⅱ) ions (compared to Zn(Ⅱ) ions, Ca(Ⅱ) ions etc). Effects of different supporting membranes, porosifier and functional monomers on the imprinted membranes' structure and permeation characteristics were investigated respectively, and pH value, cation and anion effects were also investigated. The results indicated that the membranes synthesized with PVDF membrane and cupric acetate exhibited selective permeation for Cu(Ⅱ) ions when the pH was 1 and the anion was acetate.
With Cu(Ⅱ) ions as the template, molecular imprinted polymer membranes with supporting membranes were synthesized by UV irradiation. The surface features of the membranes were analyzed by scanning electron microscopy. The imprinted membranes exhibited selective permeation for Cu(Ⅱ) ions (compared to Zn(Ⅱ) ions, Ca(Ⅱ) ions etc). Effects of different supporting membranes, porosifier and functional monomers on the imprinted membranes' structure and permeation characteristics were investigated respectively, and pH value, cation and anion effects were also investigated. The results indicated that the membranes synthesized with PVDF membrane and cupric acetate exhibited selective permeation for Cu(Ⅱ) ions when the pH was 1 and the anion was acetate.
2008, 25(8): 992-994
Abstract:
3β-Acetoxy-androstan-Δ5,15-dien-17-one was conveniently and effectively synthesized from IBX selective dehydrogen of dehydroepiandrosterone acetate in DMSO-toluene at 65~70℃ for 22 h, and the effect of the molar ratio of IBX to dehydroepiandrosterone on the yield of target product was probed, indicating that the weight yield was optimal up to 73% when the molar ratio of IBX to dehydroepiandrosterone was 1.5. The chemical structure of target product was characterized by UV, IR, 1H NMR, MS, and elemental analysis.
3β-Acetoxy-androstan-Δ5,15-dien-17-one was conveniently and effectively synthesized from IBX selective dehydrogen of dehydroepiandrosterone acetate in DMSO-toluene at 65~70℃ for 22 h, and the effect of the molar ratio of IBX to dehydroepiandrosterone on the yield of target product was probed, indicating that the weight yield was optimal up to 73% when the molar ratio of IBX to dehydroepiandrosterone was 1.5. The chemical structure of target product was characterized by UV, IR, 1H NMR, MS, and elemental analysis.
2008, 25(8): 995-997
Abstract:
Perovskite layer compounds (n-C10H21NH3)2CoCl4 and (n-C18H37NH3)2CoCl4 were synthesized, and the binary phase diagram of C10CoCl/C18CoCl was constructed using DSC data of a series of mixtures of the two compounds in the present work. The new stable materials (n-C10H21NH3)(n-C18H37NH3)CoCl4 and two invariant eutectic point(respectively 70 and 73℃) were observed.
Perovskite layer compounds (n-C10H21NH3)2CoCl4 and (n-C18H37NH3)2CoCl4 were synthesized, and the binary phase diagram of C10CoCl/C18CoCl was constructed using DSC data of a series of mixtures of the two compounds in the present work. The new stable materials (n-C10H21NH3)(n-C18H37NH3)CoCl4 and two invariant eutectic point(respectively 70 and 73℃) were observed.
2008, 25(8): 998-1000
Abstract:
The curing of epoxy resin with SMA as the curing agent and MeIm as the accelerator was studied by FT-IR and DSC, and the thermal stability of the resin was studied by DTA-TG analysis. The surface morphology of the cured product was studied by SEM. The curing mechanism was discussed. The result indicates that SMA can be used alone as the curing agent for epoxy resin, and the curing temperature could be decreased by 10℃ when MeIm was added as an accelerator, and the cured product exhibited thermal stability at below 400℃. There were two phases in the cured product, the continuous phase being epoxy and the dispersed phase being SMA.
The curing of epoxy resin with SMA as the curing agent and MeIm as the accelerator was studied by FT-IR and DSC, and the thermal stability of the resin was studied by DTA-TG analysis. The surface morphology of the cured product was studied by SEM. The curing mechanism was discussed. The result indicates that SMA can be used alone as the curing agent for epoxy resin, and the curing temperature could be decreased by 10℃ when MeIm was added as an accelerator, and the cured product exhibited thermal stability at below 400℃. There were two phases in the cured product, the continuous phase being epoxy and the dispersed phase being SMA.
