Extraction of o-aminophenol (OAP) using trialkylphosphine oxide (TRPO) was studied with different diluents. The neutral OAP was extracted using TRPO under an equilibrium pH in the range of 6—7.5, and a maximum distri...Extraction of o-aminophenol (OAP) using trialkylphosphine oxide (TRPO) was studied with different diluents. The neutral OAP was extracted using TRPO under an equilibrium pH in the range of 6—7.5, and a maximum distribution coefficient occurred. It was confirmed that the pH value and the TRPO concentration are the key factors that affect dis-tribution coefficient. Nonpolar diluents could provide better extraction distribution coefficient for the extraction of OAP and the order is: kerosene >n-octanol >chloroform.展开更多
The reaction mechanism of o-aminophenol, acetic acid and phosphorus oxytrichloride in one-pot to form 2-methyl benzoxazole was studied by density functional theory. The geometries of the reactants, transition states, ...The reaction mechanism of o-aminophenol, acetic acid and phosphorus oxytrichloride in one-pot to form 2-methyl benzoxazole was studied by density functional theory. The geometries of the reactants, transition states, intermediates and products were optimized at the GGA/PW91/DNP level. Vibration analysis was carried out to confirm the transition state structure. Two possible reaction pathways were investigated in this study. The result indicates that the reaction Re→TS1→IM1→TSA2→IMA2→TSA3→IMA3→TSA4→IMA4→TSA5→P2 is the main pathway, the activation energy of which is the lowest. Re→TS1→IM1 is the rate-limiting step, with the activation energy being 221.54 kJ·mol^(-1) and the reaction heat being 10.06 kJ·mol^(-1). The dominant product predicted theoretically is in agreement with the experiment results.展开更多
The practical use of non-conducting poly(o-aminophenol) (POAP) films in the field of the bioelectrochemistry is discussed in this paper. Particular emphasis is given to the effects of applied potential, solution pH an...The practical use of non-conducting poly(o-aminophenol) (POAP) films in the field of the bioelectrochemistry is discussed in this paper. Particular emphasis is given to the effects of applied potential, solution pH and interferents on the response current of biosensors based on POAP.展开更多
Under the condition of weak acidity of pH 5.2, a sensitive vitamin B2 electrochemical sensor based on molecularly imprinted nonconducting polymer of o-aminophenol by potentiostatic polymerization in the presence of te...Under the condition of weak acidity of pH 5.2, a sensitive vitamin B2 electrochemical sensor based on molecularly imprinted nonconducting polymer of o-aminophenol by potentiostatic polymerization in the presence of template(vitamin B2) on a glassy carbon electrode was prepared, and its performance was studied. The sensor exhibited good sensitivity and selectivity to VB2. The detection limit went down to 2.3851nM, and a linear relationship between the current incremental and the concentration was found in the range of 10~120nM. And the sensor could use in detection of VB2 real sample for a long time and show good reproducibility. The average recovery rate to VB2 was 98.41%.展开更多
The experimental arrangement in this investigation was one in which a poly(o-aminophenol) (POAP) film was supported on a thin gold film electrode whose thickness is of the order of the mean free path of conduction ele...The experimental arrangement in this investigation was one in which a poly(o-aminophenol) (POAP) film was supported on a thin gold film electrode whose thickness is of the order of the mean free path of conduction electrons of gold. This arrangement allows one to apply the surface resistance technique to study the electrochemical processes occurring at the metal film surface coated with the polymer film. The dependence of the resistance change of the thin gold film electrode on the external electrolyte composition for polymer thickness lower than 0.25 mC.cm-2, was attributed to a competition, at the gold film surface, between the redox process of the polymer and adsorption of different ion species contained in the electrolyte. This competition reflects a discontinuous character of polymer thickness lower than 0.25 mC.cm-2 at the metal polymer interface. The resistance response of the metal film becomes independent of both the external electrolyte composition and polymer thickness for polymer thickness higher than 0.8 mC.cm-2. Then, POAP thicknesses higher than 0.8 mC.cm-2 seem to be compact enough at the metal polymer interface to prevent the interaction of the species contained in the supporting electrolyte with the gold film surface. The increase of the gold film resistance in going from the reduced to the oxidized state for POAP thicknesses higher than 0.8 mC.cm-2 was attributed to the redox conversion of poly(o-aminophenol) from amine to imine groups. This resistance increase was explained as a transition from specular to diffuse scattering of conduction electrons of gold at the gold poly(o-aminophenol) interface due to a less compact distribution of oxidised sites of POAP as compared with that of the reduced ones. An attenuation of the resistance response of the gold film was observed when the POAP films were deactivated either by contact with a ferric cation solution or prolonged potential cycling. The deactivation of the polymer film was attributed to the creation of inactive gaps within the redox sites configuration of POAP. The surface resistance technique allows one to detect different redox sites configurations of POAP on the gold film, according to the method used to deactivate the polymer films. In this work, it is demonstrated that the surface resistance technique can be employed to study not only the ability of a POAP film to inhibit the interaction of different species in solution with a metal surface but also the deactivation of the polymer film.展开更多
Theo-aminophenol (OAP)-H2O2-horseradish peroxidase (HRP) voltammetric enzyme-linked immunoassay new system has extremely high sensitivity. HRP can be measured with a detection limit of 6.0×1010 g/L and a linear r...Theo-aminophenol (OAP)-H2O2-horseradish peroxidase (HRP) voltammetric enzyme-linked immunoassay new system has extremely high sensitivity. HRP can be measured with a detection limit of 6.0×1010 g/L and a linear range of 1.0×10-9-4.0×10-6 g/L. The pure product of H2O2 oxidizing OAP catalyzed by HRP was prepared with chemical method. The enzyme-catalyzed reaction has been investigated with electroanalytical chemistry, UV/Vis spectrum, IR spectrum,13C NMR,1H NMR, mass spectrum, elemental analysis, etc. Under the selected enzyme-catalyzed reaction conditions, the oxidation product of OAP with H2O2 catalyzed by HRP is 2-aminophenoxazine-3-one. The processes of the enzyme-catalyzed reaction and the electroreduction of the product of the enzymecatalyzed reaction have been described.展开更多
基金Supported by the Educational Department of Henan Province (No.2004530001).
文摘Extraction of o-aminophenol (OAP) using trialkylphosphine oxide (TRPO) was studied with different diluents. The neutral OAP was extracted using TRPO under an equilibrium pH in the range of 6—7.5, and a maximum distribution coefficient occurred. It was confirmed that the pH value and the TRPO concentration are the key factors that affect dis-tribution coefficient. Nonpolar diluents could provide better extraction distribution coefficient for the extraction of OAP and the order is: kerosene >n-octanol >chloroform.
基金Supported by the Scientific and Technological Research Program of Chongqing Municipal Education Commission(KJ1601215)the Ministry of Education "Chunhui Plan"(Z2016177)
文摘The reaction mechanism of o-aminophenol, acetic acid and phosphorus oxytrichloride in one-pot to form 2-methyl benzoxazole was studied by density functional theory. The geometries of the reactants, transition states, intermediates and products were optimized at the GGA/PW91/DNP level. Vibration analysis was carried out to confirm the transition state structure. Two possible reaction pathways were investigated in this study. The result indicates that the reaction Re→TS1→IM1→TSA2→IMA2→TSA3→IMA3→TSA4→IMA4→TSA5→P2 is the main pathway, the activation energy of which is the lowest. Re→TS1→IM1 is the rate-limiting step, with the activation energy being 221.54 kJ·mol^(-1) and the reaction heat being 10.06 kJ·mol^(-1). The dominant product predicted theoretically is in agreement with the experiment results.
文摘The practical use of non-conducting poly(o-aminophenol) (POAP) films in the field of the bioelectrochemistry is discussed in this paper. Particular emphasis is given to the effects of applied potential, solution pH and interferents on the response current of biosensors based on POAP.
文摘Under the condition of weak acidity of pH 5.2, a sensitive vitamin B2 electrochemical sensor based on molecularly imprinted nonconducting polymer of o-aminophenol by potentiostatic polymerization in the presence of template(vitamin B2) on a glassy carbon electrode was prepared, and its performance was studied. The sensor exhibited good sensitivity and selectivity to VB2. The detection limit went down to 2.3851nM, and a linear relationship between the current incremental and the concentration was found in the range of 10~120nM. And the sensor could use in detection of VB2 real sample for a long time and show good reproducibility. The average recovery rate to VB2 was 98.41%.
文摘The experimental arrangement in this investigation was one in which a poly(o-aminophenol) (POAP) film was supported on a thin gold film electrode whose thickness is of the order of the mean free path of conduction electrons of gold. This arrangement allows one to apply the surface resistance technique to study the electrochemical processes occurring at the metal film surface coated with the polymer film. The dependence of the resistance change of the thin gold film electrode on the external electrolyte composition for polymer thickness lower than 0.25 mC.cm-2, was attributed to a competition, at the gold film surface, between the redox process of the polymer and adsorption of different ion species contained in the electrolyte. This competition reflects a discontinuous character of polymer thickness lower than 0.25 mC.cm-2 at the metal polymer interface. The resistance response of the metal film becomes independent of both the external electrolyte composition and polymer thickness for polymer thickness higher than 0.8 mC.cm-2. Then, POAP thicknesses higher than 0.8 mC.cm-2 seem to be compact enough at the metal polymer interface to prevent the interaction of the species contained in the supporting electrolyte with the gold film surface. The increase of the gold film resistance in going from the reduced to the oxidized state for POAP thicknesses higher than 0.8 mC.cm-2 was attributed to the redox conversion of poly(o-aminophenol) from amine to imine groups. This resistance increase was explained as a transition from specular to diffuse scattering of conduction electrons of gold at the gold poly(o-aminophenol) interface due to a less compact distribution of oxidised sites of POAP as compared with that of the reduced ones. An attenuation of the resistance response of the gold film was observed when the POAP films were deactivated either by contact with a ferric cation solution or prolonged potential cycling. The deactivation of the polymer film was attributed to the creation of inactive gaps within the redox sites configuration of POAP. The surface resistance technique allows one to detect different redox sites configurations of POAP on the gold film, according to the method used to deactivate the polymer films. In this work, it is demonstrated that the surface resistance technique can be employed to study not only the ability of a POAP film to inhibit the interaction of different species in solution with a metal surface but also the deactivation of the polymer film.
基金Project supported by the National Natural Science Foundation of China (Grant No. 29775012)
文摘Theo-aminophenol (OAP)-H2O2-horseradish peroxidase (HRP) voltammetric enzyme-linked immunoassay new system has extremely high sensitivity. HRP can be measured with a detection limit of 6.0×1010 g/L and a linear range of 1.0×10-9-4.0×10-6 g/L. The pure product of H2O2 oxidizing OAP catalyzed by HRP was prepared with chemical method. The enzyme-catalyzed reaction has been investigated with electroanalytical chemistry, UV/Vis spectrum, IR spectrum,13C NMR,1H NMR, mass spectrum, elemental analysis, etc. Under the selected enzyme-catalyzed reaction conditions, the oxidation product of OAP with H2O2 catalyzed by HRP is 2-aminophenoxazine-3-one. The processes of the enzyme-catalyzed reaction and the electroreduction of the product of the enzymecatalyzed reaction have been described.