Amine elimination of Ln[N(SiMe3)2]3(μ-Cl)Li(THF)3 with aminophenol H[ON]{H[ON]=2-(CH2 NC5 H10)-4,6-tBu2-C6 H3OH}in 1:2 molar ratio in THF gave the monometallic rare-earth metal amide complexes[ON]2 LnN(SiMe3)2(Ln=Yb(...Amine elimination of Ln[N(SiMe3)2]3(μ-Cl)Li(THF)3 with aminophenol H[ON]{H[ON]=2-(CH2 NC5 H10)-4,6-tBu2-C6 H3OH}in 1:2 molar ratio in THF gave the monometallic rare-earth metal amide complexes[ON]2 LnN(SiMe3)2(Ln=Yb(1),Y(2),Gd(3),Sm(4),Nd(5))in 57%-73%isolated yields.All these complexes were characterized by elemental analysis.The molecular structures of complexes 1-4 were determined by single crystal X-ray diffraction.These complexes are highly active for L-Iactide polymerization to give high molecular weight polymers with unimodal molecular weight distributions.In addition,these complexes can also initiate rac-lactide polymerization with high activity to afford heterotactic-rich polylactides.展开更多
A method was developed for the determination of tetraethyl ammonium （TEA） by reversed-phase ion- pair chromatography with indirect ultraviolet detection, Chromatographic separation was achieved on a reversed-phase C...A method was developed for the determination of tetraethyl ammonium （TEA） by reversed-phase ion- pair chromatography with indirect ultraviolet detection, Chromatographic separation was achieved on a reversed-phase C18 column using background ultraviolet absorbing reagent - ion-pair reagent - organic solvent as mobile phase. The effects of the background ultraviolet absorbing reagents, detection wavelength, ion-pair reagents, organic solvents and column temperature on the determination method were investigated and the retention rules discussed. Results found that TEA could be successfully analyzed by using 0.7 mmol/L 4-aminophenol hydrochloride and 0.15 mmol/L 1-heptanesulfonic acid sodium mixed with 20% （v/v） methanol as mobile phase at a UV detection wavelength of 230 nm. Under these conditions, the retention time of tetraethyl ammonium was 2.85 min. The detection limit （S/N = 3） for TEA was 0.06 mg/L. The relative standard deviations （n = 5） for peak area and retention time were 0.35% and 0.02%, respectively. The method has been successfully applied to the determination of synthesized tetraethyl ammonium bromide. Recovery of tetraethyl ammonium after spiking was 99.1%.展开更多
The triphenyltin complex with salicylidene-2-aminophenol （C31H24NO2Sn, 1） has been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and X-ray single-crystal diffracti...The triphenyltin complex with salicylidene-2-aminophenol （C31H24NO2Sn, 1） has been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and X-ray single-crystal diffraction. The complex crystallizes in monoclinic system, P21/c space group with a = 1.09515（8）, b = 1.17739（8）, c = 2.29075（14） nm, β = 117.070（4）°, V = 2.6302（3） nm3, Z = 4, Dc = 1.417 g/cm3, ？ = 0.999 mm–1, F（000） = 1123, R = 0.0472 and wR = 0.1169. X-ray single-crystal diffraction showed that 1 demonstrates a one-dimensional chain structure. The quantum chemical calculation of 1 has been investigated. Complex 1 emits fluo- rescence at 558 nm and exhibits certain inhibitory activity against NCI-H460, A549 and MCF-7.展开更多
Various supported Pt-Pb bimetallic catalysts were prepared and applied for the catalytic conversion of nitrobenzene to p-aminophenol in the environmentally benign pressurized CO2/H2O system.Among the bimetallic cataly...Various supported Pt-Pb bimetallic catalysts were prepared and applied for the catalytic conversion of nitrobenzene to p-aminophenol in the environmentally benign pressurized CO2/H2O system.Among the bimetallic catalysts prepared,Pt-Pb/SiO2 is the best and nitrobenzene could be converted to paminophenol with a selectivity as high as 82% when the reaction was carried out using this catalyst at110 ℃ under 5 MPa CO2 and 0.2 MPa H2.展开更多
The exploration of C2-symmetric chiral aminophenols and aminonaphthols is described. Seven new ligands have been successfully synthesized using Mannich reaction as a key step. Four of them have C2-symmetry and their s...The exploration of C2-symmetric chiral aminophenols and aminonaphthols is described. Seven new ligands have been successfully synthesized using Mannich reaction as a key step. Four of them have C2-symmetry and their structure has been fully characterized by means of NMR and X-ray crystallography.展开更多
The oxidative polycondensation reaction conditions of 2-[(2-hydroxyphenyliminomethylbenzylidene)amino- phenol](2-HPIMBAP)has been accomplished by using air O_2 and NaOCl oxidants in an aqueous alkaline medium between ...The oxidative polycondensation reaction conditions of 2-[(2-hydroxyphenyliminomethylbenzylidene)amino- phenol](2-HPIMBAP)has been accomplished by using air O_2 and NaOCl oxidants in an aqueous alkaline medium between 50-90℃.The optimum reaction conditions of the oxidative polycondensation and the main parameters of the process were established.At the optimum reaction conditions,yield of the products were found to be 67.72% and 61.49% for air O_2 and NaOCl oxidants respectively.The structures of the monomer ...展开更多
The optimum reaction conditions of the oxidative polycondensation of 2-(thien-2-yl-methylene)aminophenol (2-TMAP) has been accomplished by using air O_2,H_2O_2 and NaOCl oxidants in an aqueous alkaline medium between...The optimum reaction conditions of the oxidative polycondensation of 2-(thien-2-yl-methylene)aminophenol (2-TMAP) has been accomplished by using air O_2,H_2O_2 and NaOCl oxidants in an aqueous alkaline medium between 20℃and 90℃.The structures of the monomer and oligomer were confirmed by FT-IR,UV-Vis,~1H-NMR and ^(13)C-NMR and elemental analysis.TGA-DTA,size exclusion chromatography(SEC) techniques and solubility tests were applied for characterization.The ~1H-NMR and ^(13)C-NMR data show that the polymeriz...展开更多
The gold electrodes coated by n-alkanethiol with various chain lengths were used to study the permeability of uric acid,ascorbic acid,4-aminophenol,paracetanol and phenacetin by means of linear sweep voltammetry.The r...The gold electrodes coated by n-alkanethiol with various chain lengths were used to study the permeability of uric acid,ascorbic acid,4-aminophenol,paracetanol and phenacetin by means of linear sweep voltammetry.The results show that the optimum chain length is n=10.The improvements in the selectivity and the stability of the amperometric detection of these compounds in a flow stream were obtained by n-alkanethiol self assembled monolayers modified electrodes based on their differences in the hydrophobicity and the permeability.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 syntheses of a library of new chiral aminophenolate bidentate O,N-type ligands HOC<sub>6</sub>H<sub>4</sub>(2-R- 4-R′)CH<sub>2</sub>N(Me)CH(Me)C<sub>6</sub>H<sub...The syntheses of a library of new chiral aminophenolate bidentate O,N-type ligands HOC<sub>6</sub>H<sub>4</sub>(2-R- 4-R′)CH<sub>2</sub>N(Me)CH(Me)C<sub>6</sub>H<sub>5</sub> [R = R′ = Bu<sup>t</sup>, 1;R = R′ = Pent, 2;R = Bu<sup>t</sup>, R′ = Me, 3;R = Me, R′ = Bu<sup>t</sup>, 4;R = R′ = Me, 5] and tridentate O,N,O-type ligands HOC<sub>6</sub>H<sub>4</sub>(2,4-Bu<sup>t</sup>)CH = NCH(R′′)C<sub>6</sub>H<sub>5</sub> [R′′ = Me, 6;R′′ = CH<sub>2</sub>OMe, 7] are reported. These ligands were characterized by elemental analysis, nuclear magnetic resonance spectroscopy (<sup>1</sup>H &<sup> 13</sup>C), and single crystal X-ray diffraction. These ligands serve as chiral auxiliaries for inorganic chemists to design chiral metal-based complexes for asymmetric catalysis and stereoselective polymerization reactions. Three new heteroleptic zinc complexes based on these ligands have been synthesized in moderate yields via a ligand-exchange transamination reaction between homoleptic [Zn(N(SiMe<sub>3</sub>)<sub>2</sub>)<sub>2</sub>] and one equivalent of corresponding ligands to afford [L<sup>3</sup>ZnN- (SiMe<sub>3</sub>)<sub>2</sub>] (3a), [L<sup>4</sup>ZnN(SiMe<sub>3</sub>)<sub>2</sub>] (4a), and [L<sup>7</sup>ZnN(SiMe<sub>3</sub>)<sub>2</sub>] (7a). Solvent-free polymerization of raclactide at 130°C using these zinc compounds yielded atactic polylactides with Mw 10,000 g/mol and narrow polydispersity of 1.3.展开更多
In this work, we evaluated the quality of paracetamol generic tablets while seeking its two main impurities namely 4-para-aminophenol (4-AP) and 4-para-nitrophenol (4-NP) which have nephrotoxic and teratogenic propert...In this work, we evaluated the quality of paracetamol generic tablets while seeking its two main impurities namely 4-para-aminophenol (4-AP) and 4-para-nitrophenol (4-NP) which have nephrotoxic and teratogenic properties. Ninety-four (94) samples were collected at various levels of the medicine supply chain and illegal markets in Benin for quality control tests such as visual inspection, pharmacotechnical tests as mass variation, disintegration test, dissolution test, followed by HPLC UV-Vis identification and assay of paracetamol, 4-AP and 4-NP. The analytes were separated on C18 Lichrocart column (250 mm × 4.0 mm i.d, 5 μm);the mobile phase was MeOH:10 mM ammonium acetate buffer pH 6.8 (35:65) pumped at a flow rate of 1 ml/min. The detection was done at 245 nm. Analysis of our results shows that 77.7% of the samples did not comply with the visual inspection test requirements, 2.1% did not pass the mass variation test, 24.3% of the sample batches didn’t comply with the disintegration test requirements. In addition none of these uncomply batches passed the dissolution test, even if the identification test indicated that all samples contained paracetamol. None contained 4-NP (acceptance limit < 0.05% m/m;BP), while 3 of 94 samples contained 4-AP but within acceptance limit (4-AP < 0.1% m/m;BP). As for the paracetamol assay, 80.9% complied with the specifications of the pharmacopoeias taken as reference (90% - 110%;USP). Further, broader studies should be conducted according to the same rules of good practice for a more comprehensive analysis of the situation. Generally the quality control of paracetamol in most African countries, particularly in Benin, is based on pharmacotechnical tests and paracetamol assay. This work, in addition to the usual tests, showed the importance to search for paracetamol and other drugs’ impurities during their routine quality control.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
The reaction of the cobalt(II) meso-tetraphenylporphyrin (TPP) starting material with an excess of 2-aminophenol (Hon) in organic solvents, yields the cobalt(II) porphyrin species [CoII(TPP)(Hon)2] (1). This compound ...The reaction of the cobalt(II) meso-tetraphenylporphyrin (TPP) starting material with an excess of 2-aminophenol (Hon) in organic solvents, yields the cobalt(II) porphyrin species [CoII(TPP)(Hon)2] (1). This compound has been characterized by UV-vis., IR, MSI MS and 1H NMR spectroscopy. The UV-vis data and especially the proton NMR results, for the isolated product, indicated that complex 1 is a Co(II) mesoporphyrin derivative.The X-ray molecular structure of the title compound bis(2-aminophenol) (tetraphenylporphyrinato) cobalt(II) has been determined. This structure is the first one reported of a metalloporphyrin with a 2-aminophenol axial ligand species. The central metal is hexacoordinated by the four nitrogen atoms of the pyrrole rings and the nitrogen atoms of the two Hon trans axial ligands.展开更多
MgAPO-5 molecular sieves have been synthesized using diethylaminoethanol as the templating agent in a wide range of the MgO/Al2O3 ratio.The samples were characterized by XRD,SEM,solid state NMR,FT-IR and NH3-TPD.Using...MgAPO-5 molecular sieves have been synthesized using diethylaminoethanol as the templating agent in a wide range of the MgO/Al2O3 ratio.The samples were characterized by XRD,SEM,solid state NMR,FT-IR and NH3-TPD.Using MgAPO-5 as acidic supports,bifunctional Pt/MgAPO-5 catalysts were prepared for hydrogenation of nitrobenzene to p-aminophenol (PAP).The results showed that the MgO/Al2O3 ratios influenced the Mg content and the acidity of MgAPO-5 samples,thereby greatly affecting the catalytic performance of Pt/MgAPO-5 catalysts.The selectivity to PAP over Pt/MgAPO-5 was dependent on the amount of strong acid sites of MgAPO-5.When the MgO/Al2O3 molar ratio was 0.5,the synthesized MgAPO-5 sample exhibited the largest amount of strong acid and a highest PAP yield of 41.1% was achieved over Pt/MgAPO-5 catalyst.展开更多
Recently, study on the photocatalytic degradation of harmful substances by usingsemiconductors has received much attention,because semiconductors, as a stable andinexpensive photocatalyst, may be effective for the deg...Recently, study on the photocatalytic degradation of harmful substances by usingsemiconductors has received much attention,because semiconductors, as a stable andinexpensive photocatalyst, may be effective for the degradation of pollutants from the stand-point of solar energy utilization, e.g. TiO<sub>2</sub>, the photoinduced holes with high oxidationpotential, may be used as strong oxidant to decompose a large number of展开更多
An ionic liquid bulk-modified carbon paste electrode （M-CPE） has been fabricated by using 1-heptyl-3-methylimidazolium bromide as a modifier. Cyclic voltammetry （CV） and differential pulse voltammetry （DPV） were...An ionic liquid bulk-modified carbon paste electrode （M-CPE） has been fabricated by using 1-heptyl-3-methylimidazolium bromide as a modifier. Cyclic voltammetry （CV） and differential pulse voltammetry （DPV） were used to evaluate the electrocatalytic activity of the proposed electrode by choosing p-aminophenol （p-AP） as a model compound. Both at a bare carbon paste electrode （CPE） and the M-CPE, p-AP yielded a pair of redox peaks in 0.1 mol·L^-1 phosphate buffer solution （PBS, pH 7.0）. At the CPE, the peak-to-peak potential separation （AEp） was 0.233 V, while at the M-CPE the AEp was decreased to 0.105 V. Furthermore, the current response to p-AP at the M-CPE was 10.2 times of that at the CPE by DPV. The electron transfer rate constant （ks） ofp-AP at the M-CPE was 13.3 times of that at the CPE. Under the optimal condition, a linear dependence of the catalytic current versus p-AP concentration was obtained in the range of 2.0× 10^- 6 to 3.0× 10^- 4 mol·L^-1 with a detection limit of 6.0× 10^-7 mol·L^-1 by DPV. In addition, compared to other modified method the proposed electrode exhibited distinct advantages of simple prapartion, surface renewal, good reproducibility and good stability. It has been used to determine p-AP in simulated wastewater samples.展开更多
基金Project supported by the National Natural Science Foundation of China(21572205,21971130,21871198,21674070)the Natural Science Foundation of Zhejiang Province(LY19B040002)+2 种基金the State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciencesthe Natural Science Foundation of Ningbo Municipal(2019A610030,2019A610129)K.C.Wong Magna Fund in Ningbo University。
文摘Amine elimination of Ln[N(SiMe3)2]3(μ-Cl)Li(THF)3 with aminophenol H[ON]{H[ON]=2-(CH2 NC5 H10)-4,6-tBu2-C6 H3OH}in 1:2 molar ratio in THF gave the monometallic rare-earth metal amide complexes[ON]2 LnN(SiMe3)2(Ln=Yb(1),Y(2),Gd(3),Sm(4),Nd(5))in 57%-73%isolated yields.All these complexes were characterized by elemental analysis.The molecular structures of complexes 1-4 were determined by single crystal X-ray diffraction.These complexes are highly active for L-Iactide polymerization to give high molecular weight polymers with unimodal molecular weight distributions.In addition,these complexes can also initiate rac-lactide polymerization with high activity to afford heterotactic-rich polylactides.
基金supported by the Natural Science Foundation of Heilongjiang Province(Grant No.B201307)the Ministry of Education of Heilongjiang Province(No.12531192)the Program for Scientific and Technological Innovation Team Construction in Universities of Heilongjiang Province(No. 2011TD010)
文摘A method was developed for the determination of tetraethyl ammonium （TEA） by reversed-phase ion- pair chromatography with indirect ultraviolet detection, Chromatographic separation was achieved on a reversed-phase C18 column using background ultraviolet absorbing reagent - ion-pair reagent - organic solvent as mobile phase. The effects of the background ultraviolet absorbing reagents, detection wavelength, ion-pair reagents, organic solvents and column temperature on the determination method were investigated and the retention rules discussed. Results found that TEA could be successfully analyzed by using 0.7 mmol/L 4-aminophenol hydrochloride and 0.15 mmol/L 1-heptanesulfonic acid sodium mixed with 20% （v/v） methanol as mobile phase at a UV detection wavelength of 230 nm. Under these conditions, the retention time of tetraethyl ammonium was 2.85 min. The detection limit （S/N = 3） for TEA was 0.06 mg/L. The relative standard deviations （n = 5） for peak area and retention time were 0.35% and 0.02%, respectively. The method has been successfully applied to the determination of synthesized tetraethyl ammonium bromide. Recovery of tetraethyl ammonium after spiking was 99.1%.
基金Supported by the Open Fund Project of Key Laboratory of Functional Organometallic Materials of Hengyang Normal University(15K017,14K014,13K105)Natural Science Foundation of Hunan Province(No.13JJ3112)+3 种基金Scientific&Technological Projects of Hunan Province(No.2014NK3086)Aid programs for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Provincethe Key Discipline of Hunan ProvinceProject funding for research and innovation experiment of university students in Hunan Province
文摘The triphenyltin complex with salicylidene-2-aminophenol （C31H24NO2Sn, 1） has been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and X-ray single-crystal diffraction. The complex crystallizes in monoclinic system, P21/c space group with a = 1.09515（8）, b = 1.17739（8）, c = 2.29075（14） nm, β = 117.070（4）°, V = 2.6302（3） nm3, Z = 4, Dc = 1.417 g/cm3, ？ = 0.999 mm–1, F（000） = 1123, R = 0.0472 and wR = 0.1169. X-ray single-crystal diffraction showed that 1 demonstrates a one-dimensional chain structure. The quantum chemical calculation of 1 has been investigated. Complex 1 emits fluo- rescence at 558 nm and exhibits certain inhibitory activity against NCI-H460, A549 and MCF-7.
文摘Various supported Pt-Pb bimetallic catalysts were prepared and applied for the catalytic conversion of nitrobenzene to p-aminophenol in the environmentally benign pressurized CO2/H2O system.Among the bimetallic catalysts prepared,Pt-Pb/SiO2 is the best and nitrobenzene could be converted to paminophenol with a selectivity as high as 82% when the reaction was carried out using this catalyst at110 ℃ under 5 MPa CO2 and 0.2 MPa H2.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.20172008),which is greatly appreciated.
文摘The exploration of C2-symmetric chiral aminophenols and aminonaphthols is described. Seven new ligands have been successfully synthesized using Mannich reaction as a key step. Four of them have C2-symmetry and their structure has been fully characterized by means of NMR and X-ray crystallography.
基金This work was supported by the Canakkale Onsekiz Mart University Scientific Research Projects Commission for financial support(No.2007/20).
文摘The oxidative polycondensation reaction conditions of 2-[(2-hydroxyphenyliminomethylbenzylidene)amino- phenol](2-HPIMBAP)has been accomplished by using air O_2 and NaOCl oxidants in an aqueous alkaline medium between 50-90℃.The optimum reaction conditions of the oxidative polycondensation and the main parameters of the process were established.At the optimum reaction conditions,yield of the products were found to be 67.72% and 61.49% for air O_2 and NaOCl oxidants respectively.The structures of the monomer ...
基金supported by the Government Planning Organization(GPO2002K120170-7)TUBITAK GrantsCommission for a research grant(No.TBAG-105T428).
文摘The optimum reaction conditions of the oxidative polycondensation of 2-(thien-2-yl-methylene)aminophenol (2-TMAP) has been accomplished by using air O_2,H_2O_2 and NaOCl oxidants in an aqueous alkaline medium between 20℃and 90℃.The structures of the monomer and oligomer were confirmed by FT-IR,UV-Vis,~1H-NMR and ^(13)C-NMR and elemental analysis.TGA-DTA,size exclusion chromatography(SEC) techniques and solubility tests were applied for characterization.The ~1H-NMR and ^(13)C-NMR data show that the polymeriz...
文摘The gold electrodes coated by n-alkanethiol with various chain lengths were used to study the permeability of uric acid,ascorbic acid,4-aminophenol,paracetanol and phenacetin by means of linear sweep voltammetry.The results show that the optimum chain length is n=10.The improvements in the selectivity and the stability of the amperometric detection of these compounds in a flow stream were obtained by n-alkanethiol self assembled monolayers modified electrodes based on their differences in the hydrophobicity and the permeability.
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 syntheses of a library of new chiral aminophenolate bidentate O,N-type ligands HOC<sub>6</sub>H<sub>4</sub>(2-R- 4-R′)CH<sub>2</sub>N(Me)CH(Me)C<sub>6</sub>H<sub>5</sub> [R = R′ = Bu<sup>t</sup>, 1;R = R′ = Pent, 2;R = Bu<sup>t</sup>, R′ = Me, 3;R = Me, R′ = Bu<sup>t</sup>, 4;R = R′ = Me, 5] and tridentate O,N,O-type ligands HOC<sub>6</sub>H<sub>4</sub>(2,4-Bu<sup>t</sup>)CH = NCH(R′′)C<sub>6</sub>H<sub>5</sub> [R′′ = Me, 6;R′′ = CH<sub>2</sub>OMe, 7] are reported. These ligands were characterized by elemental analysis, nuclear magnetic resonance spectroscopy (<sup>1</sup>H &<sup> 13</sup>C), and single crystal X-ray diffraction. These ligands serve as chiral auxiliaries for inorganic chemists to design chiral metal-based complexes for asymmetric catalysis and stereoselective polymerization reactions. Three new heteroleptic zinc complexes based on these ligands have been synthesized in moderate yields via a ligand-exchange transamination reaction between homoleptic [Zn(N(SiMe<sub>3</sub>)<sub>2</sub>)<sub>2</sub>] and one equivalent of corresponding ligands to afford [L<sup>3</sup>ZnN- (SiMe<sub>3</sub>)<sub>2</sub>] (3a), [L<sup>4</sup>ZnN(SiMe<sub>3</sub>)<sub>2</sub>] (4a), and [L<sup>7</sup>ZnN(SiMe<sub>3</sub>)<sub>2</sub>] (7a). Solvent-free polymerization of raclactide at 130°C using these zinc compounds yielded atactic polylactides with Mw 10,000 g/mol and narrow polydispersity of 1.3.
文摘In this work, we evaluated the quality of paracetamol generic tablets while seeking its two main impurities namely 4-para-aminophenol (4-AP) and 4-para-nitrophenol (4-NP) which have nephrotoxic and teratogenic properties. Ninety-four (94) samples were collected at various levels of the medicine supply chain and illegal markets in Benin for quality control tests such as visual inspection, pharmacotechnical tests as mass variation, disintegration test, dissolution test, followed by HPLC UV-Vis identification and assay of paracetamol, 4-AP and 4-NP. The analytes were separated on C18 Lichrocart column (250 mm × 4.0 mm i.d, 5 μm);the mobile phase was MeOH:10 mM ammonium acetate buffer pH 6.8 (35:65) pumped at a flow rate of 1 ml/min. The detection was done at 245 nm. Analysis of our results shows that 77.7% of the samples did not comply with the visual inspection test requirements, 2.1% did not pass the mass variation test, 24.3% of the sample batches didn’t comply with the disintegration test requirements. In addition none of these uncomply batches passed the dissolution test, even if the identification test indicated that all samples contained paracetamol. None contained 4-NP (acceptance limit < 0.05% m/m;BP), while 3 of 94 samples contained 4-AP but within acceptance limit (4-AP < 0.1% m/m;BP). As for the paracetamol assay, 80.9% complied with the specifications of the pharmacopoeias taken as reference (90% - 110%;USP). Further, broader studies should be conducted according to the same rules of good practice for a more comprehensive analysis of the situation. Generally the quality control of paracetamol in most African countries, particularly in Benin, is based on pharmacotechnical tests and paracetamol assay. This work, in addition to the usual tests, showed the importance to search for paracetamol and other drugs’ impurities during their routine quality control.
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The reaction of the cobalt(II) meso-tetraphenylporphyrin (TPP) starting material with an excess of 2-aminophenol (Hon) in organic solvents, yields the cobalt(II) porphyrin species [CoII(TPP)(Hon)2] (1). This compound has been characterized by UV-vis., IR, MSI MS and 1H NMR spectroscopy. The UV-vis data and especially the proton NMR results, for the isolated product, indicated that complex 1 is a Co(II) mesoporphyrin derivative.The X-ray molecular structure of the title compound bis(2-aminophenol) (tetraphenylporphyrinato) cobalt(II) has been determined. This structure is the first one reported of a metalloporphyrin with a 2-aminophenol axial ligand species. The central metal is hexacoordinated by the four nitrogen atoms of the pyrrole rings and the nitrogen atoms of the two Hon trans axial ligands.
基金supported by the National Basic Research Program of China (2010CB234602)the National Natural Science Foundation of China (20636030,20706011 & 20876033)+1 种基金the Basic Research Program of Tianjin (07JCZDJC00100)the Education Bureau of Hebei Province (2005005D)
文摘MgAPO-5 molecular sieves have been synthesized using diethylaminoethanol as the templating agent in a wide range of the MgO/Al2O3 ratio.The samples were characterized by XRD,SEM,solid state NMR,FT-IR and NH3-TPD.Using MgAPO-5 as acidic supports,bifunctional Pt/MgAPO-5 catalysts were prepared for hydrogenation of nitrobenzene to p-aminophenol (PAP).The results showed that the MgO/Al2O3 ratios influenced the Mg content and the acidity of MgAPO-5 samples,thereby greatly affecting the catalytic performance of Pt/MgAPO-5 catalysts.The selectivity to PAP over Pt/MgAPO-5 was dependent on the amount of strong acid sites of MgAPO-5.When the MgO/Al2O3 molar ratio was 0.5,the synthesized MgAPO-5 sample exhibited the largest amount of strong acid and a highest PAP yield of 41.1% was achieved over Pt/MgAPO-5 catalyst.
文摘Recently, study on the photocatalytic degradation of harmful substances by usingsemiconductors has received much attention,because semiconductors, as a stable andinexpensive photocatalyst, may be effective for the degradation of pollutants from the stand-point of solar energy utilization, e.g. TiO<sub>2</sub>, the photoinduced holes with high oxidationpotential, may be used as strong oxidant to decompose a large number of
基金Project supported by the National Natural Science Foundation of China （No. 20675062） and the Natural Science Foundation of Shaanxi Province in China （No. 2004B20）.
文摘An ionic liquid bulk-modified carbon paste electrode （M-CPE） has been fabricated by using 1-heptyl-3-methylimidazolium bromide as a modifier. Cyclic voltammetry （CV） and differential pulse voltammetry （DPV） were used to evaluate the electrocatalytic activity of the proposed electrode by choosing p-aminophenol （p-AP） as a model compound. Both at a bare carbon paste electrode （CPE） and the M-CPE, p-AP yielded a pair of redox peaks in 0.1 mol·L^-1 phosphate buffer solution （PBS, pH 7.0）. At the CPE, the peak-to-peak potential separation （AEp） was 0.233 V, while at the M-CPE the AEp was decreased to 0.105 V. Furthermore, the current response to p-AP at the M-CPE was 10.2 times of that at the CPE by DPV. The electron transfer rate constant （ks） ofp-AP at the M-CPE was 13.3 times of that at the CPE. Under the optimal condition, a linear dependence of the catalytic current versus p-AP concentration was obtained in the range of 2.0× 10^- 6 to 3.0× 10^- 4 mol·L^-1 with a detection limit of 6.0× 10^-7 mol·L^-1 by DPV. In addition, compared to other modified method the proposed electrode exhibited distinct advantages of simple prapartion, surface renewal, good reproducibility and good stability. It has been used to determine p-AP in simulated wastewater samples.
