Ethyl 3,3-diamino-2-(2-p-tolylpyrimidin-4-yl)acrylate,a new representative of hetarylketene aminals

A new representative of hetarylketene aminals, ethyl 3,3-diamino-2-(2-p-tolylpyrimidin-4-yl)acrylate, was synthesized by the reaction ofp-toluamidine with the condensation product of dimethylformamide dimethyl acetal and the difluoroboron chelate of acetyl(ethoxycarbonyl)ketene (N-benzoyl)aminal. This synthesis is an example of pyrimidine ring assembly using the methodology based on transformations of chelate complexes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1638–1640, September, 1994.This research was partially supported by the International Science Foundation (Grant No. M5QOOO).     

Electrocatalytic Determination of Ascorbic Acid at the Surface of 2,7‐Bis(ferrocenyl ethyl)fluoren‐9‐one Modified Carbon Paste Electrode

A chemically modified carbon paste electrode with 2,7‐bis(ferrocenyl ethyl)fluoren‐9‐one (2,7‐BFEFMCPE) was employed to study the electrocatalytic oxidation of ascorbic acid in aqueous solution using cyclic voltammetry, differential pulse voltammetry and chronoamperometry. The diffusion coefficient (D=1.89×10^?5 cm² s^?1), and the kinetic parameter such as the electron transfer coefficient, α (=0.42) of ascorbic acid oxidation at the surface of 2,7‐BFEFMCPE was determined using electrochemical approaches. It has been found that under an optimum condition (pH 7.00), the oxidation of ascorbic acid at the surface of such an electrode occurs at a potential about 300 mV less positive than that of an unmodified carbon paste electrode. The catalytic oxidation peak currents show a linear dependence on the ascorbic acid concentration and linear analytical curves were obtained in the ranges of 8.0×10^?5 M–2.0×10^?3 M and 3.1×10^?5 M–3.3×10^?3 M of ascorbic acid with correlation coefficients of 0.9980 and 0.9976 in cyclic voltammetry and differential pulse voltammetry, respectively. The detection limits (2δ) were determined to be 2.9×10^?5 M and 9.0×10^?6 M with cyclic voltammetry and differential pulse voltammetry, respectively. This method was also examined for determination of ascorbic acid in pharmaceutical preparations.     

Mg-Al-O-t-Bu hydrotalcite as an efficient catalyst for the transesterification of dimethyl carbonate with ethanol

Mg-Al-O-t-Bu hydrotalcite was synthesized and characterized by XRD, FT-IR and TGA-DTA. It was proved to be an active heterogeneous catalyst for the transesterification of dimethyl carbonate (DMC) with ethanol. When the reaction was carried out over Mg-Al-O-t-Bu hydrotalcite at 80°C, 7 h, molar ratio of ethanol to DMC 5:1, 1.0 wt.% of catalyst, the conversion of DMC was 86.4%, the selectivity to diethyl carbonate (DEC) was 61.2%. This heterogeneous catalyst could be used 5 times without loss of its activity.     

单分子链胶束的胶束化行为与相关新概念的提出

采用水溶液均聚合方法,制备了阳离子型表面活性单体（2-丙烯酰胺基）乙基十四烷基二甲基溴化铵（AMC14AB）的均聚物,使用荧光探针法、表面张力测定及电导测定法,重点考察了均聚物P（AMC14AB）在水溶液中的胶束化行为与表面吸附现象．在水溶液中,均聚物P（AMC14AB）呈现单分子链胶束的聚集形态,具有零临界胶束浓度（CMC=0）,从开始加入P（AMC14AB）起,水溶液中随即产生单分子链胶束,不存在Krafft温度．P（AMC14AB）在溶液表面也发生表面吸附,使水的表面张力下降,即P（AMC14AB）也具有表面活性;随着浓度增大,表面吸附量增大,水的表面张力持续下降;当表面吸附达到饱和时,表面张力一浓度曲线上出现突变点,该点应该定义为饱和的表面吸附浓度（SSAC）,而不应该再称为临界胶束浓度．P（AMC14AB）单分子链胶束溶液对疏水有机物（甲苯）的增溶情况,明显不同于普通小分子表面活性剂十六烷基二甲基溴化铵（CTAB）的多分子胶束溶液,甲苯增溶量-P（AMC14AB）浓度的关系曲线上无突变点,而且对甲苯的增溶能力高于CTAB的多分子胶束溶液．     

Synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] by incorporation of carbon dioxide into epoxide polymer and the miscibility behavior of its blends with poly(methyl methacrylate) or poly(vinyl chloride)

This study was related to the investigation of the chemical fixation of carbon dioxide to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer‐to‐polymer blends. In the synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] [poly(DOMA‐co‐EA)] from poly(glycidyl methacrylate‐co‐ethyl acrylate) [poly(GMA‐co‐EA)] and CO₂, quaternary ammonium salts showed good catalytic activity. The films of poly(DOMA‐co‐EA) with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) blends were cast from N,N′‐dimethylformamide solution. The miscibility of the blends of poly(DOMA‐co‐EA) with PMMA or PVC have been investigated both by DSC and visual inspection of the blends. The optical clarity test and DSC analysis showed that poly(DOMA‐co‐EA) containing blends were miscible over the whole composition range. The miscibility behaviors were discussed in terms of Fourier transform infrared spectra and interaction parameters based on the binary interaction model. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1472–1480, 2001     

淀粉接枝丙烯酸乙酯及其增容性

研究了在挤出机中采用高温和剪切力的作用直接引发淀粉与丙烯酸乙酯的接枝共聚合反应．讨论了反应条件对接枝反应的影响，研究了接枝物在淀粉与聚乙烯共混物中的增容作用．实验结果表明，高温和剪切力可以引发淀粉与丙烯酸乙酯的接枝共聚合反应．接枝物作为增容剂，可以明显地改善淀粉与聚乙烯共混物的力学性能和流变性能．     

Pesticide residues analysis in honey using ethyl acetate extraction method: validation and pilot survey in real samples

This paper presents a cost-effective and validated multi residue confirmatory method for the determination of 167 chemically different pesticides and a survey study on Cyprus honey samples. This method uses ethyl acetate for the extraction of pesticides from honey and the determination is performed with liquid chromatography (LC) coupled to mass spectrometry (MS) operating in tandem mode (MS/MS) and with GC–ECD (gas chromatography with electron capture detector) analysis. The LC-MS/MS analytical system is especially important in the analysis of polar and non-volatile pesticides. For the validation of the method, blank honey samples were spiked with 146 pesticides (organophosphorous, carbamates, triazoles, amides, neonicodinoids, strobilurines, phenylureas, bendimidazoles and others) for the LC-MS/MS analysis at three levels: 0.01, 0.05 and 0.1 mg kg^?1 and with 21 pesticides for the GC-ECD analysis at two levels: 0.01 and 0.05 mg kg^?1for organochlorines and 0.05 and 0.2 mg kg^?1for the pyrethroids. As blank sample, a sample of honey which did not contain detectable levels of the analytes sought was used. The validation study was in accordance to the DG SANCO guidelines. The scope of validation included recovery, linearity, limits of quantification and precision. Linearity is demonstrated all along the range of concentration that was investigated with correlation coefficients ≥0.98. Recoveries of the majority of compounds were in the 70%–120% range and were characterised by precision lower or equal to 20%. The validated method was used for a survey of 36 samples of honey produced in different areas of Cyprus and this is the first work on Cypriot honey samples investigating a broad range of pesticides. Only coumaphos was detected at concentrations higher than 0.01 mg kg^?1 in the 58.6% of the honey samples analysed for Coumaphos. The results were evaluated in accordance to the provisions of the Commission Regulation (EU) No 37/2010 on pharmacologically active substances and their classification regarding maximum residue limits (MRLs) in foodstuffs of animal origin. The concentrations of coumaphos in all positive samples were at levels much lower than the MRL.     

Enantioselective separation of the carfentrazone‐ethyl enantiomers in soil,water and wheat by HPLC

A simple enantioselective HPLC method was developed for measuring carfentrazone‐ethyl enantiomers. The separation and determination was accomplished on an amylose tris[(S)‐α‐methylbenzylcarbamate] (Chiralpak AS) column using n‐hexane/ethanol (98:2, v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 248 nm. The effects of mobile‐phase composition and column temperature on the enantioseparation were discussed. The accuracy, precision, linearity, LODs, and LOQ of the method were also investigated. LOD was 0.001 mg/kg in water, 0.015 mg/kg in soil and wheat, with an LOQ of 0.0025 mg/kg in water and 0.05 mg/kg in soil and wheat for each enantiomer of carfentrazone‐ethyl. SPE was used for the enrichment and cleanup of soil, water, and wheat samples. Recoveries for two enantiomers were 88.4–106.7% with RSD_r of 4.2–9.8% at 0.1, 0.5, and 1 mg/kg levels from soil, 85.8–99.5% with the RSD_r of 4.4?9.6% at 0.005, 0.025, and 0.05 mg/kg levels from water, and from wheat the recoveries were 86.3?91.3% with RSD_r below 5.0% at 0.2, 0.5, and 1 mg/kg levels. This method could be used to identify and quantify the carfentrazone‐ethyl enantiomers in food and environment.     

二甲基硫和乙硫醇在层状K1-2xMxTiNbO5(M=Mn2+、Ni2+)上的吸附与光催化氧化作用

采用固相法制备出具有层状结构的KTiNbO₅,通过离子交换制备K_1-2xM_xTiNbO₅(M=Mn²⁺、Ni²⁺)。采用X射线粉末衍射（XRD）和紫外－可见漫反射光谱技术对样品晶体结构与光谱响应特征进行表征,采用红外光谱方法考察样品对二甲基硫（DMS）和乙硫醇（EM）吸附与光催化氧化行为。结果表明,采用Mn²⁺和Ni²⁺对KTiNbO₅离子交换后,层板间距增加,对光谱吸收由紫外区移向可见光区,带隙能量由3.35eV相应地移至2.97eV和2.45eV。K_1-2xM_xTiNbO₅对DMS和EM的吸附作用力较弱,不受阳离子影响。K_1-2xMn_xTiNbO₅只在紫外光辐射下呈现催化活性,并将硫醚、硫醇氧化为亚砜、砜和磺酸;而K_1-2xNi_xTiNbO₅在可见与紫外光辐射下均具有光催化活性,在可见光辐射下,乙硫醇被氧化至磺酸,而在紫外光辐射下硫醇被矿化并产生硫酸盐与碳酸盐。     

以硫酸镓/凹凸棒固体酸为催化剂的肉桂酸乙酯合成综合制备实验设计

利用自制硫酸镓/凹凸棒固体酸催化剂代替浓硫酸,设计了肉桂酸乙酯合成综合制备实验,该实验由肉桂酸制备、硫酸镓/凹凸棒固体酸催化剂制备、肉桂酸乙酯合成、肉桂酸乙酯酯化率测定等部分组成。当肉桂酸乙酯合成条件为肉桂酸7.5 g、无水乙醇18 mL、反应温度120 ℃、反应时间3.0 h时,肉桂酸乙酯的酯化率不低于85%,所制催化剂经7次重复使用,肉桂酸乙酯的酯化率仍达42.3%。实验克服了浓硫酸催化法存在的缺点,具备显著的综合实验特征。