- Enantioseparation of napropamide by supercritical fluid chromatography: Effects of the chromatographic conditions and separation mechanism
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Supercritical fluid chromatography (SFC) is already used for enantioseparation in the pharmaceutical industry, but it is rarely used for the separation of chiral pesticides. Comparing with high performence liquid chromatography, SFC uses much more environmnetal friendly and economic mobile phase, supercritical CO2. In our work, the enantioseparation of an amide herbicide, napropamide, using three different polysaccharide-type chiral stationary phases (CSPs) in SFC was investigated. By studying the effect of different CSPs, organic modifiers, temperature, back-pressure regulator pressures, and flow rates for the enantioseparation of napropamide, we established a rapid and green method for enantioseparation that takes less than 2?minutes: The column was CEL2, the mobile phase was CO2 with 20% 2-propanol, and the flow rate was 2.0?mL/min. We found that CEL2 demonstrated the strongest resolution capability. Acetonitrile was favored over alcoholic solvents when the CSP was amylose and 2-propanol was the best choice when using cellulose. When the concentration of the modifiers or the flow rate was decreased, resolutions and analysis times increased concurrently. The temperature and back-pressure regulator pressure exhibited only minor influences on the resolution and analysis time of the napropamide enantioseparations with these chiral columns. The molecular docking analysis provided a deeper insight into the interactions between the enantiomers and the CSPs at the atomic level and partly explained the reason for the different elution orders using the different chiral columns.
- Zhao, Lu,Xie, Jingqian,Guo, Fangjie,Liu, Kai
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- The chiral separation and enantioselective degradation of the chiral herbicide napropamide
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The chiral pesticide enantiomers often have different toxic effects and environmental behaviors, which suggests that the risk assessments should be on an enantiomeric level. In this work, the chiral separation of the napropamide enantiomers and the stereoselective degradation in tomato, cucumber, rape, cabbage, and soil were investigated. Napropamide enantiomers could be separated absolutely by high-performance liquid chromatography (HPLC) using a Chiralpak IC column with a resolution factor of 11.75 under the optimized condition. Solid phase extraction (SPE) was used for cleanup of the enantiomers in the vegetable samples. The residue analysis method was validated. Good linearities (R 2 = 0.9997) and recoveries (71.43% -97.64%) were obtained. The limits of detection (LOD) were 0.05 mg/kg in soil and 0.20 mg/kg in vegetables. The results of degradation showed that napropamide dissipated rapidly in vegetables with half-lives of only 1.13-2.21 days, but much more slowly in soil, with a half-life of 11.95 d. Slight stereoselective degradation of the two enantiomers was only observed in cabbage, with enantiomeric fraction (EF) = 0.46, and there was no enantioselectivity in the other vegetables. The degradation of napropamide in the five matrixes was fast, and there was no enantioselectivity.
- Qi, Yanli,Liu, Donghui,Sun, Mingjing,Di, Shanshan,Wang, Peng,Zhou, Zhiqiang
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- Enantioselective Catabolism of Napropamide Chiral Enantiomers in Sphingobium sp. A1 and B2
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Napropamide [N,N-diethyl-2-(1-naphthalenyloxy)propenamide, NAP] is a highly efficient and broad-spectrum amide herbicide. Little is known about the bacterial catabolism of its different enantiomers. Here, we report the isolation of two NAP-degrading strains of Sphingobium sp., A1 and B2, and the different catabolic pathways of different enantiomers in these two strains. Strain A1 dioxygenated NAP at different positions of the naphthalene ring of different enantiomers, leading to the complete degradation of R-NAP while producing a dead-end product from S-NAP. Strain B2 cleaved the amido bonds of both enantiomers, but only the product from S-NAP could be further transformed to form α-naphthol and mineralize in strain B2. The degradation rates of R-NAP and S-NAP in the combination degradation by strains A1 and B2 were 24.8 and 7.5 times that in the single-strain degradation by strain B2 or A1, respectively, showing enhanced synergistic catabolism between strains A1 and B2. This study provides new insights into the enantioselective catabolic network of the chiral herbicide NAP in microorganisms.
- Huang, Junwei,Chen, Dian,Cheng, Xiaokun,Liu, Guiping,Wang, Guoxiang,Jiang, Jiandong
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- Preparation and characterization of a new open-tubular capillary column for enantioseparation by capillary electrochromatography
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In order to use the enantioseparation capability of cationic cyclodextrin and to combine the advantages of capillary electrochromatography (CEC) with open-tubular (OT) column, in this study, a new OT-CEC, coated with cationic cyclodextrin (1-allylimidazolium-β-cyclodextrin [AI-β-CD]) as chiral stationary phase (CSP), was prepared and applied for enantioseparation. Synthesized AI-β-CD was characterized by infrared (IR) spectrometry and mass spectrometry (MS). The preparation conditions for the AI-β-CD-coated column were optimized with the orthogonal experiment design L9(34). The column prepared was characterized by scanning electron microscopy (SEM) and elemental analysis (EA). The results showed that the thickness of stationary phase in the inner surface of the AI-β-CD-coated columns was about 0.2 to 0.5?μm. The AI-β-CD content in stationary phase based on the EA was approximately 2.77?mmol·m?2. The AI-β-CD-coated columns could separate all 14 chiral compounds (histidine, lysine, arginine, glutamate, aspartic acid, cysteine, serine, valine, isoleucine, phenylalanine, salbutamol, atenolol, ibuprofen, and napropamide) successfully in the study and exhibit excellent reproducibility and stability. We propose that the column, coated with AI-β-CD, has a great potential for enantioseparation in OT-CEC.
- Li, Yingjie,Tang, Yimin,Qin, Shili,Li, Xue,Dai, Qiang,Gao, Lidi
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p. 283 - 292
(2019/02/05)
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- METHOD FOR THE MANUFACTURE OF N, N-DIALLKYLLACTAMIDE
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The invention relates to a method for the manufacture of N,N-dialkyllactamide, whereby at least one of the compounds selected from the series consisting of alkyl lactate, lactide and polylactic acid is mixed with dialkylamine in order to form a reaction mixture, under conditions whereby aminolysis takes place in the reaction mixture. The method is characterized in that the reaction mixture further comprises a Lewis acid. As a result of the invented method, N,N-dialkyllactamides can be manufactured in high yields and with high optical purity.
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Page/Page column 11
(2016/04/26)
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- PROCESS FOR MANUFACTURE OF HIGH PURITY D-(-)-N, N-DIETHYL-2-(α- NAPHTHOXY) PROPIONAMIDE
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According to one aspect of the present invention there is provided a substantially high purity D-(-)-N,N-diethyl-2-(α -naphthoxy)propionamide and a process for the manufacture of substantially higher purity D-(-)-N,N-diethyl-2-(α-naphthoxy) propionamide having chemical purity near about or above 95%, and chiral purity near about or more than 97%. According to another aspect of the invention is to provide an agrochemical compositions containing highly pure optically active D-(-)-N,N-diethyl-2- (α-naphthoxy)propionamide.
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Page/Page column 16-19
(2009/03/07)
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