Cation-exchange chromatography was selected to extract and separate betaines from marine algae. On the basis of the special chemical characteristics of the betaines and their analogues, Dragendorff’s reagent (KBiI 4)...Cation-exchange chromatography was selected to extract and separate betaines from marine algae. On the basis of the special chemical characteristics of the betaines and their analogues, Dragendorff’s reagent (KBiI 4) was used to test the existence of betaines and their analogues in marine algae. The total content of betaines from seven species was obtained by using the Reinkeate salt precipitation method. The results showed that the content of betaines in two species of Chlorophyta and two species of Rhodophyta were relatively high,and that the content of betaines in Enteromopha prolifera could even reach to 0.9%. The content in the three species of Phaeophyta was relatively low.展开更多
Organic chelating reagent influences upon the redox adsorption of activated carbon fiber towards Au3+ were systematically investigated. The experimental results indicated that the presence of organic chelating reagent...Organic chelating reagent influences upon the redox adsorption of activated carbon fiber towards Au3+ were systematically investigated. The experimental results indicated that the presence of organic chelating reagent on activated carbon fiber strongly affects adsorption capacity of activated carbon fiber towards Au3+. The reduction-adsorption amount of Au3+ increased three times by the presence of 8-quinolinol. Furthermore, The reduction-adsorption amount of Au3+ depended on the pH value of adsorption and temperature.展开更多
Trifluoromethylation reactions are important transformations in the research and development of drugs, agrochemicals and functional materials. An oxidation/reduction process of trifluoromethyl-containing compounds is ...Trifluoromethylation reactions are important transformations in the research and development of drugs, agrochemicals and functional materials. An oxidation/reduction process of trifluoromethyl-containing compounds is thought to be involved in many recently tested catalytic trifluoromethylation reactions. To provide helpful physical chemical data for mechanistic studies on trifluoromethylation reactions, the redox potentials of a variety of trifluoromethyl-containing compounds and trifluoro- methylated radicals were studied by quantum-chemical methods. First, eoB97X-D was found to be a reliable method in predicting the ionization potentials, electron affinities, bond dissociation enthalpies and redox potentials of trifluoromethylcontaining compounds. One-electron absolute redox potentials of 79 trifluoromethyl substrates and 107 trifluoromethylated radicals in acetonitrile were then calculated with this method. The theoretical results were found to be helpful for interpreting experimental observations such as the relative reaction efficiency of different trifluoromethylation reagents. Finally, the bond dissociation free energies （BDFE） of various compounds were found to have a good linear relationship with the related bond dissociation enthalpies （BDE）. Based on this observation, a convenient method was proposed to predict one-electron redox potentials of neutral molecules.展开更多
文摘Cation-exchange chromatography was selected to extract and separate betaines from marine algae. On the basis of the special chemical characteristics of the betaines and their analogues, Dragendorff’s reagent (KBiI 4) was used to test the existence of betaines and their analogues in marine algae. The total content of betaines from seven species was obtained by using the Reinkeate salt precipitation method. The results showed that the content of betaines in two species of Chlorophyta and two species of Rhodophyta were relatively high,and that the content of betaines in Enteromopha prolifera could even reach to 0.9%. The content in the three species of Phaeophyta was relatively low.
基金Chinese Ministry of Education Doctor Fund No.: 2000055804.
文摘Organic chelating reagent influences upon the redox adsorption of activated carbon fiber towards Au3+ were systematically investigated. The experimental results indicated that the presence of organic chelating reagent on activated carbon fiber strongly affects adsorption capacity of activated carbon fiber towards Au3+. The reduction-adsorption amount of Au3+ increased three times by the presence of 8-quinolinol. Furthermore, The reduction-adsorption amount of Au3+ depended on the pH value of adsorption and temperature.
基金supported by the National Natural Science Foundation of China(21325208,21172209,21361140372,21202006)Specialized Research Fund for the Doctoral Program(20123402110051)+5 种基金Fundamental Research Funds for the Central Universities(WK2060190025)Chinese Academy of Sciences(KJCX2-EW-J02)Fok Ying Tung Education FoundationAnhui Provincial Natural Science Foundation(1308085QB38)China Grid project funded by Ministry of Education of Chinathe supercomputer center of Shanghai and University of Science and Technology of China
文摘Trifluoromethylation reactions are important transformations in the research and development of drugs, agrochemicals and functional materials. An oxidation/reduction process of trifluoromethyl-containing compounds is thought to be involved in many recently tested catalytic trifluoromethylation reactions. To provide helpful physical chemical data for mechanistic studies on trifluoromethylation reactions, the redox potentials of a variety of trifluoromethyl-containing compounds and trifluoro- methylated radicals were studied by quantum-chemical methods. First, eoB97X-D was found to be a reliable method in predicting the ionization potentials, electron affinities, bond dissociation enthalpies and redox potentials of trifluoromethylcontaining compounds. One-electron absolute redox potentials of 79 trifluoromethyl substrates and 107 trifluoromethylated radicals in acetonitrile were then calculated with this method. The theoretical results were found to be helpful for interpreting experimental observations such as the relative reaction efficiency of different trifluoromethylation reagents. Finally, the bond dissociation free energies （BDFE） of various compounds were found to have a good linear relationship with the related bond dissociation enthalpies （BDE）. Based on this observation, a convenient method was proposed to predict one-electron redox potentials of neutral molecules.
