Two procedures were compared for extraction and clean-up of 20organophosphorus and 19 pyrethroid pesticides in sediment to identify the more effective procedurefor groups of pesticides or individual compounds. In Proc...Two procedures were compared for extraction and clean-up of 20organophosphorus and 19 pyrethroid pesticides in sediment to identify the more effective procedurefor groups of pesticides or individual compounds. In Procedure I, methanol/water and n-hexane wereused for extraction, and 1:10 (v/v) dichloromethane in n-hexane and acetone were used as eluents foreluting the analyte through the cartridge, with one evaporating steps on a rotary evaporator andtwo eluting steps on the cartridge. n-hexane/acetone (2:1, v/v) was used for extraction and elutionin Procedure II with one evaporating step on a rotary evaporator and one eluting step on thecartridge. All extractions were performed under an ultrasonic bath and gas chromatography and massspectrometry were utilized for measurements. Procedure II was developed as a rapid, timesaving, lesscostly and safer substitute for Procedure I which was an old method. Procedure II was moreeffective for almost all the organophosphorus pesticides tested and 11of the 19 pyrethroidpesticides, while Procedure I was more appropriate for analysis of 5 pyrethroid pesticides. However,recoveries of most pyrethroid pesticides were fairly low. Thus, further studies should focus onadjustment and formulation of solvents for more efficient extraction and clean-up of pyrethroidpesticides from sediment samples.展开更多
A new process for the direct chlorination of 2-chloro-5-methylpyridine to yield 2-chloro-5-chloro-methylpyridine in an airlift loop reactor (ALR) has been studied. Five main reaction conditions including TR, na/ns, cp...A new process for the direct chlorination of 2-chloro-5-methylpyridine to yield 2-chloro-5-chloro-methylpyridine in an airlift loop reactor (ALR) has been studied. Five main reaction conditions including TR, na/ns, cp, Qg and dD/dR were optimized. The average molar yield and purity of 2-chloro-5-chloromethylpyridine obtained were 79% and 98.5% respectively under the optimum operating conditions. Finally, the efficiency for the preparation of 2-chloro-5-chloromethylpyridine with ALR and stirred tank reactor (STR) respectively was compared.展开更多
In order to reduce the production cost of imidacloprid, the preparation technology for the direct com-bination of 2-chloro-5-chloromethylpyridine and 2-nitryliminoglyoxaline has been optimized in a 10 L stirred tank r...In order to reduce the production cost of imidacloprid, the preparation technology for the direct com-bination of 2-chloro-5-chloromethylpyridine and 2-nitryliminoglyoxaline has been optimized in a 10 L stirred tank reactor with a new solvent, butanone, and a new catalyst, benzyl triethyl-ammonium chloride (BTEAC), which was proved to be more profitable for the production of imidacloprid. Three main affecting factors (the reaction temper-ature, the molar ratio of BTEAC to 2-nitryliminoglyoxaline and the concentration of 2-nitryuminoglyoxaline) for the production of imidacloprid were investigated and the optimum operating conditions were found. Based on the above technological optimization, an industrial process for imidacloprid with a production capacity of 50 tons per year was put in operation using a 2500 L stirred tank reactor under the same operating conditions. Good yield and purity of imidacloprid was also obtained in the industrial production.展开更多
这题目并非作者想出来的,这是今年6月在北京召开的第19届国际昆虫学大会的主题,英文的提法是 man living with insects。在一般人心目中,昆虫几乎都是坏的,因此对这样一个提法比较难于接受。事实上这是人类经过与昆虫斗争了几千年才取...这题目并非作者想出来的,这是今年6月在北京召开的第19届国际昆虫学大会的主题,英文的提法是 man living with insects。在一般人心目中,昆虫几乎都是坏的,因此对这样一个提法比较难于接受。事实上这是人类经过与昆虫斗争了几千年才取得的认识,值得撰文加以介绍。从对地球的占领说。展开更多
基金Project supported by the Outstanding Youth Fund of National Natural Science Foundation of China, the National Key Basic Research Support Foundation (NKBRSF) of China (No. 2002CB410805) and the Federal Ministry of Education and Research, Germany.
文摘Two procedures were compared for extraction and clean-up of 20organophosphorus and 19 pyrethroid pesticides in sediment to identify the more effective procedurefor groups of pesticides or individual compounds. In Procedure I, methanol/water and n-hexane wereused for extraction, and 1:10 (v/v) dichloromethane in n-hexane and acetone were used as eluents foreluting the analyte through the cartridge, with one evaporating steps on a rotary evaporator andtwo eluting steps on the cartridge. n-hexane/acetone (2:1, v/v) was used for extraction and elutionin Procedure II with one evaporating step on a rotary evaporator and one eluting step on thecartridge. All extractions were performed under an ultrasonic bath and gas chromatography and massspectrometry were utilized for measurements. Procedure II was developed as a rapid, timesaving, lesscostly and safer substitute for Procedure I which was an old method. Procedure II was moreeffective for almost all the organophosphorus pesticides tested and 11of the 19 pyrethroidpesticides, while Procedure I was more appropriate for analysis of 5 pyrethroid pesticides. However,recoveries of most pyrethroid pesticides were fairly low. Thus, further studies should focus onadjustment and formulation of solvents for more efficient extraction and clean-up of pyrethroidpesticides from sediment samples.
基金Natural Science Foundation of Tianjin(No.013605711)National Natural Science Foundation of China(No.20176040)
文摘A new process for the direct chlorination of 2-chloro-5-methylpyridine to yield 2-chloro-5-chloro-methylpyridine in an airlift loop reactor (ALR) has been studied. Five main reaction conditions including TR, na/ns, cp, Qg and dD/dR were optimized. The average molar yield and purity of 2-chloro-5-chloromethylpyridine obtained were 79% and 98.5% respectively under the optimum operating conditions. Finally, the efficiency for the preparation of 2-chloro-5-chloromethylpyridine with ALR and stirred tank reactor (STR) respectively was compared.
基金Natural Science Foundation of Tianjin(No.013605711)
文摘In order to reduce the production cost of imidacloprid, the preparation technology for the direct com-bination of 2-chloro-5-chloromethylpyridine and 2-nitryliminoglyoxaline has been optimized in a 10 L stirred tank reactor with a new solvent, butanone, and a new catalyst, benzyl triethyl-ammonium chloride (BTEAC), which was proved to be more profitable for the production of imidacloprid. Three main affecting factors (the reaction temper-ature, the molar ratio of BTEAC to 2-nitryliminoglyoxaline and the concentration of 2-nitryuminoglyoxaline) for the production of imidacloprid were investigated and the optimum operating conditions were found. Based on the above technological optimization, an industrial process for imidacloprid with a production capacity of 50 tons per year was put in operation using a 2500 L stirred tank reactor under the same operating conditions. Good yield and purity of imidacloprid was also obtained in the industrial production.
