The liquid phase Beckmann rearrangement of cyclohexanone oxime (CHO) using fuming sulfuric acid as a catalyst is a traditional method for preparing ε-caprolactam (CPL). This process has drawbacks, such as environment...The liquid phase Beckmann rearrangement of cyclohexanone oxime (CHO) using fuming sulfuric acid as a catalyst is a traditional method for preparing ε-caprolactam (CPL). This process has drawbacks, such as environmental pollution, corrosion of equipment, and low added value of by-product ammonium sulfate. This article designed and prepared a green silica gel-supported trifluoromethanesulfonic acid catalyst for the liquid-phase Beckmann rearrangement of CHO to prepare (CPL). The influencing factors of catalyst preparation and the optimal reaction conditions for Beckmann rearrangement were investigated. It was found that the optimal conditions for catalyst preparation were as follows: raw material silica gel:trifluoromethanesulfonic acid = 1:0.2 (mass ratio), room temperature, stirring time of 2.5 hours, and solvent of acetonitrile, silica gel mesh size is 100 - 200. The optimal reaction conditions for Beckmann rearrangement are CHO: catalyst = 1:2 (mass ratio), temperature of 130˚C, solvent of benzonitrile, volume of 30 mL/g CHO, and reaction time of 4 hours. Under the above conditions, the conversion of CHO is 90%, and the selectivity of CPL is 90%.展开更多
Background Mosquito control is needed to prevent dengue fever, which is mainly spread byAedes albopictus in China. Application of insecticides is one of the main mosquito control methods;however, this approach can fai...Background Mosquito control is needed to prevent dengue fever, which is mainly spread byAedes albopictus in China. Application of insecticides is one of the main mosquito control methods;however, this approach can fail due to the knockdown resistance (kdr) gene mutation that causes decreased sensitivity to insecticides inAe. albopictus. Thekdr mutation patterns among different regions in China differ significantly. However, the underlying mechanism and factors that influencekdr mutation remain unclear. To explore the potential influence of genetic background on the development of insecticide resistance inAe. albopictus, we analyzed the genetic structure ofAe. albopictus populations in China and its correlation with majorkdr mutations.Methods We collectedAe. albopictus from 17 sites in 11 provinces (municipalities) across China from 2016 to 2021 and extracted the genomic DNA from individual adult mosquitoes. We selected eight microsatellite loci for genotyping, and based on microsatellite scores, we estimated intraspecific genetic diversity, population structure, and effective population size. The association between the intrapopulation genetic variation and F1534 mutation rate was evaluated by the Pearson correlation coefficient.Results Based on variation analysis of the microsatellite loci of 453 mosquitoes representing 17 populations throughout China, more than 90% of the variation occurred within individuals, whereas only about 9% of the variation occurred among populations, indicating that field populations ofAe. albopictus are highly polymorphic. The northern populations tended to belong to gene pool I (BJFT 60.4%, SXXA 58.4%, SDJN 56.1%, SXYC 46.8%), the eastern populations tended to belong to pool III (SH 49.5%, JZHZ 48.1%), and the southern populations tended to belong to three different gene pools. Moreover, we observed that the greater the fixation index (FST), the lower the wild-type frequency of F1534 ofVSGC.Conclusions The degree of genetic differentiation amongAe. albopictus populations in China was low. These populations were divided into three gene pools, in which the northern and eastern pools are relatively homogeneous, while the southern gene pool is heterogeneous. The possible correlation between its genetic variations andkdr mutations is also noteworthy.展开更多
文摘The liquid phase Beckmann rearrangement of cyclohexanone oxime (CHO) using fuming sulfuric acid as a catalyst is a traditional method for preparing ε-caprolactam (CPL). This process has drawbacks, such as environmental pollution, corrosion of equipment, and low added value of by-product ammonium sulfate. This article designed and prepared a green silica gel-supported trifluoromethanesulfonic acid catalyst for the liquid-phase Beckmann rearrangement of CHO to prepare (CPL). The influencing factors of catalyst preparation and the optimal reaction conditions for Beckmann rearrangement were investigated. It was found that the optimal conditions for catalyst preparation were as follows: raw material silica gel:trifluoromethanesulfonic acid = 1:0.2 (mass ratio), room temperature, stirring time of 2.5 hours, and solvent of acetonitrile, silica gel mesh size is 100 - 200. The optimal reaction conditions for Beckmann rearrangement are CHO: catalyst = 1:2 (mass ratio), temperature of 130˚C, solvent of benzonitrile, volume of 30 mL/g CHO, and reaction time of 4 hours. Under the above conditions, the conversion of CHO is 90%, and the selectivity of CPL is 90%.
基金supported by grants from the Natural Science Foundation of Shanghai(No.19ZR1469600 to HP)National Natural Sciences Foundation of China(No.31970445 to YM)+1 种基金National Key Research and Development Program of China(No.2022YFC3103000 to YM)Shanghai Industrial Collaborative Innovation Project(No.2021-cyxt1-kj06 to HP).
文摘Background Mosquito control is needed to prevent dengue fever, which is mainly spread byAedes albopictus in China. Application of insecticides is one of the main mosquito control methods;however, this approach can fail due to the knockdown resistance (kdr) gene mutation that causes decreased sensitivity to insecticides inAe. albopictus. Thekdr mutation patterns among different regions in China differ significantly. However, the underlying mechanism and factors that influencekdr mutation remain unclear. To explore the potential influence of genetic background on the development of insecticide resistance inAe. albopictus, we analyzed the genetic structure ofAe. albopictus populations in China and its correlation with majorkdr mutations.Methods We collectedAe. albopictus from 17 sites in 11 provinces (municipalities) across China from 2016 to 2021 and extracted the genomic DNA from individual adult mosquitoes. We selected eight microsatellite loci for genotyping, and based on microsatellite scores, we estimated intraspecific genetic diversity, population structure, and effective population size. The association between the intrapopulation genetic variation and F1534 mutation rate was evaluated by the Pearson correlation coefficient.Results Based on variation analysis of the microsatellite loci of 453 mosquitoes representing 17 populations throughout China, more than 90% of the variation occurred within individuals, whereas only about 9% of the variation occurred among populations, indicating that field populations ofAe. albopictus are highly polymorphic. The northern populations tended to belong to gene pool I (BJFT 60.4%, SXXA 58.4%, SDJN 56.1%, SXYC 46.8%), the eastern populations tended to belong to pool III (SH 49.5%, JZHZ 48.1%), and the southern populations tended to belong to three different gene pools. Moreover, we observed that the greater the fixation index (FST), the lower the wild-type frequency of F1534 ofVSGC.Conclusions The degree of genetic differentiation amongAe. albopictus populations in China was low. These populations were divided into three gene pools, in which the northern and eastern pools are relatively homogeneous, while the southern gene pool is heterogeneous. The possible correlation between its genetic variations andkdr mutations is also noteworthy.
