The kinetics of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed aldol condensation of furfural with acetone was investigated under free solvent conditions from 50℃ - 90℃. The highest yield of 1,4-pentandien-3-on-...The kinetics of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed aldol condensation of furfural with acetone was investigated under free solvent conditions from 50℃ - 90℃. The highest yield of 1,4-pentandien-3-on-1,5-di-furanyl catalyzed by DBU reached 98.0% under optimized conditions. According to the kinetic analysis, the reaction order of furfural was estimated as 1.0, the apparent activation energy was 17.7 kJ.mol.1, and the pre-exponential factor was 2.67 L.min.1 in fitting with the Arrhenius equation, which explains the high efficiency of the DBU catalyst. DBU-catalyzed aldol condensation with free solvent offers an alternative route to simplify aldol condensation and separation into a single step.展开更多
The Third Plenary Session of the 18th Central Committee of the Communist Party of China clearly proposed to"establish a spatial planning system,delimit production,living,and ecological space development control b...The Third Plenary Session of the 18th Central Committee of the Communist Party of China clearly proposed to"establish a spatial planning system,delimit production,living,and ecological space development control boundaries,and implement use control;improve energy,water and land conservation and intensive use system",opening the prelude to territorial spatial planning in the new era.Reviewing the history of planning and development and summarizing experience and lessons is not only a necessary way to promote the development of territorial spatial planning in the new period,but also a useful reference for territorial spatial planning and construction in the new period.展开更多
This paper reviews the course of the development of the French garden system,interprets the French gardening techniques and characteristics,and analyzes its features,as well as the classical garden works at that time....This paper reviews the course of the development of the French garden system,interprets the French gardening techniques and characteristics,and analyzes its features,as well as the classical garden works at that time.Through the analysis of the concept of French garden construction,the prospect of Chinese garden construction is finally foreseen.展开更多
文摘The kinetics of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-catalyzed aldol condensation of furfural with acetone was investigated under free solvent conditions from 50℃ - 90℃. The highest yield of 1,4-pentandien-3-on-1,5-di-furanyl catalyzed by DBU reached 98.0% under optimized conditions. According to the kinetic analysis, the reaction order of furfural was estimated as 1.0, the apparent activation energy was 17.7 kJ.mol.1, and the pre-exponential factor was 2.67 L.min.1 in fitting with the Arrhenius equation, which explains the high efficiency of the DBU catalyst. DBU-catalyzed aldol condensation with free solvent offers an alternative route to simplify aldol condensation and separation into a single step.
文摘The Third Plenary Session of the 18th Central Committee of the Communist Party of China clearly proposed to"establish a spatial planning system,delimit production,living,and ecological space development control boundaries,and implement use control;improve energy,water and land conservation and intensive use system",opening the prelude to territorial spatial planning in the new era.Reviewing the history of planning and development and summarizing experience and lessons is not only a necessary way to promote the development of territorial spatial planning in the new period,but also a useful reference for territorial spatial planning and construction in the new period.
文摘This paper reviews the course of the development of the French garden system,interprets the French gardening techniques and characteristics,and analyzes its features,as well as the classical garden works at that time.Through the analysis of the concept of French garden construction,the prospect of Chinese garden construction is finally foreseen.
