A simple and ef ficient method is proposed for the synthesis of tetrahydrobenzo[b]pyrans with aromatic aldehydes, active methylene compounds, and dimedone using basic ionic liquid catalyst in water. The procedure offe...A simple and ef ficient method is proposed for the synthesis of tetrahydrobenzo[b]pyrans with aromatic aldehydes, active methylene compounds, and dimedone using basic ionic liquid catalyst in water. The procedure offers several advantages including short reaction time, good yield, easy procedure, and good recyclability of catalysts, which may be a practical alternative to conventional processes for preparation of 4-hpyrans.展开更多
A dabco-based basic ionic liquid,1-butyl-4-aza-1-azaniabicyclo[2.2.2]octane hydroxide,has been developed as a catalyst for a convenient and rapid method for the Michael addition of active methylene compounds to a b-un...A dabco-based basic ionic liquid,1-butyl-4-aza-1-azaniabicyclo[2.2.2]octane hydroxide,has been developed as a catalyst for a convenient and rapid method for the Michael addition of active methylene compounds to a b-unsaturated carboxylic esters and nitriles.The method is very simple,and the yields are very high.The catalyst can be recycled several times without much loss of activity.展开更多
Four recoverable and reusable ionic liquids based on 1,4-diazobicyclo[2.2.2]octane（DABCO） have been synthesized to catalyze the aza-Michael addition of secondary amines to a,b-unsaturated compounds.Among the catalys...Four recoverable and reusable ionic liquids based on 1,4-diazobicyclo[2.2.2]octane（DABCO） have been synthesized to catalyze the aza-Michael addition of secondary amines to a,b-unsaturated compounds.Among the catalysts tested,[DABCO-PDO][OAc] was found to be most suitable for the reaction of a wide range of cyclic substrates without any solvent at room temperature,and afford the products in good to excellent yields within an appropriate amount of time.The proposed mechanism for the dual activation of the catalyst was supported by experimental results as well as the DFT calculation.In addition,the ionic liquids used can be regenerated and recycled several times without any loss of activity.展开更多
Ionic liquids(ILs) are eco-friend and recyclable solvents for dissolution of wool keratin, and water is often used as antisolvent to regenerate keratin from IL solution. To recycle the ILs, removing water is the neces...Ionic liquids(ILs) are eco-friend and recyclable solvents for dissolution of wool keratin, and water is often used as antisolvent to regenerate keratin from IL solution. To recycle the ILs, removing water is the necessary step. However, complete removal of the water is energy-intensive and costly. The water in ionic liquids would change the physicochemical properties and cluster structures of the IL and further affect its dissolution behavior on keratin. Here, 1-ethyl-3-methylimidazolium dimethylphosphate([Emim]DMP) was used for experiments due to its good performance on dissolving keratin. The experimental and simulation results showed that the dissolving capability of [Emim]DMP was decreased and the interactions between cation and anion became weaker with water concentration increasing. Furthermore, the dissolution time of wool keratin in [Emim]DMP increased with water content rising. At the same time, the effect of water in ILs on the secondary structure distribution and thermal stability of regenerated keratin was not obvious. In this work, by taking the structures of [Emim]DMP, keratin dissolution time and properties of the regenerated keratin into consideration, a balanced range of water content in [Emim]DMP was determined, which could not only reduce recycling cost but also not affect the dissolution behavior of the IL.展开更多
基金Supported by the Zhejiang Provincial Natural Science Foundation of China(LY15B060002)the National Natural Science Foundation of China(21106090,21272169,21471110)the National Undergraduate Programs for Innovation and Entrepreneurship(201410350018)
文摘A simple and ef ficient method is proposed for the synthesis of tetrahydrobenzo[b]pyrans with aromatic aldehydes, active methylene compounds, and dimedone using basic ionic liquid catalyst in water. The procedure offers several advantages including short reaction time, good yield, easy procedure, and good recyclability of catalysts, which may be a practical alternative to conventional processes for preparation of 4-hpyrans.
文摘A dabco-based basic ionic liquid,1-butyl-4-aza-1-azaniabicyclo[2.2.2]octane hydroxide,has been developed as a catalyst for a convenient and rapid method for the Michael addition of active methylene compounds to a b-unsaturated carboxylic esters and nitriles.The method is very simple,and the yields are very high.The catalyst can be recycled several times without much loss of activity.
基金the National Natural Science Foundation of China (Nos.21106090 and 21176170)Foundation of Low Carbon Fatty Amine Engineering Research Center of Zhejiang Province (No.2012E10033)Zhejiang Provincial Natural Science Foundation of China (No.LY12B02004)
文摘Four recoverable and reusable ionic liquids based on 1,4-diazobicyclo[2.2.2]octane（DABCO） have been synthesized to catalyze the aza-Michael addition of secondary amines to a,b-unsaturated compounds.Among the catalysts tested,[DABCO-PDO][OAc] was found to be most suitable for the reaction of a wide range of cyclic substrates without any solvent at room temperature,and afford the products in good to excellent yields within an appropriate amount of time.The proposed mechanism for the dual activation of the catalyst was supported by experimental results as well as the DFT calculation.In addition,the ionic liquids used can be regenerated and recycled several times without any loss of activity.
基金supported by the National Natural Science Foundation of China(21576262)the National Natural Science Fund for Distinguished Young Scholars(21425625)+2 种基金International Cooperation and Exchange of the National Natural Science Foundation of China(51561145020)Key Research Program of Frontier Sciences,CAS(QYZDY-SSW-JSC011)“Recruitment of Outstanding Technologist”of Chinese Academy of Sciences
文摘Ionic liquids(ILs) are eco-friend and recyclable solvents for dissolution of wool keratin, and water is often used as antisolvent to regenerate keratin from IL solution. To recycle the ILs, removing water is the necessary step. However, complete removal of the water is energy-intensive and costly. The water in ionic liquids would change the physicochemical properties and cluster structures of the IL and further affect its dissolution behavior on keratin. Here, 1-ethyl-3-methylimidazolium dimethylphosphate([Emim]DMP) was used for experiments due to its good performance on dissolving keratin. The experimental and simulation results showed that the dissolving capability of [Emim]DMP was decreased and the interactions between cation and anion became weaker with water concentration increasing. Furthermore, the dissolution time of wool keratin in [Emim]DMP increased with water content rising. At the same time, the effect of water in ILs on the secondary structure distribution and thermal stability of regenerated keratin was not obvious. In this work, by taking the structures of [Emim]DMP, keratin dissolution time and properties of the regenerated keratin into consideration, a balanced range of water content in [Emim]DMP was determined, which could not only reduce recycling cost but also not affect the dissolution behavior of the IL.
