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Esterification of tert-butanol by acetic anhydride, a typical acid–base catalytic reaction, was conducted with excellent selectivity and high yield in a neutral ionic liquid [BMIm]BF4 (1-butyl-3-methylimidazolium tetrafluoroborate). Many other tertiary alcohols could also be successfully converted to the corresponding esters in [BMIm]BF4. Separation of product and recovery and reuse of ionic liquid are all convenient in this system. Here, the need for catalysts is avoided through the use of catalytically active ionic liquids as solvents.

Keywords: [BMIm]BF4; Esterification; Tertiary alcohol; Acetic anhydride

★★★☆☆ Duan ZY,Gu YL,Deng YQ. Neutral Ionic Liquid [bmim]bf4 Promoted Highly Selective Esterification Of Tertiary Alcohols By Acetic Anhydride[J]. Journal Of Molecular Catalysis A: Chemical,2006,246:70-75.

Three new protic ionic liquids based on 2-methylpyridinium were prepared and characterized. Their catalytic activities for the tert-butylation of phenol and the esterification of cyclic olefins with acetic acid were examined and satisfactory results were obtained over 2-methylpyridinium trifluoromethanesulfonate ([2-MPyH]OTf). Hammett method was used to determine the acidity order of these ionic liquids and the results are consistent with the catalytic activities observed in the acid-catalyzed probe reactions.

Keywords: Protic ionic liquids; 2-Methylpyridinium; Hammett acidity; Brønsted acidity; Acid catalysis

★★★☆☆ Duan ZY,Gu YL,Zhang J,et al. Protic Pyridinium Ionic Liquids: Synthesis, Acidity Determination And Their Performances For Acid Catalysis[J]. Journal Of Molecular Catalysis A: Chemical,2006,250:163-168.

Choline chloride·xZnCl2 (x = 1–3) or benzyltrimethylammonium chloride·xZnCl2 have been used as efficient and recyclable catalysts for protection of carbonyls to 1,3-dioxolanes and 1,3-dioxanes at room temperature under solvent-free conditions. FT-IR investigation demonstrates the four ionic liquids have similar Lewis acid strength, which is in agreement with the activities observed in the acetalization reaction. The catalytic system choline chloride·xZnCl2 can be reused up to five times without appreciable loss of activity. The simple procedures as well as easy recovery and reuse of this novel catalytic system are expected to contribute to the development of more benign acetalization procedure of carbonyl compounds.

关键词: Choline chloride·xZnCl2;  Acetalization;  Solvent-free;  Reusability;  Lewis acidity;  Green chemistry

★★★☆☆ Duan ZY,Gu YL,Deng YQ. Green And Moisture-stable Lewis Acidic Ionic Liquids (choline Chloride  xZnCl2) Catalyzed Protection Of Carbonyls At Room Temperature Under Solvent-free Conditions[J]. Catalysis Communications,2006,7:651-656.