The lipase-catalyzed enantioselective transesterification of racemic secondary alcohols was studied using vinyl acetate as acyl donor in two imidazolium-based ionic liquids vs. hexane (Scheme), both in the absence and presence of catalytic amounts of organic bases such as triethylamine (Et(3)N) or pyridine. The organic bases generally enhanced both the rate and enantioselectivity of the reaction. Further, the system 1-butyl-3-methyl-1H-imidazolium hexafluorophosphate/Candida antarctica lipase B ([bmim][PF(6)]/CALB) could be readily recycled four times without significant loss in activity or enantioselectivity.
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http://dx.doi.org/10.1002/cbdv.200790023 | DOI Listing |
Environ Sci Technol
January 2025
Department of Energy, Environmental & Chemical Engineering Washington University in St. Louis, St. Louis, Missouri 63130, United States.
The hydrolysis rates of many organic chemicals are accelerated under alkaline conditions by the presence of hydroxide (HO), which is typically assumed to be the predominant species contributing to base-catalyzed hydrolysis in both natural waters and laboratory buffers used in standard protocols. In this study, we demonstrated that weak bases (e.g.
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January 2025
Department of Life Science and Agriculture, Zhoukou Normal University Zhoukou Henan 466001 China
This study reports a green, multi-component synthesis of 2-aminoimidazole-linked quinoxaline Schiff bases using a novel superparamagnetic acid catalyst. The catalyst consists of sulfo-anthranilic acid (SAA) immobilized on MnCoFeO@alginate magnetic nanorods (MNRs), achieving high SAA loading (1.8 mmol g) and product yields (91-97%).
View Article and Find Full Text PDFFungal Biol
February 2025
School of Agricultural and Biological Engineering, Longdong University, Qingyang, 745000, China; Gansu Key Laboratory of Protection and Utilization for Biological Resources and Ecological Restoration, Longdong University, Qingyang, 745000, China.
The root of Angelica sinensis (Oliv.) Diels (Ang) is a bulk Chinese herbal medicine, and the microecological regulation is a sustainable means to enhance its quality. In this study, Angs at five bases (LZ, XZ, QS, PM, MZC) in Minxian County, Gansu Province were taken as the research objects.
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January 2025
Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK.
Nucleophilic aromatic substitutions (SAr) are amongst the most widely used processes in the pharmaceutical and agrochemical industries, allowing convergent assembly of complex molecules through C-C and C-X (X = O, N, S) bond formation. SAr reactions are typically carried out using forcing conditions, involving polar aprotic solvents, stoichiometric bases and elevated temperatures, which do not allow for control over reaction selectivity. Despite the importance of SAr chemistry, there are only a handful of selective catalytic methods reported that rely on small organic hydrogen-bonding or phase-transfer catalysts.
View Article and Find Full Text PDFMini Rev Med Chem
January 2025
Department of Chemistry, Abdul Wali Khan University, Mardan, 23200, Pakistan.
Organic compounds containing azines, di-imines, or bis-Schiff-bases have two azomethine (-CH=N-) functional groups associated with a bridging component. These constituents have attracted attention from a diversity of disciplines, comprising coordination, medicinal, agriculture chemistry, and organic synthesis, because of their comprehensive chemical reactivity and nature. This study determines common synthetic approaches and various biological and pharmacological activities of several substituted bis-Schiff byproducts.
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