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Title
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Delineating the mechanism of ionic liquids in the synthesis of quinazoline-2,4(1H,3H)-dione from 2-aminobenzonitrile and
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Author
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Abstract
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| Ionic liquids (ILs) are versatile solvents and catalysts for the synthesis of quinazoline-2,4-dione from 2-aminobenzonitrile and CO2. However, the role of the IL in this reaction is poorly understood. Consequently, we investigated this reaction and showed that the IL cation does not play a significant role in the activation of the substrates, and instead plays a secondary role in controlling the physical properties of the IL. A linear relationship between the pK(a) of the IL anion (conjugate acid) and the reaction rate was identified Tvith maximum catalyst efficiency observed at a pK(a) of > 14.7 in DMSO. The base-catalyzed reaction is limited by the acidity of the quinazoline-2,4-dione product, which is deprotonated by more basic catalysts:, leading to the formation of the quinazotide anion (conjugate acid pK(a) 14.7). Neutralization of the original catalyst and formation of the quinazolide anion catalyst leads to the observed reaction limit. |
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Language
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English
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Source (journal)
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Angewandte Chemie: international edition in English. - Weinheim
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Publication
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Weinheim
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2017
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ISSN
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1433-7851
0570-0833
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DOI
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10.1002/ANIE.201705438
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Volume/pages
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56
:35
(2017)
, p. 10559-10563
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ISI
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000434546000051
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Full text (Publisher's DOI)
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