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- Title
Delineating the Mechanism of Ionic Liquids in the Synthesis of Quinazoline-2,4(1 H,3 H)-dione from 2-Aminobenzonitrile and CO<sub>2</sub>.
- Authors
Hulla, Martin; Chamam, Sami M. A.; Laurenczy, Gabor; Das, Shoubhik; Dyson, Paul J.
- Abstract
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 p Ka of the IL anion (conjugate acid) and the reaction rate was identified with maximum catalyst efficiency observed at a p Ka 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 quinazolide anion (conjugate acid p Ka 14.7). Neutralization of the original catalyst and formation of the quinazolide anion catalyst leads to the observed reaction limit.
- Subjects
IONIC liquids; QUINAZOLINE; BENZONITRILE; CARBON dioxide; CHEMICAL synthesis
- Publication
Angewandte Chemie, 2017, Vol 129, Issue 35, p10695
- ISSN
0044-8249
- Publication type
Article
- DOI
10.1002/ange.201705438