Figures index : From Current Science to School – the Facets of Green Chemistry on the Example of Ionic Liquids : Science and Education Publishing

Figures index

World Journal of Chemical Education. 2019, 7(2), 153-165 doi:10.12691/wjce-7-2-15

Figure 1. Molecular structures of some important cations and anions used for the formation of ionic liquids and notable characteristics in the context of green and sustainable chemistry

Figure 2. Scheme of the Ruhrchemie/ Rhône-Poulenc oxo process. a) reaction scheme and structure of the rhodium catalyst. b) Formation of biphasic liquid mixture that is split in a separator to obtain the organic product phase. The catalyst remains dissolved in water and is recycled by the aqueous phas

Figure 3. Scheme of the BASIL™ process. The chlorophenylphosphine reacts with the alcohol in a jet stream reactor to the alkoxyphenylphosphine. The hydrogen chloride generated in the reaction is scavenged with 1-methylimidazole forming the IL 1-methylimidazolium chloride, that is in liquid state under the applied reaction conditions. Due to the different polarity and density, a liquid biphasic system is formed that can be easily worked up. The upper phase contains thereby the solvent-free product while the ionic liquid is localized in the lower phase. The initial 1-methylimidazole is regenerated by neutralization with sodium hydroxide for reuse in further production cycles

Figure 4. Scheme of the Brønsted acid catalyzed esterification of carboxylic acid and alcohol

Figure 5. Molecular structure of the ionic liquid 1-butyl-3-methylimidazolium hydrogen sulfate used as catalyst for the esterification

Figure 6. Reaction course of the esterification reaction with the Brønsted acidic ionic liquid [BMIM][HSO₄] as catalyst. At the beginning of the reaction, the polar educts form a homogenous mixture with the IL. After several minutes in the water bath, a second phase of the nonpolar reaction product is formed. The separation is facilitated since the density of the product is much lower compared to the density of the IL phase

Figure 7. Molecular structures of the esters synthesized with the Brønsted acidic ionic liquid [BMIM][HSO₄], their characteristic scents and the yields obtained after 30 minutes at 80°C