Ionic-liquid-catalyzed decarboxylation of glycerol carbonate to glycidol
2013
Choi, Ji Sik | Simanjuntaka, Fidelis Stefanus Hubertson | Oh, Ji Young | Lee, Keun Im | Lee, Sang Deuk | Cheong, Minserk | Kim, Hoon Sik | Lee, Hyunjoo
Decarboxylation of glycerol carbonate (GLC) to produce 2,3-epoxy-1-propanol (glycidol) was conducted using various kinds of ionic liquids (ILs) as catalysts. ILs bearing an anion with medium hydrogen-bond basicity such as NO₃ ⁻ and I⁻ exhibited the higher glycidol yields than those having an anion with low or strong hydrogen-bond. FT-IR spectroscopic analysis shows that both GLC and glycidol interact with anions of ILs through their hydroxyl groups. It was possible to improve the yield of glycidol when a zinc salt with a medium Lewis acidity was co-present along with an IL. The yield of glycidol was greatly increased up to 98% when the decarboxylation was conducted in the presence of a high-boiling aprotic solvent. Computational calculations on the mechanism using 1-butyl-3-methylimidazolium nitrate as a catalyst revealed that the first step is the NO₃ ⁻-assisted ring-opening of GLC followed by the ring closure, resulting in the formation of a 3-membered ring intermediate species.
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