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| PAPER | Synthesis 2003: 0555-0559
DOI: 10.1055/s-2003-37643 |
© Georg Thieme Verlag Stuttgart · New York
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Organic Reactions in Ionic Liquids:
Knoevenagel Condensation Catalyzed by Ethylenediammonium Diacetate
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Sub, Zhen-Chu
Chen*a,b, Qin-Guo
Zhengc |
a Ningbo Institute of Technology, Zhejiang University, Ningbo, 315104, P.
R. China
b Department of Chemistry, Zhejiang
University (Xi-xi campus), Hangzhou, 310028, P. R.
China
e-Mail: zhenchuc@mail.hz.zj.cn;
c Pharmaceutical Sciences Research Institute, Aston University, Aston Triangle, Birmingham
B4 7ET, UK
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Received
25 October 2002 |
Abstract
The moisture and air stable ionic liquids 1-butyl-3-methylimidazonium
tetrafluoroborate [bmim]BF4 and 1-butyl-3-methylimidazonium
hexafluorophosphate [bmim]PF6 were
used as ‘green' recyclable alternatives to volatile
organic solvents (VOCs) for ethylenediammonium diacetate (EDDA)
catalyzed Knoevenagel condensation between aldehydes or ketones
with active methylene compounds. Both aldehydes and ketones gave
satisfactory results. The ionic liquids containing catalyst EDDA
were recycled several times with no decreases in yields and reaction
rates. In the case of 2-hydroxybenzaldehyde, the reactions led to
the formation of 3-substituted coumarins under standard reaction
conditions. Key words
ionic liquid - condensation - ketones - aldehydes - Knoevenagel reaction - active methylene compounds
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