Raman spectroscopic study of base catalyzed di- and trimerization of malononitrile in ionic liquids and water

Multivariate Curve Resolution (MCR) and Two-Dimensional Correlation Spectroscopy (2DCoS) have been employed to analyze the Raman spectra recorded from the reaction of malononitrile with KOH carried out in the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate and water. In both cases the carbanion, which is formed by deprotonation of malononitrile, could be detected spectroscopically. When using the ionic liquid as solvent formation of the dimer was observed, whereas in aqueous solution a trimer was formed by a subsequent Michael addition. Based on the component spectra and concentration profiles obtained from MCR analysis the reaction intermediates as well as products could be identified. 2DCoS was very helpful in corroborating these results.