Newly designed pyridine and piperidine based Ionic Liquids: Aggregation behavior in ESI-MS and catalytic activity in C[sbnd]C bond formation reactions

Abstract

Material preparation using Ionic Liquids (ILs) as a catalyst was frequently related to the supramolecular aggregation behavior. Hence, understanding the aggregation behavior of ILs is very significant from basic and applied aspects. The present work suggested an efficient and green protocol for the synthesis of pyridine and piperidine based ILs with different phenoxide as anions. Furthermore, the supramolecular polymeric aggregation due to non-covalent interactions between cations and anions of these ILs were investigated through Electrospray Ionization Mass Spectrometry (ESI-MS). Moreover, assessment of the suitability of these ILs as catalyst has been done in the presence of potassium carbonate for base-catalysed carboncarbon bond formation reactions i.e. case of Knoevenagel and Claisen–Schmidt Condensation. The obtained products were characterized by spectroscopic methods such as 1H NMR, 13C NMR, ESI-MS and UV. The results revealed that the desire products were obtained in excellent yield (up to 98%). Selective ILs which contain electron with drawing group in anions such as m-nitro phenoxide ion, exhibited remarkable catalytic activity in Condensation reaction. In addition to this, ESI-MS of ILs showed that peak distributions prominently exhibited for each aggregate, a decrease in ion abundance occurred.