AMINOMETHYLATION REACTIONS IN THE PRESENCE OF IONIC LIQUIDS

The presented work summarizes and systematizes the results of scientific research in the field of using ionic liquids in aminomethylation reactions leading to the synthesis of Mannich bases. It has been shown that ionic liquids are liquids with relatively low melting points and high viscosities and thermal stability. In recent years, they have become a real "green" alternative to molecular liquids, which are traditionally used as solvents in fine organic synthesis. Due to their advantages, ionic liquids have found a very wide application as environmentally friendly catalytic systems in various organic reactions. However, the high cost of ionic liquids is currently the only obstacle to their widespread use in catalysis. This review presents the main types of ionic liquids used in the aminomethylation reaction, and considers their influence on the course of chemical reactions, as well as on the yield and enantioselectivity of the resulting adducts. In addition, the results of the author's own research are shown. The reaction of animnomethylation in the presence of two ionic liquids (N-methylpyrrolidonium hydrogen sulfate and 1,4-dimethylpiperazine dihydrosulfate) with the participation of norbor-nenylmethanol, formaldehyde, and secondary amines, leading to the synthesis of norbornene-containing Mannich bases, is considered. The effect of the nature of the ionic liquid on the yield of synthesized aminomethoxy derivatives of norbornene was shown. It is noted that N-methylpyrrolidonium hydrogen sulfate exhibits relatively higher catalytic activity in this reaction as compared to 1,4-dimethylpiperazine dihydrosulfate. In addition, the author has shown that the ionic liquids used in this work are superior in their catalytic activity to the previously used metal salts in the aminomethylation reaction with the participation of norbornenylmethanol, formaldehyde, and secondary amines