Product Class 7: Imines

Abstract

Compounds with the general structure R 1 R 2 C=NR 3 , referred to as imines, were first obtained by Schiff via condensation of ketones and aldehydes with primary amines. Therefore, the condensation products are also called Schiff bases. In addition, the nominations azomethine, ketimine (derived from ketones), aldimine (derived from aldehydes), and anil (derived from anilines) are in use. It is recommended that the terms imine(s), ketimine(s), or aldimine(s) are used, rather than Schiff base(s) or azomethine(s).Since imines have to be considered as analogues of carbonyl compounds, many of the chemical properties are similar to the latter. Imines are used in new C-C bond formations, and reactions with electrophiles (e.g., aldehydes, alkyl halides), and the C=N moiety can undergo nucleophilic reactions. Generally, imines are very useful compounds in organic synthesis, as they are used in several syntheses of aza-heterocyclic compounds. Most imines are stable in an alkaline medium and therefore can be dried over potassium hydroxide. In diluted acid, however, they are easily hydrolyzed. In many cases intermediary imines cannot be isolated because of their lability. The presence of a C=N bond creates the possibility for E/Z isomerism (syn/anti). It has been recognized that such geomet-