Nucleophilic Aromatic Substitution Reactions on 4, 5-Dicyano-2-fluoro-1-methylimidazole: Syntheses and Properties of 4, 5-Dicyano-1, 3-dimethyl-2-imidazolone and its Pseudooxocarbon Derivatives

Abstract

Nucleophilic aromatic substitution (S_N Ar) reactions of 4, 5-dicyano-2-fluoro-1-methylimidazole using disodium cyanamide or disodium malononitrile followed by methylation using dimethyl sulfate gave the 2-cyanimino and 2-dicyanomethylene pseudooxocarbon derivatives 4 and 6. The oxocarbon analog of 4 and 6, namely 4,5- dicyano-1,3-dimethyl-2-imidazolone (7), was synthesized by dimethylation of 4, 5- dicyano-2-imidazolone which, in turn was synthesized from diaminomaleonitrile (DAMN) and triphosgene. These compounds belong to the class of oxo and pseudooxocarbon compounds. Thermogravimetric analysis of 6 shows a 30 wt.% loss which might suggest the loss of the dicyanomethylene group. The fluorescence spectra of these compounds show strong emissions in the order, 6 (475 nm) < 4 (400 nm) < 7 (345 nm). Cyclic voltammetry of these compounds in CH₃CN shows irreversible cyclic voltammograms around −2.0 volts vs. Ag/Ag⁺. Compound 6 forms long crystals of weak, red-colored charge transfer complexes with tetrathiafulvalene.