4,4 ,5,5 -Tetracyano-2,2 -biimidazole

The polymer is soluble in polar aprotic solvents such as N-methyl pyrrolidinone and in aqueous base. The solubility in base is due to deprotonation of the acidic hydrogen at the 1-position of the imidazole ring. In imidazoles, the pKa of the 1-nitrogen is approximately 14, but in cyanoimidazoles the pKa of this position ranges from 2 (in 4,4, 5,5 -tetracyano-2,2 -biimidazole) to approximately 9-10 in monocyano substituted imidazoles [5]. The acidity of this position provides a handle for solution processing or for chemical modification of the polymer. 

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