The Proton Magnetic Resonance and the Tautomerism of Amines and Amides.I-II I. On the Tautomerism of Dicyandiamide and Cyanoformamidine

Functionality of amidines and amidrazones

“…Amidines are strong bases (pKa ranges from [5][6][7][8][9][10][11][12]. The protonation occurs on the imino nitrogen 4,5 leading to symmetrical amidinium ion 3 which is stabilized by resonance as in the isoelectronic carboxylate anion 4. In a strong acidic media, the dication 5 is formed, which has a localized carbon-nitrogen double bond, whereas in a strong alkaline solution the anion 6 can be formed.…”