Diprotonated proton sponges

Such compounds are very basic (p/T[, = 1.9 cf. NHj, p T, = 4.74 l-dimethyl-aminonapthalene, p/w, = 4.57). and have been nicknamed proton sponges from their avidity for hydrogen ions." - The strong, symmetric N—H—N hydrogen bond (see Chapter 8) stabilizes the conjugate acid. Note, however, that a second proton cannot be added without incurring the original steric problem Diprotonation is only half complete in 86% sulfuric acid ... 

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