Consequences of Proton Transfer in Guanidine

Abstract

Physical chemistry Physical chemistry Z 0225Consequences of Proton Transfer in Guanidine -[185 refs.]. -(RACZYNSKA, E. D.; CYRANSKI, M. K.; GUTOWSKI, M.; RAK, J.; GAL, J.-F.; MARIA, P.-C.; DAROWSKA, M.; DUCZMAL, K.; J. Phys. Org. Chem. 16 (2003) 2, 91-106; Inst. Chem., Agric. Univ., PL-02-776 Wroclaw, Pol.; Eng.) -Lindner 29-269

Gas-phase proton affinities of guanidines with heteroalkyl side chains

“…It is well known that the unusually high basicity of proton sponges is significantly influenced by the formation of intramolecular hydrogen bonds [13]. The tendency of diamines and diols to form IMHBs has been recognized for quite some time [14][15][16][17][18], but only recently, several papers of Raczynska et al [19][20][21][22][23], Koppel and coworkers [24] and theoretical investigations of Maksić and coworkers [25][26][27] have shown that the existence of flexible intramolecular hydrogen bonds plays a significant role in the tailoring of organic superbases. A representative example is provided by a guanidine bearing three 3-(N,N-dimethylamino)propyl groups, for which a gas-phase basicity comparable to those of phosphazenes has been predicted [28].…”

Oxidation and Oxygen Reduction on Polycrystalline Platinum in Aqueous Tetramethylguanidine Alkaline Electrolyte

“…In the presence of equal or excess H 2 O, the imine of TMG is rapidly and exothermically protonated 12,15,16 to form guanidinium (TMGH), yielding a hydroxyl concentration equal to that of the initial TMG. Therefore, we anticipate comparable levels of conductivity between 0.1 M TMG and 0.1 M KOH.…”

Heterocyclic superbases: retrospective and current trends

“…Amidines and, especially, guanidines have been traditionally considered among the strongest neutral organic bases due to considerable resonance stabilization of their cations 41H + and 42H + (Scheme 15) [59,60]. The basicity of amidines may be enhanced by their inclusion within bicyclic systems, which imparts molecular rigidity and eliminates the hygroscopicity so characteristic of ordinary amidines.…”