Proton accepting

The strongly electronegative (p. 49) chlorine atom becomes a chloride ion, the proton accepting the electron pair donated by the nitrogen atom. A similar reaction occurs when ammonia is passed into water, but to a much lesser extent as oxygen in water is a poorer donor of the electron pair ... 

The proton-donating strength of an acid is measured by its acidity constant the proton-accepting strength of a base is measured by its basicity constant. The smaller the constants, the weaker the respective strengths. The larger the value of pK, the weaker the acid or base. 

Inclusion Compounds Involving Readily Protonizable (Proton Accepting) Guest Molecules Salt-type Associates and Ternary Complexes of 7 and Imidazole Clathrate of 13... 

Prototropic interconversions have been the subject of much detailed study, as they lend themselves particularly well to investigation by deuterium labelling, both in solvent and substrate, and by charting the stereochemical fate of optically active substrates having a chiral centre at the site of proton departure. Possible limiting mechanisms (cf. SNl/SN2) are those (a) in which proton removal and proton acceptance (from the solvent) are separate operations, and a carbanion intermediate is involved, i.e. an intermolecular pathway and (b) in which one and the same proton is transferred intramolecularly ... 

Amino groups may act not only as proton acceptor, but also as proton donor. Acidic N—H protons interact with basic solvents. In these cases an ortho-nitro group in an aniline system competes with the solvent by an internal hydrogen bond66, as depicted in 12. The stretching frequencies (by IR spectra in carbon tetrachloride) of vnh of complexes between A-methylaniline or diphenylamine (and some nitro-anilines66) and solvents depend on the proton accepting ability of the solvent (which is a moderate base)67. The frequency shifts are linearly related to the solvent s donor number (DN)3. 

Throughout this review, A represents acid sites, and B represents proton-accepting sites. 

Since the molecule is stable as BHa++Cl2—, a third proton is required for hydrolysis, once the two potential sites for proton acceptance have been protonated. Addition of this proton is formulated in terms of structures (LXVIIIa—c). 

AVg(basicity) = relative shift in the OD band maximum in the IR spectra of CH3OD in benzene and the proton accepting solvent used as solute in reverse osmosis, cm l... 

Simultaneous ring-chain and keto-enol tautomeric equilibria were observed (90ZOR2489) in solutions of 5-hydroxy-5-phenylpentane-2,4-dione 29. Increase of the solvent polarity and proton-accepting ability in the series... 

CCI4 < CDCI3 < (003)200 < (003)280 stabilizes the diketo tautomer 29A and mostly the cyclic tautomer 29B this is caused by the ability of proton-accepting solvents to destroy the intramolecular hydrogen bond stabilizing the chelate 29A. ... 

H-NMR and C-NMR spectroscopy demonstrated a three-component equilibrium (83G91) in ( 03)280 solutions of the diastereomeric monooximes of 5-methyl-2-phenacylcyclohexanone 54 and 55. The same methods revealed the ring-chain equilibrium 56A 56B (X = H2, R = Ph) in solutions of 5-hydroxy-5-methyl-2-phenylisoxazolidines (89KGS823). An increase in the solvent proton-accepting ability shifted the equilibrium in favor of the open-chain tautomer 56A in CCI4, Kj = 1.0 and in ( 03)280,... 

A thermodynamic measure of the proton-donating or proton-accepting ability of a solvent system (or closely related thermodynamic property such as the ability of a solvent system to form Lewis adducts) ". ... 

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