Effects of the anion salt nature on the rate constants of the aqueous proton exchange reactions

2012 ◽  
Vol 14 (16) ◽  
pp. 5795 ◽  
Author(s):  
Jose M. Paredes ◽  
Andres Garzon ◽  
Luis Crovetto ◽  
Angel Orte ◽  
Sergio G. Lopez ◽  
...  
Keyword(s):  
Rate Constants ◽  
Proton Exchange ◽  
Exchange Reactions

A STUDY OF PROTON EXCHANGE REACTIONS OF SUBSTITUTED ANILINES IN TRIFLUOROACETIC ACID

1964 ◽  
Vol 42 (12) ◽  
pp. 2641-2656 ◽  
Author(s):  
W. F. Reynolds ◽  
T. Schaefer
Keyword(s):  
Trifluoroacetic Acid ◽  
Rate Constants ◽  
Ion Pair ◽  
Proton Exchange ◽  
Free Energies ◽  
Exchange Reactions ◽  
Kcal Mole ◽  
Substituted Anilines ◽  
Ionic Reaction ◽  
Acid Proton

The acid proton exchange rates of solutions of some halo-substituted anilines in trifluoroacetic acid have been determined by measuring the acid proton signal width. In addition, the proton exchange rate of protonated N,N-dimethylaniline in trifluoroacetic acid is discussed. It is suggested that proton exchange occurs via the following reaction:[Formula: see text]The reaction is believed to occur in two steps: the oppositely charged ions form ion pairs which then transfer protons internally. Experimental evidence indicates that the ion–pair dissociation constant is less than, or equal to, one.The activation energies range from 10 to 24 kcal/mole. The rate constants at 25 °C for a possible bi-ionic reaction are calculated. Ionic activity coefficients are estimated by the Debye–Hückel equation. Another set of rate constants is calculated, assuming that the ions exist partly or completely as ion pairs.The free energies, enthalpies, and entropies of activation are calculated for an ion-pair reaction and for an overall bi-ionic reaction. The free energies of activation range from 10 to 17 kcal/mole and for haloanilines are less than that of aniline. In the ortho- and para-substituted anilines, ΔF≠, in general, decreases with decreasing halogen electronegativity. ΔF≠ values for metasubstituted anilines decrease with increasing substituent electronegativity. ΔF≠ values are largest for parahaloanilines and smallest for orthohaloanilines. The ΔF≠ values for haloanilines can be rationalized by reasonable combinations of inductive and mesomeric effects. The values of entropies of activation are determined largely by the positions of the substituents. ΔS≠ values range from 35 to −10 entropy units (e.u.) with aniline and para-substituted anilines having the largest positive values and orthosubstituted anilines having negative values. The value of ΔF≠ for protonated N,N-dimethylaniline is larger than that for protonated aniline, as would be expected. ΔS≠ is quite small. This is attributed to steric hindrance of solvation of the dimethylanilinium ion.

Proton exchange reactions of C2–C4 alkanes sorbed in ZSM-5 zeolite

2012 ◽  
Vol 131 (6) ◽  
Author(s):  
Kanjarat Sukrat ◽  
Daniel Tunega ◽  
Adelia J. A. Aquino ◽  
Hans Lischka ◽  
Vudhichai Parasuk
Keyword(s):  
Proton Exchange ◽  
Exchange Reactions

Hydrocarbon-Carbanion Proton Exchange Reactions in Dimethyl Sulfoxide

1967 ◽  
Vol 89 (7) ◽  
pp. 1728-1730 ◽  
Author(s):  
John I. Brauman ◽  
Donald F. McMillen ◽  
Yoko. Kanazawa
Keyword(s):  
Dimethyl Sulfoxide ◽  
Proton Exchange ◽  
Exchange Reactions

scholarly journals Hydrogen production and deuterium-proton exchange reactions catalyzed by Desulfovibrio nickel(II)-substituted rubredoxins

1988 ◽  
Vol 85 (24) ◽  
pp. 9378-9380 ◽  
Author(s):  
P. Saint-Martin ◽  
P. A. Lespinat ◽  
G. Fauque ◽  
Y. Berlier ◽  
J. LeGall ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Proton Exchange ◽  
Exchange Reactions

Mass Spectra and Ion Chemistry of Methylphosphine, Dimethylphosphine and Dimethyldeuterophosphine, Investigated by Ion Cyclotron Resonance Spectrometry

1975 ◽  
Vol 30 (3) ◽  
pp. 329-339 ◽  
Author(s):  
Karl-Peter Wanczek
Keyword(s):  
Rate Constants ◽  
Cyclotron Resonance ◽  
Mass Spectra ◽  
Ion Cyclotron Resonance ◽  
Exchange Reactions ◽  
Ion Chemistry ◽  
Ion Molecule Reactions ◽  
Ion Cyclotron ◽  
Product Ions ◽  
Ion Cyclotron Resonance Spectrometry

The mass spectra and the ion molecule reactions of methylphosphine, dimethylphosphine and dimethyldeuterophosphine have been studied by ion cyclotron resonance spectrometry. About 50 ion molecule reaction are observed for each compound. The product ions can be classified as ions with two phosphorus atoms: P2R5+, P2R3+, P2R2+ and P2R+ (R = CH3 or H), as phosphonium and phosphinium ions and ions resulting from collision dissociations and charge exchange reactions. Tertiary ions with three phosphorus atoms like CH3P3H2+ (from CH3PH2) and (CH3)4P3H2 (from (CH3)2PH) have also been detected. The mechanisms of the ion molecule reactions, rearrangements, P -H- and C-H-reactivities and product ion structures are discussed, using in the case of dimethylphosphine the results obtained with the deuterated compound. Rate constants of formation of the more abundant product ions from the molecular ion and the CH3P+ ion, both odd electron particles, have been determined. The reactions with dimethylphosphine have much smaller rate constants than the reactions with methylphosphine.

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