Nucleophilic displacement vs. proton transfer: the system hydrated hydroxide ion + chloromethane [OH-.cntdot.(H2O)0,1,2 + CH3Cl] in the relative energy range 0.03-5 eV

1985 ◽  
Vol 107 (9) ◽  
pp. 2812-2814 ◽  
Author(s):  
Michael Henchman ◽  
Peter M. Hierl ◽  
John F. Paulson
Keyword(s):  
Proton Transfer ◽  
Energy Range ◽  
Relative Energy ◽  
Hydroxide Ion ◽  
Nucleophilic Displacement

Proton transfer from imidazole, benzimidazole, and their 1-alkyl derivatives. FMO analysis of the effect of methyl and benzo substitution

1986 ◽  
Vol 64 (6) ◽  
pp. 1240-1245 ◽  
Author(s):  
Erwin Buncel ◽  
Helen A. Joly ◽  
John R. Jones
Keyword(s):  
Proton Transfer ◽  
Reaction Scheme ◽  
Frontier Molecular Orbital ◽  
Neutral Species ◽  
Ph Profile ◽  
Hydroxide Ion ◽  
Methyl Substitution ◽  
Rate Determining Step ◽  
Alkyl Derivatives ◽  
Conjugate Acid

The rate–pH profile for detritiation from the C-2 position of 1-methylimidazole has been determined in aqueous solution at 85 °C. The profile is consistent with a mechanism involving attack by hydroxide ion on the conjugate acid of the substrate to give an ylid intermediate in the rate-determining step. At higher pH, hydroxide-catalyzed exchange of the neutral species becomes increasingly important. Comparison of the second-order rate constants derived from the rate–pH profiles of imidazole, 1-methylimidazole, benzimidazole, and 1-methylbenzimidazole showed that methyl substitution caused the rate to increase by 2-to 3-fold while benzo annelation increased the rate by 10- to 20-fold. Frontier molecular orbital (FMO) analysis of the reaction scheme for proton transfer from imidazole, benzimidazole, and their 1-alkyl derivatives has been used to explain the rate-accelerating effect of methyl substitution and benzo annelation in these processes.

scholarly journals Hydroxide Ion Carrier for Proton Pumps in Bacteriorhodopsin: Primary Proton Transfer

2020 ◽  
Vol 124 (39) ◽  
pp. 8524-8539
Author(s):  
Junichi Ono ◽  
Minori Imai ◽  
Yoshifumi Nishimura ◽  
Hiromi Nakai
Keyword(s):  
Proton Transfer ◽  
Primary Proton ◽  
Proton Pumps ◽  
Hydroxide Ion ◽  
Ion Carrier
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