16183-87-2Relevant academic research and scientific papers
A classical but new kinetic equation for hydride transfer reactions
Zhu, Xiao-Qing,Deng, Fei-Huang,Yang, Jin-Dong,Li, Xiu-Tao,Chen, Qiang,Lei, Nan-Ping,Meng, Fan-Kun,Zhao, Xiao-Peng,Han, Su-Hui,Hao, Er-Jun,Mu, Yuan-Yuan
, p. 6071 - 6089 (2013/09/12)
A classical but new kinetic equation to estimate activation energies of various hydride transfer reactions was developed according to transition state theory using the Morse-type free energy curves of hydride donors to release a hydride anion and hydride acceptors to capture a hydride anion and by which the activation energies of 187 typical hydride self-exchange reactions and more than thirty thousand hydride cross transfer reactions in acetonitrile were safely estimated in this work. Since the development of the kinetic equation is only on the basis of the related chemical bond changes of the hydride transfer reactants, the kinetic equation should be also suitable for proton transfer reactions, hydrogen atom transfer reactions and all the other chemical reactions involved with breaking and formation of chemical bonds. One of the most important contributions of this work is to have achieved the perfect unity of the kinetic equation and thermodynamic equation for hydride transfer reactions. The Royal Society of Chemistry.
Reactions of charged substrates. 4. The gas-phase dissociation of (4-substituted benzyl) dimethylsulfoniums and -pyridiniums
Buckley, Neil,Maltby, David,Burlingame, Alma L.,Oppenheimer, Norman J.
, p. 2753 - 2762 (2007/10/03)
The relative rates for the gas-phase dissociation RX- → R- + X° of five (4-Y-substituted benzyl)-dimethysulfoniums (Y = MeO, Me, H, Cl, and NO2) and 24 (4-Y-substituted benzyl)-3′-Z-pyridiniums (complete series for Z = CN, Cl, CONH2, and H, and 4-methoxy- and 4-nitrobenzyls for Z = F and CH3CO) were measured using liquid secondary ion mass spectrometry. The Hammett plot (vs δΔG° or σ-) is linear for the sulfoniums, but plots for the four pyridinium series have a drastic break between the 4-Cl and 4-NO2 substrates. Bronsted-like plots for the pyridiniums show a strong leaving group effect only for 4-nitrobenzyls. An analysis of these linear free energy relations with supporting evidence from semiempirical computations suggests that collisionally activated pyridinium substrates dissociate by two pathways, direct dissociation and through an ion-neutral complex intermediate. Comparison of these results with results for the solution reactions of some of these compounds shows that the mechanism is different in the gas and solution phases. Sufficient experimental data are not available to assign a mechanism for dissociation to the sulfonium series, but computational results show characteristics of a direct dissociative mechanism.
Hydride Transfer and Oxyanion Addition Equilibria of NAD+ Analogues
Ostovic, Drazen,Lee, In-Sook Han,Roberts, Roger M. G.,Kreevoy, Maurice M.
, p. 4206 - 4211 (2007/10/02)
Equilibrium constants, K, have been determined for the reduction of 10-methylacridinium ion by 15 N-heterocyclic hydride donors: acridine, quinoline, pyridine, and phenanthridine derivatives.The solvent was a mixture of 2-propanol and water in the ratio 4 : 1 by volume.Reduction potentials have been estimated for the corresponding cations in aqueous solution by assuming that the K's would be the same and accepting -361 mV as the reduction potential of the 3-(aminocarbonyl)-1-benzylpyridinium ion.These reduction potentials span 430 mV.Values of pKR have also been determined for six of the cations in the same solvent.For derivatives of the same ring system, -ΔlogK is approximately equal to ΔpKR, but a 4 log unit discrepancy appears when phenanthridine derivatives are compared with the 9-methylacridinium ion.
Hydride vs. Electron Transfer in the Reduction of Flavin and Flavin Radical by 1,4-Dihydropyridines
Powell, Michael F.,Bruice, Thomas C.
, p. 1014 - 1021 (2007/10/02)
Literature dealing with the existing controversy concerning the mechanism of hydride equivalent (H- or e-, H+, e-) transfer from N-alkyl-1,4-dihydronicotinamides is presented.Included are references to the dihyd
Kinetics of the Reduction of Isoquinolinium Cations by 1,4-Dihydronicotinamides
Bunting, John W.,Chew, Vivian S. F.,Chu, Gary
, p. 2303 - 2307 (2007/10/02)
The kinetics of the reduction of a series of 2-methyl-4-X-isoquinolinium cations and 2-methyl-5-X-phthalazinium cations by 1-benzyl-1,4-dihydronicotinamide (5) have been measured in 20percent CH3CN-80percent H2O (v/v) at pH 7, 25 deg C, and an ionic strength of 1.0.Pseudo-first-order rate constants (kobsd) show kinetic saturation at high concentrations of 4 (X = H and Br), and association constants of 2.1 and 1.5 M-1, respectively, have been evaluated for 1:1 complex formation.Interpretation of these data and earlier data for the reduction of the 2-methyl-5-nitroisoquinolinium cation (3) in terms of nonproductive complex formation leads to a linear free-energy relationship between the second-order rate constant (k2) for reduction and pKR+ for pseudobase formation by these cations: log k2 = -0.50pKR+ + 4.9.Substituent effects upon k2 for the reduction of 3 and 4 (X = CONH2, CN) by 1-benzyl-3-W-1,4-dihydropyridines (W = CN, CONH2, CONHCH3, CON(CH3)2) are similar to the substituent effects for cyanide ion dissociation from the corresponding 1-benzyl-4-cyano-3-W-1,4-dihydropyridines.The current study indicates that the relatively strong 1:1 complexes observed in the reduction of 5-nitroisoquinolinium cations by 1,4-dihydronicotinamides are nonproductive and also provides further evidence in support of a one-step hydride-transfer mechanism for these reactions.
