15519-25-2Relevant articles and documents
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.
Thermodynamic diagnosis of the properties and mechanism of dihydropyridine-type compounds as hydride source in acetonitrile with molecule id card
Zhu, Xiao-Qing,Tan, Yue,Cao, Chao-Tun
scheme or table, p. 2058 - 2075 (2010/07/16)
A series of 45 dihydropyridine-type organic compounds as hydride source were designed and synthesized. The thermodynamic driving forces (defined as enthalpy changes or redox potentials in this work) of the dihydropyridines to release hydride anions, hydrogen atoms (hydrogen for short), and electrons in acetonitrile,the thermodynamic driving forces of the radical cations of the dihydropyridines to release protons and hydrogens in acetonitrile, and the thermodynamic driving forces of the neutral pyridine-type radicals of the dihydropyridines to release electron in acetonitrile were determined by using titration calorimetry and electrochemical methods. The rates and activation parameters of hydride transfer from the dihydropyridines to acridinium perclorate, a well-known hydride acceptor, were determined by using UV-vis absorption spectroscopy technique. The relationship between the thermodynamic driving forces and kinetic rate of the hydride transfer was examined. Thermodynamic characteristic graph (TCG) of the dihydropyridines as an efficient Molecule ID Card was introduced. The TCG can be used to quantitatively diagnose or predict the characteristic chemical properties of the dihydropyridines and their various reaction intermediates. The mechanism of hydride transfer from the dihydropyridines to acridinium perclorate was diagnosed and elucidated by using the determined thermodynamic parameters and the activation parameters..
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.
