56875-26-4Relevant articles and documents
Importance of proton-coupled electron transfer in cathodic regeneration of organic hydrides
Ilic, Stefan,Alherz, Abdulaziz,Musgrave, Charles B.,Glusac, Ksenija D.
, p. 5583 - 5586 (2019)
Electrochemical regeneration of organic hydrides is often hindered by the rapid dimerization of organic radicals produced as the first intermediates of these electrochemical transformations. In this work, we utilize proton-coupled electron transfer to outcompete the undesired dimerization and achieve successful hydride regenerations of two groups of organic hydrides-acridines and benzimidazoles. This work provides an analysis of the critical factors that control the regeneration pathways of organic hydrides.
Hydride Transfer from Iron(II) Hydride Compounds to NAD(P)+ Analogues
Zhang, Fanjun,Jia, Jiong,Dong, Shuli,Wang, Wenguang,Tung, Chen-Ho
, p. 1151 - 1159 (2016/06/01)
Iron(II) hydride complexes of the "piano-stool" type, Cp?(P-P)FeH (P-P = dppe (1H), dppbz (2H), dppm (3H), dcpe (4H)) were examined as hydride donors in the reduction of N-benzylpyridinium and acridinium salts. Two pathways of hydride transfer, "single-step H-" transfer to pyridinium and a "two-step (e-/H?)" transfer for acridinium reduction, were observed. When 1-benzylnicotinamide cation (BNA+) was used as an H- acceptor, kinetic studies suggested that BNA+ was reduced at the C6 position, affording 1,6-BNAH, which can be converted to the more thermally stable 1,4-product. The rate constant k of H- transfer was very sensitive to the bite angle of P-Fe-P in Cp?(P-P)FeH and ranged from 3.23 × 10-3 M-1 s-1 for dppe to 1.74 × 10-1 M-1 s-1 for dppm. The results obtained from reduction of a range of N-benzylpyridinium derivatives suggest that H- transfer is more likely to be charge controlled. In the reduction of 10-methylacridinium ion (Acr+), the reaction was initiated by an e- transfer (ET) process and then followed by rapid disproportionation reactions to produce Acr2 dimer and release of H2. To achieve H? transfer after ET from [Cp?(P-P)FeH]+ to acridine radicals, the bulkier acridinium salt 9-phenyl-10-methylacridinium (PhAcr+) was selected as an acceptor. More evidence for this "two-step (e-/H?)" process was derived from the characterization of PhAcr? and [4H]+ radicals by EPR spectra and by the crystallographic structure confirmation of [4H]+. Our mechanistic understanding of fundamental H- transfer from iron(II) hydrides to NAD+ analogues provides insight into establishing attractive bio-organometallic transformation cycles driven by iron catalysis.
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.
