100-22-1Relevant articles and documents
Mobilities of Radical Cations and Anions, Dimer Radical Anions, and Relative Electron Affinities by Times of Flight in n-Hexane
Lim, S. K.,Burba, M. E.,Albrecht, A. C.
, p. 9665 - 9675 (1994)
The mobilities of several radical cations and anions are measured in n-hexane using a thin-sheet time-of-flight (TOF) technique.We observe the radical cations of N,N,N',N'-tetramethyl-p-phenylenediamine, zinc tetraphenylporphine, and pyrene and the radical anions of perfluorobenzene, p-benzoquinone, anthraquinone, chloranil, buckminsterfullerene (C60), and octafluoronaphthalene.For all electron acceptors but C60, the dependence of the anionic TOF on acceptor concentration reveals the appearance of the homodimer radical anion at sufficiently high concentrations.The equilibrium constant for the monomer anion/monomer acceptor association reaction is obtained from the concentration studies.A Born-Haber cycle is then applied to estimate the difference between the electron affinities of the monomer and dimer molecules in the gas phase.
A new route to polykis(dialkylamino)benzenes and -naphthalenes based on protodefluorination of electron-rich fluoroaromatics: Anion radicals of arenes as a simple and effective alternative to 'classical' LAH-based systems
Sorokin, Vladimir Igorevich,Ozeryanskii, Valery Anatolievich,Borodkin, Gennady Sergeevich
, p. 97 - 102 (2006)
A simple and effective procedure for protodefluorination of electron-rich fluoroaromatic compounds has been developed. It operates with aromatic anion radicals as reducing agents and shows superior results over 'classical' lithium aluminum hydride based s
Cauquis,Serve
, p. 2222 (1972)
Continuum of outer- and inner-sphere mechanisms for organic electron transfer. Steric modulation of the precursor complex in paramagnetic (ion-radical) self-exchanges
Rosokha, Sergiy V.,Kochi, Jay K.
, p. 3683 - 3697 (2007)
Transient 1:1 precursor complexes for intermolecular self-exchange between various organic electron donors (D) and their paramagnetic cation radicals (D+.), as well as between different electron acceptors (A) paired with their anion radicals (A .), are spectrally (UV-NIR) observed and structurally (X-ray) identified as the cofacial (π-stacked) associates [D, D+.] and [A-.· A], respectively. Mulliken-Hush (two-state) analysis of their diagnostic intervalence bands affords the electronic coupling elements (HOA), which together with the Marcus reorganization energies (λ) from the NIR spectral data are confirmed by molecular-orbital computations. The HDA values are found to be a sensitive function of the bulky substituents surrounding the redox centers. As a result, the steric modulation of the donor/acceptor separation (rDA) leads to distinctive electron-transfer rates between sterically hindered donors/acceptors and their more open (unsubstituted) parents. The latter is discussed in the context of a continuous series of outer- and inner-sphere mechanisms for organic electron-transfer processes in a manner originally formulated by Taube and co-workers for inorganic (coordination) donor/acceptor dyads-with conciliatory attention paid to traditional organic versus inorganic concepts.
Pott,Kommandeur
, p. 373,383 (1967)
A general method for N-methylation of amines and nitro compounds with dimethylsulfoxide
Jiang, Xue,Wang, Chao,Wei, Yawen,Xue, Dong,Liu, Zhaotie,Xiao, Jianliang
, p. 58 - 63 (2014)
DMSO methylates a broad range of amines in the presence of formic acid, providing a novel, green and practical method for amine methylation. The protocol also allows the one-pot transformation of aromatic nitro compounds into dimethylated amines in the presence of a simple iron catalyst. Not just a solvent: DMSO methylates a broad range of amines in the presence of formic acid, providing a novel, green and practical method for amine methylation. The protocol also allows the one-pot transformation of aromatic nitro compounds into dimethylated amines in the presence of a simple iron catalyst. Copyright
Two-electron oxidation of N,N,N′,N′-tetramethylphenylenediamine with a chromium(v) salen complex
Chaka, Gezahegn,Bakac, Andreja
, p. 318 - 321 (2009)
The oxidation of tetramethylphenylenediamine (TMPD) with (salen)Cr VO+ generates initially the 2-electron product TMPD 2+, followed by the reaction with excess TMPD to yield the radical cation, TMPD+. The kineti
Reactions of Oxidizing Radicals with 4,6-Dihydroxypyrimidines as Model Compounds for Uracil, Thymine, and Cystosine
Novais, H. M.,Steenken, S.
, p. 426 - 433 (1987)
The reactions of the oxidizing radicals OH, O-, SO4-, and Br2- with 4,6-dihydroxypyrimidine (4,6-DHP) and with 2- and 5-methyl-4,6-DHP were investigated by using in situ radiolysis and photolysis ESR and pulse radiolysis techniques.In the pH range 1-6 the OH radical reacts with these compounds -1 s-1> selectively by addition at C-5 to produce radicals characterized by two pairs of magnetically equivalent nitrogens and exchangeable protons.On the basis of the coupling constants and from the increased pKa value (8.3) of the radical from 4,6-DHP relative to that (5.3) of the parent compound, a diketo-type structure is suggested for the OH adducts.At pH 8-12 a base-catalyzed dehydration of the radical anions takes place which leads to the formation of species formally derived from the ionized parent compound by one-electron oxidation followed by deprotonation.These radicals can also be produced by reaction with SO4- or Br2-.Those from 4,6-DHP and from 2-Me-4,6-DHP were seen in two different protonation states: as a neutral radical between pH 3 and 5, and as the radical anion above pH ca. 5.Methyl groups on the 4,6-DHP molecule increase the rate of dehydration of the OH adducts.The O- radical reacts with the methylated 4,6-DHP's by H abstraction from the methyl groups.The structures of all the radicals from the 4,6-DHP's are compared with those from naturally occuring dioxopyrimidines such as the uracils.
Spectral, kinetics, and redox studies on the transients formed on pulse radiolysis of aqueous solution of (4-methylthiophenyl)methanol
Mohan,Mittal
, p. 1649 - 1659 (2001)
Pulse radiolysis technique has been employed to investigate the nature and the redox properties of the transient species generated on radiolysis of aqueous solution of (4-methylthiophenyl)methanol (MTPM). Pulse radiolysis in 1,2-dichloroethane, reaction with specific one-electron oxidants (Cl2-, SO4-, Tl2+, Br) and reaction of OH radicals in acidic solution showed absorption bands at 320 and 545 nm; these are assigned to solute radical cation with positive charge on the benzene ring. OH-adduct was observed in neutral solution. The oxidation potential for MTPM/MTPM+ couple is determined to be 1.55 ± 0.04 V vs NHE. eaq- reacts with a bimolecular rate constant of 1.5 × 109 dm3 mol-1 s-1 and the transient absorption bands (λax = 320, 470 nm) are assigned to the solute radical anion. E0 value for MTPM/MTPM- couple is determined to be -1.84 ± 0.04 V vs NHE. The redox properties of the transient species formed on reaction with OH, H, and O- have been evaluated.
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Uneyama et al.
, p. 1928,1930, 1936 (1968)
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Metallopolymer Photochemistry. Photophysical, Photochemical, and Photoelectrochemical Properties of (bpy)2RuII< Sites Bound to Poly(4-vinylpyridine)
Calvert, Jeffrey M.,Caspar, Jonathan V.,Binstead, Robert A.,Westmoreland, T. David,Meyer, Thomas J.
, p. 6620 - 6627 (1982)
The photochemical and photophysical properties of the polymer-bound chromophore Ru(bpy)2(PVP)22+ (PVP is poly(4-vinylpyridine)) have been investigated in homogeneous solution.Results have been obtained with polymers both dilute and concentrated in chromophore.Lifetime and quantum yield data are interpreted in terms of models of excited-state behavior previously proposed for analogous mopnomeric poly(pyridyl) complexes of Ru(II).Excited-state sites within the metallopolymers undergo oxidative and reductive electron-transfer quenching.The quenching reaction were investigated by Stern-Volmer quenching and conventional microsecond flash photolysis.Sensitization of n-TiO2 to visible light has been observed on a semiconductor coated with a film of the metallopolymer.
Hollow Anatase TiO2 Octahedrons with Exposed High-Index {102} Facets for Improved Dye-Sensitized Photoredox Catalysis Activity
Wang, Fan,Sun, Liming,Li, Yanan,Zhan, Wenwen,Wang, Xiaojun,Han, Xiguang
, p. 4550 - 4555 (2018)
The high activity of exposed facets and large surface area have significant effects on the performance of photocatalysts because most of the photoreactivity properties of materials are related to surface processes. The strategy of combining high-index facets and a hollow structure into one material will provide a new way for designing effective photocatalysts, possessing active exposed facets and a large surface area at the same time. However, fabricating one material with both high-index facets and a hollow structure is still a great challenge due to their thermodynamic instability. Here, hollow anatase TiO2 octahedrons exposed with high-index (102) facets (HTO-102) were successfully fabricated for the first time by a facile hydrothermal method using HF and H2O2 as morphology controlling agents. Compared with two other catalysts (a solid sharp octahedron with (101) facets (SSO-101) and a hollow sharp octahedron with (101) facets (HSO-101)), HTO-102 particles exhibit a better photochemical activity for the selective aerobic oxidation of organic sulfides under visible-light irradiation. Experimental results and theoretical calculations indicate that the excellent photocatalytic activity of HTO-102 particles is mainly due to the synergistic effects of its hollow structure and exposed high-index (102) facets.
Photocatalytic selective aerobic oxidation of amines to nitriles over Ru/γ-Al2O3: The role of the support surface and the strong imine intermediate adsorption
Zhu, Pengqi,Zhang, Jin,Wang, Jie,Kong, Peng,Wang, Yunwei,Zheng, Zhanfeng
, p. 440 - 449 (2020)
Hydroxyl coordinated ruthenium dispersed on the surface of γ-Al2O3 can be applied to the selective oxidation of amines with light irradiation and an atmospheric pressure of O2 at room temperature. Sunlight is also an effective light source for the selective aerobic oxidation of primary amines to corresponding nitriles. The high photocatalytic activity and selectivity over Ru/γ-Al2O3 originate from the adsorption of amines and imine intermediates on the abundant surface OH groups of the photocatalyst and further formation of Ru-amide species by ligand exchange of adsorbed amines and imine intermediates with adjacent exposed active Ru sites. Light is introduced to the system successfully via the formation of Ru-amide species, which are used as the light absorption sites of the photocatalytic selective oxidation of amines. Primary amines are directly converted to corresponding nitriles via a two-step oxidative dehydrogenation process.
Imura et al.
, p. 3185 (1971)
Catalyst-free one-pot reductive alkylation of primary and secondary amines and N,N-dimethylation of amino acids using sodium borohydride in 2,2,2-trifluoroethanol
Tajbakhsh, Mahmood,Hosseinzadeh, Rahman,Alinezhad, Heshmatollah,Ghahari, Somayeh,Heydari, Akbar,Khaksar, Samad
, p. 490 - 496 (2011)
A simple and convenient procedure for the reductive alkylation of primary and secondary amines and N,N-dimethylation of amino acids is described using sodium borohydride as a reducing agent in 2,2,2- trifluoroethanol without use of a catalyst or any other additive. The solvent can be readily recovered from reaction products in excellent purity for direct reuse. Georg Thieme Verlag Stuttgart - New York.
Metal-Free Photoredox-Catalyzed Hydrodefluorination of Fluoroarenes Utilizing Amide Solvent as Reductant
Toriumi, Naoyuki,Yamashita, Kazuya,Iwasawa, Nobuharu
, p. 12635 - 12641 (2021)
A metal-free photoredox-catalyzed hydrodefluorination of fluoroarenes was achieved by using N,N,N’,N’-tetramethyl-para-phenylenediamine (1) as a strong photoreduction catalyst. This reaction was applicable not only to electron-rich monofluoroarenes but also to polyfluoroarenes to afford non-fluorinated arenes. The experimental mechanistic studies indicated that the amide solvent NMP plays an important role for regeneration of the photocatalyst, enabling additive-free photoreduction catalysis.
Simplified preparation of a graphene-co-shelled Ni/NiO@C nano-catalyst and its application in theN-dimethylation synthesis of amines under mild conditions
Liu, Jianguo,Ma, Longlong,Song, Yanpei,Zhang, Mingyue,Zhuang, Xiuzheng
supporting information, p. 4604 - 4617 (2021/06/30)
The development of Earth-abundant, reusable and non-toxic heterogeneous catalysts to be applied in the pharmaceutical industry for bio-active relevant compound synthesis remains an important goal of general chemical research.N-methylated compounds, as one of the most essential bioactive compounds, have been widely used in the fine and bulk chemical industries for the production of high-value chemicals. Herein, an environmentally friendly and simplified method for the preparation of graphene encapsulated Ni/NiO nanoalloy catalysts (Ni/NiO@C) was developed for the first time, for the highly selective synthesis ofN-methylated compounds using various functional amines and aldehydes under easy to handle, and industrially applicable conditions. A large number of primary and secondary amines (more than 70 examples) could be converted to the correspondingN,N-dimethylamines with the participation of different functional aldehydes, with an average yield of over 95%. A gram-scale synthesis also demonstrated a similar yield when compared with the benchmark test. In addition, it was further proved that the catalyst could easily be recycled because of its intrinsic magnetism and reused up to 10 times without losing its activity and selectivity. Also, for the first time, the tandem synthesis ofN,N-dimethylamine products in a one-pot process, using only a single earth-abundant metal catalyst, whose activity and selectivity were more than 99% and 94%, respectively, for all tested substrates, was developed. Overall, the advantages of this newly developed method include operational simplicity, high stability, easy recyclability, cost-effectiveness of the catalyst, and good functional group compatibility for the synthesis ofN-methylation products as well as the industrially applicable tandem synthesis process.
