19519-71-2Relevant academic research and scientific papers
NMR Study of the Monomer-Dimer Equilibria of Dimethylnitrosobenzenes in Solution. Identification of Mixed Azodioxy Dimeric Species
Orrell, Keith G.,Stephenson, David,Rault, Thierry
, p. 368 - 376 (1989)
The monomer-dimer equilibria of 2,6- and 3,5-dimethylnitrosobenzenes in CDCl3 solution were investigated by 1H and/or 13C NMR spectroscopy.The mixed systems nitrosobenzene + 2,6-dimethylnitrosobenzene and 2,6-dimethylnitrosobenzene + 3,5-dimethylnitrosobenzene were also studied, and mixed azodioxy dimers were identified.In all systems exchange occurs exclusively between dimer and monomer species, rates and activation energies being calculated from time-dependent 1H 1D spectra and/or 1H 2D-EXSY spectra measured at different temperatures. KEY WORDS 1H NMR 13C NMR 2,6-Dimethylnitrosobenzene 3,5-Dimethylnitrosobenzene Monomer-dimer equilibria Mixed azodioxy dimers
Titania-Supported Gold Nanoparticles Catalyze the Selective Oxidation of Amines into Nitroso Compounds in the Presence of Hydrogen Peroxide
Fountoulaki, Stella,Gkizis, Petros L.,Symeonidis, Theodoros S.,Kaminioti, Eleni,Karina, Athanasia,Tamiolakis, Ioannis,Armatas, Gerasimos S.,Lykakis, Ioannis N.
supporting information, p. 1500 - 1508 (2016/05/19)
In this article, the catalytic activity of titania-supported gold nanoparticles (Au/TiO2) was studied for the selective oxidation of amines into nitroso compounds using hydrogen peroxide (H2O2). Gold nanoparticles deposited on Degussa P25 polymorphs of titania (TiO2) have been found to promote the selective formation of a variety of nitroso arenes in high yields and selectivities, even in a large-scale synthesis. In contrast, alkyl amines are oxidized to the corresponding oximes under the examined conditions. Kinetic studies indicated that aryl amines substituted with electron-donating groups are oxidized faster than the corresponding amines bearing an electron-withdrawing functionality. A Hammett-type kinetic analysis of a range of para-X-substituted aryl amines implicates an electron transfer (ET) mechanism (ρ=-1.15) for oxidation reactions with concomitant formation of the corresponding N-aryl hydroxylamine as possible intermediate. We also show that the oxidation protocol of aryl amines in the presence of 1,3-cyclohexadiene leads in excellent yields to the corresponding hetero Diels-Alder adducts between the diene and the in situ formed nitrosoarenes.
Selective N-oxidation of aromatic amines to nitroso derivatives using a molybdenum acetylide oxo-peroxo complex as catalyst
Biradar, Ankush V.,Kotbagi, Trupti V.,Dongare, Mohan K.,Umbarkar, Shubhangi B.
, p. 3616 - 3619 (2008/09/19)
The molybdenum acetylide oxo-peroxo complex obtained in situ by the treatment of the corresponding molybdenum acetylide carbonyl complex, CpMo(CO)3(C{triple bond, long}CPh); Cp = η5-C5H5 with H2O2, has been used as an efficient catalyst for selective N-oxidation of primary amines to nitroso derivatives. Excellent amine conversion (up to 100%) and very high selectivity for nitroso compounds (99%) have been obtained using 30% hydrogen peroxide as an oxidant. The oxo peroxo Mo(VI) complex has also been found to be very active for the oxidation of various substituted primary aromatic amines with electron donating as well as electron withdrawing substituents on the aromatic ring.
Kinetics and mechanism of nitrosation of toluene, o-xylene, and m-xylene in trifluoroacetic acid, or in acetic-sulfuric acid mixtures, under nitric oxide
Atherton, John H.,Moodie, Roy B.,Noble, Darren R.
, p. 699 - 705 (2007/10/03)
The title reactions give good yields with m-xylene, and modest yields with toluene and o-xylene which are successfully directly nitrosated for the first time. The advantages of purging with nitric oxide are demonstrated and discussed. The kinetics have been successfully interpreted in terms of a mechanism in which both the aromatic substrate and the nitrosoaromatics form, reversibly, complexes with nitrosonium ion. The nitrosoaromatics are unstable under the acid conditions and the method is successful only because of the protective complexation with the nitrosonium ion.
Enthalpies of combustion of 2,2',4,4',6,6'-hexamethylazobenzene-N,N-dioxide, 2,2',6,6'-tetramethylazobenzene-N,N-dioxide, 2,4,6-trimethylnitrobenzene, and 2,6-dimethylnitrobenzene: the dissociation enthalpies of the N=N and N-O bonds
Acree, W. E.,Tucker, Sheryl A.,Pilcher, G.,Chowdhary, Afza,Silva, Maria D. M. C. Ribeiro da,Monte, M. J. S.
, p. 1253 - 1262 (2007/10/02)
The standard (po=0.1 MPa) molar enthalpies of combustion at the temperature T=298.15 K were measured by static-bomb calorimetry for crystalline 2,2',4,4',6,6'-hexamethylazobenzene-N,N-dioxide (HMABOO), 2,2',6,6'-tetramethylazobenzene-N,N-dioxide (TMABOO), 2,4,6-trimethylnitrobenzene (NITME), and liquid 2,6-dimethylnitrobenzene (NITXY).The enthalpies of sublimation at the temperature 298.15 K of HMABOO and TMABOO were assessed from vapour-pressure measurements; the enthalpy of sublimation of NITME and the enthalpy of vaporization of NITXY were measured by microcalorimetry. .The standard molar enthalpies of decomposition of the crystalline N,N-dioxides to the corresponding gaseous monomeric nitroso-compounds at T=298.15 K were measured by microcalorimetry: for HMABOO, (18.1+/-2.5) kJ*mol-1, and for TMABOO, (179.2+/-2.2) kJ*mol-1.For HMABOO and TMABOO, D(N=N)/(kJ*mol-1) was derived as (74.1+/-12.2) and (72.2+/-12.2), and /(kJ*mol-1) as (285.7+/-6.8) and (287.8+/-6.6), respectively.D(N-O)/(kJ*mol-1) in NITME and in NITXY was derived as (383.4+/-2.9) and (380.4+/-2.3), respectively.
PRESSURE EFFECT ON DIMERIZATION EQUILIBRIA OF A SERIES OF SUBSTITUTED NITROSOBENZENES IN SOLUTION.
Yoshimura,Nakahara
, p. 46 - 50 (2007/10/02)
The effect of pressure was studied on the dimerization reactions of six di- and tri-substituted nitrosobenzenes in carbon tetrachloride at 25 degree C. The obtained configurational volume changes for the prototype one bond formation reactions are in the range of minus 17 to minus 21 cm**3 mol** minus **1 at 6. 13 MPa. The volume changes were interpreted in terms of the perturbation theory of liquid; they were dominated by the volume change in the reference system composed of hard spheres. Small differences between the observed and theoretical reference volume changes were ascribed to the perturbation due to electrostatic interactions between the solute and solvent; the perturbation volume changes were estimated by the Kirkwood theory of dipolar solvation.
Low-temperature Proton Nuclear Magnetic Resonance and Ultraviolet Absorption Spectra and Photochemistry of the System Nitrosobenzene-Azodioxybenzene and its Methyl Derivatives
Azoulay, Michel,Fischer, Ernst
, p. 637 - 642 (2007/10/02)
The title compounds crystallize in their dimeric, azodioxy form, but their dilute solutions at room temperature contain only the monomeric, nitroso form.By dissolving the crystals at temperatures below -60 deg C, dilute solutions of the dimers could be obtained, because thermal equilibration of the monomer and dimer no longer takes place at this temperature.The absorption spectra of the dimers, their dissociation kinetics at various temperatures above -60 deg C, and their photochemistry in solution at and below -60 deg C were thus investigated.The only photochemistry observed was a very efficient photo-dissociation of dimer to monomer, which takes place with close to unity yield even at -170 deg C.The activation energies for the thermal dissociation of the dimers were found to be 80-100 kJ mol-1.
