573-79-5Relevant academic research and scientific papers
The polyhedral nature of selenium-catalysed reactions: Se(iv) species instead of Se(vi) species make the difference in the on water selenium-mediated oxidation of arylamines
Capperucci, Antonella,Dalia, Camilla,Tanini, Damiano
supporting information, p. 5680 - 5686 (2021/08/16)
Selenium-catalysed oxidations are highly sought after in organic synthesis and biology. Herein, we report our studies on the on water selenium mediated oxidation of anilines. In the presence of diphenyl diselenide or benzeneseleninic acid, anilines react with hydrogen peroxide, providing direct and selective access to nitroarenes. On the other hand, the use of selenium dioxide or sodium selenite leads to azoxyarenes. Careful mechanistic analysis and 77Se NMR studies revealed that only Se(iv) species, such as benzeneperoxyseleninic acid, are the active oxidants involved in the catalytic cycle operating in water and leading to nitroarenes. While other selenium-catalysed oxidations occurring in organic solvents have been recently demonstrated to proceed through Se(vi) key intermediates, the on water oxidation of anilines to nitroarenes does not. These findings shed new light on the multifaceted nature of organoselenium-catalysed transformations and open new directions to exploit selenium-based catalysis.
Nb2O5 supported on mixed oxides catalyzed oxidative and photochemical conversion of anilines to azoxybenzenes
De Carvalho, Gustavo Senra Gon?alves,Chagas, Luciano Honorato,Fonseca, Carla Grijó,De Castro, Pedro P?ssa,Sant'Ana, Ant?nio Carlos,Leit?o, Alexandre Amaral,Amarante, Giovanni Wilson
supporting information, p. 5863 - 5871 (2019/04/17)
The synthesis of novel supported niobium oxide catalysts and their application for aniline conversion to azoxybenzenes is described. The catalysts were successfully prepared by thermal decomposition of layered double hydroxides (LDHs), containing M2+ (M = Mg2+ and/or Zn2+) and Al3+ as layer cations, followed by niobium oxide incorporation employing the wetness impregnation method. These catalysts were fully characterized by both experimental techniques and theoretical calculations, and then successfully applied to the selective conversion of anilines into azoxybenzene derivatives, with up to 98% conversion and 92% isolated yield in the presence of violet light. Control experiments and DFT calculations revealed that the catalyst has a dual role in this transformation, acting both as a Lewis acid in the oxidative step and as a photocatalyst in the dimerization of the nitrosobenzene intermediate.
An exceptionally stable Ti superoxide radical ion: A novel heterogeneous catalyst for the direct conversion of aromatic primary amines to nitro compounds
Dewkar, Gajanan K.,Nikalje, Milind D.,Ali, Iliyas Sayyed,Paraskar, Abhimanyu S.,Jagtap,Sudalai
, p. 405 - 408 (2007/10/03)
A matrix-bound superoxide radical anion, generated by treating Ti(OR)4 (R =iPr, nBu) with H2O2, is a selective heterogeneous catalyst for the oxidation of anilines to the corresponding nitroarenes with 50 % aqueous H2O2 [Eq. (1)]. Yields of 82-98 % are obtained, even with anilines bearing electron-withdrawing substituents (R = NO2, COOH).
Synthesis, Spectral Studies and C-S Bond Fission of Some Alkyl- Diacetates
Gohar, G. A.
, p. 43 - 58 (2007/10/03)
Some methyl and ethyl diacetates have been synthesized and their structures were identified. A correlation was found between δ-values of benzylidene protons and ?-Hammett values. The internal chemical shift of the methylene proton was found to be structural and applied field dependent. The carbon-sulfur bond fission by the action of sodium hydroxide solution in 50 percent aqueous-dioxane medium, in addition to the alkaline ester hydrolysis was studied. 2- or 4-Nitro compounds gave dicarboxyazoxybenzenes. This led to the suggestion that the reaction might proceed through two intermediates namely diacetic acid and nitrosobenzoic acid. However, the C-S bond fission of other compounds gave aldehydes, supporting that, no α-proton abstraction took place for these compounds.
Electrosynthesis and in situ chemical rearrangement of o-nitrosobenzamides
Guilbaud-Criqui, A.,Moinet, C.
, p. 101 - 110 (2007/10/02)
Primary and secondary o-nitrosobenzamides can be prepared in a "redox" cell but are unstable in the solvent used for electrolysis (acetate buffer-alcohol).At room temperature N-aryl-2-nitrosobenzamides give 2-carboxyazobenzenes.N-alkyl-2-nitrosobenzamides decompose thermally into 2-methoxy or 2-ethoxycarbonylphenylhydrazones according to the alcohol used.Similarly, methyl benzoate (or ethyl benzoate) is obtained from 2-nitrosobenzamide.A possible mechanism involves an unstable heterocycle formed by the coupling of the two nitrogen atoms (nitroso and amide) followed by cleavage of the carbonyl-nitrogen bond resulting from nucleophilic attack of the solvent (water or alcohol). Key Words: flow cell electrosynthesis / 2-nitrosobenzamides / 2-carboxyazobenzenes / 2-alkoxycarbonylphenylhydrazones / indazol-3-one
Peroxomonophosphoric Acid Oxidation. V. A Kinetic and Mechanistic Study of Oxidation of Aminobenzoic Acids in Acid Medium. Double Bell Shaped pH Rate Profile
Panigrahi, Ganesh Prasad,Panda, Abhina Kumar
, p. 1554 - 1558 (2007/10/02)
Anthranilic acid and p-aminobenzoic acid were oxidized with peroxomonophosphoric acid in aqueous acid medium to the corresponding azoxy derivatives.Suitable rate laws for the double bell shaped pH rate profile were derived and rationalized on the basis of protonation of the amino group and ionization of the carboxyl group.The mechanism of oxidation involves the nucleophilic attack of nitrogen on the electrophilic peroxo oxygen.The reactivity of the different peroxomonophosphoric acid species has been estimated.
