98-67-9Relevant articles and documents
Spontaneous Oxidation of Aromatic Sulfones to Sulfonic Acids in Microdroplets
Cooks, R. Graham,Psimos, Michael D.,Qiu, Lingqi
, (2022/04/07)
Reactions in microdroplets can be accelerated and can present unique chemistry compared to reactions in bulk solution. Here, we report the accelerated oxidation of aromatic sulfones to sulfonic acids in microdroplets under ambient conditions without the addition of acid, base, or catalyst. The experimental data suggest that the water radical cation, (H2O)+?, derived from traces of water in the solvent, is the oxidant. The substrate scope of the reaction indicates the need for a strong electron-donating group (e.g., p-hydroxyl) in the aromatic ring. An analogous oxidation is observed in an aromatic ketone with benzoic acid production. The shared mechanism is suggested to involve field-assisted ionization of water at the droplet/air interface, its reaction with the sulfone (M) to form the radical cation adduct, (M + H2O)+?, followed by 1,2-aryl migration and C-O cleavage. A remarkably high reaction rate acceleration (～103) and regioselectivity (～100-fold) characterize the reaction.
Cornforth and Corey-Suggs reagents as efficient catalysts for sulfonation of aromatic and heteroaromatic compounds using NaHSO3 under solvent free and microwave conditions
Fatima, Touheeth,Duguta, Govardhan,Purugula, Venkanna,Yelike, Hemanth Sriram,Kamatala, Chinna Rajanna
, p. 1001 - 1006 (2020/07/27)
Cornforth and Corey-Suggs reagents Pyridinium Dichromate (PDC) and Pyridinium Chlorochromate (PCC) were explored as efficient catalysts for sulfonation of aromatic and heteroaromatic compounds using NaHSO3 in aqueous acetonitrile medium at room temperature within 1–4 h, while microwave assisted reactions took place within 1–4 min under solvent-free conditions. These observations indicate significant rate accelerations in microwave assisted reactions. which were explained due to the bulk activation of molecules induced by insitu generated high temperatures and pressures when microwaves are transmitted through reaction medium.
Electrophilic alkylation of arenes with 5-bromopyrimidine en route to 4-aryl-5-alkynylpyrimidines
Aksenov, Alexander V.,Domenyuk, Dmitriy A.,Magometov, Artyom Yu.,Rubin, Michael,Shcherbakov, Stanislav S.,Shcherbakova, Viktoriia Yu.,Zelensky, Vladimir A.
, p. 10315 - 10321 (2020/03/23)
A new synthetic protocol for preparation of medicinally important 4-aryl-5-alkynylpyrimidines is described. The featured approach involves a sequence of chemo- and regioselective Br?nsted acid-catalyzed electrophilic alkylation of arenes with 5-bromopyrimidine, followed by oxidative re-aromatization of the formed dihydropyrimidine ring. Finally, palladium-catalyzed Sonogashira cross-coupling reaction provided an end-game strategy.
Catalytic degradation of Acid Orange 7 with hydrogen peroxide using CoxOy-N/GAC catalysts in a bicarbonate aqueous solution
Duan, Lian,Chen, Yanling,Zhang, Kaixuan,Luo, Huoyan,Huang, Jianxin,Xu, Aihua
, p. 84303 - 84310 (2015/10/28)
The cobalt-based heterogeneous catalysts CoxOy-N/GAC were prepared by pyrolysis of a cobalt-phenanthroline complex on granular active carbon (GAC) in a nitrogen atmosphere, and tested for the degradation of Acid Orange 7 using hydrogen peroxide as a benign oxidant in a bicarbonate aqueous solution. Characterization by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and electron spin resonance spectroscopy revealed the formation of a cobalt oxide nanoparticle shell with a metallic Co core on the surface of GAC; and the nitrogen substituted the selected carbon atoms during the pyrolysis process and bonded to cobalt. The catalysts were active for dye decolorization in an aqueous solution containing 10 mM H2O2 and 5 mM NaHCO3 at room temperature. They also presented good stability with nearly no loss of cobalt ions after the reaction, in comparison with the high leaching of Co (0.25 mg L-1) from the CoxOy/GAC catalyst without nitrogen. The production of intermediates, the formation of reactive radicals and the effect of HCO3- were also investigated to further explore the efficiency of the catalyst. This study can provide a promising way for the activation of the green oxidant H2O2 in a bicarbonate aqueous solution by heterogeneous cobalt catalysts for environmental remediation.
Activating water: Important effects of non-leaving groups on the hydrolysis of phosphate triesters
Kirby, Anthony J.,Medeiros, Michelle,Oliveira, Pedro S. M.,Orth, Elisa S.,Brandao, Tiago A. S.,Wanderlind, Eduardo H.,Amer, Almahdi,Williams, Nicholas H.,Nome, Faruk
supporting information; experimental part, p. 14996 - 15004 (2012/02/03)
The high rate of spontaneous hydrolysis of tris-2-pyridyl phosphate (TPP) is explained by the activating effects of the non-leaving ("spectator" ) groups on P-OAr cleavage, and not by intramolecular catalysis. Previous work on phosphate-transfer reactions has concentrated on the contributions to reactivity of the nucleophile and the leaving group, but our results make clear that the effects of the non-leaving groups on phosphorus can be equally significant. Rate measurements for three series of phosphate triesters showed that sensitivities to the non-leaving groups are substantial for spontaneous hydrolysis reactions, although significantly smaller for reactions with good nucleophiles. There are clear differences between triaryl and dialkyl aryl triesters in sensitivities to leaving and non-leaving groups with the more reactive triaryl systems showing lower values for both βLG and βNLG. Intramolecular catalysis of the hydrolysis of TPP by the neighbouring pyridine nitrogens is insignificant, primarily because of their low basicity.
Photo-Fenton and photo-Fenton-like processes for the degradation of methyl orange in aqueous medium: Influence of oxidation states of iron
Devi, L. Gomathi,Kumar, S. Girish,Raju, K. S. Anantha,Rajashekhar, K. Eraiah
experimental part, p. 378 - 385 (2011/10/09)
Degradation of methyl orange (MO) was carried out by the photo-Fenton process (Fe2+/H2O2/UV) and photo-Fenton-like processes (Fe3+/H2O2/UV, Fe2+/S2O82-/UV, and Fe3+/S2O82-/UV) at the acidic pH of 3 using hydrogen peroxide and ammonium persulfate (APS) as oxidants. Oxidation state of iron had a significant influence on the efficiency of photo-Fenton/photo-Fenton-like processes. It was found that a process with a source of Fe3+ ions as the catalyst showed higher efficiency compared to a process with the Fe2+ ion as the catalyst. H2O2 served as a better oxidant for both oxidation states of iron compared to APS. The lower efficiency of APS is attributed to the generation of excess protons which scavenges the hydroxyl radicals necessary for degradation. Further, the sulfate ions produced from S2O82- form a complex with Fe2+/Fe3+ ions thereby reducing the concentration of free iron ions in the solution. This process can also reduce the concentration of hydroxyl radicals in the solution. Efficiency of the various MO degradation processes follows the order: Fe3+/H2O2/UV, Fe3+/APS/UV, Fe2+/H2O2/UV, Fe2+/APS/UV.
One step hair coloring compositions using salts
-
, (2008/06/13)
A hair coloring composition comprising the following two compositions which are mixed just prior to application to the hair: (a) a composition comprising a water-soluble peroxygen oxidizing agent; and (b) a composition comprising one or more oxidative hair coloring agents selected from the group consisting of an aromatic diamine, an amino phenol, a naphthol, a polyhydric phenol, a catechol and mixtures thereof; wherein the composition comprising one or more oxidative hair coloring agents further comprises al least one water soluble carbonate releasing salts; and optionally a water soluble ammonium salt, is described.
Transition metal complexes as dye forming catalysts in hair coloring compositions
-
, (2008/06/13)
A hair coloring composition comprising a first composition which comprises: (a) a dye forming transition metal salt or complex; which is first applied to the hair; and a second composition which comprises the following two compositions which are mixed just prior to application to the hair: (a) a composition comprising a water-soluble peroxygen oxidizing agent; and (b) a composition comprising one or more oxidative hair coloring agents selected from the group consisting of an aromatic diamine, an aminophenol, a polyhydric phenol a catechol and mixtures thereof.
Substituent effects on azo dye oxidation by the FeIII-EDTA-H2O2 system
Nam, Sangkil,Renganathan,Tratnyek, Paul G.
, p. 59 - 65 (2007/10/03)
The effect of substituents on the oxidation of azo dyes in the FeIII-EDTA-H2O2 system was examined at pH 7. 4-(4′-sulfophenylazo)phenol and 2-(4′-sulfophenylazo)phenol, with methyl, methoxy, and halo substituents on the phenolic ring, were used as model systems. Oxidation of the naphthol dyes Orange I and Orange II were also examined. All of the dyes tested were decolorized in the FeIII-EDTA-H2O2 system, but the degree of decolorization varied over a factor of 10. Dyes substituted with one or two halogens were oxidized to a greater extent than the corresponding methyl- or methoxy-substituted dyes. One explanation for the effect of halogen substituents is that they make the phenolic moieties more acidic, which favors the phenolate anion, which is more readily attacked by ·OH. This explanation is supported by the observed correlation between charge density of the phenolate anion and the degree of decolorization. Based on an analysis of products formed from Orange II, a probable mechanism for decolorization of phenolic azo dyes by ·OH is proposed. In addition, the optimal levels of H2O2 needed for the process have been examined. It appears that high levels of H2O2 could reduce decolorization by scavenging the ·OH.
Structure-reactivity correlations in the dissociative hydrolysis of 2′,4′-dinitrophenyl 4-hydroxy-X-benzenesulfonates
Cevasco, Giorgio,Thea, Sergio
, p. 6814 - 6817 (2007/10/03)
The hydrolysis reactions of several title esters in water at 60°C follow the rate law kobs = (ka + kb[OH-])/(1 + αH/Ka), where Ka is the ionization constant of the hydroxy group of the ester and kb is the second-order rate constant for the SN2(S) attack of hydroxide ion on the ionized ester. Hammett and Br?nsted correlations are consistent with a previous proposal that the mechanism related to ka is dissociative. An unusual relationship between ka values and redox equilibrium constants for substituted quinones is found to hold: this finding further supports the dissociative nature of the pathway related to ka.
