- Spontaneous Oxidation of Aromatic Sulfones to Sulfonic Acids in Microdroplets
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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.
- Cooks, R. Graham,Psimos, Michael D.,Qiu, Lingqi
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- Electrophilic alkylation of arenes with 5-bromopyrimidine en route to 4-aryl-5-alkynylpyrimidines
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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.
- Aksenov, Alexander V.,Domenyuk, Dmitriy A.,Magometov, Artyom Yu.,Rubin, Michael,Shcherbakov, Stanislav S.,Shcherbakova, Viktoriia Yu.,Zelensky, Vladimir A.
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p. 10315 - 10321
(2020/03/23)
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- Cornforth and Corey-Suggs reagents as efficient catalysts for sulfonation of aromatic and heteroaromatic compounds using NaHSO3 under solvent free and microwave conditions
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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.
- Fatima, Touheeth,Duguta, Govardhan,Purugula, Venkanna,Yelike, Hemanth Sriram,Kamatala, Chinna Rajanna
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p. 1001 - 1006
(2020/07/27)
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- Catalytic degradation of Acid Orange 7 with hydrogen peroxide using CoxOy-N/GAC catalysts in a bicarbonate aqueous solution
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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.
- Duan, Lian,Chen, Yanling,Zhang, Kaixuan,Luo, Huoyan,Huang, Jianxin,Xu, Aihua
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p. 84303 - 84310
(2015/10/28)
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- Activating water: Important effects of non-leaving groups on the hydrolysis of phosphate triesters
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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.
- 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
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supporting information; experimental part
p. 14996 - 15004
(2012/02/03)
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- Photo-Fenton and photo-Fenton-like processes for the degradation of methyl orange in aqueous medium: Influence of oxidation states of iron
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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.
- Devi, L. Gomathi,Kumar, S. Girish,Raju, K. S. Anantha,Rajashekhar, K. Eraiah
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experimental part
p. 378 - 385
(2011/10/09)
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- One step hair coloring compositions using salts
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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.
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- Transition metal complexes as dye forming catalysts in hair coloring compositions
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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.
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- Substituent effects on azo dye oxidation by the FeIII-EDTA-H2O2 system
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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.
- Nam, Sangkil,Renganathan,Tratnyek, Paul G.
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- Structure-reactivity correlations in the dissociative hydrolysis of 2′,4′-dinitrophenyl 4-hydroxy-X-benzenesulfonates
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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.
- Cevasco, Giorgio,Thea, Sergio
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p. 6814 - 6817
(2007/10/03)
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- NMR Characterization of Sulfonation Products of Phenylchloroformate with Verification of NOE Effects by Molecular Modeling
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In the trial scale-up of the sulfonation of phenylchloroformate and subsequent formation of sulfonated phenyl carbonates, samples from the batch process showed a number of unexpected by-products.Because they were suspected to have an unusual ring substitution pattern, phenylchloroformate sulfonation was studied by 1H and two-dimensional nuclear magnetic resonance (NMR) techniques.Distance geometry was used to compute internuclear distances, which were used to substantiate the observation of the nuclear Overhauser effect.The reaction mechanism leading to these by-products is proposed.Index Headings: Phenylchloroformate; Sulfonation; 1H NMR; Two-dimensional NMR; Potential energy computation.
- Kwoh, David,Kerschner, Judith L.,Jensen, Arnold,Cece, Anthony
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p. 407 - 412
(2007/10/02)
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- Triphendioxazine dyestuffs
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The novel triphendioxazine dyestuffs of the formula STR1 in which the substituents R, R', T1, T2, X, Y and n have the meanings given in the description are highly suitable for the dyeing and printing of cellulose-containing or amido-containing material.
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- THE DESULFONATION OF PHENOLSULFONIC ACIDS IN AQUEOUS SODIUM HYDROGEN SULFATE MIXTURES
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Phenol and phenolsulfonic acids are rapidly sulfonated and desulfonated in aqueous sodium hydrogen sulfate, with or without added sulfuric acid.At temperatures above 130 deg C, desulfonation competes with sulfonation sufficiently to allow steam stripping of phenol from the reaction mixtures, even under conditions of low water content.Above 170 deg C removal of phenol is less efficient because the water content is very low and the predominant species in the reaction mixture is 2,4,6-phenoltrisulfonate.Key words: Phenol; phenolsulfonic acid sulfonation; desulfonation; sodium hydrogen sulfate; kinetics; HPLC.
- Jason, Mark E.
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- Sulfonation of anisole, phenol, toluene and related alkyl and alkoxy derivatives with SO3. The influence of the solvent system on the reactivity and the sulfonic acid product distribution
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The reactions of anisole (1), phenol (2), the alkoxy- and alkylphenyl ethers 3-11, toluene (12) and the o-dialkylbenzenes 13-15 with sulfur trioxide in dichloromethane or trichlorofluoromethane have been studied.Our results have been compared with those obtained with the same substrates upon reaction with SO3 in nitromethane and dioxane.We show that ortho substitution is enhanced for sterically unhindered phenyl ethers and phenols due to complex formation between SO3 and the C(sp2)-bonded oxygen when dichloromethane is used as solvent instead of nitromethane or dioxane.This is mainly as a result of intramolecular SO3 transfer from the oxygen to the ortho carbon and subsequent conversion of the resulting ?-complex into the ortho sulfonic acid.
- Ansink, Harold R. W.,Cerfontain, Hans
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p. 183 - 187
(2007/10/02)
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- A practical regiospecific synthesis of ortho- and meta-hydroxybenzenesulfonic acids
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The first regiospecific route to the ortho-hydroxybenzenesulfonic acid and competitive way to its meta regioisomer are reported.Both compounds were obtained from the silylation of the corresponding chlorophenols, followed by sulfonation of the arylsilane intermediates.Keywords: silylation / sulfonation / chlorophenols / hydroxybenezensulfonic acids
- Babin, P.,Bennetau, B.,Bourgeois, P.,Rajarison, F.,Dunogues, J.
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- Process for aryl-quinone and aryl-naphthoquinone diazide sulfonic acids
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A process for the preparation of aryl-diazide-sulfonic acids by a series of sequential in-situ process steps. The process comprises the nitrosation of a hydroxyarylsulfonic acid; conversion of the nitroso-derivative to a sulfamate which is then diazotized to the diazide. Temperature and pH are maintained in predetermined ranges to maintain the reaction products in solution without the formation side-products or the need to isolate intermediates. The process of the invention is particularly useful in the preparation of light-sensitive materials such as naphthoquinonediazide sulfonic acids which are used in the preparation of photoresist compositions. The invention provides a high purity product at a high material efficiency, high equipment utilization, low effluent discharge, and reduced cost.
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- Sulfonation and sulfation in reactions of C-methylated phenols and anisoles with sulfur trioxide. 4-Substituted phenyl hydrogen sulfates: effective reagents for transsulfonation
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The sulfation and sulfonation of the methyl- and dimethylphenols with 0.9 and 4.0 equiv. of SO3 in nitromethane at 0 deg C have been studied.On using 0.9 equiv. of SO3, the sulfonic acid product distributions are determined by the ortho- and para-directing effect of the activating hydroxy substituent.In the reactions with 4.0 equiv. of SO3, the sulfonic acid product distributions are affected by the predominant initial formation and the subsequent sulfonation of the corresponding phenyl hydrogen sulfates, of which the bulky OSO3H substituent is electronically deactivating and (mainly) para-directing.For comparison, the sulfonation of the methylanisoles, phenyl methanesulfonate and 2,3-dihydrobenzofuran was also studied.The sulfonation of 1,3-dimethoxybenzene in (2H8)dioxane at 17.0 deg C has been studied using 4-substituted phenyl hydrogen sulfates as transsulfonating agents.The transsulfonation was found to be first order with respect to the phenyl hydrogen sulfates and independent of the 1,3-dimethoxybenzene concentration.The reaction constant of the transsulfonation reaction was determined to be ρ=2.0+/-0.2.
- Goossens, Hans D.,Lambrechts, Hans J. A.,Cerfontain, Hans,Wit, Peter de
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p. 426 - 430
(2007/10/02)
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- On the intermediacy of phenyl hydrogen sulfates in the sulfonation of phenols. Sulfonation of phenol, anisole, methyl phenyl sulfate, the 2-halogenophenols, a series of phenyl methanesulfonates together with 2,6-dimethylaniline and its N-methylsulfonyl derivative
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The sulfonation of methyl phenyl sulfate (4) with concentrated aqueous sulfuric acid at 25 deg C yields the 4-sulfonic acid.This initial product then decomposes to give phenol-4-sulfonic acid, which is subsequently sulfonated to phenol-2,4-disulfonic acid.From the first-order-rate coefficients obtained for sulfonation of phenyl methanesulfonate (3) and (4) in 93,2percent H2SO4, for which acid concentration the sulfonating entity is H2S2O7, the ?p+ values of the OSO2Me and OSO2OMe substituents have been determined to be 0.40 and 0.46, respectively.The sulfonation of both 2-chlorophenyl (10) and 2-methylphenyl methanesulfonate (14) with 2.0 equiv of SO3 in nitromethane at 0.0 deg C yields the 4-sulfonic acid as the exclusive product, whereas 2-methoxyphenyl methanesulfonate (13), under the same conditions, forms exclusively the 5-sulfonic acid. 2-Chloro- (6), 2-bromo- (7) and 2-iodophenol (8) with 1.0 and 4.0 equiv of SO3 in nitromethane yield exclusively the 4-sulfonic acid, while 2-fluorophenol (5) with 2.0 and 5.0 equiv of SO3 yields in addition the 5-sulfonic acid to the extent of 4 and 30percent, respectively.In the reactions of 2,6-dimethylphenol (15) and 2,6-dimethylaniline (17) with at least 1 equiv of SO3 in nitromethane, the 3-SO3H/4-SO3H ratio was found to increase on increasing the relative amount of SO3.For both 15 and 17, the limiting 3-SO3H/4-SO3H ratio at high SO3/ArOH ratios is 86/14 and this value is considered to be the ratio for the sulfonation of both 2,6-dimethylphenyl hydrogen sulfate and 2,6-dimethylaniline-N-sulfonic acid.This assumption is supported by the observation that the sulfonation of 2,6-dimethylphenyl methanesulfonate (16) and N-(methylsulfonyl)-2,6-dimethylaniline (18) with SO3 leads to a similar 3-SO3H/4-SO3H ratio.
- de Wit, Peter,Woldhuis, Alex F.,Cerfontain, Hans
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p. 668 - 675
(2007/10/02)
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- Aromatic Sulphonation. Part 91. The Sulphonation of Anisole, Phenol, Phenyl Methanesulphonate, Potassium Phenyl Sulphate, and a Series of Methyl-, Bromo-, and Chloro-substituted Anisoles and Phenols in Concentrated Aqueous Sulphuric Acid
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The (homogeneous) sulphonation of a number of aromatic ethers and alcohols, viz. anisole (1), 3-methyl- (2), 4-methyl- (3), 2-bromo- (4), 4-bromo- (5), 2-chloro- (6), and 4-chloro-anisole (7), phenol (8), 2-methyl- (9), 3-methyl- (10), 4-methyl- (11), 4-bromo- (12), 2-chloro- (13), and 4-chloro-phenol (14), phenyl methanesulphonate (15), and potassium phenyl sulphate (16) in concentrated aqueous sulphuric acid at 25.0 deg C has been studied, and rates and isomer distributions have been determined.The sulphonation is first-order in the aromatic substrate, and from the rate measurements it is concluded that the species undergoing sulphonation in the phenyl ring is an unprotonated substrate species.In the lower acid concentrations the sulphonating entity is H3SO4(1+).With increasing sulphuric acid concentration there is a gradual change-over in the sulphonating entity from H3SO4(1+) to H2S2O7.The acid concentrations of equal rate contribution by the two entities for anisole and phenol are 87 and 90 +/- 1percent, respectively.Sulphonation on the oxygen atom (i.e., sulphation) does not occur.The o/p-ratios for (1) and (8) do not vary over the studied sulphuric acid range of 75-90percent H2SO4.Partial rate factors for the 2- and 4-position of (1) and (8) are reported.The very low partial rate factors for the 4-substitution of (1) and (8) and the observed extreme suppression and compression of the reactivities of the substrates (1)-(14) are ascribed to hydrogen bonding of the substrates with the acidic solvent species present.It is tentatively suggested that the relatively high contents of sulphonation ortho to -OR with anisole (36percent) and phenol (48percent) are due to specific complexation of the substrates with the sulphonating electrophile.
- Cerfontain, Hans,Lambrechts, Hans J. A.,Schaasberg-Nienhuis, Zwaan R. H.,Coombes, Robert G.,Hadjigeorgiou, Panicos,Tucker, Geoffrey
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p. 659 - 668
(2007/10/02)
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- Sulfonation of three Symmetrical 2,6-Dialkylphenols, 2,6-Dichlorophenol, Phenol, and 2,6-Dimethylanisole. Sulfation and Sulfonation Product Distribution and Mechanisms
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The sulfonation of four symmetrically substituted 2,6-disubstituted phenols, phenol, 2,6-dimethylanisole with SO3 in aprotic solvents was studied.With the phenols the initial product is the phenyl hydrogen sulfate, which is slowly converted into the phenolsulfonic acids via O-desulfonation and subsequent C-sulfonation if the phenol is in excess and via C-sulfonation and subsequent O-desulfonation if the SO3 is in excess.The ratio of partial rate factors for 3- and 4-sulfonation (f3/f4) for 2,6-dimethylphenol (1) in nitromethan strongly decreases on replacing the methyl groups by i-Pr, t-Bu (steric effects), and Cl (electronic effects).The strong increase of f3/f4 on increasing the SO3:1 ratio from 0.9 to 6.0 is ascribed to increasing sulfonation of the phenyl hydrogensulfate for which because of steric inhibition of resonance f3/f4 is higher (3.9) than that of the phenol 1 (0.01) and of 2,6-dimethylanisole (5) (0.01).The protic sulfonation of 1 and 5 in concentrated sulfuric acid was also studied.The large variations in f3/f4 with increasing sulfuric acid concentration are discussed in terms of steric inhibition of resonance for the entities undergoing sulfonation, viz., 1, its hydrogen sulfate, and 5 by the various sulfonating entities in the sulfuric acid range 75 - 107 percent H2SO4.
- Cerfontain, Hans,Koeberg-Telder, Ankie,Lambrechts, Hans J.A.,de Wit, Peter
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p. 4917 - 4923
(2007/10/02)
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- Enzyme-activated oxidative process for coloring hair
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An enzyme-based oxidative process for coloring hair wherein the hair is exposed to a solution having a pH of about 4 to about 10 and containing hydrogen peroxide, soybean peroxidase enzyme and one or more oxidation dye precursors.
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