- 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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- New insight into the electrochemical reduction of different aryldiazonium salts in aqueous solutions
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Electrochemical reduction of different aryldiazonium salts in aqueous solution was studied in this work and it is shown that the aryldiazonium salts are converted to the corresponding aryl radical and aryl anion. The results of this research indicate that the reduction of aryldiazonium salts takes place in two single-electron steps. Our data show that when the substituted group on the phenyl ring is H, Cl, OH, NO2, OCH3or SO3?, the corresponding diazonium salt shows poor adsorption characteristics, but when the substituted group is methyl, the corresponding diazonium salt shows strong adsorption characteristics. In the latter case, the voltammogram exhibits three cathodic peaks. In addition, the effect of various substitutions on the aryldiazonium reduction was studied by Hammett's method. The data are show that with increasing electron withdrawing capacity of the substituent, the reduction of corresponding diazonium salt becomes easier.
- Goljani, Hamed,Nematollahi, Davood,Sepehrmansourie, Hassan,Tavakkoli, Zahra,Zolfigol, Mohammad Ali
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p. 25811 - 25815
(2021/08/09)
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- Sustainable access to sulfonic acids from halides and thiourea dioxide with air
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A sustainable and mild one-step strategy is explored for the synthesis of aryl and alkyl sulfonic acids using a facile combination of halides and sulfur dioxide surrogates under air. The cheap industrial material thiourea dioxide was employed as an eco-friendly and easy-handling sulfur dioxide surrogate, while air was used as a green oxidant. Both aryl and alkyl sulfonic acids were obtained under transition metal-catalyzed or transition metal-free conditions. Mechanistic studies demonstrated that sulfinate was involved as an intermediate in this transformation. Notably, this protocol has been applied to the late-stage sulfonation of the drugs naproxen, isoxepac and ibuprofen.
- Zhang, Hui,Wang, Ming,Jiang, Xuefeng
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supporting information
p. 8238 - 8242
(2020/12/29)
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- Aryl and alkyl sulfonic acid compounds as well as construction method adopting inorganic sulfur salt and application
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The invention discloses aryl and alkyl sulfonic acid compounds as shown in a formula (1) and a synthesis method thereof. The method comprises the following step: aromatic iodine and an inorganic sulfur source or alkyl bromide and an inorganic sulfur source as reaction raw materials react in a solvent under the action of alkali, a catalyst or an additive to obtain a series of aryl and alkyl sulfonic acid compounds. According to the method, the aryl and alkyl sulfonic acid compounds are constructed in one step by taking an inorganic sulfur reagent as a sulfur source, so that the defect of the mode in which the aryl and alkyl sulfonic acid compounds are synthesized by taking concentrated sulfuric acid, chlorosulfonic acid or sulfur dioxide gas and the like as sulfonating reagents in the priorart is avoided. The aryl and alkyl sulfonic acid compounds developed by the invention can be used for synthesizing aryl and alkyl sulfonic acid drug analogues.
- -
-
Paragraph 0046-0049; 0055-0058
(2020/09/16)
-
- Discovery of a Gut-Restricted JAK Inhibitor for the Treatment of Inflammatory Bowel Disease
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To identify Janus kinase (JAK) inhibitors that selectively target gastrointestinal tissues with limited systemic exposures, a class of imidazopyrrolopyridines with a range of physical properties was prepared and evaluated. We identified compounds with low intrinsic permeability and determined a correlation between permeability and physicochemical properties, clogP and tPSA, for a subset of compounds. This low intrinsic permeability translated into compounds displaying high colonic exposure and low systemic exposure after oral dosing at 25 mg/kg in mouse. In a mouse PK/PD model, oral dosing of lead compound 2 demonstrated dose-dependent inhibition of pSTAT phosphorylation in colonic explants post-oral dose but low systemic exposure and no measurable systemic pharmacodynamic activity. We thus demonstrate the utility of JAK inhibitors with low intrinsic permeability as a feasible approach to develop gut-restricted, pharmacologically active molecules with a potential advantage over systemically available compounds that are limited by systemic on-target adverse events.
- Leonard, Kristi A.,Madge, Lisa A.,Krawczuk, Paul J.,Wang, Aihua,Kreutter, Kevin D.,Bacani, Genesis M.,Chai, Wenying,Smith, Russell C.,Tichenor, Mark S.,Harris, Michael C.,Malaviya, Ravi,Seierstad, Mark,Johnson, Marguerite E.,Venable, Jennifer D.,Kim, Suzie,Hirst, Gavin C.,Mathur, Ashok S.,Rao, Tadimeti S.,Edwards, James P.,Rizzolio, Michele C.,Koudriakova, Tatiana
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p. 2915 - 2929
(2020/04/08)
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- Bimolecular proximity of a ruthenium complex and methylene blue within an anionic porous coordination cage for enhancing photocatalytic activity
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The charge repulsion between a catalyst and substrate will significantly reduce the contact occurring between them, resulting in low reactivity. Herein, we report an anionic porous coordination cage that is capable of encapsulating both a cationic catalyst and cationic substrate in its cavity at the same time. After encapsulating the [Ru(bpy)3]2+Cl2 (bpy = bipyridine) catalyst, the cage/catalyst composite serves as an active heterogeneous catalyst for the photo-degradation of methylene blue (MB). The highly negatively charged cavity of PCC-2 allows for the sequential encapsulation of the cationic methylene blue substrate and the Ru catalyst, which in turn significantly shortens the distance between them, yielding an increased possibility of MB degradation. Moreover, the encapsulated Ru catalyst dramatically outperformed its homogeneous counterpart in terms of overall degradation performance and recyclability.
- Fang, Yu,Xiao, Zhifeng,Kirchon, Angelo,Li, Jialuo,Jin, Fangying,Togo, Tatsuo,Zhang, Liangliang,Zhu, Chengfeng,Zhou, Hong-Cai
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p. 3529 - 3534
(2019/03/28)
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- Exogenous-oxidant-and catalyst-free electrochemical deoxygenative C2 sulfonylation of quinoline: N-oxides
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An exogenous-oxidant-and catalyst-free electrochemical deoxygenative C2 sulfonylation reaction has been achieved. By employing quinoline N-oxides as the starting materials, the electrochemical C-H sulfonylation of electron-deficient quinolines was indirectly achieved at room temperature and a variety of sulfonylated quinoline derivatives were synthesized in modest to high yield with excellent regioselectivity. Notably, this protocol is the first example for synthesizing sulfonylated electron-deficient heteroarenes/arenes through electrochemistry.
- Jiang, Minbao,Yuan, Yong,Wang, Tao,Xiong, Yunkui,Li, Jun,Guo, Huijiao,Lei, Aiwen
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p. 13852 - 13855
(2019/11/21)
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- Regioselective Sulfonation of Aromatic Compounds over 1,3-Disulfonic Acid Imidazolium Chloride under Aqueous Media
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1,3-Disulfonic acid imidazolium chloride ([Dsim]Cl), as a Bronsted acidic ionic liquid, is introduced for the sulfonation of aromatic compounds by in situ generation of sulfuric acid at 50 °C under mild conditions and in aqueous medium.
- Moosavi-Zare, Ahmad Reza,Zolfigol, Mohammad Ali,Noroozizadeh, Ehsan
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p. 1682 - 1684
(2016/07/06)
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- Method for synthesizing p-nitrobenzenesulfonic
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The invention relates to a method for synthesizing p-nitrobenzenesulfonic and belongs to the technical field of organic chemical synthesis. The method comprises the steps of subjecting benzene serving as the raw material and sulfuric acid to sulfonation to obtain benzenesulfonic acid; pumping chlorine into benzenesulfonic acid, adding deionized water and zinc dibutyl dithiocaarbamate, and stirring the mixture; adding nitric acid and acetic anhydride into the mixture for water-bath heating, and then performing cooling through ice water; slowly adding a sodium hydroxide solution dropwise into the cooled mixture, performing heating reflux after dropping reaction, cooling the mixture to the room temperature, and obtaining p-nitrobenzenesulfonic through separation, recovery and drying. The method has the advantages that the reaction time is shortened by 30% of time needed by a 3-nitrobenzene acid synthesis method, pollution cannot be produced during reaction, and operation steps are simple.
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Paragraph 0008
(2016/10/07)
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- Synthetic method for 4-chloro-8-aminoquinoline
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The invention relates to a synthetic method for 4-chloro-8-aminoquinoline, belonging to the technical field of organic chemical synthesis. The method comprises the following steps: firstly adding benzene into concentrated sulfuric acid and carrying out sulfonation so as to obtain benzene sulfonic acid, then subjecting benzene sulfonic acid to mixing with water, polyethylene glycol and nitric acid, carrying out heating and stirring with zinc chloride, then carrying out reaction with iron and hydrochloric acid under stirring, carrying out anaerobic fermentation and desulfurization, then subjecting obtained fermented substances and chloropropanol to mixing and stirring, and finally carrying out reduction reaction so as to obtain the 4-chloro-8-aminoquinoline. The invention has the following beneficial effects: the synthetic method provided by the invention has simple operation steps and mild reaction conditions, can generate strong fluorescent characteristic in application process of the 4-chloro-8-aminoquinoline at the same time, and can be applied in detection of the contents of metal ions.
- -
-
Paragraph 0005; 0008
(2016/11/17)
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- A preparing method for phenol
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The invention relates to a preparing method for phenol. Benzene and concentrated sulfuric acid are adopted as raw materials. The method includes subjecting the raw materials in a certain ratio to polymerization, distillation, alkali fusion, acidification and crystallization. The mass ratio of the benzene to the concentrated sulfuric acid is 1.5-2.5:1. The concentrated sulfuric acid is concentrated sulfuric acid the concentration of which is 98%. The alkali fusion step is a step of adding benzenesulfonic acid into a container, adding sodium hydroxide powder the mass of which is 2-3 times of the mass of the benzene after the benzenesulfonic acid is fully fused, and continuously stirring for 1-3 h to produce sodium phenolate. The acidification step is a step of dissolving a mixture containing the sodium phenolate and other compounds with water, and bubbling in sulfur dioxide gas at room temperature under atmospheric pressure. The crystallization step is a step of cooling the solution, filtering, dissolving filter residue with distilled water the temperature of which is 65-75 DEG C, and cooling. The method is reasonable in design. Reactions are not performed at high temperature. The amounts of the acid and the sodium hydroxide are reduced. Equipment corrosion is low. A phenol yield is high.
- -
-
Paragraph 0020
(2016/12/07)
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- New (green) methodology for efficient hydrazine cleavage
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An efficient method for removal of the hydrazine group from (hetero)aromatic substrates has been developed. It can be realized both on a solid support and in solution by synthesis employing a low concentration solution of trimethylsilanolate in tetrahydrofuran or N,N-dimethylformamide. For water-soluble substrates, the reaction can be performed in water, highlighting the eco-friendly attributes of this methodology.
- Kubovi?ová, Lenka,Bürglová, Kristyna,Hlavá?, Jan
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supporting information
p. 4824 - 4828
(2016/06/13)
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- Kinetic and mechanistic studies on the oxidative decolourisation of orange-II dye with alkaline chloramine-T
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The mono-azo dye, Orange-II (acid orange 7), is mainly used to dye materials like textiles, paper, leather and cosmetics. It is important to understand the kinetic and mechanistic aspects of the oxidative decolourisation of Orange-II dye. A simple, efficient and cost-effective oxidation method is developed for the reaction. A detailed kinetic study of the oxidative decolourisation of orange-II dye with chloramine-T (CAT) in alkaline medium at 308 K has been carried out spectrophotometrically at 486 nm. The reaction shows a first-order dependence of rate both on [CAT]o and [Orange-II]o and an inverse-fractional- order on [OH-]. The reaction was studied at different temperatures and the thermodynamic parameters have been evaluated. The reaction was subjected to change in (i) ionic strength, (ii) p-toluenesulfonamide and (iii) chloride ions, and the effects of these on the reaction rate were determined. Oxidation products of Orange-II were characterised as 1,2-naphthaquinone and benzenesulfonic acid by GC-MS analysis. The observed kinetic results have been explained by a general mechanism to understand the elementary pathways of this redox system. The relevant kinetic modelling has been worked out.
- Vaz, Nirmala,Manjunatha,Puttaswamy
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p. 363 - 367
(2015/08/11)
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- Nucleophilic Substitution Reactions of 2,4-Dinitrophenyl X-Substituted-Benzenesulfonates and Y-Substituted-Phenyl 4-Nitrobenzenesulfonates with Azide Ion: Regioselectivity and Reaction Mechanism
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The second-order rate constants for reactions of 2,4-dinitrophenyl X-substituted-benzenesulfonates (4a-4f) and Y-substituted-phenyl-4-nitrobenzenesulfonates (5a-5f) with N3- ion have been measured spectrophotometrically. The reactions of 4a-4f proceed through S-O and C-O bond fission pathways competitively. Fraction of the S-O bond fission decreases rapidly as the substituent X in the benzenesulfonyl moiety changes from an electron-withdrawing group to an electron-donating group. The Hammett plots for reactions of 4a-4f are linear with ρX=1.87 and 0.56 for the S-O and C-O bond fission, respectively. The fact that the substituent X is further away from the reaction site of the C-O bond fission than that of the S-O bond fission is one reason for the smaller ρX value. The nature of the reaction mechanism (i.e., a stepwise mechanism in which expulsion of the leaving group occurs after the rate-determining step) is also responsible for the smaller ρX value obtained from the C-O bond fission. The Bronsted-type plot for the reactions of 5a-5f is linear with βlg=-0.63, which is typical for reactions reported previously to proceed through a concerted mechanism. Effects of substituents X and Y on regioselectivity and reaction mechanism are discussed in detail.
- Moon, Ji-Hyun,Kim, Min-Young,Han, So-Yeop,Um, Ik-Hwan
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p. 1360 - 1365
(2015/07/15)
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- RuCl3 Catalyzed and Uncatalyzed Oxidative Decolorization of Acid Orange 7 Dye with Chloramine-B in Acid Medium: Spectrophotometric, Kinetic and Mechanistic Study
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Acid orange 7, chemically known as sodium 4-[(2E)-2-(2-oxonaphthalen-1-ylidene)hydrazinyl]benzenesulfonate, is extensively used for dyeing textiles, paper and leather. The discharge of wastewater containing this dye, causes environmental and health related problems. Therefore, in the present research, we have developed optimum conditions for the facile oxidative decolorization of this dye with sodium N-chlorobenzenesulfonamide or chloramine-B (CAB). The kinetics and mechanism of oxidative decolorization of acid orange 7 dye with CAB in acidic medium have also been studied spectrophotometrically at 303 K in the presence and absence of RuCl3 catalyst. Under similar experimental conditions, the reaction exhibits a first-order dependence of rate each on [CAB]o and [dye]o, and an inverse-fractional-order dependence on [H+] for both the RuCl3 catalyzed and uncatalyzed reactions. The order with respect to RuCl3 is fractional. Activation parameters have been computed. Dielectric effect is negative in both the cases. Oxidation products of the acid orange 7 dye are identified as 1,2-naphthoquinone and benzenesulfonic acid by GC-MS data. The RuCl3 catalyzed reaction is about four fold faster than the uncatalyzed reaction. The chemical oxygen demand value of the dye was determined. The mechanistic pathways and kinetic modelings have been computed based on experimental results. The developed oxidative decolorization method is expected to be helpful to treat acid orange 7 dye present in wastewater after suitable modifications. (Chemical Equation Presented).
- Manjunatha, Adalagere Somashekar,Puttaswamy
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p. 1312 - 1321
(2015/08/06)
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- The synthesis of diarylsulfones with simple arenes and K2S2O8 through double C-S bond formation
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An unprecedented double C-S bond formation method has been developed to prepare both symmetric and unsymmetric diarylsulfones with simple arenes in a single step. This represents the first example that K2S2O8 can be employed as a highly effective sulfonating agent to synthesize diarylsulfones. The reaction demonstrates excellent reactivity, good functional group tolerance and high yields.
- Yang, Yiqing,Chen, Zhang,Rao, Yu
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supporting information
p. 15037 - 15040
(2014/12/11)
-
- Photocatalytic, optical and magnetic properties of Fe-doped ZnO nanoparticles prepared by chemical route
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Polyvinyl pyrrolidone (PVP) capped Zn1-xFe xO (0.000001 ≤ x ≤ 0.1) nanocrystalline powders were prepared by chemical co-precipitation technique. Structural, optical and magnetic characterizations of the annealed samples were performe
- Kumar, Khanesh,Chitkara, Mansi,Sandhu, Inderjit Singh,Mehta,Kumar, Sanjeev
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p. 681 - 689
(2014/01/06)
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- 1-Acetylferroceneoxime-based photoacid generators: Application towards sol-gel transformation and development of photoresponsive polymer for controlled wettability and patterned surfaces
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A newsworthy class of carboxylate and sulfonate esters of 1-acetylferroceneoxime has been demonstrated as non-ionic photoacid generators (PAGs). PAGs based on 1-acetylferroceneoxime were synthesized in good yields by simple treatment of 1-acetylferroceneoxime with various carboxylic and sulfonyl chlorides. Newly developed PAGs of 1-acetylferroceneoxime showed good absorbance >350 nm. On irradiation using UV light (≥365 nm), carboxylates and sulfonates of 1-acetyl ferroceneoxime in aqueous acetonitrile solvent underwent efficient homolytic cleavage of N-O bond, resulting in the generation of carboxylic and sulphonic acids, respectively, with high chemical and good quantum yields. Further, we demonstrated the application of our newly developed 1-acetylferroceneoxime-based PAGs for gelation of biopolymer alginate on UV irradiation. More interestingly, we synthesized a ferroceneoxime bound photoresponsive polymer, 1-acetylferroceneoxime-polycaprolactone (AFO-PCL), and demonstrated its controlled surface wettability and generation of patterned surfaces.
- Ikbal, Mohammed,Banerjee, Rakesh,Barman, Shrabani,Atta, Sanghamitra,Dhara, Dibakar,Singh, N.D. Pradeep
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p. 4622 - 4630
(2014/06/09)
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- Supported iron oxide nanoparticles: Recoverable and efficient catalyst for oxidative S-S coupling of thiols to disulfides
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Supported iron oxide nanoparticles are found to be efficient and recoverable catalyst in the selective oxidation of thiols to their corresponding disulfides using hydrogen peroxide as green oxidant at room temperature. The protocol features an easy work-up, simplicity and the utilizing mild reaction conditions, as well as high selectivity toward disulfides, are highly advantageous compared to alternative reported methodologies. The supported iron oxide nanoparticles could be easily recovered and reused several times without any loss of activity. ICP-MS results prove that there is no metal leaching observed, and demonstrating the stability of the catalyst under the reaction conditions.
- Rajabi, Fatemeh,Kakeshpour, Tayeb,Saidi, Mohammad Reza
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- Synthesis of sulfonyl chlorides and sulfonic acids in SDS micelles
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H2O2/POCl3 is found to be a reactive reagent system that can be used in sodium dodecyl sulfate (SDS) micellar solution in aqueous media for the direct oxidative chlorination of thiol and di-sulfide derivatives to give the desired sulfonyl chlorides. The oxidation of thiols and disulfides to sulfonic acids with this system is also reported. In most cases, these reactions are highly selective, simple, and clean, affording products in excellent yields and high purity. Georg Thieme Verlag Stuttgart · New York.
- Bahrami, Kiumars,Khodaei, Mohammad M.,Abbasi, Jamshid
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experimental part
p. 316 - 322
(2012/03/26)
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- Optimization of HNO production from N, O - Bis -acylated hydroxylamine derivatives
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A wide range of N,O-bis-acylated hydroxylamine derivatives with chloro or arenesulfonyl leaving groups, and a related set of N-hydroxy-N-acylsulfonamides, have been synthesized and evaluated for nitroxyl (HNO) production. Mechanistic studies have revealed that the observed aqueous chemistry is more complicated than originally anticipated, and have been used to develop a new series of efficient HNO precursors (4u-4x, 7c-7d) with tunable half-lives.
- Sutton, Art D.,Williamson, Morgan,Weismiller, Hilary,Toscano, John P.
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p. 472 - 475
(2012/03/26)
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- Development of 1-Hydroxy-2(1H)-quinolone-Based Photoacid Generators and Photoresponsive Polymer Surfaces
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A new class of carboxylate and sulfonate esters of 1-hydroxy-2(1H)- quinolone has been demonstrated as nonionic photoacid generators (PAGs). Irradiation of carboxylates and sulfonates of 1-hydroxy-2(1H)-quinolone by UV light (γ≥310 nm) resulted in homolysis of weak N-O bond leading to efficient generation of carboxylic and sulfonic acids, respectively. The mechanism for the homolytic N-O bond cleavage was supported by time-dependent DFT calculations. Photoresponsive 1-(p-styrenesulfonyloxy)-2-quinolone-methyl methacrylate (SSQL-MMA) and 1-(p-styrenesulfonyloxy)-2-quinolone-lauryl acrylate (SSQL-LA) copolymers were synthesized from PAG monomer 1-(p-styrenesulfonyloxy) -2-quinolone, and subsequently controlled surface wettability was demonstrated for the above-mentioned photoresponsive polymers. Copyright
- Ikbal, Mohammed,Banerjee, Rakesh,Atta, Sanghamitra,Jana, Avijit,Dhara, Dibakar,Anoop, Anakuthil,Singh, N. D. Pradeep
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p. 11968 - 11975
(2012/10/29)
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- Synthesis, photophysical and photochemical properties of photoacid generators based on N-hydroxyanthracene-1,9-dicarboxyimide and their application toward modification of silicon surfaces
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We have introduced a series of nonionic photoacid generators (PAGs) for carboxylic and sulfonic acids based on N-hydroxyanthracene-1,9-dicarboxyimide (HADI). The newly synthesized PAGs exhibited positive solvachromatic emission (λmax(hexane) 461 nm, λmax(ethanol) 505 nm) as a function of solvent polarity. Irradiation of PAGs in acetonitrile (ACN) using UV light above 410 nm resulted in the cleavage of weak Na-O bonds, leading to the generation of carboxylic and sulfonic acids in good quantum and chemical yields. Mechanism for the homolytic Na-O bond cleavage for acid generation was supported by time-dependent density functional theory (TD-DFT) calculations. More importantly, using the PAG monomer N-(p-vinylbenzenesulfonyloxy)anthracene- 1,9-dicarboxyimide (VBSADI), we have synthesized N-(p-vinylbenzenesulfonyloxy) anthracene-1,9-dicarboxyimidea-methyl methacrylate (VBSADI-MMA) and N-(p-vinylbenzenesulfonyloxy)anthracene-1,9-dicarboxyimidea-ethyl acrylate (VBSADI-EA) copolymer through atom transfer radical polymerization (ATRP). Finally, we have also developed photoresponsive organosilicon surfaces using the aforementioned polymers.
- Ikbal, Mohammed,Banerjee, Rakesh,Atta, Sanghamitra,Dhara, Dibakar,Anoop, Anakuthil,Singh, N. D. Pradeep
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p. 10557 - 10567
(2013/02/22)
-
- COMPOSITION COMPRISING PERFLUOROPOLYETHER
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A composition is disclosed which comprises an aryl perfluoropolyether, optionally a halogenated oil, and further optionally a thickening agent. The composition can be used as a lubricant itself or as an additive to an oil or grease lubricant and can withstand temperatures higher than 300° C. without decomposition. The halogenated oil can be a perfluoropolyether, a fluorosilicone, a polytrifluorochloroethylene, or combinations of two or more thereof. The thickening agent can be finely divided silica, boron nitride, clay, soap, poly(tetrafluoroethylene), clay, talc, silica, titanium dioxide, polydimethylsiloxane, polyurea, polyurethane, or combinations of two or more thereof.
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- The mechanisms of acid-catalyzed hydrolysis of n-(4-substituted arylthio) phthalimides
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The acid-catalyzed hydrolysis of N-(4-substitutedarylthio)phthalimides was studied in aqueous solutions of sulfuric, perchloric, and hydrochloric acids at 40.0 ±0.1° C. Analysis of the data by the excess acidity method, activation parameters, and substituent effects indicates hydrolysis by an A-2 mechanism at low acidity. At higher acidities, a changeover to an A-1 mechanism is observed.
- Kutuk, Halil,Yakan, Hasan
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p. 1460 - 1469
(2011/10/05)
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- Sensitive kinetic-spectrophotometric determination of protein based on its inhibitive effect on the decolorization of dibromo-p-methylsulfonazo
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A novel kinetic spectrophotometric method for the determination of protein is developed on the basis of kinetic effect of bovine serum albumin (BSA) on the inhibitory effect on the oxidation reaction of dibromo-p-methylsulfonazo by potassium periodate. The absorbance differences (δA) between inhibitive and non-inhibitive systems are maximum at 558 nm. The absorbance difference is linearly related with the concentration of bovine serum albumin over the range of 5.0-55.0 μg/mL and fitted the equation: δA = 8.988 × 10 -3 C (C: μg/mL) + 0.0185, with a regression coefficient of 0.9960 at the wavelength. The detection limit of the method was 1.55 μg/mL. The method was used to determine protein in pure milk. The relative standard deviation was 1.58 and 1.49 % for 13 replicate determinations. The recovery of the standard addition was 101.1 and 99.33 %.
- Yu, Hui,Zhai, Qing-Zhou,Hu, Wei-Hua,Xiang, Song-Bai
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experimental part
p. 3984 - 3988
(2012/01/13)
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- Photoacid generators (PAGs) based on N-acyl-N-phenylhydroxylamines for carboxylic and sulfonic acids
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Simple and efficient photoacid generators (PAGs) for carboxylic and sulfonic acids based on N-acyl-N-phenylhydroxylamines have been demonstrated. Irradiation of o-carboxylates and thermally rearranged o-arenesulfonates of N-acyl-N-phenylhydroxylamines using UV light (≥254 nm) in aqueous methanolic solution resulted in efficient generation of carboxylic and sulfonic acids, respectively. The carboxylic acid generation ability of N-acyl-N- phenylhydroxylamines was found to be dependent on their N-acyl substituents. Further, polymer bearing o-arenesulfonates of N-acyl-N-phenylhydroxylamine was synthesized and demonstrated as PAG for sulfonic acids.
- Ikbal, Mohammed,Jana, Avijit,Singh, N.D. Pradeep,Banerjee, Rakesh,Dhara, Dibakar
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experimental part
p. 3733 - 3742
(2011/06/21)
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- Removal of electrophilic potential genotoxic impurities using nucleophilic reactive resins
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Potential genotoxic impurities (PGI) are chemical compounds that could potentially damage DNA and lead to mutation. Controlling the occurrence of PGIs in active pharmaceutical ingredients (APIs) poses a big challenge for chemists, as levels of these compounds must be reduced well below the amounts required for other types of less toxic impurities. In situations where formation of PGIs cannot be avoided, an ideal solution would allow the complete removal of PGIs after the synthesis is complete, for example, by recrystallization, preparative chromatography or other downstream processing approaches. Some disadvantages of using these approaches are potential high yield loss, high solvent consumption, and additional time and resources required for process development. In this work, we present a simple and rapid approach to remove electrophilic PGIs from APIs. A selected nucleophilic resin can be added to the final API solution to reduce or totally remove the PGI. Esters of methanesulfonic acid (MSA), benzenesulfonic acid (BSA), and ρ-toluenesulfonic acid (pTSA) were used as model electrophilic PGIs. Several nucleophilic resins were screened, and the resins with the highest efficiency of PGI removal were chosen. A recommended procedure is presented for the removal of MSA, BSA, and pTSA esters. The kinetics of PGI removal, resin loading capacity, solvent effects, and API matrix effects are demonstrated.
- Lee, Claire,Helmy, Roy,Strulson, Christopher,Plewa, Jolanta,Kolodziej, Elizabeth,Antonucci, Vincent,Mao, Bing,Welch, Christopher J.,Ge, Zhihong,Al-Sayah, Mohammad A.
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experimental part
p. 1021 - 1026
(2011/03/20)
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- The SN3-SN2 spectrum. Rate constants and product selectivities for solvolyses of benzenesulfonyl chlorides in aqueous alcohols
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Rate constants for a wide range of binary aqueous mixtures and product selectivities (S) in ethanol - Water (EW) and methanol-water (MW) mixtures, are reported at 25 °C for solvolyses of benzenesulfonyl chloride and the 4-chloro - Derivative. S is defined as follows using molar concentrations: S =([ester product]/[acid product]) × ([water solvent]/[alcohol solvent]). Additional selectivity data are reported for solvolyses of 4-Z-substituted sulfonyl chlorides (Z - OMe, Me, H, Cl and NO2) in 2, 2, 2-trifluoroethanol-water. To explain these results and previously published data on kinetic solvent isotope effects (KSIEs) and on other solvolyses of 4-nitro and 4-methoxybenzenesulfonyl chloride, a mechanistic spectrum involving a change from third order to second order is proposed. The molecularity of these reactions is discussed, along with new term 'SN3-SN2 spectrum' and its connection with the better established term 'S N2-SN1 spectrum'. Copyright
- Bentley, T. William,Jones, Robert O,Kang, Dae Ho,Koo, Sun
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scheme or table
p. 799 - 806
(2010/06/16)
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- Selective oxidation reactions of diaryl- and dialkyldisulfides to sulfonic acids by CH3ReO3/hydrogen peroxide
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Diaryl- and dialkyl disulfides were oxidized in acetonitrile at 20 °C by CH3ReO3/H2O2 oxidant system to yield selectively the corresponding sulfonic acids in short reaction times and in high yields.
- Ballistreri, Francesco P.,Tomaselli, Gaetano A.,Toscano, Rosa M.
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experimental part
p. 6231 - 6232
(2010/01/11)
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- A kinetic study of acid-catalyzed hydrolysis of some arylsulfonyl phthalimides
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The acid-catalyzed hydrolysis of arylsulfonyl phthalimides was studied in aqueous solutions of sulfuric, perchloric, and hydrochloric acid at 35.0 ± 0.1C. Analysis of the data by the excess acidity method and activation parameters, as well as substituent and solvent isotope effects, indicate hydrolysis by an A-2 mechanism at low acidity. At higher acidities, a changeover to an A-1 mechanism is observed.
- Kutuk, Halil,Ozturk, Seyhan
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scheme or table
p. 332 - 340
(2009/09/25)
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- Selective and mild oxidation of thiols to sulfonic acids by hydrogen peroxide catalyzed by methyltrioxorhenium
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Aromatic and aliphatic thiols are oxidized in acetonitrile at 20 °C by hydrogen peroxide in the presence of methyltrioxorhenium as the catalyst to yield the corresponding sulfonic acids in high isolated yields (85-94%).
- Ballistreri, Francesco P.,Tomaselli, Gaetano A.,Toscano, Rosa M.
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p. 3291 - 3293
(2008/09/20)
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- Catalysis and inhibition of ester hydrolysis in the presence of resorcinarene hosts functionalized with dimethylamino groups
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Complexation and catalysis of two calixresorcinarene (RES) derivatives with nucleophilic N,N-dimethylamino functions attached to their upper rims in the hydrolysis of carboxylate and sulfonate esters of 4-nitrophenol and 2,4-dinitrophenol have been investigated. Rate constants obey the complexation equation: kobs = kb × Ks + k c[Host]/Ks + [Host] Values of the dissociation constant (Ks) of the complexes are within the range exhibited by other systems such as cyclodextrins-ester complexes. The reactions of sulfonate esters only exhibit inhibition by the macrocyclic hosts. The reactions of the carboxylate esters exhibit catalysis and inhibition depending on the pH of the system. It is proposed that the dimethylamino function in RES3 and RES5 behaves as a nucleophile to form a reactive acylammonium species which subsequently decomposes and regenerates the catalytic amine. In the reaction of substituted phenyl acetates with RES3 the effective charge on the leaving oxygen in the complexed state (+0.88) is slightly more positive than that in the free ester (+0.70). The effective charge on the leaving oxygen in the transition structure is substantially more positive (+0.04 units) than in a model intramolecular reaction of tertiary dimethylamines with aryl esters (-0.53 units). The influence of the host on the reaction in the complex includes an electronic component which is ascribed to solvation of the transition structure of the rate-limiting step by water molecules located within the cavity of the host. It is suggested that this solvation is stronger than that occurring in the transition state for the model intramolecular reaction. Copyright
- Cevasco, Giorgio,Thea, Sergio,Vigo, Daniele,Williams, Andrew,Zaman, Flora
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p. 630 - 636
(2008/02/08)
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- Benzenesulfonyl chloride with primary and secondary amines in aqueous media - Unexpected high conversions to sulfonamides at high pH
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We have determined pH-yield profiles under pseudo-first-order conditions of the reactions of benzenesulfonyl chloride with a set of primary and secondary water-soluble alkylamines, and have found with certain amines, such as dibutylamine, a profile taking the form of a sigmoid pH-yield curve with relatively high yields of the sulfonamide persisting with increasing basicity up to and including 1.0 mol/L sodium hydroxide. This behaviour is quantitatively accounted for by invoking, in addition to the usual second-order reaction of the sulfonyl chloride with the amine, two third-order terms (i) one first-order in sulfonyl chloride, amine and hydroxide anion, and (H) another first-order in sulfonyl chloride and second-order in the amine. The importance of the third-order terms correlates approximately with the total number of alkyl carbon atoms in the amine, and this in turn is regarded as related to the hydrophobic character of the amine. Experiments to test this picture included: (i) observation of a bell-shaped curve with bis(2-methoxyethyl)amine, (H) in the reaction of dibutylamine in THF-H2O (1:1), and also (iii) in the reaction of dibutylamine in 1.0 mol/L tetrabutylammonium bromide, and (iv) increase in the contributions of the third-order terms in 1.0 mol/L aqueous sodium chloride. Preparative reactions with dibutylamine, 1-octylamine, and hexamethylenimine in 1.0 mol/L aqueous sodium hydroxide with a 5% excess of benzenesulfonyl chloride gave, respectively, 94%, 98%, and 97% yields of the corresponding sulfonamides.
- King, James F.,Gill, Manjinder S.,Ciubotaru, Petru
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p. 1525 - 1535
(2007/10/03)
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- A novel method for sulfonation of aromatic rings with silica sulfuric acid
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Direct and chemoselective sulfonation of aromatic compounds with silica sulfuric acid in 1,2-dichloeoethane or under solvent-free conditions.
- Hajipour, Abdol R.,Mirjalili, Bi Bi F.,Zarei, Amin,Khazdooz, Leila,Ruoho
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p. 6607 - 6609
(2007/10/03)
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- Effect of Amine Nature on Reaction Rate and Mechanism in Nucleophilic Substitution Reactions of 2,4-Dinitrophenyl X-Substituted Benzenesulfonates with Alicyclic Secondary Amines
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Second-order rate constants have been measured for reactions of 2,4-dinitrophenyl X-substituted benzenesulfonates with a series of alicyclic secondary amines. The reaction proceeds through S-O and C-O bond fission pathways competitively. The S-O bond fission occurs more dominantly as the amine basicity increases and the substituent X in the sulfonyl moiety becomes more strongly electron withdrawing, indicating that the regioselectivity is governed by the amine basicity as well as the electronic nature of the substituent X. The S-O bond fission proceeds through an addition intermediate with a change in the rate-determining step at pKa° = 9.1. The secondary amines are more reactive than primary amines of similar basicity for the S-O bond fission. The k1 value has been determined to be larger for reactions with secondary amines than with primary amines of similar basicity, which fully accounts for their higher reactivity. The second-order rate constants for the S-O bond fission result in linear Yukawa-Tsuno plots while those for the C-O bond fission exhibit poor correlation with the electronic nature of the substituent X. The distance effect and the nature of reaction mechanism have been suggested to be responsible for the poor correlation for the C-O bond fission pathway.
- Um, Ik-Hwan,Chun, Sun-Mee,Chae, Ok-Mi,Fujio, Mizue,Tsuno, Yuho
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p. 3166 - 3172
(2007/10/03)
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- Clean-chemistry sulfonation of aromatics
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A solution of TFAA/H2SO4 is an atom-efficient liquid-phase system for rapid sulfonation of aromatic structures; H2SO4 is consumed stoichiometrically and the spent trifluoroacetic anhydride (TFAA) is readily recovered as trifluoroacetic acid (TFA) which can be recycled to TFAA.
- Corby, Brian W.,Gray, Anthony D.,Meaney, Padraig J.,Falvey, Michael J.,Lawrence, Gregory P.,Smyth, Timothy P.
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p. 326 - 327
(2007/10/03)
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- Competitive Reaction Pathways in the Nucleophilic Substitution Reactions of Aryl Benzenesulfonates with Benzylamines in Acetonitrile
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The reactions of aryl benzenesulfonates (YC6H4SO2OC6H4Z) with benzylamines (XC6H4CH2NH2) in acetonitrile at 65.0 deg C have been studied. The reactons proceed competitevely by S-O (kS-O) and C-O (kC-O) bond scission, but the former provides the major reaction pathway. On the basis of analysis of the Hammet and Broensted coefficients together with the cross-interaction constants ρXY, ρYZ, and ρXZ, stepwise mechanisms are proposed in which the S-O bond cleavage proceeds by rate-limiting formation of a trigonal-bipyramidal pentacoordinate (TBP-5C) intermediate, whereas the C-O bond scission takes place by rate-limiting expulsion of the sulfonate anion (YC6H4SO3-) from a Meisenheimer-type complex.
- Choi, Jin Heui,Lee, Byung Choon,Lee, Hai Whang,Lee, Ikchoon
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p. 1277 - 1281
(2007/10/03)
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- The quest for sulfoquinone imine intermediates in the reaction of sulfanilic acid derivatives with nucleophiles
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Data from kinetic and trapping studies suggest that the alkaline hydrolyses of sulfanilyl chloride and of the corresponding N-acetyl derivative follow different reaction pathways. While results for the latter compound are fully consistent with the occurrence of the common associative, SN2 mechanism, the former shows somewhat different features suggesting the incursion of a mechanism of the dissociative type involving a sulfoquinone imine species as a reaction intermediate. The alkaline hydrolyses of the corresponding sulfonyl fluorides and 2,4-dinitrophenyl esters, whose leaving groups are worse than Cl- as leaving groups, are all associative.
- Thea, Sergio,Vigo, Daniele,Cevasco, Giorgio
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p. 611 - 614
(2007/10/03)
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- Amidino derivatives and their use as thrombin inhibitors
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There is provided compounds of formula I, wherein R1, R2, R3, Y, n and B have meanings given in the description which are useful as competitive inhibitors of trypsin-like proteases, such as thrombin, and in particular in the treatment of conditions where inhibition of thrombin is required (e.g. thrombosis) or as anticoagulants.
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- Nucleophilic reactivity towards electrophilic fluorinating agents: Reaction with N-fluorobenzenesulfonimide ((PhSO2)2NF)
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Second-order rate constants for the reaction of N-fluorobenzenesulfonimide (FBS) with nucleophilic reagents, kNu (M-1 s-1), have been measured in aqueous solution at 25°C. Analysis of the reaction products shows that soft polarizable nucleophiles (I-, SCN-, Br-) react at fluorine, whereas hard nucleophiles (oxygen and nitrogen nucleophiles) react at sulfur. The ambident behaviour of this electrophile seems to be related to the relative contribution of electrostatic and orbital interactions in reaching the transition state. The preferential reaction of soft nucleophiles at fluorine and the correlation of kNu values with the one-electron oxidation potentials of the nucleophiles in water suggest that nucleophilic reactivity at fluorine is largely determined by the ease of one-electron transfer from the nucleophile to the electrophile. Nucleophilic addition to fluorine is far more sensitive to the nature of the attacking nucleophile than the corresponding reactions at both saturated (n scale) and unsaturated carbon (N+ scale). Comparison of the rate constants for the reaction of nucleophiles at the sulfonyl group with those for reaction of the same nucleophiles with 2,4-dinitrophenyl acetate reveals a similar reactivity pattern for sulfonyl sulfur and carbonyl carbon as electrophilic centres.
- Antelo, Juan M.,Crugeiras, Juan,Leis, J. Ramon,Rios, Ana
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p. 2071 - 2076
(2007/10/03)
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- Oxidation of thiols with hydrogen peroxide under phase transfer catalysis conditions
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Theophenol was shown to be oxidized with hydrogen peroxide under conditions of phase transfer catalysis in the presence of sodium metavanadate to afford benzenesulfonic acid, diphenyl disulfide, phenyl benzenesulfonate, and diphenyl sulfone. The yield of oxidation products increases with increasing temperature, catalyst concentration, and lipophilicity of the phase transfer catalyst.
- Lesnugin,Anisimov,Tarakanova
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p. 423 - 425
(2007/10/03)
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- Phenylthio-derivatives of α-methylene-γ-lactones as pro-drugs of cytotoxic agents
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A series of substituted phenylthio-derivatives of grosheimin (1), a natural cytotoxic guaianolide, were investigated with the aim of providing insight into their mechanism of action as cytotoxic agents against KB cell lines. Hydrolysis data, kinetics, in the presence and in the absence of H2O2, and the valuation of lipophilicity were correlated with cytotoxicity values and with Hammett-σ-values of substituents (R) at the thiophenol ring. These compounds behave as 'pro-drugs' which release the cytotoxic agent grosheimin by sulphur-oxidation promoted by H2O2 and subsequent retro- elimination which depends on the nature and position of the R substituent.
- Fardella, Giuseppe,Barbetti, Paolo,Grandolini, Giuliano,Chiappini, Ione,Ambrogi, Valeria,Scarcia, Vito,Furlani Candiani, Ariella
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p. 515 - 523
(2007/10/03)
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- Reactivity of sterically hindered aromatic sulfonic acid derivatives: VII.* hydrolysis of arenesulfonyl chlorides in aqueous acetonitrile
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Hydrolysis of sterically hindered arenesulfonyl chlorides in aqueous acetonitrile is accelerated by both electron-acceptor and some electron-donor substituents in the benzene ring. A multifactor kinetic model of the process is proposed. 1998 MAHK Hayka/Interperiodica Publishing.
- Rubleva,Krut'ko,Mitchenko
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p. 1006 - 1009
(2007/10/03)
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- Therapeutic agent for osteoporosis and triazepine compound
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Therapeutic agents for osteoporosis comprising, as an active ingredient, a triazepine compound of the formula ?I! STR1 wherein R1 is aryl or heteroaryl; R2 is hydrogen atom, hydroxy, halogen atom or lower alkyl; R4 is hydrogen atom or halogen atom, or R2 and R4 form carbonyl combinedly together with the carbon atom to which they bond; R3 is hydrogen atom, lower alkyl, lower alkoxy, cycloalkyl, aryl, heteroaryl, --X--Y wherein X is --(CH2)m --, --CO--, --COCH2 --, --NH--, --NHCH2 --, --CH2 NH--, --CH2 NHCO--, --OCH2 --, --(CH2)n O-- or --CH2 S-- and Y is halogen atom, cycloallyl, aryl or heteroaryl; and A is benzene ring or thiophene ring, or a salt thereof, novel triazepine compounds, and intermediate triazepine compounds for producing these triazepine compounds. The triazepine compounds of the formula ?I! have superior bone resorption-inhibitory action and are useful as therapeutic agents for osteoporosis.
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- Oxidative hydrolysis of phosphorus(V) esters of thiols by peroxymonosulfate ion. Reactions of peroxymonosulfate ion with phosphorus(V) esters of thiols
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Peroxymonosulfate ion, HSO5-, as Oxone, readily converts phosphorus(V) esters of thiols into the phosphorus(V) and sulfonic acids. The esters were Ph2PO·SC6H4R(p) with R=MeO (1a), Me (1b), H (1c), Cl (1d) and NO2 (1e), (EtO)2PO·SPh (2), Ph2OI·SEt (3) and PhPO(OEt)SEt (4). Reactions are first order in each reactant and second-order rate constants, k2, for 1a-e fit the Hammett equation with ρ=-0.46. The rate constants increase markedly with increasing water content of H2O-MeCN, the activation enthalpies are low and the entropies are negative. Despite the low value of -ρ, these esters are much less reactive than thiol ethers, but the rate constants of reactions of these compounds and acyl thiols qualitatively follow the ionization potentials of the ethers and the esters.
- Blasko, Andrei,Bunton, Clifford A.,Kumar, Anurag
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p. 427 - 434
(2007/10/03)
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- Photoinduced electron transfer reactions of benzyl phenyl sulfides promoted by 9,10-dicyanoanthracene
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The photoinduced oxidation of benzyl phenyl sulfides 1-3 has been investigated in MeCN using 9,10-dicyanoanthracene as sensitizer in the presence of O2. In this reaction a sulfide radical cation is formed, which undergoes one or more of the three main reaction pathways opened to these species: C-S bond cleavage, C-H bond cleavage and S-oxidation. The former route (leading to benzylic products) was observed with all the substrates investigated, whereas the second (leading to benzaldehydes) operates only with 1 and 2. Formation of sulfoxides was found solely in the photooxidation of 1. The influence of substrate structures on the relative contribution of the three pathways as well as the role of O2- in this respect are discussed.
- Baciocchi, Enrico,Crescenzi, Cristina,Lanzalunga, Osvaldo
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p. 4469 - 4478
(2007/10/03)
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- Kinetics and mechanism of the aminolysis of cycloalkylmethyl arenesulfonates
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Nucleophilic substitution reactions of cycloalkylmethyl arenesulfonates (CmH2n-1 CH2OSO2C6H4Z) with anilines (XC6H4NH2) in methanol at 65.0 °C were studied. The reactivity order (n=4>6>7>5) reflects largely the order of steric effect of the ring size (SEs term) except for n=5, which exhibits the least reactivity. This reversal of the order for n=5 is considered to result from large rate retardation due to polar effect of the ρ*σ* term. Application of the Taft equation to the rate data for n=5 and 6 gives ρ=17·4 and 5=2·3 with correlation coefficient of 0·90. The σ* values for n=4 and 7 are estimated to be - 0·23 and - 0·11, respectively. The positive ρxz values of ca 0·3 are consistent with previous results for the reactions at primary reaction centers.
- Oh, Hyuck Keun,Song, Se Jeong,Jo, Dong-Soo,Lee, Ikchoon
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- Molecular rearrangement of sulfur compounds(VII). A pyrolysis of arenesulfonylhydrazine derivatives
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N-Phenyl-N′-arenesulfonylhydrazine(I-II) on pyrolysis by refluxing in an atmosphere of nitrogen at ca. 240°C give SO2, H2S, NH3, arene, biaryl, aniline, azobenzene, diaryl sulfide, diaryl sulfone, arenesulfonic acid, phenyl hydrazine and carbazole derivatives. N-Benzylidene-N′-benzenesulfonylhydrazone(III) on similar treatment gives the previous products in addition to benzonitrile, bibenzyl, stilbene, 2-phenylindole and 2,3,4,5-tetraphenylthiophene. The observed results have been interpreted in terms of a free radical mechanism involving the homolysis of N - N and S - N bonds.
- Gaber, Abd El-Aal M.,Atalla, Ahmed A.,Kamal El-Dean, Adel M.
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p. 131 - 136
(2007/10/03)
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- Differentiation of catalytic pathways in the hydrolysis of benzenesulfonyl chloride
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General base and nucleophilic pathways in the hydrolysis of benzenesulfonyl chloride in aqueous acetonitrile, catalyzed by tertiary amines, were kinetically distinguished by the effect of chloride ion and water on the reaction rate. The modified Taft equation was used to show that both pathways are more sensitive to inductive rather than steric effects of substituents in the amines. 1996 MAEe Cyrillic signΚ Hayκa/Interperiodica Publishing.
- Bezrodnyi,Kiprya,Skrypnik
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p. 511 - 518
(2007/10/03)
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