Journal articles: 'Acide sulfonique'

1

Garrigues, Bernard, Lucien Lopez Et, and Michel Mulliez. "ACIDES α ET β AMIDINO SULFONIQUES." Phosphorus, Sulfur, and Silicon and the Related Elements 57, no. 3-4 (March 1991): 195–202. http://dx.doi.org/10.1080/10426509108038850.

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Sladek, Alexander, Wolfgang Schneider, Klaus Angermaier, Andreas Bauer, and Hubert Schmidbaur. "Polynuclear Gold(I) Complexes of Mercaptocarboxylic Acids." Zeitschrift für Naturforschung B 51, no. 6 (June 1, 1996): 765–72. http://dx.doi.org/10.1515/znb-1996-0602.

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Abstract In a search for air-stable and water-soluble mercapto compounds of gold with a high gold content, benzylthiol, a-m ercapto-acetic acid, β-mercapto-propionic acid, and thiosalicylic acid were converted into aurated sulfonium salts by treatment with reagents of the type [(R3P)Au]3O+ BF4- or [(R3)P)Au]+ BF4-. - BzSH served as a mono-functional model thiol, which was converted into BzS[Au(PMe3)]2+ BF4- (1). The small tertiary phosphine was chosen in order to minimize steric effects. In the crystal the cations are associated into centrosymmetrical dimers through short Au-A u contacts (auriophilicity). - The two carboxylic acids with thiol functions, HSCH2COOH and HSCH2CH2COOH, gave triply aurated species of the type {[(Ph3P)Au]2S(CH2)nCOOAu(PPh3)}+ BF4- (2: n = 2, 3; n = 3). The crystal structure analysis of the representative compound 2 showed again the presence of centrosymmetrical cation dimers with geometrical details of the sulfonium part of the molecules very similar to those of the reference compound 1. In addition, the carboxyl groups in 2 and 3 bear a (phosphine)gold unit mono-hapto bound at one of the oxygen atoms. -2-HS-C6H4-COOH was converted into a sulfonium salt {[(Ph3P)Au]2S-C6H4-COOH}+ BF4- (4), which crystallizes free of solvent from dry dichloromethane, and as a monohydrate with one mole of dichloromethane (4a = 4 H2O-CH2CI2) from hydrous CH2CI2. In the solvent-free crystalline phase (4) the cations are associated into dimers with the usual intermolecular double A u-A u contacts, but in 4a there are monomeric cations with the water molecule hydrogen-bonded to the carboxylic acid function

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3

Li, Pingfan. "Sulfur-Mediated Reactions through Sulfonium Salts and Ylides." Synlett 32, no. 13 (March 5, 2021): 1275–80. http://dx.doi.org/10.1055/a-1409-0906.

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AbstractThis Account discusses several new reaction methods developed in our group that utilize sulfur-mediated reactions through sulfonium salts and ylides, highlighting the interplay of rational design and serendipity. Our initial goal was to convert aliphatic C–H bonds into C–C bonds site-selectively, and without the use of transition-metal catalysts. While a proof-of-concept has been achieved, this target is far from being ideally realized. The unexpected discovery of an anti-Markovnikov rearrangement and subsequent studies on difunctionalization of alkynes were much more straightforward, and eventually led to the new possibility of asymmetric N–H insertion of sulfonium ylides through Brønsted acid catalysis.1 Introduction2 Allylic/Propargylic C–H Functionalization3 Anti-Markovnikov Rearrangement4 Difunctionalization of Alkynes5 Asymmetric N–H Insertion of Sulfonium Ylides6 Conclusion

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Oost, Rik, James D. Neuhaus, Antonio Misale, Ricardo Meyrelles, Luís F. Veiros, and Nuno Maulide. "Catalyst-dependent selectivity in sulfonium ylide cycloisomerization reactions." Chemical Science 9, no. 35 (2018): 7091–95. http://dx.doi.org/10.1039/c8sc02815j.

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An unusual example of π-acid catalyst-dependent selectivity in the cycloisomerization of alkene-tethered sulfonium ylides affords cyclopropanes or dihydrofurans with excellent control of chemoselectivity.

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5

Et. al., R. Joy Salomi,. "An Approximate Analytical Solution Of Nonlinear Equations In N-Aminopiperidine Synthesis: New Approach Of Homotopy Perturbation Method)." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 1S (April 11, 2021): 595–605. http://dx.doi.org/10.17762/turcomat.v12i1s.1935.

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the synthesis of N-aminopiperidine (NAPP) using hydroxylamine-O-sulfonic acid (HOSA) is based on system of nonlinear rate equations. The new approach to homotopy perturbation method is applied to solve the nonlinear equations. A simple analytical expression for concentrations of hydroxylamine-O-sulfonique acid (HOSA), piperidine (PP), N-aminopiperidine (NAPP), sodium hydroxide (NaOH) and diazene (N2H2) along with NAPP yield is obtained and is compared with numerical result. Satisfactory agreement is obtained in the comparison of approximate analytical solution and numerical simulation. The obtained analytical result of NAPP yield is compared with the experimental results. The influence of reagents ratio p and rate constants ratio r on yield has been discussed.

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Mąkosza, Mieczysław, and Rafał Loska. "Introduction of Perfluoroalkyl Substituents into Heteroarenes via Nucleophilic Substitution of Hydrogen." Zeitschrift für Naturforschung B 63, no. 4 (April 1, 2008): 363–74. http://dx.doi.org/10.1515/znb-2008-0403.

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AbstractA summary of research in the area of fluoroalkylation of electron-deficient aromatic compounds is presented. The reaction of dinitro- and cyanonitroarenes with trifluoromethyl-trimethylsilane (Me3SiCF3) and tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF) and subsequently with DMD provides trifluoromethylated cyano- and nitrophenols via oxidative nucleophilic substitution of hydrogen. Addition of fluorinated carbanions, generated either by addition of F− anions to hexafluoropropene or by activation of Me3SiCF3, to N-alkylazinium salts leads to dihydropyridines, dihydroquinolines etc., oxidation of which affords the respective fluoroalkylated heterocycles.1,3-Dipolar cycloaddition of azine N-oxides to hexafluoropropene gives 2-heteroaryl-2,3,3,3-tetrafluoropropionic acid fluorides, which react with various protic nucleophiles to give esters and amides of 2-heteroarylperfluoropropionic acids, whereas reaction with water and decarboxylation of the free acids gives azines with a 1,2,2,2-tetrafluoroethyl group at C-2.

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7

Ivashkin, K. V., E. A. Izatullaev, and V. R. Korneeva. "Gastric Cytoprotection as Basis of Gastrointestinal Mucosa Protection and Repair in Erosive Ulcerative Lesions of Various Aetiologies." Russian Journal of Gastroenterology, Hepatology, Coloproctology 30, no. 5 (December 3, 2020): 7–17. http://dx.doi.org/10.22416/1382-4376-2020-30-7-17.

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Aim. Assessment of efficacy and the mechanism of action of gastrointestinal mucosa (GM) protection in current treatment settings with methylmethionine-sulfonium chloride (vitamin U) to illustrate its applicability in erosive ulcerative lesions of various aetiologies.Key points. Aside to damage prevention in exposure to aggressive agents, gastroprotection implies healing promotion under the preserved level of hydrochloric acid secretion. Prostaglandins (PG) and SH-antioxidants are key mediators of gastroprotection in acute and chronic damage. SH-containing endogenous substances (L-cysteine, D,L-methionine, GSH) and exogenous molecules (methylmethionine-sulfonium chloride (MMSC), N-acetylcysteine) prevent damage due to the ability to absorb/neutralise free radicals released in xenobiotic-triggered cell damage, inhibit TNF-α expression, reduce the aspirin-induced leukocyte-endothelium adhesion and stimulate mucin release. In experiment, MMSC prevented the ethanol-induced GM damage, stimulated mucin release and its redistribution on the GM surface; in clinical trials, MMSC effectively facilitated remission in duodenal ulcer.Conclusion. Preparations exerting a protective effect on gastroduodenal mucosa, such as methylmethionine-sulfonium chloride (vitamin U), may improve basic treatment settings and facilitate remission in erosive ulcerative lesions of upper gastrointestinal tract.

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8

Backer, H. J., and H. Mulder. "L'Acétylation de Quelques Acides 1, 1-Amino-Sulfoniques et 1, 1-Hydrazinosulfoniques." Recueil des Travaux Chimiques des Pays-Bas 53, no. 12 (September 3, 2010): 1120–27. http://dx.doi.org/10.1002/recl.19340531209.

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9

Taverne, H. J. "Sur L'Anhydride-O-Sulfobenzoique et les Acides Benzamide- et Méthylbenzamide-O-Sulfoniques." Recueil des Travaux Chimiques des Pays-Bas 39, no. 9 (September 3, 2010): 542–48. http://dx.doi.org/10.1002/recl.19200390905.

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10

Delarge, J., and C. L. Lapiere. "Synthèses dans la Série des Acides Pyridine-Carboxy-Sulfoniques et Pyridine Disulfoniques." Bulletin des Sociétés Chimiques Belges 75, no. 5-6 (September 2, 2010): 321–27. http://dx.doi.org/10.1002/bscb.19660750507.

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11

Polívka, Zdeněk, Miloš Buděšínský, Jiří Holubek, Bohdan Schneider, Zdeněk Šedivý, Emil Svátek, Oluše Matoušová, et al. "4H-Benzo[4,5]cyclohepta[1,2-b]thiophenes and 9,10-dihydro derivatives - Sulfonium analogues of pizotifen and ketotifen; Chirality of ketotifen; Synthesis of the 2-bromo derivative of ketotifen." Collection of Czechoslovak Chemical Communications 54, no. 9 (1989): 2443–69. http://dx.doi.org/10.1135/cccc19892443.

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Reaction of ketone IX with 4-tetrahydrothiopyranylmagnesium bromide and the following dehydration with thionyl chloride afforded the sulfide III which was transformed to the methiodide II (sulfonium analogue of pizotifen). Similar sequence starting from the ketone XXIV and concluded by dehydration of the alcohol XX, cleavage of the enol ether, and by treatment with methyl iodide resulted in the formation of the sulfonium analogue of ketotifen (V). Three modified routes leading to ketotifen (IV) are being described. The chirality of ketotifen was proven by 1H NMR spectroscopy with the help of the optically active NMR shift reagent. The resolution of racemic ketotifen (IV) was achieved by crystallization of salts with optically active O,O'-diacyltartaric acids and homogeneous enantiomers were obtained. The X-ray crystallographic analysis of (+)-IV (-)-O,O'-di(p-toluoyl)-(R)-tartarate led to the three-dimensional structure of the molecule of (+)-ketotifen which enabled to determine its absolute configuration to be (R). One of the products of bromination of the ketone IX, the following methanolysis and dehydrobromination, identified as XXVII, was transformed by reaction with 1-methyl-4-piperidylmagnesium chloride, by the following acid-catalyzed dehydration, and cleavage of the enol ether to the 2-bromo derivative of ketotifen XXXIV. (R) (+)-Ketotifen (IV) was found to be the more active ketotifen enantiomer but the stereoselectivity of its action is only a partial one. The 2-bromo derivative of ketotifen (XXXIV) is much less active than ketotifen in the line of antihistamine activity.

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12

Zhang, Wei Min, Wen Guang Wang, and Jia Ling Pu. "A Study on the Photolysis Behavior of Photoacid Generators." Advanced Materials Research 284-286 (July 2011): 2073–76. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.2073.

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A method for evaluating the photolysis behavior of photoacid generator in solvent and high polymer film has been established through spectrophotometry and fluorospectrophotometry by using the acid-sensitive Rhodamine B as tracer. Results showed that this method is feasible and practicable for evaluating the acid generating efficiency of photoacid generator in organic solvents or polymer film, yielding quantitatively precise data of the photochemical reaction and acid generating behavior, thus is very useful for evaluating the quality of different types of photacid generators e.g. triazines, sulfonium salts etc.

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13

Zhang, Cheng-Pan, Ji Cai, Chang-Bing Zhou, Xiao-Ping Wang, Xing Zheng, Yu-Cheng Gu, and Ji-Chang Xiao. "Copper-mediated trifluoromethylation of arylboronic acids by trifluoromethyl sulfonium salts." Chemical Communications 47, no. 33 (2011): 9516. http://dx.doi.org/10.1039/c1cc13460d.

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14

Ladhari, Néji, Hamid Aleboyeh, and Azam Aleboyeh. "Etude de la réaction de condensation des acides naphtalène-sulfoniques avec du formaldéhyde." Annales de chimie Science des Matériaux 33, no. 1 (February 1, 2008): 1–16. http://dx.doi.org/10.3166/acsm.33.1-16.

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15

Liu, Hui, and B. Mario Pinto. "Design and synthesis of selenonium and sulfonium ions related to the naturally occurring glucosidase inhibitor salacinol." Canadian Journal of Chemistry 84, no. 10 (October 1, 2006): 1351–62. http://dx.doi.org/10.1139/v06-100.

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Four series of analogues of the naturally occurring glucosidase inhibitor salacinol were synthesized for structure–activity studies with different glycosidase enzymes. The target zwitterionic compounds were synthesized by means of nucleophilic attack at the least-hindered carbon atom of the 1,3-cyclic sulfates derived from D-glucose and D-mannose by the isopropylidene-protected 1,4-anhydro-4-thio- and seleno-D-allitols and the 4-thio- and seleno-L-allitols. Deprotection of the coupled products afforded the novel sulfonium and selenonium ions containing polyhy droxylated acyclic chains of four and six carbons, with different stereochemistry at the stereogenic centers and with 1,4-anhydro-4-seleno or 4-thio-D- or L- alditol heterocyclic rings. The compounds showed no significant activity against recombinant human maltase glucoamylase (MGA), a critical intestinal glucosidase involved in the processing of oligosaccharides of glucose into glucose itself.Key words: glycosidase inhibitors, zwitterionic, selenonium salts, sulfonium salts, cyclic sulfates, L-ascorbic acid, D-gulonic-γ-lactone.

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16

Ouelbani, Rayene, Souheir Bensari, Mustafa Abdullah Yilmaz, Chawki Bensouici, Esma Gökalp, Meroua Ahmedchaouch, and Douadi Khelifi. "Chemical profiling and in vitro antioxidant, antibacterial and anticholinesterase activities of an endemic North African species Bellevalia mauritanica Pomel." Acta Scientifica Naturalis 7, no. 3 (November 1, 2020): 26–45. http://dx.doi.org/10.2478/asn-2020-0031.

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AbstractThe aim of this study was to evaluate antioxidant, antibacterial, and anticholinesterase activities of different extracts of an uninvestigated endemic species Bellevalia mauritanica Pomel, and identification of its phenolic and flavonoid content by a comprehensive and validated LC-MS/MS method using 37 phytochemical standards. Moreover, the phytochemical profiling of the studied extracts was accomplished by LC-MS-IT-TOF technique. Among all the tested extracts, ethyl acetate (EtOAc) of BRCE (bulbs-roots crude extract) was the most active one. It exhibited a medium antibacterial activity, good inhibition of acetylcholinesterase and a good antioxidant activity in ABTS•+ (2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonique), DPPH• (1,1’-diphenyl-2-picrylhydrazyl radical), and superoxyde DMSO (dimethyl sulfoxide) alkaline scavenging assays. LC-MS/MS analysis revealed that EtOAc extract had caffeic acid (1240.7 µg/g extract) and chloroform extract had vanillin (2048.5 µg/g extract) in considerable amounts. They also contained good amounts of certain phytochemicals such as protocatechuic acid (274.3 and 145.2 µg/g extract), p-coumaric acid (382.8 and 310.9 µg/g extract), ferulic acid (361.2 and 969.4 µg/g extract) and kaempferol (146.7 and 150.6 µg/g extract) respectively. LC-MS-IT-TOF screening revealed the presence of 91 major phytochemicals in the three extracts derived from bulb-roots crude extract.

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17

Zhang, Cheng-Pan, Ji Cai, Chang-Bing Zhou, Xiao-Ping Wang, Xing Zheng, Yu-Cheng Gu, and Ji-Chang Xiao. "ChemInform Abstract: Copper-Mediated Trifluoromethylation of Arylboronic Acids by Trifluoromethyl Sulfonium Salts." ChemInform 42, no. 50 (November 17, 2011): no. http://dx.doi.org/10.1002/chin.201150030.

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18

Massardier, V., A. Guyot, and V. H. Tran. "Direct conversion of sulfonium precursors into poly(p-phenylene vinylene) by acids." Polymer 35, no. 7 (March 1994): 1561–63. http://dx.doi.org/10.1016/0032-3861(94)90360-3.

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19

Ito, Takatoshi, Yuta Inoue, Tetsuo Iwasawa, Shuhei Sumino, Fukashi Matsumoto, Toshiyuki Iwai, Kazuyuki Moriwaki, Yuko Takao, Takumi Mizuno, and Toshinobu Ohno. "Regioselective Synthesis of [6,6]-Phenyl-C71-Butyric Acid Methyl Esters via Sulfur Ylides for Use in Bulk Heterojunction Solar Cells." Synlett 28, no. 12 (April 10, 2017): 1457–62. http://dx.doi.org/10.1055/s-0036-1588770.

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We herein report the development of a regioselective synthetic route to [70]methanofullerenes, which have potential for application as electron acceptors in solution-processed bulk heterojunction solar cells. Sterically hindered sulfur ylide, generated in situ from their corresponding sulfonium salts in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as the base, smoothly reacted with [70]fullerene to afford the α-type [6,6]-phenyl-C71-butyric acid methyl ester ([70]PCBM) in high purity (up to 98%). Furthermore, we successfully demonstrated the gram-scale synthesis of [70]PCBM.

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20

Mkrtchyan, Satenik, Michał Jakubczyk, Suneel Lanka, Michael Pittelkow, and Viktor O. Iaroshenko. "Cu-Catalyzed Arylation of Bromo-Difluoro-Acetamides by Aryl Boronic Acids, Aryl Trialkoxysilanes and Dimethyl-Aryl-Sulfonium Salts: New Entries to Aromatic Amides." Molecules 26, no. 10 (May 16, 2021): 2957. http://dx.doi.org/10.3390/molecules26102957.

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We describe a mechanism-guided discovery of a synthetic methodology that enables the preparation of aromatic amides from 2-bromo-2,2-difluoroacetamides utilizing a copper-catalyzed direct arylation. Readily available and structurally simple aryl precursors such as aryl boronic acids, aryl trialkoxysilanes and dimethyl-aryl-sulfonium salts were used as the source for the aryl substituents. The scope of the reactions was tested, and the reactions were insensitive to the electronic nature of the aryl groups, as both electron-rich and electron-deficient aryls were successfully introduced. A wide range of 2-bromo-2,2-difluoroacetamides as either aliphatic or aromatic secondary or tertiary amides were also reactive under the developed conditions. The described synthetic protocols displayed excellent efficiency and were successfully utilized for the expeditious preparation of diverse aromatic amides in good-to-excellent yields. The reactions were scaled up to gram quantities.

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21

Kaldre, Dainis, Immo Klose, and Nuno Maulide. "Stereodivergent synthesis of 1,4-dicarbonyls by traceless charge–accelerated sulfonium rearrangement." Science 361, no. 6403 (August 16, 2018): 664–67. http://dx.doi.org/10.1126/science.aat5883.

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The chemistry of the carbonyl group is essential to modern organic synthesis. The preparation of substituted, enantioenriched 1,3- or 1,5-dicarbonyls is well developed, as their disconnection naturally follows from the intrinsic polarity of the carbonyl group. By contrast, a general enantioselective access to quaternary stereocenters in acyclic 1,4-dicarbonyl systems remains an unresolved problem, despite the tremendous importance of 2,3-substituted 1,4-dicarbonyl motifs in natural products and drug scaffolds. Here we present a broad enantioselective and stereodivergent strategy to access acyclic, polysubstituted 1,4-dicarbonyls via acid-catalyzed [3,3]-sulfonium rearrangement starting from vinyl sulfoxides and ynamides. The stereochemistry at sulfur governs the absolute sense of chiral induction, whereas the double bond geometry dictates the relative configuration of the final products.

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22

Saeva, Franklin D., Bradley P. Morgan, and Henry R. Luss. "Photochemical conversion of sulfonium salts to sulfides via a 1,3-sigmatropic rearrangement. Photogeneration of Broensted acids." Journal of Organic Chemistry 50, no. 22 (November 1985): 4360–62. http://dx.doi.org/10.1021/jo00222a031.

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23

Duguet, M. "Sur les écarts constatés dans les points de fusion de quelques nouvelles amides dérivant des acides sulfoniques aliphatiques: (Docteures Sciences)." Recueil des Travaux Chimiques des Pays-Bas et de la Belgique 25, no. 7 (September 3, 2010): 213–28. http://dx.doi.org/10.1002/recl.19060250702.

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24

Pakhomova, I. G. "Potential use of methylmethionine sulfonium chloride as a component of combination therapy for peptic ulcer and gastroduodenitis." Medical Council, no. 14 (October 10, 2018): 28–32. http://dx.doi.org/10.21518/2079-701x-2018-14-28-32.

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It is known that gastritis, gastroduodenitis and peptic ulcer belong to the group of acid-dependent diseases, which occupy a significant proportion among the digestive system diseases. Despite the use of proton pump inhibitors in therapy, the discovery of an important role of H. pylori infection in the genesis of these diseases and the development of eradication schemes, the urgency of the problem persists due to the development of formidable complications (bleeding, perforation). The modern therapeutic concept of treatment of peptic ulcer (including gastroduodenitis) provides active therapeutic tactics and includes multicomponent drug regimens. Along with proton pump inhibitors, the dietary recommendations, appointment of gastro-cytoprotectors, including ones of natural origin, and the individual approach to the patient in each specific case have not outlived their usefulness. Methylmethionine sulfonium chloride (vitamin U) Gastrarex, which improves the secretory and reparative function of the stomach, may be administered as one of the components of the complex therapy of peptic ulcer and gastroduodenitis.

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25

Trottmann, Felix, Keishi Ishida, Jakob Franke, Aleksa Stanišić, Mie Ishida‐Ito, Hajo Kries, Georg Pohnert, and Christian Hertweck. "Sulfonium Acids Loaded onto an Unusual Thiotemplate Assembly Line Construct the Cyclopropanol Warhead of a Burkholderia Virulence Factor." Angewandte Chemie International Edition 59, no. 32 (May 29, 2020): 13511–15. http://dx.doi.org/10.1002/anie.202003958.

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Trottmann, Felix, Keishi Ishida, Jakob Franke, Aleksa Stanišić, Mie Ishida‐Ito, Hajo Kries, Georg Pohnert, and Christian Hertweck. "Sulfonium Acids Loaded onto an Unusual Thiotemplate Assembly Line Construct the Cyclopropanol Warhead of a Burkholderia Virulence Factor." Angewandte Chemie 132, no. 32 (May 29, 2020): 13613–17. http://dx.doi.org/10.1002/ange.202003958.

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27

Subramaniam, Perumal, and Thamil Selvi. "Dynamics of cetyltrimethylammonium bromide mediated reaction of phenylsulfinylacetic acid with Cr(VI): Treatment of pseudo-phase models." Journal of the Serbian Chemical Society 80, no. 8 (2015): 1019–34. http://dx.doi.org/10.2298/jsc140916001s.

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micellar effect % Hammett correlation % Piszkiewicz cooperative model KR nema The influence of cetyltrimethylammonium bromide, CTon the oxidative decarboxylation of phenylsulfinylacetic acid, PSAA and several meta- and para-substituted PSAAs by Cr(VI) was investigated in 95 % H2O-5 % CH3CN medium. The rate profile displayed a peculiar trend with an initial rate increase at low [CTAB] followed by sharp rate inhibition at higher [CTAB]. The initial rate acceleration can be explained by strong binding of SO42- on the positively charged micellar surface. The specific partitioning of PSAA in micellar phase by hydrophobic interaction and the oxidizing species, HCrO3+ in aqueous phase by electrostatic repulsion accounted the rate retardation at higher [CTAB]. The Hammett plot with different substituted PSAAs showed an excellent correlation affording negative ? value which supports the proposed mechanism involving a sulfonium cation intermediate formation. The obtained ? value in CTmedium is found to be slightly lower than that in aqueous medium. The quantitative analysis of rate data for the inhibition shown by CTwas performed using Menger-Portnoy and Piszkiewicz pseudo-phase models. The binding constant for PSAA with micelle was evaluated from Piszkiewicz cooperative model.

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Murphy, John A. "Free radicals in synthesis. Clean reagents affording oxidative or reductive termination." Pure and Applied Chemistry 72, no. 7 (January 1, 2000): 1327–34. http://dx.doi.org/10.1351/pac200072071327.

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Neurotoxic organotin reagents currently play a key role in radical chemistry. As a result, this is an important area for development of new clean replacement reactions. The pharmaceutical industry in particular has had to avoid use of radical methodology for the formation of carbon_carbon bonds for this reason. With the current dawn in green chemistry, a host of new clean radical methods is beginning to flourish. Our aim has been to develop new nontoxic methodology for carbon_carbon bond formation by radical chemistry, which would provide either reductive termination (giving a hydrogen atom to the ultimate radical, as happens with tributyltin hydride), or oxidative functionalization, installing a useful polar group at the site of the ultimate radical. Two methods for effecting radical reactions in an environmentally friendly way are presented: (i) The tetrathiafulvalene (TTF)-mediated radical-polar crossover reaction converts arenediazonium salts to aryl radicals, which have sufficient lifetime to cyclize onto alkenes—the resulting alkyl radicals couple with TTF+• to afford sulfonium salts which, in turn, undergo solvolysis to alcohols, ethers or amides. The method provides the key step in a synthesis of (±)-aspidospermidine. (ii) Hypophosphite salts and hypophosphorous acid, on the other hand, form C_C bonds with reductive termination. These economical reagents afford radicals efficiently, starting from aryl iodides, alkyl bromides, and alkyl iodides, and give very easy separation of products from by-products.

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Pichereau, Vianney, Jean-Alain Pocard, Jack Hamelin, Carlos Blanco, and Théophile Bernard. "Differential Effects of Dimethylsulfoniopropionate, Dimethylsulfonioacetate, and Other S-Methylated Compounds on the Growth of Sinorhizobium meliloti at Low and High Osmolarities." Applied and Environmental Microbiology 64, no. 4 (April 1, 1998): 1420–29. http://dx.doi.org/10.1128/aem.64.4.1420-1429.1998.

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ABSTRACT An extract from the marine alga Ulva lactuca was highly osmoprotective in salt-stressed cultures of Sinorhizobium meliloti 102F34. This beneficial activity was due to algal 3-dimethylsulfoniopropionate (DMSP), which was accumulated as a dominant compatible solute and strongly reduced the accumulation of endogenous osmolytes in stressed cells. Synthetic DMSP also acted as a powerful osmoprotectant and was accumulated as a nonmetabolizable cytosolic osmolyte (up to a concentration of 1,400 nmol/mg of protein) throughout the growth cycles of the stressed cultures. In contrast, 2-dimethylsulfonioacetate (DMSA), the sulfonium analog of the universal osmoprotectant glycine betaine (GB), was highly toxic to unstressed cells and was not osmoprotective in stressed cells of wild-type strains of S. meliloti. Nonetheless, the transport and accumulation of DMSA, like the transport and accumulation of DMSP and GB, were osmoregulated and increased fourfold in stressed cells of strain 102F34. Strikingly, DMSA was not toxic and became highly osmoprotective in mutants that are impaired in their ability to demethylate GB and DMSA. Furthermore, 2-methylthioacetate and thioglycolic acid (TGA), the demethylation products of DMSA, were excreted, apparently as a mechanism of cellular detoxification. Also, exogenous TGA and DMSA displayed similar inhibitory effects in strain 102F34. Thus, on the basis of these findings and other physiological and biochemical evidence, we infer that the toxicity of DMSA in wild-type strains ofS. meliloti stems from its catabolism via the GB demethylation pathway. This is the first report describing the toxicity of DMSA in any organism and a metabolically stable osmoprotectant (DMSP) in S. meliloti.

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Taha, Samir, Moumen Baroudi, and Jalal Halwani. "Influence du pH sur la rétention des révélateurs photographiques hydroquinones par nanofiltration." 24, no. 1 (April 1, 2011): 1–7. http://dx.doi.org/10.7202/045823ar.

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Résumé L’objet de ce travail est d’étudier l’influence du pH sur le taux de rétention lors de la nanofiltration des solutions d’hydroquinone, d’hydroquinone monosulfonate et d’hydroquinone disulfonate seules ou en mélange, qui sont présents dans les bains révélateurs photographiques. Les résultats nous montrent que les taux de rétention et de dissociation de l’hydroquinone sont liés. L’exploitation des courbes de dosage des acides par NaOH conduit à déterminer le pKa pour l’hydroquinone sulfonique acide comme étant égal à 2,82. Les deux acidités de l’hydroquinone disulfonique acide sont caractérisées par pKa1 = 2,28 et pKa2 = 2,44. Quand il n’existe aucune forme ionisée, le taux de rétention reste faible (TR = 10 %). Dès l’apparition d’une ionisation, alors le taux de rétention augmente considérablement (TR = 50 %). A l’apparition de A2-, le taux de rétention subit une nouvelle augmentation (TR = 98 %). Lorsque pH < pKa1, l’hydroquinone est sous forme moléculaire, la rétention est liée à la taille de la molécule. Les taux de rejet sont faibles (TR = 30 %). Lorsque pH > pKa1 et pH > pKa2, la molécule est ionisée. La rétention est en relation avec la répulsion des charges négatives de la membrane. Les taux de rejet deviennent importants (TR = 90 %). Bien que les taux de rétention de l’hydroquinone, l’hydroquinone sulfonique acide et l’hydroquinone disulfonique acide suivent la même évolution lorsque le composé est seul ou en mélange, on notera un petit décalage entre les courbes du composé en mélange et du composé seul. Nous attribuons ceci aux propriétés chimiques des composés hydroquinones de la solution, à savoir leur mobilité et leur concentration, etc. Une étude relative à l’influence de ces paramètres serait donc envisageable afin de confirmer ces suppositions.

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"Equilibrium and Isotherm Modeling of Toxic dye Adsorption onto Modified Apricot Stone." Advance in Environmental Waste Management & Recycling 1, no. 1 (April 6, 2018). http://dx.doi.org/10.33140/aewmr.01.01.03.

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In the present study, adsorption of toxic dye Diret red 28 (acid benzidinediazo-bis-1- naphtylamine - 4- sulfonique) from aqueous solution was investigated using activated carbon synthesized with Phosphoric Acid activation. The synthesized adsorbent was analyzed using BET, FT-IR and SEM techniques. The BET analysis showed that the area provided by the synthesized activated carbon was 88.01 m2 g-1. The adsorption isotherms of Toxic dye onto ASAC are determined and correlated with common isotherms equations. The smaller RMSE values obtained for the Langmuir and Dubinin-R models indicate the better curves fitting, the monolayer adsorption capacity of toxic dye is found to be 32.85 mg.g-1 at temperature 25 o C and 23.42 mg.g-1 at temperature 65 o C at pH 13. The adsorption of toxic dye was carried out using a batch system and the effects of pH, contact time, adsorbent dosage, initial concentration and temperature on the adsorption capacity of synthesized adsorbent were investigated. Kinetics studies proved that for both metals, the kinetic data follows the pseudo second order kinetic model. In addition, the thermodynamics studies proved that the adsorption process of toxic dye could be considered spontaneous and endothermic.

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Orlandi, Manuel. "Basic principles of substrate activation through non-covalent bond interactions." Physical Sciences Reviews 5, no. 5 (April 4, 2020). http://dx.doi.org/10.1515/psr-2018-0090.

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AbstractIn the last twenty years, chiral Brønsted acid and chiral counteranion catalysis have emerged as a fundamental area of organocatalysis. The development of chiral acidic catalysts has allowed extending many known Brønsted catalyzed reactions to the stereoselective domain. Moreover, the controlled conditions under which these catalysts can be used, allowed accessing reactivity of increasing complexity with extraordinary selectivity levels. However, compared to the explosion of this branch of organocatalysis in an applicative direction, only little has been done to understand and rationalize the observed reaction outcomes. This is due, in part, to the complex nature of the weak interactions (H-bonds, electrostatic, and dispersion interactions) governing this class of reactions. Here we review relevant mechanistic analyses from both chiral Brønsted acid and chiral counteranion directed catalysis. Both experimental and computational work is included that aimed at unveiling the nature of the interactions governing the a number of reactions. These include the: enantioselective reduction of ketoimines with Hantzsch esters; ring opening reactions of epoxides, oxetanes, aziridinium, and sulfonium ions; stereoselective fluorination of allylic alcohols; oxidative aminations of benzylic thioethers (enantioselective Pummerer reaction). These case studies are analyzed and discussed in order to highlight key features and similarities across the different catalytic systems.

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Yang, Jianping, Xinfeng Li, Xinlei Wang, Xin Wen, Tongtong Zhang, and Wenjie Xu. "Effects of Methylmethionine Sulfonium Chloride on Activity and Tight Junction Protein Expression of Intestinal Porcine Jejunum Epithelial Cells (IPEC-J2)." Indian Journal of Animal Research, Of (September 3, 2021). http://dx.doi.org/10.18805/ijar.b-1384.

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Background: The intestinal mucosal epithelium acts as a physical and biochemical barrier and plays an important role in regulating of barrier function and immune homeostasis. Methylmethionine sulfonium chloride (MMSC) is a multifaceted amino acid that is critical to the normal physiology of the gastrointestinal tract. The present study investigated the effects of extracellular MMSC on intestinal epithelial cell line (IPEC-J2). Methods: IPEC-J2 cells were treated with 0.1, 0.5 and 1 mM MMSC, respectively for an additional 24 h. CCK-8 assay was used to evaluate cell proliferation. The cell Annexin V-FITC/PI apoptosis were analyzed by flow cytometry (FCM) method. The mRNA transcript and protein expression levels of tight junction proteins in IPEC-J2 cells were detected by real-time quantitative polymerase chain reaction (RT-qPCR) and western blotting (WB). Result: The results showed that MMSC could stimulate IPEC-J2 cells proliferation and inhibit cell apoptosis. In addition, the RT-qPCR and WB results indicated that 0.5 mM MMSC significantly increased the mRNA and protein expression of tight junction proteins, including occludin, claudin-1 and zonula occludin-1 (Zo-1). These findings may provide valuable information to investigate further the possible mechanism and function of MMCS on the intestinal barrier function.

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Moulay, Saad. "C-Methylation Of Organic Substrates. A Comprehensive Overview. Part Iva. Methylating Agents Other Than Methane, Methanol, And Methyl Metals." Current Chinese Chemistry 01 (August 4, 2021). http://dx.doi.org/10.2174/2666001601666210804114443.

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: C-Methylation of organic substrates was accomplished with a number of methylating agents other than methane, methanol, and methyl metals. They include methyl halides (MeX, X = I, Br, Cl, F), methyl-containing halogenated reagents, methyl peroxides, dimethyl carbonate (DMC), dimethylsulfoxide (DMSO), N,N-dimethyl formamide (DMF), diazomethane, formate salts, trioxane, CO/H2, CO2/H2, and dimethyl ether (DME). Under particular conditions, some methyl-containing molecules such as polymethylbenzenes, methylhydrazine, tris(diethylamino)sulfonium difluorotrimethylsilicate, methyl tosylate, long-chain alkyl alcohols, and acetic acid unexpectedly C-methylated a variety of organic substrates. A few cases of C-methylation only were reported to occur in the absence of catalysts. Otherwise, transition metal complexes as catalysts in conjunction with specific ligands and bases were ubiquitously present in most C-methylation reactions. Of the reactions, Suzuki-Miyaura-type cross-coupling remained of paramount importance in making 11CH3-bearing positron emission tomography tracers (PETs), one of the best applications of such methylation. Methylation proceeded at C(aromatic)-X, C(sp3)-X C(sp2)-X, and C(sp)-X of substrates (X = H, halogen). Ortho-methylation was regioselectively observed with aromatic substrates when they bear moieties such as pyridyl, pyrimidyl, amide, and imine functionalities, which were accordingly coined ‘ortho-directing groups’.

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Epstein, A. J., J. Joo, R. S. Kohlman, A. G. Macdiarmid, J. M. Weisinger, Y. Min, J. P. Pouget, and J. Tsukamoto. "The Metallic State of Conducting Polymers: Microwave Dielectric Response and Optical Conductivity." MRS Proceedings 328 (1993). http://dx.doi.org/10.1557/proc-328-145.

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ABSTRACTRecent advances in processing of polyaniline and polyacetylene have resulted in a new generation of conducting polymers with higher dc conductivities. We present the temperature (T) dependent microwave frequency dielectric constant, dc conductivity, and Kramers-Kronig analysis of conducting polyaniline and polyacetylene. The low temperature dielectric constant, ε, increases with the square of the x-ray crystalline domain length for preparations of HCl protonated polyaniline. For the highest crystalline polyaniline samples, ε increases dramatically with increasing T, supporting formation of three-dimensional (3-D) coupled “mesoscopic” Metallic regions. A “metallic” negative ε is observed for d,1-camphor sulfonie acid doped polyaniline prepared in m-cresol. Optical studies show a linear increase in reflectivity below 7000 cm-1. Below 600 cm-1 the reflectance increases rapidly. Kramers-Kronig analysis of the ir-visible results are presented. Highly conducting polyaniline is shown to have two plasma frequencies, one at ∼ 1.1 eV involving all the conduction band electrons, and one at ∼0.015 eV (120 cm-1) that is suggested to arise from the most delocalized electrons. The concept of inhomogeneous disorder is introduced. The results for polyaniline are compared to those of highly doped polyacetylene which also show metallic negative ε demonstrating the intrinsic metallic nature of the new generation of conducting polymers.

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Journal articles on the topic 'Acide sulfonique'

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