- SCAVENGING OF RADICALS FROM THE GAS PHASE BY FREEZING WITH DIMETHYL DISULFIDE: 1. TEST OF THE METHOD FOR LIGHT RADICALS.
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H and O atoms and methyl radicals produced in microwave discharges of H//2/He, O//2/He and CH//4/He mixtures, respectively, were scavenged by supersonic nozzle probing with subsequent freezing and reaction with dimethyl disulfide on a liquid nitrogen cooled wall. The main reaction products for the three kinds of radicals were CH//3SH, CH//3S(O)SCH//3 and CH//3SCH//3, respectively. The scavenging efficiencies for the different radicals were determined and measured as a function of the gas phase radical concentration, the flow of scavenger molecules, the pressure in the vacuum chamber, and the conditions of the discharge and the flow through the sampling nozzle. It is concluded that this method is suitable for light radicals with reservations in the case of H atoms and can probably be used with still better success for heavier radicals.
- Schottler,Homann
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- Inhibitory effect of methyl methanethiosulfinate on β-glucuronidase activity
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Minced or cut-up leaves of Chinese chive (Allium tuberosum Rottler) contain thiosulfinates and their disproportionate reaction products. Among these organosulfur compounds, methyl methanethiosulfinate was found to be an uncompetitive inhibitor of β-glucur
- Watanabe, Yuko,Muroi, Ryoko,Tsuchiya, Haruna,Uda, Yasushi,Hashimoto, Kei
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- (E,Z)-Ajoene: A potent antithrombotic agent from garlic
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A report is presented of the structural characterization and simple synthesis of (E,Z)-ajoene.
- Block,Ahmad,Jain,et al.
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- Synthesis of a Cyclic 3-Methylsulfonyl Enol Ether
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Electrophilic introduction of a methylmercapto group into dihydropyran gives 3-methylmercaptodihydropyran, which is readily oxidized to 3-methylsulfonyldihydropyran.
- Bennua-Skalmowski, Baerbel,Vorbrueggen, Helmut
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- Photooxidations of Sulfenic Acid Derivatives 2. A Remarkable Solvent Effect on the Reactions of Singlet Oxygen with Disulfides.
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Photooxidations of a series of 9 disulfides reveal that the thiosulfinate/thiosulfonate product ratios can be dramatically influenced by the nature of the solvent.The unique ability of methanol to influence this ratio is attributed to nucleophilic addition to a thiopersulfoxide intermediate.
- Clennan, Edward L.,Wang, Dongyi,Zhang, Houwen,Clifton, Christine H.
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- Thermal degradation of sulforaphane in aqueous solution
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Sulforaphane, a cancer chemopreventive agent identified from broccoli, was degraded in an aqueous solution at 50 and 100 °C. The reaction mixtures were extracted with methylene chloride and analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Dimethyl disulfide, S- methyl methylthiosulfinate, S-methyl methylthiosulfonate, methyl (methylthio)methyl disulfide, 1,2,4-trithiolane, 4-isothiocyanato-1- (methylthio)-1-butene, and 3-butenyl isothiocyanate were identified as volatile decomposition products. After methylene chloride extraction, the aqueous layer was dried and silica gel column chromatography was used to separate and purify the nonvolatile decomposition products. The major thermal degradation compound was determined by 1H NMR, 13C NMR, and FAB-MS as N,N'-di(4-methylsulfinyl)butyl thiourea. A possible mechanism for the formation of these products is proposed.
- Jin, Yi,Wang, Mingfu,Rosen, Robert T.,Ho, Chi-Tang
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- Direct Bis-Alkyl Thiolation for Indoles with Sulfinothioates under Pummerer-Type Conditions
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A base-free bis-alkyl thiolation reaction of indoles with sulfinothioates under Pummerer-type conditions is described. Sulfinothioates, activated with 2,2,2-trifluoroacetic anhydride, are demonstrated to be an efficient thiolation reagent for wide applica
- Chen, Ning,Du, Hongguang,Qi, Peng,Sun, Fang
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p. 1133 - 1143
(2022/02/07)
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- A tissue homogenate method to prepare gram-scale allium thiosulfinates and their disulfide conjugates with cysteine and glutathione
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The health benefits of Allium vegetables are widely attributed to the enzyme-derived organosulfur compounds called thiosulfinates (TS). However, the lack of a suitable method to prepare TS in good yields has hampered the evaluation of their biological activities. This paper describe a simple enzymatic method using Allium tissue homogenates as a reaction system to prepare gram-scale TS, including those enriched in 1-propenyl groups, which are particularly difficult to obtain. This method is simple, easy to scale up, and requires no column purification step, making it suitable for practical large-scale production of Allium TS. The prepared TS were further utilized to prepare the disulfide conjugates with cysteine and glutathione (CySSR and GSSR, R = methyl, ethyl, propyl, 1-propenyl, and allyl), which are the presumptive metabolites of TS. Among all of the Allium CySSR and GSSR conjugates, the newly prepared glutathione conjugate with 1-propenyl TS, GSSPe, showed the most potent effect to induce quinone reductase (QR, a representative phase II enzyme) in murine hepatoma cells (Hepa 1c1c7) and inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated macrophage cells (RAW 264.7).
- Zhang, Guodong,Parkin, Kirk L.
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p. 3030 - 3038
(2013/08/25)
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- Thiophilic addition of organolithiums to trithiocarbonate oxides (sulfines). Synthesis of β-oxoketene dithioacetals, 1,4-dicarbonyl compounds, and allyl sulfoxides
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Reaction of trithiocarbonates with meta-chloroperoxybenzoic acid in CH2Cl2 at 0°C affords the corresponding S-oxides. These sulfines are relatively stable comppounds which can be purified by chromatography. They react readily with organolithiums in THF at -78°C in a thiophilic manner to give carbanions which are stabilized by three sulfur groups. Hydrolysis affords trithioorthoester oxides. The thermal behaviour of these hindered products has been investigated and new rearrangenrent processes have been evidenced. The former carbanions are soft nucleophiles: 1,4-addition of these intermediates to α-enones was achieved selectively to lead to β-oxo ketenedithioacetals, which are easily transformed into 4-oxoalkanethioates. This 'Umpolung' route allows the formal use of the (alkylthio)carbonyl anion. A thiophilic addition was also observed with allylsilanes in the presence of n-Bu4NF furnishing allyl sulfoxides.
- Leriverend, Catherine,Metzner, Patrick,Capperucci, Antonella,Degl'Innocenti, Alessandro
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p. 1323 - 1342
(2007/10/03)
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- Unsensitized photooxidation of sulfur compounds with molecular oxygen in solution
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The short wavelength irradiation of aliphatic disulfides, sulfides and of n-butanethiol in alcohols or aqueous acetonitrile in the presence of oxygen was investigated: the corresponding sulfonic acids are produced in good yields for short alkyl chain compounds, together with smaller amounts of sulfuric and carboxylic acids. In acetonitrile, the influence of added water on the reaction course is evidenced: increased reaction rate and acid yields, control of sulfuric acid formation. Intermediates such as sulfinic acid and thiosulfonate were detected and their rates of formation were monitored. The reaction appears to involve thiyl radicals giving rise to sulfonyl radicals in the presence of oxygen. A first tentative hypothesis concerning the mechanism is advanced.
- Robert-Banchereau, Evelyne,Lacombe, Sylvie,Ollivier, Jean
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p. 2087 - 2102
(2007/10/03)
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- OXIDATION OF DISULPHIDES BY HYDROGEN PEROXIDE UNDER INTERPHASE CATALYSIS CONDITIONS
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It has been shown that aliphatic and aromatic disulphides are oxidized by hydrogen peroxide in the presence of sodium tungstate and molybdate and an interphase catalyst to the corresponding thiolsulphonates and disulphones.The structure of the oxidation products depends on the interphase catalyst used: in the presence of triethylbenzylammoniumbromide, thiosulphonates are formed, while in the presence of cetyltrimethylammoniumbromide, disulphones are formed.The main reason for this difference is the solubility in the organic phase of the intermediate peroxy complex formed by the reaction of hydrogen peroxide with the metal compound in the presence of phosphoric acid.The rate of the reaction and the yields of oxidation products depend on the temperature, the solvent used and the ratio of the reactants.
- Anisimov, A. V.,Mohammed, R. A.,Tarakanova, A. V.,Borisenkova, S. A.
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p. 407 - 412
(2007/10/02)
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- Zwitterion-accelerated -Sigmatropic Rearrangements and -Sigmatropic Rearrangements of Sulphoxides and Amine Oxides
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The effect of a zwitterionic moiety on -sigmatropic rearrangements has been studied.The allyl vinyl sulphoxide 5 underwent a -sigmatropic rearrangement at 23 deg C under neutral conditions to give the thione S-oxide 6 (96percent).This rearrangement (k1 = 1.56 +/- 0.04 x 10-1 h-1) was 45 times faster than conversion of the corresponding sulphide 3 into the thione 4 ( k1 = 3.5 +/- 0.1 x 10-3 h-1).At 23 deg C, the sulphoxide 7 also rearranged to give a mixture of (E)- and (Z)-thial S-oxide 8 (90percent).These experiments showed that the accelerating effect of the charges in the sulphoxide, a zwitterionic moiety, did not cancel out.Instead, the sulphoxide moiety significantly facilitated the -sigmatropic rearrangement.In the thermolysis of hexa-1,5-dienes with a zwitterionic moiety attached to the C-3 position ( e.g., 9 and 24), -sigmatropic rearrangements occurred.The conversion of the allyl sulphoxide 21 into the corresponding sulphenate ester 22 by a process was used as the key step in a total synthesis of yomogi alcohol 23, a biologically active monoterpenoid.
- Hwu, Jih Ru,Anderson, Denise A.
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p. 3199 - 3206
(2007/10/02)
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- Analysis of Radicals from Flames by Scavenging with Dimethyl Disulfide
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Larger hydrocarbon radicals in flames, which are difficult to detect by optical methods, can be analyzed quantitatively by radical scavenging with dimethyl disulfide in the condensed phase. - Gas samples taken from a sooting ethyne/oxygen flame by a nozzle beam were frozen at liquid-N2-temperature on the inner surface of a hollow sphere simultaneously with the radical scavenger dimethyl disulfide.The latter was admitted in large excess as a gas and was condensed uniformly on the inner wall of the sphere.The mixture of condensable stable flame products and scavenging products in the excess CH3SSCH3 was separated and identified by GC/MS. - Larger hydrocarbons (CxHy, x >= 6) condensed quantitatively.H, CH3, C4H3 and the phenyl radical were scavenged as mono(methylthio) compounds; C2 and the carbenes CH2, C3H2, C5H2 yielded bis(methylthio) compounds; other bis(methylthio) compounds observed were C2nH2(SCH3)2 with n = 1, 2, 3 and 4.CH, C3H and C2H3 were identified by the respective tris(methylthio) compounds.Any consecutive reactions of radicals with stable flame products and their recombinations in the cold trap were supressed by their scavenging reaction.
- Hausmann, M.,Homann, K. H.
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p. 1308 - 1312
(2007/10/02)
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- SCAVENGING OF RADICALS FROM THE GAS PHASE BY FREEZING WITH DIMETHYL DISULFIDE: 2. RADICALS FROM DISCHARGES AND A FLAME OF ACETYLENE.
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The method of detecting radicals from low-pressure gas-phase systems by scavenging with dimethyl disulfide (DMD) has been applied to microwave discharges in C//2H//2/He mixtures and to a C//2H//2/O//2 flame. It was accomplished by condensing a supersonic nozzle beam from the reaction system together with a beam of DMD on a liquid-N//2 cooled surface. The scavenging products were measured by GC/MS after warming-up. Radicals measured in the discharge were C//2H, C//4H, C//6H, C//3H//2, C//2 besides H atoms. Preliminary measurements on the flame showed that C//6H//5 (phenyl), CH//2, C//3H//2, besides H and O atoms were prominent radicals at the end of the oxidation zone. The concentration of phenyl is of the same order as that of e. g. naphthalene.
- Kubitza,Schottler,Homann
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p. 695 - 700
(2007/10/02)
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- STUDIES RELATED TO PENICILLINS. PART 23. PREPARATION OF THE N-PHENYLACETYL AND N-TRIPHENYLMETHYL DERIVATIVES OF (3R,4R)-3-AMINO-4-t-BUTHYLTHIOAZETIDIN-2-ONE
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Addition of hypobromous acid to the alkene moiety of the 6-substituent of (1S,5R)-3-benzyl-6-(2-methylprop-1-enyl)-4-oxa-2,6-diazabicyclohept-2-en-7-one (7a) was effected by the action of N-bromoacetamide in aqueous acetone.On the basis of 1H NMR s
- Corbett, David F.,Kaura, Arun C.,Maycock, Christopher D.,Stoodley, Richard J.
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p. 2009 - 2016
(2007/10/02)
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- Observation of Intermediates during the Reaction of Linear Alkanesulfinyl Chlorides with Activated Zerovalent Zinc
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Methane- (2), ethane- (3), propane- (4), butane (5), pentane- (6), hexane- (7), octane- (8), and dodecanesulfinyl chloride (9) reacted with activated zinc to give the corresponding alkanesulfonothioic S-alkyl esters (12-19) in 40-89percent yield.The reaction of methanesulfinyl chloride (2) with activated zerovalent zinc under nitrogen in anhydrous diethyl ether at -30, -20, and 0 deg C was investigated by 1H NMR and 13C NMR spectroscopy.The 13C NMR spectrum of the partially converted -30 deg C reaction mixture showed the presence of methanesulfinyl chloride (2), S-methyl methanesulf onothioate (12), methanesulfinic acid (24) or zinc methanesulfinate (25), methanesulfonyl chloride (26), dimethyl sulfide (27), S-methyl methanesulfinothioate (28), and methanesulfinyl methyl sulfone (29). vic-Dimethyl disulfoxides (31) and OS-methyl methanesulfino(thioperoxoates) (32) are proposed as two of several transient reaction intermediates.
- Freeman, Fillmore,Angeletakis, Christos N.,Keindl, Monica C.
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p. 454 - 458
(2007/10/02)
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- A New Acid-catalysed Rearrangement of Thiosulphinates to α-Acetylthio-sulphoxides in Acetic Anhydride
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Some thiosulphinates with at least one proton on the carbon adjacent to the sulphenyl sulphur react with acetic anhydride containing acetic acid to afford the corresponding α-acetylthio-sulphoxides.The mechanism of this reaction was studied using thiosulphinates labelled with (2)H, (13)C, and (18)O.These tracer experiments demonstrated that the reaction proceeds via an initial Ei reaction to form the corresponding sulphenic acid ant thioaldehyde followed by recombination in which the sulphur atom of the sulphenic acid adds to the carbon atom of the thioaldehyde, eventually affording the rearranged α-acetylthio-sulphoxide.The formation of the sulphenic acid was confirmed by trapping it with methyl acrylate.The mechanism of the reaction is discussed.
- Furukawa, Naomichi,Morishita, Tsuyoshi,Akasaka, Takeshi,Oae, Shigeru
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p. 432 - 440
(2007/10/02)
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