- Stereoelectronic Effects in the Gas Phase. 2. Negative Ion Reactions of 1,3-Dithianes and 1,3-Dithiane 1-Oxides
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Reactions of gaseous anions (methoxide, hydroxide, and thermal electrons) with cis-4,6-dimethyl-1,3-dithiane and the corresponding axial and equatorial 1-oxides have been investigated using the techniques of ion cyclotron resonance (ICR) spectroscopy and pulsed positive-negative ion chemical ionization (PPNICI) spectroscopy.Deprotonation to (M-H)(1-) ions and extensive fragmentation to ions m/z 99 and 101 were observed for all three compounds with all three reactant anions.When compounds labeled with deuterium specifically at the C2 position were used, it was foundthat deprotonation occurred at C2 and elsewhere in the molecule.The axial hydrogen at C2 was removed as readily or more so than the equatorial hydrogen, depending on the reactants and conditions of ion generation. (These results differ from the corresponding condensed-phase reactions, which show strong selectivity for C2 equatorial deprotonation).Deuterium isotope effects were estimated to be 1.2 and 1.3 for ions generated by MeO(1-) and e, respectively.Exchange (H/D) between hydroxide and cis-4,6-dimethyl-1,3-dithiane-2-d2 was insignificant, although exchange was observed in comparable reactions of hydroxide with 1,3-dithiane-d2 and bis(methylthio)methane-d2.Stereoelectronic effects that may contribute to selectivity in solution do not account for the gas-phase results.Ab initio calculations at the 3-21G(*) level applied to methanedithiol and the anion (HS)2CH(1-) (as models for the 1,3-dithiane system) provide insight into the nature of the gas-phase reactions.Possible reaction pathways are discussed.
- Fisher, Cindy L.,Kahn, Scott D.,Hehre, Warren J.,Caserio, Marjorie C.
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- Formation of Dithioacetals by Treatment of Sulfoxides Carrying α-Hydrogens with Magnesium Amides
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Sulfoxides carrying α-hydrogens were allowed to react with magnesium amides generated in situ by the treatment of ethylmagnesium bromide with secondary amines such as 2,2,6,6-tetramethylpiperidine or diisopropylamine in diethyl ether to give the corresponding dithioacetals in moderate to good yields.
- Kobayashi, Kazuhiro,Kawakita, Masataka,Mannami, Tohru,Morikawa, Osamu,Konishi, Hisatoshi
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- Static and dynamic structures of pentacarbonyl-chromium(0) and -tungsten(0) complexes of dithioether ligands I. Symmetrical dithioether complexes and X-ray crystal structure of
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The complexes (M=Cr, R=Et, iPr, t-Bu; M=W, R=Me, Et, iPr, t-Bu) were synthesised.Total bandshape NMR analysis was used to measure energies of inversion of the coordinated S atom in the tungsten complexes. ΔG (298.15 K) values were in the range 34-42 kJ mol-1.An X-ray structure of was obtained.
- Abel, Edward W.,Orrell, Keith G.,Rahoo, Haji,Sik, Vladimir,Mazid, Mohammed A.,Hursthouse, Michael B.
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- Effect of Zinc Oxide on the Thermal Decomposition of Dimethyl Sulfoxide
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Dimethyl sulfoxide (DMSO) is widely used in the chemical industry. However, it has a non-neglectful thermal runaway risk due to the nature of self-accelerating decomposition near the boiling point. Under the background that zinc oxide (ZnO) may extend the isothermal induction period of thermal decomposition of DMSO, this article conducts an in-depth study for the phenomenon with the techniques such as differential scanning calorimetry (DSC), accelerating rate calorimetry (ARC), gas chromatography-mass spectrometry (GC-MS), X-ray photoelectron spectroscopy (XPS), and X-ray diffractometry (XRD). After being mixed with ZnO, the maximum decomposition rate of DMSO was significantly reduced and the adiabatic induction period of DMSO decomposition was extended by 3.27 times, indicating that the thermal decomposition intensity of DMSO was obviously reduced. It was experimentally demonstrated that ZnO did not change the decomposition pathways of DMSO, but it could promote the decomposition of methanethiol, which was a decomposition intermediate of DMSO and could potentially serve as a promoter on the decomposition of DMSO.
- Chen, Liping,Chen, Wanghua,Guo, Zichao,Li, Huabo,Weng, Shichun,Wu, Wenqian
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- Photocatalytic Deoxygenation of Sulfoxides Using Visible Light: Mechanistic Investigations and Synthetic Applications
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The photocatalytic deoxygenation of sulfoxides to generate sulfides facilitated by either Ir[(dF(CF3)ppy)2(dtbbpy)]PF6 or fac-Ir(ppy)3 is reported. Mechanistic studies indicate that a radical chain mechanism operates, which proceeds via a phosphoranyl radical generated from a radical/polar crossover process. Initiation of the radical chain was found to proceed via two opposing photocatalytic quenching mechanisms, offering complementary reactivity. The mild nature of the radical deoxygenation process enables the reduction of a wide range of functionalized sulfoxides, including those containing acid-sensitive groups, in typically high isolated yields.
- Clarke, Aimee K.,Parkin, Alison,Rossi-Ashton, James A.,Taylor, Richard J. K.,Unsworth, William P.
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p. 5814 - 5820
(2020/07/21)
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- Nickel phosphide nanoalloy catalyst for the selective deoxygenation of sulfoxides to sulfides under ambient H2pressure
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Exploring novel catalysis by less common, metal-non-metal nanoalloys is of great interest in organic synthesis. We herein report a titanium-dioxide-supported nickel phosphide nanoalloy (nano-Ni2P/TiO2) that exhibits high catalytic activity for the deoxygenation of sulfoxides. nano-Ni2P/TiO2 deoxygenated various sulfoxides to sulfides under 1 bar of H2, representing the first non-noble metal catalyst for sulfoxide deoxygenation under ambient H2 pressure. Spectroscopic analyses revealed that this high activity is due to cooperative catalysis by nano-Ni2P and TiO2. This journal is
- Fujita, Shu,Mitsudome, Takato,Mizugaki, Tomoo,Yamaguchi, Sho,Yamasaki, Jun,Yamazoe, Seiji
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supporting information
p. 8827 - 8833
(2020/11/23)
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- Rh-Catalyzed Hydrogenation of CO2 to Formic Acid in DMSO-based Reaction Media: Solved and Unsolved Challenges for Process Development
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Process concepts have been conceived and evaluated for the amine-free homogeneous catalyzed hydrogenation of CO2 to formic acid (FA). Base-free DMSO-mediated production of FA has been shown to avoid the formation of stable intermediates and presumably the energy-intensive FA recovery strategies. Here, we address the challenges in the development of an overall process: from catalyst immobilization to the FA isolation. The immobilization of the homogeneous catalyst was achieved using a multiphasic approach (n-heptane/DMSO) ensuring high retention of the catalyst (>99%) and allowing facile separation of the catalyst-free product phase. We show that the strong molecular interactions between DMSO and FA on the one hand shift the equilibrium towards the product side, on the other hand, lead to the formation of an azeotrope preventing a simple isolation step by distillation. Thus, we devised an isolation strategy based on the use of co-solvents and computed the energy demands. Acetic acid was identified as best co-solvent and its compatibility with the catalyst system was experimentally verified. Overall, the outlined process involving DMSO and acetic acid as co-solvent has a computed energy demand on a par with state-of-the art amine-based processes. However, the insufficient chemical stability of DMSO poses major limitations on processes based on this solvent. (Figure presented.).
- Jens, Christian M.,Scott, Martin,Liebergesell, Bastian,Westhues, Christian G.,Sch?fer, Pascal,Franciò, Giancarlo,Leonhard, Kai,Leitner, Walter,Bardow, André
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supporting information
p. 307 - 316
(2018/11/10)
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- Deoxygenation of sulfoxides to sulfides in the presence of zinc catalysts and boranes as reducing reagents
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In the present study, the zinc-catalyzed deoxygenation of aliphatic and aromatic sulfoxides in the presence of boranes as reducing reagent has been explored. After investigation of different reaction parameters the abilities of catalytic amounts of Zn(OTf)2 has been demonstrated in the deoxygenation of various sulfoxides. Moreover, various experiments have been performed to shed light on the underlying reaction mechanism.
- Enthaler, Stephan,Krackl, Sebastian,Irran, Elisabeth,Inoue, Shigeyoshi
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p. 1003 - 1010
(2012/10/29)
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- Zinc-catalyzed deoxygenation of sulfoxides to sulfides applying [B(Pin)]2 as deoxygenation reagents
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In the present study, the zinc-catalyzed deoxygenation of aliphatic and aromatic sulfoxides in the presence of 4,4,4',4',5,5,5',5'-octamethyl-2,2'-bi-1, 3, 2-dioxaborolane [B(Pin)]2 as reducing reagent to produce the corresponding sulfides has been investigated. After examination of various reaction parameters the abilities of catalytic amounts of Zn(OTf)2 has been proven in the deoxygenation of various sulfoxides. Especially, a high functional group tolerance was noticed for the Zn(OTf)2/ B(Pin) 2 system. Springer Science+Business Media, LLC 2012.
- Enthaler, Stephan
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p. 1306 - 1311
(2013/01/15)
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- Reduction of sulfoxides to sulfides in the presence of copper catalysts
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Copper complexes catalyze the reduction of aliphatic and aromatic sulfoxides in the presence of silanes as reducing reagent. The influence of different reaction parameters on the catalytic activity is investigated in detail. The scope and limitations of the described catalyst is demonstrated in the reduction of various sulfoxides. In most cases, high conversion and excellent chemoselectivity are obtained. Graphical Abstract: [Figure not available: see fulltext.]
- Enthaler, Stephan,Weidauer, Maik
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experimental part
p. 833 - 838
(2012/02/14)
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- Reactions of dichloromethane with chalcogens and dimethyl chalcogenides in the hydrazine hydrate-alkali system
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Methods of synthesis of compounds MeY(CH2Y) n Me (Y=S, Se, Te; n = 1-3) containing several identical or different chalcogen atoms are suggested. The methods are based on the reactions of dichloromethane with elemental chalcogens (Ys
- Levanova,Vshivtsev,Sukhomazova,Grabel'nykh,Russavskaya,Zhanchipova,Klyba,Albanov,Korchevin
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experimental part
p. 1734 - 1741
(2009/02/07)
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- The effect of basicity on fluorodenitration reactions using tetramethylammonium salts
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The fluorodenitration of several nitroaromatics with tetramethylammonium salts has been found to be dependent on the basicity of the fluorinating species. Tetramethylammonium fluoride is highly basic and is capable of inducing H-D exchange in 1,3-dinitrobenzene, as well as deprotonating N,N- dimethylacetamide. Reaction of the fluoride with phthalic anhydride forms the bifluoride in situ. Tetramethylammonium bifluoride gives higher yields of the required fluoroaromatic, but slower reaction rates than the corresponding fluoride.
- Adams, Dave J.,Clark, James H.,Nightingale, David J.
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p. 7725 - 7738
(2007/10/03)
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- Solution reactivity of thiyl radicals with molecular oxygen: Unsensitized photooxidation of dimethyldisulfide
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Irradiation of dimethyldisulfide in a protic solvent in the presence of molecular oxygen leads to the formation of sulfonic and sulfuric acids as major products. The addition of molecular oxygen on the thiyl radical formed by S-S bond cleavage is postulated.
- Banchereau, Evelyne,Lacombe, Sylvie,Ollivier, Jean
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p. 8197 - 8200
(2007/10/02)
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- Reactions of Sulfoxides with Magnesium Amides. Transformations of Sulfoxides into Sulfides, Dithioacetals and Vinyl Sulfides
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The reactions of sulfoxides with magnesium amides generated in situ from the reaction of ethylmagnesium bromide and seconday amines, such as diisopropylamine (DIPA) or 2,2,6,6-tetramethylpiperidine (TMP) in diethyl ether, were examined.Diaryl sulfoxides were heated with the diisopropylaminomagnesium reagent in diethyl ether to give the corresponding diaryl sulfides in 42-52percent yields.Sulfoxides bearing hydrogens at the α-position only(RSOCH2R1) reacted with the tetramethylpiperidinomagnesium reagent at room temperature to produce the corresponding dithioacetals (RSCHR1SR) in 47-86percent yields.The treatment of sulfoxides bearing hydrogens both at the α-and β-positions (RSOCHR1CHR2R3) with the magnesium amides at room temperature afforded the corresponding vinyl sulfides (RSCR1=CR2R3) in 52-72percent yields accompanying 2.3-27percent yields of the corresponding dithioacetals.The pathways leading to the products involving the formation of the sulfur-stabilized carbonium ion intermediates are discussed.
- Kobayashi, Kazuhiro,Kawakita, Masataka,Yokota, Kouichi,Mannami, Tohru,Yamamoto, Koji,et al.
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p. 1401 - 1408
(2007/10/02)
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- The Lawesson reagent as selective reducing agent for sulfoxides
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Different functionalized sulfoxides can be selectively deoxygenated by Lawesson reagent to yield the corresponding sulfides in high amounts.
- Bartsch,Erker
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p. 199 - 200
(2007/10/02)
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- 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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p. 688 - 694
(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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- REACTION OF SULFOXIDES WITH NITRILES IN PRESENCE OF TRIFLUOROACETIC ANHYDRIDE AND TRIFLUOROACETIC ACID: A CASE OF RITTER REACTION OF PUMMERER INTERMEDIATE
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Reaction of various sulfoxides 9, with nitriles 10 in presence of trifluoroacetic anhydride and trifluoroacetic acid gave the corresponding amides 11 via a Ritter reaction on Pummerer intermediate derived from the sulfoxides.
- Vankar, Yashwant D.,Rao, C. Trinadha
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p. 3405 - 3410
(2007/10/02)
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- Reaction of methanethiol with species produced in a microwave discharge through water vapor
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The products of reaction of methanethiol with species produced by passage of water vapor through a microwave discharge were studied.Mass spectrometric analysis demonstrated the presence of SO2, CH3SSCH3, CH3SSSCH3, CH3SSSSCH3, CH3SSCH2SCH3, CH3SCH2SCH3, and S8.These products are consistent with a mechanism involving abstraction of hydrogen from CH3SH by OH and other radicals as the important primary process.
- Chang, C. H.,Goodfriend, P. L.,Bentley, M. D.,Anderegg, R. J.
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p. 1617 - 1619
(2007/10/02)
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- The chemistry of small ring compounds. Part 46. Reduction of 1-halocyclopropyl sulfides by thiolates
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The reaction of 1-halocyclopropyl sulfides with sodium alkanethiolates in protic or aprotic solvents leads to high yields of cyclopropyl sulfides, in which halogen has been replaced by hydrogen.The complementary oxidized product is, in most cases, the thioketone or thioaldehyde derived from the alkanethiolate.The reduction is unaffected by radical scavengers or by one-electron donors.Reaction kinetics indicate that the reduction proceeds via the 1-(alkylthio)cyclopropyl cation.A mechanism is discussed (Scheme 9) in which this ambident cation is attacked by thiolate on sulfur.In the intermediary sulfonium ylid an intramolecular hydrogen shift leads to the observed products.
- Jorritsma, R.,Steinberg, H.,Boer, Th. J. de
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p. 288 - 298
(2007/10/02)
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- UNKNOWN REACTIONS OF POLYCHLORINATED CYCLOPENTENONES WITH DIMETHYL SULFOXIDE
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It was shown that perchloro-2-cyclopenten-1-one, perchloro-2-cyclopentene-1,4-dione, perchloro-2,5-dihydrofuran-2-one, perchloroindenone, and 2,3,4,4,5-pentachloro-2-cyclopenten-1-one enter into the Pummerer reaction with dimethyl sulfoxide like acid chlorides.
- Maslennikov, E. I.,Talzi, V. P.,Gunbin, V. N.,Yasman, Ya. B.,Gudoshnikov, S. K.
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p. 2258 - 2260
(2007/10/02)
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- Electrophilic Methylthiomethylation of Enol Ethers and Activated Aromatic Compounds. Application of the Former Reaction to the Synthesis of the Macrocycle, 3,3,7,7,11,11,15,15-Octamethyl-1,9-dithia-5,13-diazacyclohexadecane
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Enol ethers of dialkylacetaldehydes, either as such, or generated in situ from the corresponding acetals, undergo ready methylthiomethylation when heated with dimethyl sulphoxide-acetic anhydride (or methylthiomethyl acetate) in the presence of boron trifluoride-diethyl ether.These same reagent combinations can be used to methylthiomethylate certain activated aromatic compounds.The synthetic utility of the former reaction is demonstrated in the synthesis of 2,2,6,6-dimethyl-4-thiaheptanedial (4) which has been converted into 3,3,7,7,11,11,15,15-octamethyl-1,9-dithia-5,13-diazacyclohexadecane (7).
- McCrindle, Robert,McAlees, Alan J.,Stephenson, Donald K.
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p. 3070 - 3073
(2007/10/02)
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