- Novel episulfone substitution and ring-opening reactions via α-sulfonyl carbanion intermediates
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Three-membered cyclic sulfones undergo substitution on treatment with base-electrophile mixtures, such as LDA-Me3SiCl and tBu-P4-phosphazene base-PhCHO, to give either substituted episulfones or the corresponding alkenes following loss of SO2-In the absence of Me3SiCl, reaction of episulfones with LDA results in ring-opening to give alkenyl sulfinate intermediates, which can be alkylated to give (E)-alkenyl sulfone products in stereoselective fashion.
- Simpkins, Nigel S.
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Read Online
- Method for preparing taurine
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The invention relates to a method for preparing taurine. The method comprises the following steps: (1) conducting an addition reaction on ethylene and SO2 to obtain thiirane 1,1-dioxide; and (2) conducting an aminolysis reaction on the thiirane 1,1-dioxide, ammonia and water to obtain taurine. The used raw materials, that is, ethylene, SO2 and ammonia are relatively cheap and readily available, and the used ethylene has no safety hazard of ethylene oxide. In addition, the taurine synthesis method provided by the invention has the advantages of green environment-friendly process, convenient operation, low cost, high yield and easy industrial production.
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Page/Page column 5-6
(2019/04/26)
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- A kinetic investigation, supported by theoretical calculations, of steric and ring strain effects on the oxidation of sulfides and sulfoxides by dimethyldioxirane in acetone
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The oxidations of alkyl 4-nitrophenyl, and dialkyl, sulfides and sulfoxides by dimethyldioxirane in acetone occur by concerted mechanisms but the sulfides respond differently from the sulfoxides to variation in the alkyl group. The reactions of the sulfides are inhibited by the steric effects of alkyl groups and these predominate over their inductive effects. By contrast, the reactions of these limited sets of sulfoxides are insensitive to alkyl steric effects but there is an indication of steric acceleration when a broader set of sulfoxides is considered. This behaviour is rationalised in terms of the differences in dipolar charge and its solvation between the ground state and transition state for the two types of substrate. The oxidations of cyclic sulfides and sulfoxides also exhibit contrasting behaviour. The reactivity of the sulfides is insensitive to ring strain but is explicable in frontier orbital terms whereas that of the sulfoxides is partly dependent upon the change in ring strain between reactant and product on oxidation, a difference rationalised in terms of the relative positions of the transition states in the reaction coordinates of the two oxidations. The reactivity of 4-, 5- and 6-membered cyclic sulfoxides is also dependent on a ring-size related property of the transition state. Calculations at the B3-LYP/6-31G* level of density functional theory on both ground states and transition states, including simulation of solvation by acetone, strongly support the mechanistic conclusions reached in this and earlier work.
- Hanson, Peter,Hendrickx, Ramon A. A. J.,Lindsay Smith, John R.
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scheme or table
p. 65 - 84
(2011/01/07)
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- Observed and calculated 1Hand 13C chemical shifts induced by the in situ oxidation ofmodel sulfides to sulfoxides and sulfones
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A series of model sulfides was oxidized in the NMR sample tube to sulfoxides and sulfones by the stepwise addition of meta-chloroperbenzoic acid in deuterochloroform. Various methods of quantum chemical calculations have been tested to reproduce the observed 1H and 13C chemical shifts of the starting sulfides and their oxidation products. It has been shown that the determination of the energy-minimized conformation is a very important condition for obtaining realistic data in the subsequent calculation of the NMR chemical shifts. The correlation between calculated and observed chemical shifts is very good for carbon atoms (even for the 'cheap' DFT B3LYP/6-31G* method) and somewhat less satisfactory for hydrogen atoms. The calculated chemical shifts induced by oxidation (the δd values) agree even better with the experimental values and can also be used to determine the oxidation state of the sulfur atom (-S-, -SO-, -SO2 -). Copyright
- Dracinsky, Martin,Pohl, Radek,Slavetinska, Lenka,Budesinsky, Milos
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experimental part
p. 718 - 726
(2011/05/15)
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- Efficient synthesis of episulfones and of SO2 with any variation of oxygen isotopes using HOF·CH3CN
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Episulfones are quite unstable and difficult to make compounds. HOF·CH3CN, a powerful oxygen transfer agent operating under very mild conditions, was successfully employed in converting episulfides to episulfones. Unlike other oxidizing agents,
- Harel, Tal,Amir, Elizabeta,Rozen, Shlomo
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p. 1213 - 1216
(2007/10/03)
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- The first preparation of episulfones from episulfides: Oxidation using Oxone/trifluoroacetone
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For the first time, episulfones have been prepared by oxidation of the corresponding episulfides. Seven examples are given, most of which proceed in good to excellent yield. The first oxidation of an episulfoxide to an episulfone is also reported as part of a preliminary mechanistic study.
- Johnson, Paul,Taylor, Richard J. K.
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p. 5873 - 5876
(2007/10/03)
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- Episulfone substitution and ring-opening reactions via α-sulfonyl carbanion intermediates
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Three-membered cyclic sulfones undergo substitution on treatment with base-electrophile mixtures, such as LDA-Me3SiCl and Bu′-P4 phosphazene base-PhCHO, to give either substituted episulfones or the corresponding alkenes following loss of SO2. The structure of a trisilylated episulfone product, 2a, was determined by X-ray crystallography. In the absence of Me3SiCl, reaction of episulfones with lithium diisopropylamide results in ring-opening to give alkenyl sulfinate intermediates, which can be alkylated to give (E)-alkenyl sulfone products in stereoselective fashion.
- Dishington, Allan P.,Douthwaite, Richard E.,Mortlock, Andrew,Muccioli, Adriano B.,Simpkins, Nigel S.
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p. 323 - 337
(2007/10/03)
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- Secondary Reactions of Sulfenes from Sulfonyl Chlorides and Tertiary Amines. 2. Formation of Episulfones, Sulfonylsulfene - Amine S,N-Adducts and Chlorsulfines from Primary Sulfonyl Chlorides and Tertiary Amines
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The reaction of primary sulfonyl chlorides 1b-m with the tertiary amine bases quinuclidine, DABCO, Me3N, Et3N, Bu3N, EtiPr2N, and 1,2,2,6,6-pentamethylpiperidine is studied in acetonitrile solution between -40 and 80 deg C.The 2,3-dialkylthiirane 1,1-dioxides 4 (trans/cis > 1) and the alkenes 5 1> are obtained in high yields with Et3N at -40 deg C.The stereochemistry is influenced by the amine base B in the ring-closure reaction and partially by epimerization of the episulfones 4.Hindered bases favor the cis, β-branched sulfonyl chlorides the trans isomer.Competing formation of the sulfonylsulfene - amine S,N-adducts 7 is only observed with quinuclidine, DABCO, and Me3N, which are also the most active amines in the epimerization of the cis-2,3-diarylthiirane 1,1-dioxides 4.Methanesulfonyl chloride (1a) yields the mesylsulfene - amine S,N-adducts 7a with Me3N and Et3N in MeCN, but thiirane 1,1-dioxide (4a) with EtiPr2N in MeCN or with Et3N in Et2O.Formation of chlorosulfines 10 is favored by higher temperature (T > 20 deg C), hindered amine bases and β-branched sulfonyl chlorides.Isolation of 10g and 10h in high yields shows that tert-alkylchlorosulfines are rather stable sulfines.
- Opitz, Guenter,Ehlis, Thomas,Rieth, Karlheinz
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p. 1989 - 1998
(2007/10/02)
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- SYMMETRISCHE ALKENE UEBER EPISULFONE AUS PRIMAEREN SULFONYLCHLORIDEN
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Primary sulfonyl chlorides RCH2SO2Cl (R=Alk or Ar) react with triethylamine in acetonitrile solution at -40 degC to give mixtures of cis- and trans-2,3-disubstituted thiirane-1,1-dioxides which can be thermolyzed to the corresponding Z- and E-alkenes.
- Opitz, Guenter,Ehlis, Thomas,Rieth, Karlheinz
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p. 3131 - 3132
(2007/10/02)
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- COORDINATION AND CATALYTIC REACTIONS OF UNSATURATED COMPOUNDS: IV.* INTERPRETATION OF THE MECHANISM OF EPOXIDATION OF ETHYLENE BY SULFUR DIOXIDE
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Sulfur dioxide reacts with ethylene (but not with higher 1-alkenes) under conditions of heterogeneous catalysis at 300-400 deg C to form ethylene oxide and sulfur together with other products.The epoxidation evidently results from complex formation between the ethylene, sulfur dioxide, and catalyst with subsequent colligation of the C-S bonds, ring enlargement through insertion of an oxygen atom at one of these bonds, and elimination of SO from the unstable cyclic sulfinate.Elemental sulfur is formed in all the secondary transformations (during the decomposition of SO and the reduction of SO2 by the oxirane).
- Devekki, A. V.,Koshelev, Yu. V.,Malov, Yu. I.
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p. 829 - 834
(2007/10/02)
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