- From symmetrical tetrasulfides to trisulfide dioxides: Via photocatalysis
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A straightforward strategy involving photocatalysis has been established for accessing trisulfide dioxides from readily achieved symmetrical tetrasulfides. Stern-Volmer analysis and radical quenching experiments demonstrated the occurrence of a single electron transfer between the photocatalyst and sulfinic acid. Bioactive molecules such as the antihypertensive drug captopril, allicin derivatives, amino acids and terpenes were efficiently and reversibly linked through sulfur-sulfur covalent bonds. Furthermore, flow-setup syntheses of trisulfide dioxides were successfully achieved on the gram scale, indicating the great potential of the developed protocol for practical industrial applications. This journal is
- Gong, Kai,Jiang, Xuefeng,Zhou, Yilin
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supporting information
p. 9865 - 9869
(2021/12/24)
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- Sandmeyer-Type Reductive Disulfuration of Anilines
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A transition metal/ligand-free disulfuration of anilines with disulfur transfer reagents (dithiosulfonate or tetrasulfide) is reported herein. The reaction, which can be considered as a reductive disulfuration variation of the classic Sandmeyer reaction, is performed under mild conditions and exhibits broad scope across the aniline substrate and disulfur transfer reagent classes. The gram-scale synthesis of disulfides is successfully achieved through this method, rendering the approach highly valuable.
- Chen, Shiqi,Cao, Si,Liu, Chaoyang,Wang, Baoxu,Ren, Xiaorui,Huang, Hang,Peng, Zhihong,Wang, Xi
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supporting information
p. 7428 - 7433
(2021/10/12)
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- Radical Substitution Provides a Unique Route to Disulfides
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Radical substitution on tetrasulfides is demonstrated to be a highly effective means to prepare unsymmetric disulfides. Alkyl and aryl radicals generated thermally or photochemically underwent substitution on readily prepared dialkyl, diaryl, and diacyl tetrasulfides to yield the corresponding disulfides in good to excellent yields. Classic and contemporary thermal and photochemical radical sources could be employed; while photoredox catalysis approaches led to either oxidation or reduction of the tetrasulfide, energy transfer photocatalysis was particularly useful. The success of the approach is driven by the thermodynamic stability of the perthiyl radicals formed upon substitution on the tetrasulfide; they simply combine under the reaction conditions to provide the starting tetrasulfide. Competition kinetic experiments reveal that alkyl radical substitution on tetrasulfides is a rapid reaction (6 × 105 M-1 s-1) that is enhanced at least 6-fold upon moving from dialkyl tetrasulfide to diacyl tetrasulfide due to favorable polar effects. This unique and versatile reaction enables introduction of disulfide moieties from a variety of radical precursors and straightforward access to hydropersulfides.
- Wu, Zijun,Pratt, Derek A.
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p. 10284 - 10290
(2020/07/27)
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- The antioxidant activity of polysulfides: It's radical!
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Olefin sulfurization, wherein alkenes and sulfur are heated together at high temperatures, produces branched polysulfides. Due to their anti-wear properties, they are indispensible additives to lubricants, but are also added to other petroleum-derived products as oxidation inhibitors. Polysulfides also figure prominently in the chemistry and biology of garlic and other plants of the Allium species. We previously reported that trisulfides, upon oxidation to their corresponding 1-oxides, are surprisingly effective radical-trapping antioxidants (RTAs) at ambient temperatures. Herein, we show that the homolytic substitution mechanism responsible also operates for tetrasulfides, but not trisulfides, disulfides or sulfides. Moreover, we show that this reactivity persists at elevated temperature (160 °C), enabling tetrasulfides to not only eclipse their 1-oxides as RTAs, but also hindered phenols and alkylated diphenylamines-the most common industrial antioxidant additives. The reactivity is unique to higher polysulfides (n ≥ 4), since homolytic substitution upon them at S2 yields stabilized perthiyl radicals. The persistence of perthiyl radicals also underlies the greater reactivity of polysulfides at elevated temperatures relative to their 1-oxides, since homolytic S-S bond cleavage is reversible in the former, but not in the latter. These results suggest that olefin sulfurization processes optimized for tetrasulfide production will afford materials that impart significantly better oxidation stability to hydrocarbon-based products to which polysulfides are added. Moreover, it suggests that RTA activity may contribute to the biological activity of plant-derived polysulfides.
- Chauvin, Jean-Philippe R.,Griesser, Markus,Pratt, Derek A.
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p. 4999 - 5010
(2019/05/29)
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- Oxidation of thiols to bisulfides by elemental sulfur without contamination by higher polysulfides
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Dialkyl disulfides were prepared in near quantitative yield by oxidation of alkanethiols with elemental sulfur using NaOH and ethoxylated alcohols as catalysts. Tergitol 15-S-7 was one of several ethoxylated alcohols which was used. Contamination by trisulfides was essentially eliminated in the disulfide products. The ratios of disulfide to trisulfide ranged from 100/0 to 99.6/0.4 for reactions with primary and secondary alkanethiols (100% excess) such as 1-propanethiol, 1-octanethiol, 2-propanethiol, and 2-butanethiol. The process did not work for tertiary alkanethiols such as 2-methyl-2-propanethiol where the trisulfide was greatly favored.
- Shaw, James E.,McAfee, Marilyn G.
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p. 125 - 131
(2007/10/03)
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- Synthesis and decomposition of some dialkyl oxide derivatives of organotrisulfides
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The isolation or detection of sulfenic sulfonic thioanhydrides 1 (e.g., 6), sulfenyl vic-disulfoxides 4 (e.g., 9, 14), and sulfinic thioanhydrides 5 (e.g., 20) has been carried out by oxidative procedures at various temperatures. The decomposition of these compounds has been investigated and is shown to be consistent with the mechanism proposed for the decomposition of trisulfide monoxides.
- Derbesy, Gerard,Harpp, David N.
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p. 991 - 997
(2007/10/03)
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- Use of a sacriflcial-sulfur electrode in electroorganic chemistry. V. Formation of the sequence CSSSC from S and thiols or thiolates
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At a working potential of about +2.0 V (vs SCE) the carbon-sulfur electrode is a source of the electrogenerated cation S2+. In organic media, this electrophile reacts with thiols (or thiolates) to give a mixture of polysulfides of which the trisulfide is the main product. The reaction between electrogenerated Sy2- and alkyl halides is less selective. Elsevier,.
- Do, Quang Tho,Elothmani, Driss,Simonet, Jacques,Guillanton, Georges Le
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p. 273 - 281
(2007/10/03)
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- The Chemistry of Alkylsulfenyl Alkylsulfinyl Thioanhydrides. The Mechanism of Decomposition
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The decomposition mechanism of alkylsulfenyl alkylsulfinyl thioanhydrides has been investigated.Although the product mixture is complex in most cases, a detailed decomposition study as well as a careful analysis of the products allows for a proposal for a general mechanism which is interesting and not simple.We find, however, that the decomposition process is consistent with that of related systems.
- Derbesy, Gerard,Harpp, David N.
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p. 4468 - 4474
(2007/10/02)
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- A simple method to prepare unsymmetrical di- tri- and tetrasulfides
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Unsymmetrical di- tri- and tetrasulfides can be prepared in a one-pot reaction using SO2Cl2 SCl2 and S2Cl2 respectively to permit coupling of the appropriate thiols.
- Derbesy, Gerard,Harpp, David N.
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p. 5381 - 5384
(2007/10/02)
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- Anodic Oxidation of Di-tert-butyl Disulfide: a Facile Method for the Preparation of N-tert-Butylamides
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The electrochemical oxidation of di-tert-butyl disulfide is shown to correspond to a one electron process; at 1.3 V, one carbon-sulfur bond is cleaved yielding two intermediate species; the tert-butyl cation and the radical t-BuS-S; a Ritter reaction occurs with the cation when the solvent is a nitrile and the cation dimerizes into a tetrasulfide; at a more positive potential (1.9 V) the two carbon-sulfur bonds are cleaved giving t-Bu cation and sulfur.
- Elothmani, Driss,Do, Quang Tho,Simonet, Jacques,Guillanton, Georges Le
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p. 715 - 717
(2007/10/02)
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- Peroxidation of S-(2-Methyl-2-propyl) 2-Methyl-2-propanesulfinothioate
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Oxidation of 1 equiv of S-(2-methyl-2-propyl) 2-methyl-2-propanesulfinothioate (1) with 2 equiv of m-chloroperoxybenzoic acid (MCPBA) gives S-(2-methyl-2-propyl) 2-methyl-2-propanesulfonothioate (4, 13percent), 2-methyl-2-propanesulfenic 2-methyl-2-propanesolfonic thioanhydride (5, 32percent), 2-methyl-2-propyl-3-chlorobenzoate (11, 4percent), 2-methyl-2-propyl 2-methyl-2-propanesulfinate (12, 22percent), and small amounts of bis(2-methyl-2-propyl) trisulfide (7) and bis(2-methyl-2-propyl) tetrasulfide (10).Possible mechanisms for product formation are discussed.
- Freeman, Fillmore,Lee, Choonsun
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p. 1263 - 1266
(2007/10/02)
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- Electro-organic Reactions. Part 24. Preparative and Mechanistic Aspects of the Anodic Oxidation of Dithioacetals and 1,3-Dithianes
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Anodic oxidation of the title compounds is a convenient and efficient method for deprotection, i.e. for the regeneration of carbonyl compounds. A detailed investigation of sulphur-containing products confirmed that the initial, 2 F mol-1, products are disulphides which, in aqueous acetonitrile, are oxidised further to alkyl alkane thiosulphinates and the corresponding thiosulphonates.In some cases alkyl polysulphides and N-alkylacetamides are important products.Unsymmetrical dithioacetals are oxidised anodically to the three possible disulphides, i.e. cross-coupling occurs.Unsymmetrical disulphides are similarly oxidised to a complex mixture of symmetrical and unsymmetrical thiosulphinates and thiosulphonates. These results, combined with those of cyclic voltammetric and coulometric experiments, suggest a mechanism in which the key step in carbon-sulphur bond cleavage in the initially formed radical cation.The direction of the cleavage is determined by understandable substituent effects.
- Porter, Quentin N.,Utley, James H. P.,Machion, Pedro D.,Pardini, Vera L.,Schumacher, Paolo R.,Viertler, Hans
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p. 973 - 979
(2007/10/02)
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- REACTION OF SULFUR DIOXIDE WITH THIOLS CATALYZED BY BORON TRIFLUORIDE ETHERATE. EVIDENCE FOR A POSSIBLE INTERVENTION OF DITHIOSULFITE AS A REACTION INTERMEDIATE.
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The reaction of sulfur dioxide (SO//2) with 1-propanethiol (NPT), 2-propanethiol (IPT), or 2-methyl-2-propanethiol (TBT) catalyzed by boron trifluoride ethrate (BF//3OEt//2) was investigated. The ratios of dialkyl trisulfide to dialkyl disulfide obtained (RSSSR/RSSR) at an early stage of the reaction were larger than 1 for the reaction of TBT and less than 1 for the reaction of NPT or IPT. The reaction of dithiosulfites with BF//3OEt//2 in the presence or absence of thiol was investigated. From a consideration of the similarity of the composition of the sulfides formed in the reaction of dithiosulfites with BF//3OEt//2 to those in the reaction of SO//2 witn thiol in the presence of BF//3OEt//2, the possibility of the intervention of dithiosulfite as a reaction intermediate in the reaction of SO//2 with thiol is discussed.
- Akiyama
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p. 2657 - 2660
(2007/10/02)
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- Reactions of tert-butylsulfinyl chloride with tert-butyl hydroperoxide and tert-butyl hydrodisulfide in the presence of pyridine. Observation of 1H CIDNP effects
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tert-Butylsulfinyl chloride (1) reacts smoothly with tert-butyl hydroperoxide (2) in the presence of pyridine to afford a variety of products including pyridinium tert-butylsulfonate, tert-butyl tert-butylthiolsulfonate, tert-butanol and tert-butylsulfonyl chloride.The mechanistic pathway most likely involves homolytic cleavage of the initially formed tert-butyl tert-butylperoxysulfinate (5) via a radical cage process. 1H CIDNP effects provide strong evidence in support of the radical pair mechanism.The homolytic dissociation of 5 contrasts with the preferred heterolytic cleavage of peroxysulfonates.Under similar reaction conditions, 1 reacts with tert-butyl hydrodisulfide (3) to afford tert-butylsulfinyl tert-butyldisulfide (13) in a yield of 90percent.As compared with 5, thermal decomposition of 13 is much slower, reflecting the higher SO-S bond dissociation energy in 13, relative to the low O-O bond dissociation energy in 5.At elevated temperatures, 13 yields tert-butyl tert-butylthiolsulfonate and di-tert-butyl tetrasulfide, probably via a homolytic pathway.
- Bleeker, Ido P.,Engberts, Jan B. F. N.
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p. 459 - 461
(2007/10/02)
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