Dialkyl Disulfides Research Articles

Phase-Controlled Colloidal Syntheses of Iron Sulfide Nanocrystals via Sulfur Precursor Reactivity and Direct Pyrite Precipitation

In the colloidal synthesis of iron sulfides, a series of dialkyl disulfides, alkyl thiols, and dialkyl disulfides (allyl, benzyl, tert-butyl, and phenyl) were employed as sulfur sources. Their reactivity was found to tune the phase between pyrite (FeS2), greigite (Fe3S4), and pyrrhotite (Fe7S8). DFT was used to show that sulfur-rich phases were favored when the C–S bond strength was low in the organosulfurs, yet temperature dependent studies and other observations indicated the reasons for phase selectivity were more nuanced; the different precursors decomposed through different reaction mechanisms, some involving the oleylamine solvent. The formation of pyrite from diallyl disulfide was carefully studied as it was the only precursor to yield FeS2. Raman spectroscopy indicated that FeS2 forms directly without an FeS intermediate, unlike most synthetic procedures to pyrite. Diallyl disulfide releases persulfide (S–S)2– due to the lower C–S bond strength relative to the S–S bond strength, as well as facile ...

Catalytic synthesis of dialkyl sulfides from dialkyl disulfides

Dialkyl disulfides R2S2 where R = Me, Et, or Pr, both as individual compounds and as their mixtures, isolated from petroleum products can turn into alkanethiols and dialkyl sulfides under the action of catalysts having strong acid sites and medium-strength basic sites on their surface. In a helium atmosphere, the main conversion products are alkanethiols, while dialkyl sulfides form in low yield at a selectivity of no higher than 20%. A much higher dialkyl sulfide selectivity is attained in the reaction involving methanol. The most efficient catalyst for this reaction is alumina, with which the dialkyl sulfide selectivity is up to 99%.

Fatty Acid Methyl Esters with Two Vicinal Alkylthio Side Chains and Their NMR Characterization

AbstractThe addition reaction of dimethyl disulfide (DMDS) to double bonds in alkenes and monounsaturated fatty acid esters in the presence of iodine or other catalysts to give bis(methylthio) derivatives has largely served analytical purposes in mass spectrometry with scattered reports on the addition of other disulfides to alkenes also existing. In this work, this iodine‐catalyzed reaction was expanded to include the addition of other dialkyl disulfides (RSSR; R=ethyl, propyl, butyl, iso‐propyl) besides DMDS to the double bonds in monounsaturated fatty acid methyl esters with 16, 18, 20, and 22 carbon atoms in the fatty acid chain to give the corresponding methyl 1,2‐bis(alkylthio)alkanoates. The products are obtained in high to moderate yield after a facile purification procedure and are analytically characterized not only by mass spectrometry but also 1H and 13C NMR. The threo and erythro diastereomers obtained from (Z) and (E) fatty acid methyl esters, respectively, can be easily distinguished by the NMR shifts of the protons and carbons in and close to the 1,2‐bis(alkylthio) moiety. Various other effects in the NMR spectra are discussed. The 1,2‐bis(alkylthio) derivatives of a symmetrical alkene, 7(E)‐tetradecene, serve to confirm the NMR assignments besides NMR techniques such as 2D correlations and DEPT. The compounds may show properties of interest for various applications.

Simple and green method for synthesis of symmetrical dialkyl disulfides and trisulfides from alkyl halides in water; PMOxT as a sulfur donor

ABSTRACTAn environmentally new, mild and efficient method has been developed for the synthesis of dialkyl disulfides and dialkyl trisulfides in aqueous conditions by a reaction between alkyl halides (and tosylate) and potassium-5-methyl-1,3,4-oxadiazole-2-thiolate (PMOxT) as a sulfur transfer reagent. The advantages of this method are that it occurs under mild reaction conditions, it is base free, it uses water as the solvent and it occurs in high yields. A variety of dialkyl disulfides and dialkyl trisulfides can be obtained in good to excellent yields up to 98%.

Autocatalytic, bistable, oscillatory networks of biologically relevant organic reactions.

Networks of organic chemical reactions are important in life and probably played a central part in its origin. Network dynamics regulate cell division, circadian rhythms, nerve impulses and chemotaxis, and guide the development of organisms. Although out-of-equilibrium networks of chemical reactions have the potential to display emergent network dynamics such as spontaneous pattern formation, bistability and periodic oscillations, the principles that enable networks of organic reactions to develop complex behaviours are incompletely understood. Here we describe a network of biologically relevant organic reactions (amide formation, thiolate-thioester exchange, thiolate-disulfide interchange and conjugate addition) that displays bistability and oscillations in the concentrations of organic thiols and amides. Oscillations arise from the interaction between three subcomponents of the network: an autocatalytic cycle that generates thiols and amides from thioesters and dialkyl disulfides; a trigger that controls autocatalytic growth; and inhibitory processes that remove activating thiol species that are produced during the autocatalytic cycle. In contrast to previous studies that have demonstrated oscillations and bistability using highly evolved biomolecules (enzymes and DNA) or inorganic molecules of questionable biochemical relevance (for example, those used in Belousov-Zhabotinskii-type reactions), the organic molecules we use are relevant to metabolism and similar to those that might have existed on the early Earth. By using small organic molecules to build a network of organic reactions with autocatalytic, bistable and oscillatory behaviour, we identify principles that explain the ways in which dynamic networks relevant to life could have developed. Modifications of this network will clarify the influence of molecular structure on the dynamics of reaction networks, and may enable the design of biomimetic networks and of synthetic self-regulating and evolving chemical systems.

Self-Assembled Monolayers prepared from alkanethiols or dialkyl disulfides on Au: evidence of influence of the anchoring group.

Mainly based on electrochemical investigations, this work provides evidence of discrimination between self-assembled monolayers (SAMs) prepared from alkanethiols or symmetrical dialkyl disulfides on gold. Gravimetric experiments carried out by quartz crystal microbalance during the elaboration of ferrocene based SAMs (from alkanethiols FcC15SH and dialkyl disulfides FcC15SSC15Fc), showed significant differences between monolayers made from the two precursors. The recorded mass was almost 60 % more important with FcC15SH by comparison with FcC15SSC15Fc. The resulting cyclic voltammograms also highlighted a 60 % difference concerning the surface coverage of ferrocene heads. Moreover, dialkyl disulfide and thiol anchoring groups led to symmetrical and dissymmetrical peaks, respectively, suggesting not insignificant differences concerning interactions between adsorbed species into the two kinds of elaborated monolayers. These observations were confirmed on SAMs obtained from other precursors possessing shorter chain length or another functional moiety.

Symmetrical disulfide synthesis via nickel-catalysis using potassium sulfide as sulfur source

An efficient one-pot method for the synthesis of organic disulfides from aryl and alkyl halides and potassium sulfide has been described. K2S acts as an inexpensive and readily available sulfur source. A variety of symmetric diaryl and dialkyl disulfides was prepared in good to excellent yields using NiCl2·6H2O and acetylacetone as the catalytic system.

ChemInform Abstract: K2S2O8/I2 Promoted Syntheses of α‐Thio‐β‐dicarbonyl Compounds via Oxidative C—S Coupling Reactions under Transition Metal‐Free and Solvent‐Free Conditions.

A K2S2O8/I2 promoted C–S coupling reaction of β-diketones with disulfides has been described. The resulting α-thio-β-diketone compounds were obtained in good to excellent yields. Both diaryl and dialkyl disulfides coupled well with a variety of β-diketones under transition metal-free and solvent-free conditions.

An efficient one-pot method for the direct synthesis of organic disulfides from aryl/alkyl halides in the presence of CuCl using morpholin-4-ium morpholine-4-carbo-dithioate

A novel and expedient route is described for the one-pot synthesis of symmetric diaryl (dialkyl) disulfides derivatives via morpholin-4-ium morpholine-4-carbo-dithioate and aryl (alkyl) halides reactions in the presence of CuCl in an aqueous solvent system. Morpholin-4-ium morpholine-4-carbo-dithioate used as new solid, stable and easy handle sulfur Sourcage.

Direct synthesis of disulfides from alkyl halides using thiourea and CCl4 in glycerol

Dialkyl disulfides were obtained on the basis of the reaction of alkyl halides and thiourea in the presence of CCl4 and Et3N. This procedure enables the odorless and one-pot synthesis of disulfides by employing cheap, easy-to-handle and readily available reagents and substrates in wet glycerol.

Disulfide linkage Raman markers: a reconsideration attempt

During the last decades, Raman spectroscopy has been routinely used for probing the conformational features of disulfide linkages in peptides and proteins. However, the interpretation of disulfide Raman markers is currently performed by a simple rule derived from the earliest observations on dialkyl disulfides. More precisely, this rule consists of the following: (1) in analyzing the Raman bands in the 550–500 cm−1 region ascribed to disulfide bond stretch motion, namely, ν(S‐S), and (2) assigning the three types of Raman markers observed at ~500, ~520, and ~540 cm−1 to three families of rotamers defined along the three successive bonds of the ‐C‐S‐S‐C‐ moiety, referred to as ggg, ggt, and tgt. In this report, we attempt to show that an accurate analysis of disulfide vibrational features needs the use of the five torsion angles (χ1, χ2, χ3, χ2', and χ1') along the five successive bonds joining the two α‐carbon atoms in the cystine (Cys‐Cys) unit. The present work is inspired by the disulfide conformational investigations performed by a statistical scan of numerous protein crystal and nuclear magnetic resonance data, taking into account the handedness (right and left) of a disulfide bridge, its spatial shape (Staple, Hook, and Spiral), as well as the signs of the two extreme torsion angles χ1 and χ1'. It appears that the combined use of the old and recent conformational notations allows a more accurate structural and vibrational analysis of disulfide linkage. Copyright © 2014 John Wiley & Sons, Ltd.

Silver-mediated oxidative vinylic C-H bond sulfenylation of enamides with disulfides.

A silver-mediated oxidative vinylic C-H bond sulfenylation of enamides was developed. This method is compatible with diaryl and dialkyl disulfides to deliver biologically precious chalcogenated olefins efficiently. A plausible non-chain radical mechanism was proposed for understanding this novel sulfenylation based on the mechanistic studies.

Disulfide Oil Hazard Assessment Using Categorical Analysis and a Mode of Action Determination

Diethyl and diphenyl disulfides, naphtha sweetening (Chemical Abstracts Service [CAS] # 68955-96-4), are primarily composed of low-molecular-weight dialkyl disulfides extracted from C4 to C5 light hydrocarbon streams during the refining of crude oil. The substance, commonly known as disulfide oil (DSO), can be composed of up to 17 different disulfides and trisulfides with monoalkyl chain lengths no greater than C4. The disulfides in DSO constitute a homologous series of chemical constituents that are perfectly suited for a hazard evaluation using a read-across/worst-case approach. The DSO constituents exhibit a common mode of action that is operable at all trophic levels. The observed oxidative stress response is mediated by reactive oxygen species and free radical intermediates generated after disulfide bond cleavage and subsequent redox cycling of the resulting mercaptan. Evidence indicates that the lowest series member, dimethyl disulfide (DMDS), can operate as a worst-case surrogate for other members of the series, since it displays the highest toxicity. Increasing the alkyl chain length or degree of substitution has been shown to serially reduce disulfide toxicity through resonance stabilization of the radical intermediate or steric inhibition of the initial enzymatic step. The following case study examines the mode of action for dialkyl disulfide toxicity and documents the use of read-across information from DMDS to assess the hazards of DSO. The results indicate that DSO possesses high aquatic toxicity, moderate environmental persistence, low to moderate acute toxicity, high repeated dose toxicity, and a low potential for genotoxicity, carcinogenicity, and reproductive/developmental effects.

An efficient and convenient synthesis of unsymmetrical disulfides from thioacetates

We have developed convenient methods for the synthesis of functionalized unsymmetrical dialkyl disulfides under mild conditions in very good yields. The designed method is based on the reaction of (5,5-dimethyl-2-thioxo-1,3,2-dioxaphosphorinan-2-yl)-disulfanyl derivatives 1 with functionalized alkyl thiolate anions, generated in situ from thioacetates 2 and sodium methoxide or butylamine. The developed method allows the preparation of unsymmetrical disulfides bearing additional hydroxy, carboxy, amino, azido, biotin, or maleimide functionalities.

An evaluation of alkylthiols and dialkyl disulfides on deactivation of Cu/Zn catalyst in hydrogenation of dodecyl methyl ester to dodecanol

Deactivation of co-precipitated Cu/Zn catalyst caused by exposure to either alkylthiols or dialkyl disulfides in catalytic hydrogenation of dodecyl methyl ester to dodecanol is explored in a stirred batch reactor. Catalytic activity decrement is highly dependent on levels of poisons, types of thiols/disulfides, chain length of alkanes. XRD, EDS and XPS are employed to characterize the fresh and spent Cu/Zn catalysts. It is evident that sulfuric species prefer to attack zinc oxide, forming chemically adsorbed Zn-SR at low sulfur levels, and ZnS is formed in the highly reductive atmosphere before sulfuric species attacking copper (forming Cu7S4 or Cu31S16).

Acyl iodides in organic synthesis. reaction of acetyl iodide with Dialkyl sulfides and disulfides

Reactions of acetyl iodide with dialkyl and dialkenyl sulfides RSR (R = Et, Bu, CH2=CH, CH2=CHCH2) and with disulfides RSSR (R = Pr, C6H13, PhCH2) were studied. Dialkyl sulfides reacted with MeCOI to give the corresponding alkyl ethanethioates and alkyl iodides as a result of cleavage of the S-C bond. The reactions of acetyl iodide with divinyl and diallyl sulfides involved addition across the double bond and subsequent polymerization of 1-alkenylsulfanyl-2(3)-iodoalkyl methyl ketones. Dialkyl disulfides RSSR (R = Pr, C6H13) and dibenzyl disulfide reacted with acetyl iodide via cleavage of the S-S bond to produce the corresponding ethanethioates and organylsulfenyl iodides. The latter underwent disproportionation to form the initial disulfide and molecular iodine.

Aerobic oxidation of thiols to disulfides under ball-milling in the absence of any catalyst, solvent, or base

An efficient aerobic chemoselective oxidation of thiols to disulfides has been achieved under ball-milling over neutral aluminium oxide (grinding auxiliary) in the absence of any catalyst, co-oxidant, solvent, or base. A wide variety of functionalized diaryl, diheteroaryl and dialkyl disulfides have been obtained in high yields.

A novel copper-catalyzed, one-pot synthesis of symmetric organic disulfides from alkyl and aryl halides: potassium 5-methyl-1,3,4-oxadiazole-2-thiolate as a novel sulfur transfer reagent

A new method is reported for the synthesis of symmetric diaryl and dialkyl disulfides from aryl and alkyl halides in the presence of copper using potassium 5-methyl-1,3,4-oxadiazole-2-thiolate as the base, ligand, and sulfur-transfer reagent.

Scent Chemicals of the Brushtail Possum, Trichosurus vulpecula

The common brushtail possum (Trichosurus vulpecula) is the most widespread browsing marsupial in Australia, where it occupies woodland, agricultural, and urban environments. Following its introduction into New Zealand in the 19th century it has become a major feral pest, threatening native forests. The adaptability of the possum is thought to be due in part to its social organization, in which chemical communication is important. Possums have cloacal glands and exhibit related marking behavior. This study sought to characterize the chemicals involved in scent marking. Swabs were taken of the cloacal region of 15 possums (5 females, 10 males) from north-eastern Tasmania and analyzed by gas chromatography-mass spectrometry. There was a large number of compounds present, including 81 branched and unbranched, and saturated and unsaturated, fatty acids (C(4)-C(15)) and alcohols (C(6)-C(26)); 27 esters of 2,6- and 2,7-dimethyloctanol; 29 esters of formic acid; 39 sulfur compounds including S(8) and a series of dialkyl disulfides, trisulfides, and tetrasulfides (C(4)-C(10)); and several alkylglycerol ethers. Many of these cloacal compounds are new to biology. There was considerable individual variability in the relative amounts of compounds found, and no evident sex differences, although the study was not designed to test this. This pattern suggests that these compounds may be acting collectively as a signature mixture of semiochemicals, carrying information on the individual, its kinship, and physiological and social status. This is the first detailed description of putative semiochemicals in any marsupial species.

ChemInform Abstract: Synthesis of Diaryl Disulfides via Mild Reduction of Arylsulfinates with Hydrazine Monohydrate in DMSO.

AbstractThe reaction is not suitable to aliphatic sulfinates as the corresponding dialkyl disulfides are obtained in less than 10% yield.