Alkyl Thiosulfates Research Articles

Tetrafluoroborate and Hexafluorophosphate Ions are not Interchangeable: A Density Functional Theory Comparison of Hydrogen Bonding

AbstractDue to their similarities in charge and composition, the tetrafluoroborate (BF4−) and hexafluorophosphate (PF6−) ions are often used interchangeably in chemical studies. As a result, the ability of BF4−, but not PF6−, to inhibit the hydrolysis of alkyl thiosulfates in non‐aqueous solution was surprising. This divergence in reactivity may reflect differences in the ability of these ions to form strong hydrogen bonds to hydronium ion, which catalyzes the hydrolysis, and prompted the current computational studies. Calculations using density functional theory (DFT) gave atomic partial charges, occupation numbers, and energies relevant to hydrogen bonding of these anions. Topological analysis using the Atoms‐in‐Molecule (AIM) method elucidated the nature of the interactions, and natural‐bonding‐orbital (NBO) analysis provided insight on the strength of hydrogen bonding within the different tetrafluoroborate and hexafluorophosphate complexes. The calculated second‐order perturbation energies (E(2)) revealed that BF4− and H3O+ formed stronger hydrogen bonds than did PF6− and H3O+, suggesting that clusters formed by the former pair are more stable.

ChemInform Abstract: Ligand‐Controlled Divergent Cross‐Coupling Involving Organosilicon Compounds for Thioether and Thioester Synthesis.

AbstractVarious aryl‐ and alkyl thiosulfates are used for a base‐free, odorless reaction with triethoxy(het)arylsilanes, and depending on the reaction conditions thioethers or, in the presence of carbon monoxide, thioesters are formed in moderate to often high yields.

Mechanism of Spontaneous Formation of Monolayers on Gold from Alkyl Thiosulfates

The kinetics of adsorption of self-assembled monolayers (SAMs) from solutions of hexadecyl thiosulfate in tetrahydrofuran was studied under a variety of experimental conditions to elucidate the mechanism(s) important in this process. Monolayers did not form in the absence of water, which ruled out the direct addition of the alkyl thiosulfate to the gold surface and implicated hydrolysis as a route to surface-active adsorbates. The role of tetrafluoroborate ion, known to inhibit SAM formation in this system, was also examined. These studies, too, were consistent with hydrolysis as an intermediate step in the formation of monolayer films in this system.

Direct Route to Well-Defined, Chemically Diverse Electrode Arrays

The selective placement of molecules of interest at specific locations on surfaces is a keystone for the bridge between interfacial science and technology. One approach to this problem is the use of electrochemistry to direct interfacial reactions that immobilize species from solution onto surfaces. In this study, sets of individually functionalized gold electrodes were formed by the selective formation of monolayers from four different alkyl thiosulfates. Analysis of the arrays using spatially resolved X-ray photoelectron spectroscopy (XPS) revealed each type of functionality exclusively on the electrode to which it was directed. The wetting behavior of these surfaces was also consistent with homogeneous monolayers placed selectively on each electrode. The flexibility of this method provides the ability to produce a wide variety of chemical patterns at interfaces of interest for a range of technological applications.

Electrochemically directed two-component monolayers on gold

Abstract

ChemInform Abstract: Indium-Mediated Reaction in Aqueous Media. Synthesis of Phenacyl Sulfides by Reactions of α-Bromoketones with Sodium Alkyl Thiosulfates.

Phenacyl sulfides are synthesized in moderate to good yields via reaction of α-haloketones with sodium alkyl thiosulfates promoted by indium metal in aqueous media.

ChemInform Abstract: Metallic Samarium Promoted Reductive Dimerization Cyclization of gem-Diactivated Alkenes, Reductive Debromination of vic-Dibromides, and Reduction of Sodium Alkyl Thiosulfates in Aqueous Media.

Abstract In saturated NH 4 Cl (ap.)-THF solution at room temperature, metallic samarium promoted reductive dimerization cyclization of gem -diactivated alkenes, reductive debromination of vic -dibromides, and reduction of sodium alkyl thiosulfates occur to afford corresponding functionalized cyclopentenes, ( E )-alkenes, and disulfides, respectively in good yield. Only sub-stoichiometric quantities of samarium are employed in the former reactions and the trans - or trans,trans -form isomer is the majority product of the polysubstituted cyclopentene products.

Sodium 2-propenyl thiosulfate derived from garlic induces phase II detoxification enzymes in rat hepatoma H4IIE cells

There is evidence that onions and garlic protect against cancer in humans. It has been suggested that this effect is partly due to the organosulfur compounds in Allium vegetables and that these substances act through induction of phase II detoxification enzymes. Here, we hypothesized that alk(en)yl thiosulfates, sodium n-propyl thiosulfate (NPTS), and sodium 2-propenyl thiosulfate (2PTS), which were identified in onions and garlic, respectively, may induce phase II enzymes. Therefore, rat hepatoma cells (H4IIE) were cultured with 1 to 100 micromol/L of NPTS or 2PTS for 48 hours at 37 degrees C; and the activities and messenger RNA (mRNA) expression levels of phase II enzymes in H4IIE cells were investigated. The effects of diallyl trisulfide and tert-butylhydroquinone, known as phase II inducers, were also examined as positive controls and compared with the responses of NPTS and 2PTS. Quinone reductase (QR) activity and mRNA expression levels of QR and epoxide hydrolase 1 were significantly increased by 2PTS (P < .05-.005). In particular, QR activity was increased at a relatively low concentration of 2PTS (10 micromol/L). However, glutathione S-transferase activity and mRNA expression levels of glutathione S-transferase A5 and uridine diphosphate glucuronosyl transferase 1A1 were not changed by 2PTS. In contrast, NPTS did not affect the activities and mRNA expression levels of these phase II enzymes. These results show that 2PTS can induce phase II enzymes, and its inductive effect is comparable or superior to that of diallyl trisulfide and tert-butylhydroquinone.

Compatibility of ω-Functionality in the Electrochemically Directed Self-Assembly of Monolayers on Gold from Alkyl Thiosulfates

Self-assembled monolayers were formed on gold electrochemically from omega-functionalized alkyl thiosulfates (Bunte salts). The resulting SAMs were characterized using X-ray photoelectron spectroscopy (XPS), contact-angle goniometry, and ellipsometry. A range of terminal functionality was examined, including CH(3), perfluoroalkyl, CO(2)H, CO(2)CH(3), CONH(2), CH(2)OH, and vinyl groups. Side-reactions involving some of these functional groups were consistent with intermediates proposed in our earlier publications and begin to define the scope of this method for building chemical structures at interfaces.

Direct Synthesis of Large Water-Soluble Functionalized Gold Nanoparticles Using Bunte Salts as Ligand Precursors

The widespread use of functionalized gold nanoparticles (AuNPs) in a rapidly increasing number of sensing and biomedical applications has made the development of synthetic methods that combine precise surface chemistry control (functionality) with effective core size control over the range of 1-20 nm crucial. Although a variety of effective methods exist for controlling the core size and functionality during gold nanoparticle synthesis, there is a lack of synthetic methods that permit the direct synthesis of thiol-protected gold nanoparticles with core diameters greater than 5.0 nm. Inspired by previous reports on the use of alkyl thiosulfates (Bunte salts) as ligand precursors, we anticipated that the slow passivation kinetics of these masked thiols would provide a method to synthesize large functionalized AuNPs directly. We found that Bunte salts produce larger AuNPs under the same synthesis conditions than do thiols. We investigated the effect of the ligand/gold ratio, temperature, and reducing agent concentration on the particle diameter and dispersity to understand better how to control particle size. The AuNP core size can be systematically controlled by varying the ratio of ligand precursor/gold (L/Au) and the temperature of the reaction. The synthesis produces functionalized AuNPs ranging from 1.5 to 20.0 nm in diameter. The use of Bunte salts provides a convenient synthetic platform for the synthesis of AuNPs across this size range that possess a variety of surface functionalities, including positive, negative, and neutral functional groups.

Water Effects on SmI2 Reductions: A Novel Method for the Synthesis of Alkyl Thiols by SmI2‐Promoted Reductions of Sodium Alkyl Thiosulfates and Alkyl Thiocyanates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Growth inhibitory effect of alk(en)yl thiosulfates derived from onion and garlic in human immortalized and tumor cell lines

Two alk(en)yl thiosulfates, sodium n-propyl thiosulfate (NPTS) and sodium 2-propenyl thiosulfate (2PTS), are natural constituents of onion and garlic, respectively, which were identified originally as causative agents of onion- and garlic-induced hemolytic anemia in dogs. As a continuation of our studies on the beneficial functions of NPTS and 2PTS, in the present study, we investigated the antitumor effects of these compounds. They were shown to inhibit the in vitro proliferation of three human tumorigenic cell lines, WiDr, 293 and HL-60, in a dose-dependent manner. Overall, NPTS seemed to have weak activity for inhibiting cell growth compared with 2PTS, though not in WiDr cells, which were sensitive to both compounds. NPTS and 2PTS caused oxidative damage to HL-60 cells and induced apoptosis. The extent of apoptosis was approximately proportional to that of the oxidative damage and also to that of the cytotoxicity caused by these compounds. These results suggest that the alk(en)yl thiosulfates have an antitumor effect through the induction of apoptosis initiated by oxidative stress.

A Novel Reduction of Sodium Alkyl Thiosulfates with InCl3(cat.)/Sm(0) System in Aqueous Media: Facile Synthesis of Disulfides.

A novel reduction of sodium alkyl thiosulfates with InCl3(cat.)/Sm(0) system in aqueous media has been developed, which generates the corresponding disulfides in good yields. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:376–379, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20023

Water Effects on SmI2 Reductions: A Novel Method for the Synthesis of Alkyl Thiols by SmI2‐Promoted Reductions of Sodium Alkyl Thiosulfates and Alkyl Thiocyanates

Water as a cosolvent has significant improving effect on the reductivity of SmI2 in the reduction of sodium alkyl thiosulfates and alkyl thiocyanates. A new method for synthesis of alkyl thiols by SmI2/THF/H2O system has been developed.

Acceleration of superoxide generation in polymorphonuclear leukocytes and inhibition of platelet aggregation by alk(en)yl thiosulfates derived from onion and garlic in dogs and humans

We recently identified sodium n-propyl thiosulfate (NPTS) and sodium 2-propenyl thiosulfate (2PTS) from boiled onion and garlic, respectively, as causative agents of hemolytic anemia in dogs. We present here data concerning the effects of these alk(en)yl thiosulfates on superoxide (O 2 −) generation in peripheral polymorphonuclear leukocytes (PMNs) and on adenosine 5′-diphosphate (ADP)-induced platelet aggregation in dogs and humans in vitro. Both NPTS and 2PTS increased O 2 − generation significantly ( P<0.05 at 1 mM NPTS, P<0.005 at 0.1 and 1 mM 2PTS) and reduced its reaction time significantly ( P<0.05 between 0.01 and 1 mM NPTS and at 1 mM 2PTS) in canine PMNs stimulated by phorbol 12-myristate 13-acetate, compared with the control without alk(en)yl thiosulfates. However, a tendency to return to the control level was observed at 10 mM of the alk(en)yl thiosulfates in both O 2 − generation and its reaction time. Although NPTS and 2PTS did not exert any significant effect on the O 2 − generation in human PMNs, 2PTS reduced its reaction time significantly ( P<0.05) at 1 and 10 mM compared with the control, showing that 2PTS accelerated O 2 − generation in human PMNs. The difference in effects on O 2 − generation may be due to that in susceptibility to alk(en)yl thiosulfates between canine and human PMNs. On the other hand, NPTS and 2PTS were shown to significantly inhibit ADP-induced platelet aggregation at 0.01 mM ( P<0.01) in canine platelets and at 0.001–0.1 mM ( P<0.05) in human platelets. In contrast, the maximal aggregation percentage returned to the control level at 1 mM of alk(en)yl thiosulfates in both canine and human platelets. From these results, we conclude that NPTS and 2PTS have the potential to promote immune functions and prevent cardiovascular diseases.

A Novel Reduction of Sodium Alkyl Thiosulfates Using Samarium Metal Without an Activating Agent in Water.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A novel reduction of sodium alkyl thiosulfates using samarium metal without an activating agent in water

A novel metallic samarium promoted reduction of sodium alkyl thiosulfates in the absence of an activating agent occurs to afford the corresponding disulfides with good yields in water at 90°C.

Characterization of Self-Assembled Monolayers Formed from Sodium S-Alkyl Thiosulfates on Copper

We report the formation of self-assembled monolayers (SAMs) from sodium S-alkyl thiosulfates (CH3(CH2)n-1S2O3-Na+) onto copper in aqueous and organic solvents. These ionic compounds are considerably more soluble in water than alkanethiols, and they adsorb to the copper surface primarily as thiolates. Characterization by electrochemical impedance spectroscopy (EIS) reveals that SAMs formed from longer-chained thiosulfates (n = 12, 14) exhibit comparable barrier properties to those of thiol-based SAMs when formed in organic solvents but diminished effectiveness when formed in aqueous solution. However, the water-borne thiosulfate-based SAMs do provide an increase in corrosion resistance by ∼2−3 orders of magnitude compared to that of uncoated copper. Analysis by infrared (IR) spectroscopy indicates that the thiosulfate-based SAMs are less crystalline and less densely packed than thiol-based SAMs. Wetting measurements suggest that the surfaces of thiosulfate-based SAMs expose a greater number of methylene groups in comparison to that for the well-ordered methyl structure of alkanethiol-based SAMs. The combination of these analyses leads to a proposed structure for thiosulfate-based SAMs on copper in which the films contain molecular-scale defects, lower adsorbate density, and more disordered alkyl chains than SAMs formed from alkanethiols. A comparison of thiosulfate-based SAMs to those formed from benzotriazole (BTAH), a widely used corrosion inhibitor for copper, shows that longer-chained thiosulfates may be useful in inhibiting the corrosion of copper in aqueous environments.

A Novel synthesis of Selenosulfides from Diselenides by Samarium Diiodide

Diselenides were reduced by samarium diiodide in tetrahydrofuran (THF) to produce samarium selenolate. This selenolate anion reacted smoothly with sodium alkyl thiosulfates and phenylsulfenyl chloride to give selenosulfides in moderate to good yields.

Water Accelerated Sm/TMSCl Reductive System: Debromination of VIC—Dibromides and Reduction of Sodium Alkyl Thiosulfates

A simple and efficient method for the debromination of vic-dibromides to (E)-alkenes and reduction of sodium alkyl thiosulfates to disulfides promoted by Sm/TMSCl/H2O (trace) has been described.