Dibutyl Sulphide Research Articles

Corrosion Resistance, Electrochemical and Surface Morphology Studies of Mild Steel in a Sulfuric Acid Medium by using Dibutyl Sulphide

Corrosion Resistance, Electrochemical and Surface Morphology Studies of Mild Steel in a Sulfuric Acid Medium by using Dibutyl Sulphide

Comparative study of MCM-22 and MCM-56 modified with molybdenum – Impact of the metal on acidic and oxidative properties of zeolites

Hydrogen forms of layered MCM-22 and delaminated MCM-56 zeolites were modified with molybdenum species. The structure/texture and surface properties as well as catalytic activity in methanol transformation and dibutyl sulphide oxidation were compared for the two types of modified zeolites. The difference in the distribution of hydroxyls in HMCM-22 and HMCM-56 (more Brønsted acid sites (BAS) on HMCM-22, their high strength on HMCM-22, and domination of external silanols in HMCM-56) determines the location and properties of MoO3. Mo species interact with BAS on Mo/HMCM-22, which results in good dispersion of MoO3 and harder reducibility of molybdenum. Preferential interaction of Mo species with silanols on the external surface of HMCM-56 leads to larger crystallites of MoO3 which are easier to reduce. The strength of BAS is lower in HMCM-56 than in HMCM-22 and it is reduced in HMCM-22 after modification with Mo species. The lower strength of BAS in HMCM-56 results in a higher selectivity to 2-butene in the transformation of methanol, reaching 98.5% for Mo/HMCM-56. Mo species play a crucial role in the oxidation of sulphide to sulphoxide by H2O2. MoO3 is less stable in Mo/HMCM-56 because of the weaker interaction with the external zeolite surface. It is leached to the solution during oxidation of dibutyl sulphide. Therefore, Mo/HMCM-22, where Mo species are stronger bound to the surface, is more effective catalyst for this reaction.

Scientific Opinion on the safety and efficacy of aliphatic and aromatic mono‐ and di‐thiols and mono‐, di‐, tri‐, and polysulphides with or without additional oxygenated functional groups (chemical group 20) when used as flavourings for all animal species

Chemical group 20 consists of aliphatic and aromatic mono- and di-thiols and mono-, di-, tri-, and polysulphides with or without additional oxygenated functional groups, of which 31 are currently authorised for use as flavours in food. The FEEDAP Panel was unable to perform an assessment of six compounds (methanethiol, methyl propyl disulphide, dipropyl trisulphide, 3-mercaptobutan-2-one, 3-(methylthio)butanal and 3-methyl-1, 2,4-trithiane) because of issues related to the purity of the compounds. The FEEDAP Panel concludes that the following 25 compounds are safe for the target species at the proposed maximum dose level (0.05 mg/kg complete feed): 3-(methylthio)propionaldehyde, methyl 3-(methylthio)propionate, allylthiol, dimethyl sulphide, dibutyl sulphide, diallyl disulphide, diallyl trisulphide, dimethyl trisulphide, dipropyl disulphide, allyl isothiocyanate, dimethyl disulphide, 2-methylbenzene-1-thiol, S-methyl butanethioate, allyl methyl disulphide, 3-(methylthio)propan-1-ol, 3-(methylthio)hexan-1-ol, 1-propane-1-thiol, diallyl sulphide, 2,4-dithiapentane, 2-methyl-2-(methyldithio)propanal, 2-methylpropane-1-thiol, methylsulfinylmethane, propane-2-thiol, 3,5-dimethyl-1, 2,4-trithiolane and 2-methyl-4-propyl-1, 3-oxathiane. No safety concern for the consumer would arise from the use of these 25 compounds of CG 20 up to the highest safe level in feedingstuffs for all animal species, with the exception of allyl isothiocyanate. Although additional exposure to this substance through its low use level in animal feeds would not substantially increase consumer exposure, the FEEDAP Panel notes that the estimated exposure of consumers is already higher than the acceptable daily intake (ADI). All compounds should be considered irritant to skin, eyes and respiratory tract and as skin sensitisers. The proposed concentration of 0.05 mg flavour/kg feed is not expected to cause detrimental effects to the environment, except for 2-methylpropane-1-thiol, for which 0.04 mg/kg is expected to be safe. Since all 25 compounds are used in food as flavourings and their function is essentially the same as that in food, no further demonstration of efficacy is necessary.

Utilization of Mass and Elastic Loading in Oxide Materials Based SAW Devices for the Detection of Mustard Gas Simulant

The properties (mass loading and elastic changes) of different oxide materials (ZnO, TeO2, SnO2, TiO2) in thin film form has been explored for the enhanced detection of DBS (di butyl sulphide), a simulant of sulphur mustard gas. All the four oxide materials are deposited on to the surface of SAW (Surface Acoustic Wave) devices to impart sensitivity and selectivity. ZnO and SnO2 films are crystalline whereas TiO2 and TeO2 films are amorphous in nature. All the films are transparent with transparency greater than 75 % in the visible region. The SAW devices coated with different oxide materials were placed in the feedback loop of colpitt oscillator. With the exposure of DBS vapors, differential frequency increases for TiO2 thin films whereas for other oxide coatings (ZnO, TeO2 and SnO2) it decreases. ZnO coated SAW sensor is found to be maximum sensitive to DBS vapors. Investigation of sensing mechanism revealed that mass loading effect is pronounced in TiO2 thin film whereas for other films change in elasticity is dominant. The oxide coatings are very less sensitive to the other interferants.

Gold and gold–iron modified zeolites—Towards the adsorptive deodourisation

Zeolites exhibiting different structures (Y, Beta, and ZSM-5) were modified with gold and iron and applied for odour adsorption from the air containing dibutyl sulphide (Bu 2S) used as a representative odour producing compound. The structure of the zeolites used determines the rate of adsorption (higher on Y type zeolites and smaller on two other zeolites), whereas hydrophilicity affects the selectivity towards Bu 2S adsorption increasing in the order: Y < Beta < ZSM-5. For the same zeolite structure, Bu 2S adsorption selectivity depends on the total acidity of zeolites which increases after iron modification. The texture and surface properties of the modified zeolites were studied by XRD, XPS, UV–vis, TEM, pyridine adsorption and FTIR, test reactions (acetonylacetone cyclisation, isopropanol decomposition).

Investigation of DBS electro-oxidation reaction in the aqueous-organic solution of LiClO4

A process of dibutyl sulphide (DBS) electro-oxidation using electrolysis and cyclic voltamperometry was investigated in water-methanol solution using different electrodes (platinum, boron doped diamond, graphite and glassy carbon). Obtained results indicate that the DBS electro-oxidation process is irreversible in voltamperometric conditions. It was shown that during DBS electrolytic oxidation on Pt, at the low anode potential (1.8 V), DBS was oxidized to sulphoxide and sulphone. Electrolysis at higher potential (up to 3.0 V) resulted in complete DBS oxidation and formation of various products, including: butyric acid, sulphuric acid, butanesulphinic acid, butanesulphonic acid, identified using gas chromatography (GC-AED) and mass spectrometry (GC-MS) methods.

In-situ degradation of sulphur mustard using (1R)-(-)-(camphorylsulphonyl) oxaziridine impregnated adsorbents

Bis-2-chloroethyl sulphide (sulphur mustard or HD) is an extremely toxic and persistent chemical warfare agent. For in-situ degradation of HD and its analogues (simulants), i.e., dibutyl sulphide (DBS) and ethyl 2-hydroxyethyl sulphide (HEES), different adsorbents systems loaded with (1R)-(-)-(camphorylsulphonyl) oxaziridine were prepared. Solution of sulphur mustard and its simulants was prepared in carbon tetrachloride and taken for uniform adsorption on the impregnated systems using incipient volume. Degradation kinetics monitored by GC/FID were found to be first-order. The half-life of degradation reactions for simulants was obtained in less than 30 and for HD in 120 min. From the studied kinetics it was observed that reaction was very rapid with simulants and decreased rate was found for HD. The order of reactivity of MgO/Oxa system for HD and simulants was found to be DBS > HEES > HD. Reaction products of the oxidation reaction of simulants and HD on adsorbents were extracted in dichloromethane and analysed by GC–MS. The products were found to be non-toxic sulphoxide. The objective of the study is to develop a reactive adsorbent for in-situ degradation of sulphur mustard which could be used in nuclear biological and chemical (NBC) filtration systems.

Liquid crystal coating for SAW sensors

This paper presents results on measurements of surface acoustic wave (SAW) sensor, using polymer liquid crystal layer. The sensitivity and response time for different test probes have been studied. The sensitivity of the order of 4 Hz/ppm or higher, towards such compounds as N,N-dimethylacetamide (DMA), dimethyl methylphosphonate and dibutyl sulphide, was found. The results show that the very high sensitivity towards DMA results from interaction of DMA with structurally ordered liquid crystalline material.

In-situ degradation of sulphur mustard and its simulants on the surface of impregnated carbon systems

Bis-2-chloroethyl sulphide (sulphur mustard or HD) is an extremely toxic and persistent chemical warfare agent. For in situ degradation of HD and its analogues (simulants), i.e., dibutyl sulphide (DBS) and ethyl 2-hydroxyethyl sulphide (HEES), different carbon systems such as 11-molybdo-1-vanadophosphoric acid impregnated carbon (V 1/C), ruthenium chloride impregnated carbon (Ru/C) and combination of these two (V 1/Ru/C) were prepared. These carbons were characterized for cumulative micropore volume and surface area by N 2 BET. The kinetics of the in situ degradation of HD and its simulants were studied and found to be following the first order kinetics. Kinetic rate constants and t 1/2 values were determined. Products were characterized using NMR, IR and GC–MS. Reaction products were found to be sulphoxide and sulphone. The combined system, i.e., 11-molybdo-1-vanadophosphoric acid plus ruthenium chloride (V 1/Ru/C) was found to be best for in-situ degradation of HD and its simulants. In-situ degradation by polyoxometalate based system was found to be stoichiometry based while Ru/C oxidized HD in presence of chemisorbed oxygen. In combined system of V 1/Ru/C ruthenium worked as a catalyst and polyoxometalate acted as a source of oxygen. Effect of moisture was also studied in combined system. Rate of degradation of HD was found to be increasing with increased percentage of moisture content.

Identification of trace volatile compounds in freshly distilled Calvados and Cognac: Carbonyl and sulphur compounds

Carbonyl and sulphur compounds were investigated in freshly distilled Calvados and Cognac. Forty-eight aldehydes and ketones were identified in both products using specific extraction, with Girard's T reagent supported on silica-gel. The recovery procedure of these compounds in a high ethanolic medium was optimized. Samples contained a majority of saturated aliphatic aldehydes and ketones. The presence of unsaturated aliphatic aldehydes and ketones, such as alkenals, oct-1-en-3-one, 6-methylhept-5-en-2-one and β -damascenone, was also detected. Numerous terpenoic or norisoprenoic carbonyl compounds were characterized and seem to be specific to Cognac. Twenty-seven sulphur compounds were quantified in the same samples; small amounts of thiols were detected. Concentrations of dimethyl disulphide were from 50–500 μg L −1 of pure alcohol (PA), and a high content of dibutyl sulphide (20–100 μg L −1 of PA) was recorded. Concentrations of ethyl propyl sulphide and diethyl sulphide, which were not significant in Calvados, were above 25 μg L −1 of PA in Cognac. 2- and 3-thiophenecarboxaldehyde were also quantified, and concentrations as high as 1000 μg L −1 in some samples, were the most important in Cognac. The ratio of 3- and 2-thiophenecarboxaldehyde was higher than 10 for Calvados, but was less than 0.5 for Cognac. Although weak concentrations of methional were recorded, this may contribute to the overall aroma of these two spirits due to extremely low detection threshold. The total concentration of sulphur compounds in Cognac samples was five to six times that of Calvados samples.

Radiochemical extraction of mercury(II) from acidic chloride solutions using dialkylsulphides

Abstract The liquid-liquid extraction behavior of Hg(II) from aqueous acidic chloride solutions has been investigated by tracer techniques using dialkylsulphides (R2S) namely, dibutylsulphide (DBS) and dioctylsulphide (DOS) as extractants. These extraction data have been analyzed by both graphical and theoretical methods by taking into account complexation of the metal ion in the aqueous phase with inorganic ligands and all plausible complexes extracted into the organic phase. The results clearly indicate that Hg(II) is extracted into xylene as HgCl2 . nDBS/nDOS (where n = 2 and 3). The equilibrium constants of the extracted complexes have been deduced by non-linear regression analysis. The separation possibilities of Hg(II) from other metal ions viz. Ca(II), Mg(II), Ba(II) and Fe((III), which are present in the industrial wastes of the chlor-alkali industry has also been discussed.

Oxidative properties of niobium-containing mesoporous silica catalysts

Oxidative properties of MCM-41 molecular sieves containing niobium in the framework or/and in the extra framework positions were studied by means of H 2-TPR, FTIR+NO, ESR techniques and were tested in the oxidation of dibutyl sulphide with hydrogen peroxide. The application of various Nb-sources in the synthesis of NbMCM-41 materials allows the estimation of a role of oxalate ions in the generation of active centres. The activity of Nb-containing mesoporous molecular sieves in the oxidation of thioethers with H 2O 2 requires the presence of Nb–O − species in the framework. The growth of a concentration of niobium (from Si/Nb=32 to Si/Nb=16) results in the decrease of the number of active centres due to the release of oxygen during the activation procedure. Niobium species in the extra framework positions of MCM-41 catalysts are not active in the dibutyl sulphide oxidation with H 2O 2 unless they are leached to the solution. Oxidative centres on the catalyst surface cause the formation of nitrite/nitrate species after the adsorption of NO.

A new simple method for monitoring permeation through clothing materials of dibutyl sulphide, a chemical warfare agent simulant

A new simple method is proposed for monitoring permeation of dibutyl sulphide through protective clothing materials. The method is based upon the reaction of sodium nitroprusside with sulphide ions in alkaline medium. It is carried out as a spot test on the filter paper previously impregnated with sodium nitroprusside as indicator compound or directly on clothing material. The violet colour that indicates the presence of sulphide ions is detectable with a magnifying glass and even with the naked eye. The method was applied for the determination of breakthrough times of some intermediates in the fabrication of protective clothing materials, based on polyester fibres technologically treated among other chemicals, with 4,4′-dithiomorpholine, 2-mercaptobenzothiazole disulphide and dipentamethylenethiuram tetrasulphide. The widely recommended fluorescence quenching technique was in this case shown to be inapplicable because of severe interferences caused by technological pretreatment of clothing materials, resulting in diminished fluorescence signals of indicator compounds by mere contact with clothing materials. The new analytical method is sensitive enough, shows no interferences and is a simple, fast, and low cost test for permeation monitoring of dibutyl sulphide.

A new technique to measure the deactivation rate of edible oil catalysts due to sulphur poisoning

A new experimental set up has been applied to accurately monitor the H 2 absorption rate in edible oil hydrogenation by using a Peteric Pressflow Controller. This technique was used to determine the deleterious effect on the rate of hydrogenation of a S-component, namely dibutyl sulphide, added to soybean oil in amounts of 0.5, 1, 2 and 4 times the amount required to poison the Ni surface with one S per two Ni atoms. This new technique proved to be a valuable method which made it possible to follow the iodine value as a function of time and to calculate the reduction in the hydrogenation rate accurately. The turnover numbers calculated for the initial rates and based on two different, estimated, values for the effective H 2 diffusion coefficient were about a factor 5 to 8 times lower due to the presence of sulphur.

Oxygen exchange between sulphoxides and sulphides. Part 3. The HCl-catalysed reduction of aryl methyl sulphoxides by dialkyl sulphides in aqueous methanol

Dialkyl sulphides reduce aryl methyl Sulphoxides in aqueous methanol in the presence of ca. 4 mol dm–3 HCl. Ring substitution in phenyl methyl sulphoxides moderately affects their reactivity towards dibutyl sulphide, the overall effect resulting in a Hammett ρ value of –1.6. This parameter is a measure of the effect of structural changes on a protonation pre-equilibrium, the formation of chlorosulphonium ion, and its subsequent partitioning between reduction and return to reactants by the action of water. Changing the alkyl moiety of the sulphides induces moderate reactivity changes suggesting a compensation of opposite polar and steric effects. Sulphoxides with electron-releasing groups display the highest selectivity towards dialkyl sulphides. When a large concentration of sulphide is used, both racemization of chiral sulphoxide and 18O exchange with the aqueous solvent are suppressed and this suggests that the species ArR1SCl+ is a common intermediate for these processes and for the reduction reaction. These and other kinetic findings indicate that the reduction step involves the displacement at the ArR1SCl+ chlorine of a sulphide by a sulphide molecule rather than by chloride ion and rules out, for the racemization too, the hypothesis involving a free halogen intermediate.

Determination of platinum and gold in biological materials by neutron activation analysis

A procedure for platinum and gold determination utilizing, neutron activation combined with radiochemical separation, has been developed. The reaction198Pt (n, ′γ)199\(Pt\xrightarrow{\beta }\) is used for Pt determination. Four procedures for gold separation are examined: (1) adsorption on untreated polyurethane foam (UPF). (2) extraction with dibutyl sulphide. (3) reduction of gold to elementary state in conc. H2SO4, and extraction of gold as diethyldithiocarbamate complex. The extraction with Cu(DDC)2 is chosen as the most suitable process and applied to platinum and gold determinations in Bowen's Kale and mice organs, previously treated with Biocisplatinum® specimens.

Storage stability of jet fuels

Storage stabilities of jet fuels derived from petroleum were determined using laser light scattering, sediment formation and oxygen uptake measurements. Fuel degradation was monitored in the presence of the following added specific compounds: 2,5-dimethylpyrrole (DMP), N-methyl pyrrole (NMP), thiophenol, thiophene, decanethanol, dibutyl sulphide, dibutyl disulphide, tetrahydrothiophene, hexadiene, 1-hexene, indene, iron(II), and copper(II)-phthalocyanines (FePc, CuPc) and mixtures of some of these at various temperatures. The light scattering results are correlated with extent of deposit formation, which is an accepted measure of stability, and with oxygen uptake results. Light scattering intensity, weight of deposit and oxygen uptake increase with increase in storage time, concentration of added specific compound and stress temperature. Temperature variations of these measurements give activation energies of the degradation reactions. The first direct evidence has been obtained of the pyrrole radicals in DMP and NMP when a fuel is degraded in the presence of pyrrole. These two pyrrole radicals give different electron paramagnetic resonance parameters: g and linewidth values. The degradation products obtained in the presence of FePc and CuPc show properties which indicate that CuPc interacts with petroleum JP-5 with added DMP more strongly than does FePc.

Assay of platinum and gold in biological material by neutron activation analysis

Compounds of both gold and platinum are used in medicine, the former as salts to treat arthritides and the latter as the metal complex cisplatin to treat cancer. We have investigated neutron activation analysis with the Slowpoke II reactor as an assay method for both elements using human blood plasma as a matrix. Neutron activation of platinum gives rise to 3.15 day199Au while that of gold produces 2.7 day198Au. Activated samples are dissolved during heating in test tubes and the gold extracted by adding dibutyl sulphide to the same tube. The latter is formed to able to quantitate Pt down to 60 ng and Au down to 60 pg. The dissolution technique and possible interferences in the assay are discussed.

The oxygen exchange between sulphoxides and sulphides. The hydrogen chloride catalysed reaction between p-chlorophenyl methyl sulphoxide and dibutyl sulphide

Alkyl aryl sulphoxides are reduced by dialkyl sulphides in 2 : 1 methanol–water in the presence of 4M-HCl. The kinetics of the reaction between p-chlorophenyl methyl sulphoxide and dibutyl sulphide and the basic properties of the sulphoxide have been investigated in detail. Reaction orders, acid catalysis, and comparison of the reduction rate with that of the loss of optical activity by the (+)-R-sulphoxide indicate a predominant role for the chlorosulphonium cation. A mechanism is suggested in which the changes of the oxidation states occur through the reaction between the sulphide and this intermediate.

The influence of radioactive n-dibutyl sulphide on the corrosion and polarization of steel and its electrocapillary behaviour in in sulphuric acid

The corrosion and polarization of steel have been investigated in 1N sulphuric acid, containing n-dibutyl sulphide labelled with radioactive sulphur atom. In addition, the electrocapillary behaviour of the radioactive substance on a mercury surface in the acid has been tested. Similar experiments employing non-radioactive dibutyl sulphide (d.b.s.) and hydrogen peroxide have been carried out. The inhibition of corrosion of steel in IN sulphuric acid by d.b.s. is significantly reduced and under some conditions corrosion is accelerated by the radioactive form. The polarization and the electrocapillary behaviour of radioactive d.b.s. solutions are clearly different from that of the non-radioactive compound. There is some similarity in the effects produced by radioactive d.b.s. and by a combination of non-radioactive d.b.s. and hydrogen peroxide, in respect of corrosion inhibition and electrocapillary behaviour. It is concluded that the effects produced by radioactive d.b.s. can be attributed mainly to the hydrogen peroxide produced by radiolysis, though the radioactivity can also affect the electrical characteristics at the metal-solution interface.