Benzyl Sulfides Research Articles

Kinetics and mechanism of phase transfer catalyzed synthesis of aromatic thioethers by H2S-rich methyldiethanolamine

Hydrogen sulphide (H2S) removal and its efficient utilization is a big challenge for many petroleum refinery industries now-a-days. The present investigation involves absorption of H2S in aqueous methyldiethanolamine (MDEA) followed by sulphidation of benzyl chloride (BC) by H2S-rich MDEA to yield dibenzyl sulphide (DBS) selectively using tetrabutylphosphonium bromide (TBPB) as a phase transfer catalyst. Ninety per cent selectivity of DBS was obtained at some level of process condition. A suitable mechanism has been proposed. An empirical kinetic model was also developed and correlated with experimental data. The present work has a potential to be used as an alternative to Claus process.

Formation of Corrosive Sulfur with Dibenzyl Disulfide in Fluid-Filled Transformers

The formation of corrosive sulfur as a result of the addition of dibenzyl disulfide (DBDS) to transformer oils has been investigated. Corrosive sulfur in a transformer affects all aspects of its insulation and conductive components by deposition of Cu2S. Previous studies have suggested that the formation of Cu2S was initiated by a DBDS–Cu complex. This work shows an alternate pathway via thiolate formation for the deposition of corrosive sulfur on copper conductors. The open circuit potential results showed no reduction of DBDS onto copper surfaces, but the degradation products of DBDS, which include dibenzyl sulfide and benzyl mercaptan, were both found to adsorb on copper surfaces, forming a copper thiolate. The formation of copper thiolates was also demonstrated by a heterogeneous reaction of CuO and benzyl mercaptan. Thermal degradation of the thiolate eventually produced copper sulfide Cu7.2S4 as identified by X-ray diffraction analysis.

Visible-Light-Induced Cyclization of Electron-Enriched Phenyl Benzyl Sulfides: Synthesis of Tetrahydrofurans and Tetrahydropyrans

A new approach to the preparation of tetrahydrofurans and tetrahydropyrans through a photoredox catalytic process is described. The introduction of a phenylsulfanyl auxiliary group permits the substrates to be readily oxidized to form cationic intermediates for sequential intramolecular cyclization. The method features mild reaction conditions and operational simplicity.

Biocatalytic Desulfurization Capabilities of a Mixed Culture during Non-Destructive Utilization of Recalcitrant Organosulfur Compounds.

We investigated the biodesulfurization potential of a mixed culture AK6 enriched from petroleum hydrocarbons-polluted soil with dibenzothiophene (DBT) as a sulfur source. In addition to DBT, AK6 utilized the following compounds as sulfur sources: 4-methyldibenzothiophene (4-MDBT), benzothiophene (BT), and 4,6- dimethyldibenzothiophene (4,6-DM-DBT). None of these compounds supported the growth of AK6 as the sole carbon and sulfur source. AK6 could not grow on dibenzylsulfide (DBS) as a sulfur source. The AK6 community structure changed according to the provided sulfur source. The major DGGE bands represented members of the genera Sphingobacterium, Klebsiella, Pseudomonas, Stenotrophomonas, Arthrobacter, Mycobacterium, and Rhodococcus. Sphingobacterium sp. and Pseudomonas sp. were abundant across all cultures utilizing any of the tested thiophenic S-compounds. Mycobacterium/Rhodococcus spp. were restricted to the 4-MDBT culture. The 4-MDBT culture had the highest species richness and diversity. Biodesulfurization of DBT by resting cells of AK6 produced 2-hydroxybiphenyl (2-HBP) in addition to trace amounts of phenylacetate. AK6 transformed DBT to 2-hydroxybiphenyl with a specific activity of 9 ± 0.6 μM 2-HBP g dry cell weight−1 h−1. PCR confirmed the presence in the AK6 community of the sulfur-specific (4S) pathway genes dszB and dszC. Mixed cultures hold a better potential than axenic ones for the development of a biodesulfurization technology.

Indium-catalyzed direct preparation of dibenzyl sulfides from benzyl alcohols and elemental sulfur with a hydrosilane and its application to the preparation of dibenzyl selenide

We describe how a reducing system composed of InI3 and a hydrosilane efficiently and directly introduce elemental sulfur into the structure of dibenzyl sulfides via a nucleophilic substitution of benzyl alcohols. Also, we describe the application of this reducing system in the direct preparation of a dibenzyl selenide derivative with selenium.

Synthesis and Evaluation of some New 5-Substituted-1,3,4- oxadiazol-2yl-4-(morpholin-4yl Sulfonyl)benzyl Sulfides as Antibacterial Agent

Purpose: To synthesise a new series of 5-substituted-1,3,4-Oxadiazol-2yl-4-(morpholin-4yl sulfonyl)benzyl sulfide and evaluate their antibacterial activity. Methods: Different organic acids were converted consecutively into corresponding esters, hydrazides and 5-substituted-1,3,4-Oxadiazol-2-thiols ( 4a-e ). The targets, 6a-e were synthesized by stirring 4a-e with 4-(4-(bromomethyl)phenylsulfonyl) morpholine ( 5 ) in the presence of N,N-dimethylformamide (DMF) and sodium hydride (NaH). All the structures were elucidated by modern spectroscopic techniques and screened against bacteria using standard procedure and ciprofloxacin drug as positive control. Results: The yield of the synthesized compounds ( 4a-e and 6a-e ) were moderate (65 - 90 %). Compounds 6a-e had antibacterial activity against Pseudomonas aeruginosa, Bacillis subtilis and Staphylococcus aureus while some had activity against the other bacteria used. One of the compounds, 6b , exhibited significant activity against all the bacterial strains, i.e., S. typhi (-), E. coli (-), K. pneumoniae (-), P. aeruginosa (-), B. subtilis (+) and S. aureus (+) with MIC (μM) values of 11.01 ± 0.31, 15.37 ± 3.33, 16.11 ± 1.14, 9.70 ± 1.96, 10.01 ± 2.70 and 9.15 ± 0.29, respectively. However, none of the compounds had any inhibitory activity against any bacteria as high as that of ciprofloxacin. Conclusion: Five new compounds with antibacterial activities have been synthesized. Their potential as therapeutic agents is, however, yet to be evaluated. Keywords: 1,3,4-Oxadiazole, Benzyl sulfide, 4-(4-(bromomethyl)phenylsulfonyl)morpholine, Spectral analysis, Antibacterial activity

ChemInform Abstract: TBATB Mediated Debenzylative Cross‐Coupling of Aryl Benzyl Sulfides with Electron Rich Compounds: Synthesis of Diaryl Sulfides.

An efficient TBATB mediated debenzylative cross coupling of aryl benzyl sulfides with electron rich compounds provides diaryl sulfides in moderate to excellent yield. The salient features of the present protocol are simplicity, high efficiency and compatibility of the reaction with various electron rich compounds.

Synthesis, Structural Analysis, and Screening of Some Novel 5-Substituted Aryl/Aralkyl-1,3,4-Oxadiazol-2-Yl 4-(Morpholin-4-Ylsulfonyl)Benzyl Sulfides As Potential Antibacterial Agents

GRAPHICAL ABSTRACT

ChemInform Abstract: Indium‐Catalyzed Reductive Sulfidation of Aromatic Carboxylic Acids and Aldehydes with Elemental Sulfur to Prepare Symmetrical Benzyl Sulfides.

Described herein is a direct approach to symmetrical thioethers from either aromatic carboxylic acids or aromatic aldehydes with elemental sulfur (S8) by using a reducing system combined with InI3 and 1,1,3,3-tetramethyldisiloxane (TMDS). This sulfidation does not require functionalized sulfur reagents, such as sulfides, disulfides, or metal sulfides, and it simultaneously forms two carbon–sulfur bonds in a single catalytic system.

The search for exceptions in the highly enantioselective titanium catalysed oxidation of aryl benzyl sulfides

After the discovery of a few cases of lower enantioselectivity in the oxidation of aryl benzyl sulfides with hydroperoxides in the presence of a complex between titanium isopropoxide and (S, S)-hydrobenzoin, a screening of the oxidation of new substrates that are related to the structures that gave low ee values, was performed. From this screening, we confirmed that only a few sulfides remain as exceptions within a framework of exceptionally high stereoselectivity of the oxidation reaction. Moreover, the exceptions are clearly identified and are connected to particular coordinating moieties present on the aryl groups.

Indium‐Catalyzed Reductive Sulfidation of Aromatic Carboxylic Acids and Aldehydes with Elemental Sulfur to Prepare Symmetrical Benzyl Sulfides

AbstractDescribed herein is a direct approach to symmetrical thioethers from either aromatic carboxylic acids or aromatic aldehydes with elemental sulfur (S8) by using a reducing system combined with InI3 and 1,1,3,3‐tetramethyldisiloxane (TMDS). This sulfidation does not require functionalized sulfur reagents, such as sulfides, disulfides, or metal sulfides, and it simultaneously forms two carbon–sulfur bonds in a single catalytic system.

The differences in potential corrosive effects of sulfides and disulfides in insulating oils

This paper describes work performed in an attempt to bring more clarity regarding the differences in potential corrosive effect between sulfides and disulfides at specified reaction conditions as defined in ASTM 1275 B. SEM/EDS was used to further evaluate testing results. The results show that Dibenzyl disulfide (DBDS) has a strong tendency to form copper sulfides while Dibenzyl sulfide (DBS) display no tendency at all to form copper sulfides in the virgin insulating oils, but the reactivity of DBS increase if in the thermally degraded oils. In addition, the insulating paper decrease the oxidation of the copper surface due to that oxygen is adsorbed and consumed when migrating through the cellulose phase. With the improvement of surface smoothness, the specific surface area accessible for reactions will decrease and consequently it is more difficult for the copper to be corroded by DBDS.

TBATB mediated debenzylative cross-coupling of aryl benzyl sulfides with electron rich compounds: synthesis of diaryl sulfides

An efficient TBATB mediated debenzylative cross coupling of aryl benzyl sulfides with electron rich compounds provides diaryl sulfides in moderate to excellent yield.

Palladium-catalyzed debenzylative cross-coupling of aryl benzyl sulfides with aryl bromides: synthesis of diaryl sulfides.

A novel debenzylative approach to synthesize diaryl sulfides from aryl benzyl sulfides and aryl bromides in good to excellent yields is reported. Mechanistic studies suggest a single catalyst, derived from Pd(dba)2 and NiXantPhos, efficiently catalyzes α-arylation of sulfides, C-S bond cleavage, and C-S bond formation in a tricatalytic cycle.

BrF3–KHF2: An air-stable fluorinating reagent

BrF3–KHF2, an air-stable solid prepared from BrF3 and KHF2, was used in the various fluorination reactions, including desulfurizing fluorination reactions of benzylic sulfides, ketone and aldehyde dithioacetals, (phenylthio)glycosides, and trimethyl trithioorthocarboxylates. As the results, one to three fluorine atoms were selectively introduced to the substrates.

Elucidation of formation mechanism of by-products of copper sulfide deposition on insulating paper in oil-immersed transformer

Copper sulfide deposition on cellulosic insulating materials in oil-immersed transformers is evaluated by heating tests stipulated by IEC 62535. Although this method is suitable for evaluation of the corrosivity of unused insulating oil, the subject remains in diagnosis of the insulating oil used. It is because dibenzyl disulfide (DBDS), which is the prime compounds that cause copper sulfide deposition, is consumed by the reaction with copper during operating of transformer. Therefore, it is necessary to detect the existence of DBDS in insulating oil diagnosed as non-corrosivity by IEC 62535. The proceeding paper [6] reports that Bibenzyl (BiBz) and Dibenzyl sulfide (DBS) will be formed in the insulating oil as by-products of copper sulfide formation between copper and DBDS in oxygen-poor atmosphere which imitated the closed-type transformers. These by-products are considered to be the indication of copper sulfide formation. However, the influence of oxygen and addition agent (e.g. 2,6-di-tert-butylp- cresol) on the mechanism of the by-product formation is unclear. The purpose of this study is to elucidate the influence of oxygen and DBPC in by-products formation for development of diagnosis. It became apparent that benzyl alcohol, benzaldehyde and benzoic acid generate as by-products of copper sulfide formation in the air atmosphere which imitated the open-breathing transformers. Furthermore, it became apparent that the reaction product of benzyl radical and the radical of DBPC generates as by-product of copper sulfide formation in the insulating oil containing DBPC. These by-products are detectable even if DBDS disappears. Therefore, it is thought that diagnosis of the open-breathing transformer is possible by detecting these by-products.

Preferential desulfurization of dibenzyl sulfide by an isolated Gordonia sp. IITR100

Several organosulfur compounds are present in the crude oil, and are required to be removed before its processing into transport fuel. For this reason, biodesulfurization of thiophenic compounds has been studied extensively. However, studies on the sulfide compounds are scarce. In this paper, we describe desulfurization of a model sulfidic compound, dibenzyl sulfide (DBS) by an isolated Gordonia sp. IITR100. The reaction was accompanied with the formation of metabolites dibenzyl sulfoxide, dibenzyl sulfone and benzoic acid. Studies with recombinant E. coli revealed that enzyme DszC of this isolate metabolizes DBS into dibenzyl sulfoxide and dibenzyl sulfone, but the reaction downstream to it is mediated by some enzyme other than its DszA. In reactions where DBS and dibenzothiophene (DBT) were present together, both IITR100 and recombinant E. coli exhibited preference for the desulfurization of DBS over DBT. The newly identified capability of IITR100 for desulfurization of both thiophenic and sulfidic compounds suggests its potential use in improved desulfurization of petroleum fractions.

Investigation of steric and electronic effects in the copper-catalysed asymmetric oxidation of sulfides

Steric and electronic effects in the copper-catalysed asymmetric oxidation of aryl benzyl, aryl alkyl and alkyl benzyl sulfides have been investigated. The presence of an aryl group directly attached to the sulfur is essential to afford sulfoxides with high enantioselectivities, with up to 97% ee for 2-naphthyl benzyl sulfoxide, the highest enantioselectivity achieved to date for copper-catalysed asymmetric sulfoxidation. In contrast, the benzyl substituent can be replaced by sterically comparable groups with no effect on enantioselectivity. Copper-mediated oxidation of substituted aryl benzyl sulfides display modest steric and electronic effects resulting in comparable or lower enantioselectivities to those obtained with the unsubstituted benzyl phenyl sulfide.

Design, synthesis and insecticidal activity of novel anthranilic diamides with benzyl sulfide scaffold

Abstract A series of novel anthranilic diamides with benzyl sulfide scaffold were synthesized, in which N -pyridylpyrazole moiety generally regarded as key pharmacophore was abandoned. The target compounds were characterized by 1 H NMR, 13 C NMR, 19 F NMR and HRMS. The preliminary bioassays indicated that half of the title compounds were endowed with good insecticidal activities against armyworm ( Mythimna sepatara ) at the concentration of 500 mg/L. Exhilaratingly, the synthesized compound 3a was also active against Tetranychus cinnabarinus at 100 mg/L. The difference in activities between the target compounds was influenced by the substituents, which provided some hints for further investigation on structure modifications.

The effect of nitrogen atoms in the enantioselective oxidation of aryl or heteroaryl benzyl sulfides

Some aminophenyl benzyl sulfides or benzyl pyridyl sulfides were asymmetrically oxidized with tert-butyl hydroperoxide in the presence of a complex between titanium i-propoxide and (S, S)-hydrobenzoin, an oxidation system that works particularly well with a vast set of aryl benzyl sulfides. Notwithstanding the presence of nitrogen-containing moieties that, in principle, could interfere with the correct co-ordination of the sulfide to the metal center, satisfactory levels of enantioselectivity (up to 78%) were measured for this oxidation process.