Alkyl Mercaptans Research Articles

Polyethylene glycol: an efficient solid–liquid transfer agent for K2CO3-catalyzed oxidative coupling reaction of alkyl mercaptan with sulfur as oxidant

Polyethylene glycol: an efficient solid–liquid transfer agent for K2CO3-catalyzed oxidative coupling reaction of alkyl mercaptan with sulfur as oxidant

Hydrogen sulfide (H2S) production by selenium-binding protein 1: SELENBP1 is a copper-dependent alkyl mercaptan oxidase (AMO)

Hydrogen sulfide (H2S) production by selenium-binding protein 1: SELENBP1 is a copper-dependent alkyl mercaptan oxidase (AMO)

Wear test and thermal stability analysis of commercial oil with three types of alkyl mercaptans

Wear test and thermal stability analysis of commercial oil with three types of alkyl mercaptans

Concise Synthesis of 1-Thioalkyl Glycoside Donors by Reaction of Per-O-acetylated Sugars with Sodium Alkanethiolates under Solvent-Free Conditions.

A relatively green method for synthesizing 1-thioalkyl glycosides has been developed, where sodium alkanethiolates were used to react with per-O-acetylated sugars instead of odorous alkyl mercaptans in the presence of BF3·Et2O without the use of solvents under mild conditions. Furthermore, we found that 1,2-trans-β-thioglycosides can be converted into corresponding 1,2-cis-α-thioglycosides in the presence of trifluoromethanesulfonic acid in nonpolar solvents under mild conditions. This provides a simple and efficient new approach for synthesizing challenging 1,2-cis-α-thioglycosides.

Self-Assembled Monolayers of Alkanethiols on Nickel Insert: Characterization of Friction and Analysis on Demolding Quality in Microinjection Molding.

When the part geometry scaling down from macro to microscale level, the size-induced surface effect becomes significant in the injection molding process. The adhesion between polymer and nickel (Ni) mold insert during the process can lead to defects in necking, warping and deformation of microstructure. In this study, the self-assembled monolayers (SAMs) with low surface energy were deposited on the Ni surface to reduce the adhesion and further improve the demolding quality of the microstructure. Results show that the alkyl mercaptan SAMs with chemical bonds and close alignment can be successfully deposited on the surface of Ni by the solution deposition method. The contact angle, surface free energy, and friction coefficient before and after anti-adhesion treatment on the surface of mold insert were measured. In addition, the anti-adhesion properties of different alkyl mercaptan materials and the correspondingly replication quality of microstructure parts after injection molding were analyzed. It is found that the Ni mold insert treated by the perfluorodecanethiol has the best wear resistance and still shows good reproducibility at the 100th demolding cycle.

A New Approach for the Synthesis of Perfluoroalkanesulfenic Acids

AbstractA new and more practical method for the preparation of solution‐stable perfluoroalkanesulfenic acids was successfully developed. Starting from perfluoroalkyl iodides, perfluoroalkyl sulfoxides were synthesized by their substitution reaction with alkyl mercaptans and the following oxidation of resulting perfluoroalkyl sulfides with m‐CPBA. Subsequent β‐H elimination of perfluoroalkyl sulfoxides under heating conditions gave the corresponding perfluoroalkanesulfenic acids in good yields.

Scavenging Alkyl Mercaptans: Elucidation of Reaction Mechanisms and Byproduct Characterization

The removal of alkyl mercaptans via chemical means in the oil and gas industry has received very little attention compared with the much more extensive work on hydrogen sulfide (H2S) scavenging. The removal of H2S from produced liquids, aqueous, hydrocarbon, and gas is a vitally important part of the oil and gas industry. Typically, liquid chemical scavengers are employed for H2S levels up to approximately 5000 ppm. Above this, sequestering-type methods are employed such as amine recycling units from which the H2S can be regenerated and used most typically to produce elemental sulfur. It has been known for some time that mercaptan scavenging is possible but anecdotally reported as being less effective than H2S scavenging. This current study seeks to improve the understanding of the efficacy and mechanism of mercaptan scavenging by the common H2S scavengers in use today. A thorough literature review is provided of the current state of the art in mercaptan scavenging is provided. For the first time, a systematic series of quantified scavenging performance results for a variety of prominent scavengers with volatile alkyl mercaptans have been presented using the well-known autoclave method. These results are directly compared with the corresponding values for H2S under identical reaction conditions; overall, the best product was 1,3,5-trimethylhexahydrotriazine (MMA-triazine). The chemical structures of the reaction byproducts with alkyl mercaptans, to date only suggested but never confirmed, have been proven by the application of rigorous analytical methods. Results for both MMA-triazine and 1,3,5-tris(2-hydroxyethyl)hexahydro-s-triazine (MEA-triazine) reactions with ethyl, propyl, and butyl mercaptan comprehensively show, via the use of GCMS(-EI) analysis, representatives from each step in the sequential reaction pathway, containing each 1, 2, and 3 nitrogen atoms showing definitive evidence for the proposed reaction pathway.

Electro-Oxidative S-H/S-H Cross-Coupling with Hydrogen Evolution: Facile Access to Unsymmetrical Disulfides.

Sulfur is an essential element because it exists widely in proteins. The disulfide bond is an important moiety in many different types of significant organic molecules. A new approach for oxidant- and catalyst-free S-H/S-H cross-coupling, with hydrogen evolution, to construct unsymmetrical disulfides was developed. Under the conditions of an undivided cell at room temperature, a series of unsymmetrical disulfides were prepared with up to 87 % yield from the direct coupling of an aryl mercaptan and alkyl mercaptan. Gram-scale synthesis also highlights the synthetic utility of this electrochemical strategy.

Electro‐Oxidative S−H/S−H Cross‐Coupling with Hydrogen Evolution: Facile Access to Unsymmetrical Disulfides

AbstractSulfur is an essential element because it exists widely in proteins. The disulfide bond is an important moiety in many different types of significant organic molecules. A new approach for oxidant‐ and catalyst‐free S−H/S−H cross‐coupling, with hydrogen evolution, to construct unsymmetrical disulfides was developed. Under the conditions of an undivided cell at room temperature, a series of unsymmetrical disulfides were prepared with up to 87 % yield from the direct coupling of an aryl mercaptan and alkyl mercaptan. Gram‐scale synthesis also highlights the synthetic utility of this electrochemical strategy.

Potentiation of Surface Stability of AMPA Receptors by Sulfhydryl Compounds: A Redox-Independent Effect by Disrupting Palmitoylation.

Sulfhydryl compounds such as dithiothreitol (DTT) and β-mercaptoethanol (β-ME) are widely used as redox agents. Previous studies in our group and other laboratory have reported the effect of sulfhydryl compounds on the function of glutamate receptor, including plasticity. Most of these findings have focused on the N-methyl-D-aspartic acid receptor, in contrast, very little is known about the effect of sulfhydryl compounds on α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPAR). Here, we observed that DTT (100μM), β-ME (200μM) and L-cysteine (200μM) significantly elevated the surface expression of AMPARs via reducing their palmitoylation in rat hippocampal slices in vitro. Increased surface stability of AMPARs was not be correlated with the altered redox status, because the chemical entities containing mercapto group such as penicillamine (200μM) and 2-mercapto-1-methylimidazole (200μM) exhibited little effects on the surface expression of AMPARs. Computing results of Asp-His-His-Cys (DHHC) 3, the main enzyme for palmitoylation of AMPARs, indicated that only the alkyl mercaptans with chain-like configuration, such as DTT and β-ME, can enter the pocket of DHHC3 and disrupt the catalytic activity via inhibiting DHHC3 auto-palmitoylation. Collectively, our findings indicate a novel redox-independent mechanism underlay the multiple effects of thiol reductants on synaptic function.

ChemInform Abstract: Intermolecular Carbene S—H Insertion Catalyzed by Engineered Myoglobin‐Based Catalysts.

AbstractEngineered variants of sperm whale myoglobin are found to efficiently catalyze C—S bond forming transformation across a diverse set of aryl and alkyl mercaptan substrates and α‐diazoester carbene donors, providing high conversions (60—99%) and catalytic turnover numbers.

Tribological Behavior of Sandwich-Like Self-Assembled Films Containing Silver Nanoparticles: The Influence of Outer Molecular Structure and Chain Length

Alkanethiols with different chain length, composition and structure were grafted onto the surface of 3-mercaptopropyl trimethoxy silane (MPTS)–Ag dual-layer film consisting of Ag outerlayer and MPTS underlayer, thereby generating self-assembled trilayer films with “sandwich” structure on Si substrate. As-prepared films were characterized by atomic force microscopy and X-ray photoelectron spectroscopy. Moreover, the tribological behavior of as-prepared films was evaluated with an atomic force microscope and a ball-on-plate tribometer as well. It was found that as-prepared MPTS–Ag–C12 (C12 refer to 12 carbon chain of alkyl mercaptan; the same hereafter) film possesses excellent friction-reducing and antiwear properties. Particularly, MPTS–Ag–C8F (C8F refers to perfluorooctanethiol) film with lower interfacial energy exhibits a longer antiwear life than MPTS–Ag–C8 film.

Three-component reaction of isocyanide with dialkyl acetylenedicarboxylate and alkyl mercaptan: preparation of new derivatives of stable ketenimines

Three-component synthesis of stable ketenimines containing a sulfur group based on a capture profile of a zwitterionic intermediate is described. Thus, the reactions of zwitterions, generated from isocyanide and dialkyl acetylenedicarboxylate, react with alkyl mercaptans in CH2Cl2 to afford ketenimines in good yields.

Simple and sensitive method for the measurement of volatile alkyl mercaptans in gasoline for remote field deployment

Trace sulfur species, such as elemental sulfur, hydrogen sulfide, and volatile alkyl mercaptans, adversely affect silver based devices, such as gasoline level sensors, used in most vehicles. Identification and measurement of the sulfur species are key to developing a process control and/or treatment system to solve the problem at the refinery, prior to product distribution. A new and innovative method was developed for the analysis of specific mercaptan species in gasoline, and is reported here. The initial sample treatment stage is precipitation and stabilization of mercaptans as silver mercaptides. This stabilization could be successfully utilized in the field to mitigate the instability of mercaptans in gasoline samples. Another advantage of this step is that silver nitrate (AgNO3) precipitation concentrates the mercaptans allowing for trace level detection. The silver mercaptides are converted to pentafluorobenzyl derivatives and analyzed by gas chromatography (GC) with mass spectrometric (MS) detection. Results based on this technique show that alkyl mercaptans can be accurately measured in the full scan mode of MS with a limit of detection (LOD) of 0.02mg/L when a 100mL gasoline sample is used. The recovery of mercaptans spiked into gasoline was 85 to 120% (n=5). Gasoline producers will find knowing the exact levels of mercaptans in their products a useful tool to avoid distribution delays.

Temperature-Programmable Resistively Heated Micromachined Gas Chromatography and Differential Mobility Spectrometry Detection for the Determination of Non-Sulfur Odorants in Natural Gas

A portable, fast gas chromatographic method for the direct measurement of the parts per billion level of sulfur-free odorants in commercially available natural gas is introduced. The approach incorporates a resistively heated, temperature-programmable silicon micromachined gas chromatograph that employs a standard capillary column for the fast separation of methyl and ethyl acrylate from the natural gas matrix. The separation approach is coupled to a micromachined differential mobility detector to enhance analyte detectability, and the overall selectivity obtained against the matrix is described. A complete analysis can be conducted in less than 70 s. Furthermore, these two compounds can be measured accurately in the presence of other common volatile sulfur-based odorants such as alkyl mercaptans and alkyl sulfides. Repeatability of less than 3% RSD (n = 20) over a range from 0.5 to 5 ppm was obtained with a limit of detection for the target compounds at 50 ppb (v/v) and a linear range from 0.5 to 50 ppm with a correlation coefficient of at least 0.997.

ChemInform Abstract: Organocatalytic Asymmetric C—S Bond Formation: Synthesis of α‐Methylene‐β‐mercapto Esters with Simple Alkyl Thiols.

AbstractA highly efficient asymmetric reaction of Morita—Baylis—Hillman carbonates (I) and (IV) with alkyl mercaptans (II) is achieved in the presence of MgSO4 and (DHQD)2‐PHAL as organocatalyst.

Biodegradation of Tertiary Butyl Mercaptan in Water

Tertiary butyl mercaptan (TBM) belongs to the alkyl mercaptan family and possesses a characteristic odor. Tertiary butyl mercaptan (TBM) can enter aquatic environments through anthropogenic activities as well as the natural processes. Undefined microbial cultures from different soils along with a pure culture were used to study the biodegradation of TBM in water under aerobic conditions. There were about 17% losses in gas phase TBM concentrations attributed to abiotic losses over the period of 14 days. Environmental microbial consortium from sandy soils with low organic matter content and significantly lower heterotrophs resulted in the lowest biodegradation, only slightly higher than abiotic losses. Microbial cultures isolated from soils with previous contamination history resulted in higher degradation rates. In general, biodegradation of TBM in water followed first-order kinetics. The first-order kinetic constant ranged from 0.002 to 0.005 h -1 . TBM was partly degraded to two significant intermediate products and partly mineralized to CO 2 in water with mixed culture isolated from a petroleum contaminated soil. The half- life of TBM in water with this mixed culture was only six days. A Gram-ve bacterium isolated from a grey-water bioprocessor, Alcaligines faecalis subsp. phenolicus subsp. nov, was able to mineralize 50% of TBM within four days under laboratory conditions. The degradation rate was slightly increased with the addition of tertiary butyl alcohol while slightly inhibited with the addition of phenol.

MALDI‐TOF Mass Spectrometric Analysis of Enzyme Activity and Lectin Trapping on an Array of N‐Glycans

Active arrays: Complex lipid-tagged oligosaccharides, including large multiantennary species, can be efficiently immobilized on self-assembled monolayers of alkyl mercaptans (see picture). These arrays can be used to follow the action of a galactosyltransferase (GalT) and a hydrolase. The utility of the system for the selective trapping and identification of a lectin from a complex mixture was also demonstrated.

Dual-purpose gas chromatographic injection device for pressurized liquid and gas injection

A dual-purpose gas chromatographic injection device, capable of injecting pressurized liquid sample of up to 5000 psig and gas sample with a volume as high as 5000 μL, has been successfully developed and implemented. The injection device is synergized by the effectiveness of a classical flash vaporization of a syringe injection and the reliability of a proven rotary valve. Depending on the matrix involved, this injection device employs either a commercially available four-port internal valve for liquid sampling or a six-port external valve for gas sampling, a modified removable needle used in standard liquid syringe, and an auxiliary flow stream that can be either mechanical or electronic flow controlled for solute transfer. For pressurized liquid, the device was found suitable of up to nC 16 hydrocarbon with no observable carry-over despite the injection device was operating at ambient temperature. A relative standard deviation of less than 2% ( n = 20) was obtained for hydrocarbon compounds ranging from nC 8 to nC 16. For gas injection, the device performed well even under difficult chromatographic conditions such as with a low column inlet pressure of less than 1 psig. A relative standard deviation of less than 0.5% ( n = 10) was obtained for reactive sulfur compounds such as alkyl mercaptans. The device can be operated manually or automated with pneumatic or electrical actuator, is platform neutral, and can be moved amongst instruments without hardware modification as well as implemented for on-line or in situ applications. In this paper, the utility of the device was also demonstrated with selected GC applications of industrial significance.

Practical method for the measurement of Alkyl mercaptans in natural gas by multi-dimensional gas chromatography, capillary flow technology, and flame ionization detection

Volatile sulfur compounds such as alkylmercaptans are undesired impurities in natural gas streams. As a result, natural gas treatment and purification services are essential in many industries that utilize natural gas either as a fuel or in a chemical process. While there are many analytical methods that can be employed for the measurement of mercaptans, a simple, practical, and easy-to-implement method is required for remote field deployment. An analytical method, based on multi-dimensional gas chromatography (MDGC), capillary flow technology and flame ionization has been successfully developed for the application described. Results based on the technique showed alkylmercaptans can be accurately measured with a minimum detection limit of 200 ppb (v/v) or better, a linear range of up to 100 ppm (v/v), and a relative standard deviation ( n = 10) of 1.2% or less were obtained by manual injection with a total sample-to-sample analysis time of less than 15 min.