Tetrabutylammonium Bromide Research Articles

Molecular Insights into the Concentration Dependent Promotion Effect of Tetrabutylammonium Bromide on Hydrate Growth: A Molecular Dynamics Simulation Study.

Tetrabutylammonium bromide (TBAB) has been proven to improve the growth of hydrate via experimental methods, which may be attributed to its different concentrations. In this study, the molecular dynamics (MD) simulation is employed to investigate the concentration dependent promotion effect of TBAB on the growth of CO2 hydrate. The tetrahedral order parameter, number of cages, hydrate crystal growth trajectories, significant microconfigurations, and distribution of CO2 and TBAB are analyzed in detail. It is found that the promotion effect of TBAB is more prominent at low concentrations (5 and 10 wt %) than that at high concentrations (15 and 20 wt %). During the growth of hydrate crystal, tetrabutylammonium (TBA+) ions adsorb on the hydrate crystal and serve as guest molecules to form TBA+ semiclathrate hydrate cages. Then, the TBA+ semiclathrate hydrate cages undergo a self-adjustment process and induce the generation of CO2 hydrate cages. At high concentrations, the great accumulation of TBA+ at the hydrate-liquid interface disturbs the effective adsorption and self-adjustment processes, and the tightly packed arrangement of TBA+ at the gas-liquid interface partially inhibits the mass transfer of CO2. This study provides visible mechanisms of the concentration dependent promotion effect of TBAB from the microscopic level, which complements the vacancy in experimental studies.

Electric Response of a Negative Dielectric Anisotropy Nematic Liquid Crystal Doped with Ionic Dopant

The electrical properties measurements have been performed in a homogeneous alignment parallelepiped cell containing 4-methoxy benzylidene- 4-butylaniline (MBBA) liquid crystal doped with 0.02%wt tetrabutylammonium bromide (TBAB). The measurement of the complex permittivity was conducted in the nematic phase, covering a frequency range of 42 Hz to 5 MHz. A new relaxation mode was observed in the low-frequency region, which was not present in pure MBBA. The obtained dielectric dispersion could be fitted using the double Cole–Cole formula to determine the relaxation frequencies. The steady-state current exhibited a nonlinear dependence on the applied voltage, and hysteresis was observed in the transient current-voltage characteristic curve.

Influences of hydrogen-bond promoting hydroxyl group on photophysical and catalytic properties of lanthanide pyridine dicarboxylate frameworks

To study the influences of hydrogen bonding interactions on photophysical properties and catalytic activities with insignificant interference from structural disparity, two new isostructural [LnIII2(OH-pda)(ox)2(H2O)4]∙4H2O coordination polymers (LnIII = EuIII (I) and NdIII (IIa), OH–H2pda = 4-hydroxypyridine-2,6-dicarboxylic acid, H2ox = oxalic acid) were synthesized and characterized. They are also isostructural to [NdIII2(pda)(ox)2(H2O)4]∙4H2O (IIb), H2pda = pyridine-2,6-dicarboxylic acid) containing pda2− instead of OH-pda2-. The identical framework structure of IIa and IIb with additional hydrogen bonding interactions in IIa due to –OH group of OH-pda2- has been presented. Based on IIa and IIb, the effects of the –OH group on photophysical properties and catalytic activities were then investigated without structural bias. With reference to the UV–vis absorption and phosphorescent emission spectroscopy, the singlet (S1) and triplet (T1) state energies of OH–H2pda (41,600 and 19,200 cm−1), H2pda (48,200 and 23,300 cm−1), OH-pda2- (IIa, 41,400 and 22,500 cm−1) and pda2− (IIb, 47,100 and 23,300 cm−1) were determined from which the influences of the –OH group have been revealed. Important roles of the –OH group as electron-donating group as well as hydrogen bond promoter have been proposed. Catalytic activities of IIa and IIb were comparatively examined using the solvent-free CO2 cycloaddition reaction at atmospheric pressure with epichlorohydrin in the presence of tetrabutylammonium bromide. The inferior performance of IIa (maximum yield of 62(±2)%) to IIb (maximum yield of 68(±2)%) was unexpectedly disclosed and the drawback of the substantial involvement of the catalytic sites in hydrogen bonding interactions has been demonstrated. Their reusability was additionally explored.

A novel electrochemical sensor based on ꞵ-cyclodextrin/bismuth oxybromide/multi-walled carbon nanotubes modified electrode with in situ addition of tetrabutylammonium bromide for the simultaneous detection and degradation of tebuconazole.

A novel electrochemical sensor-based glassy carbon electrode (GCE) was fabricated and appliedtosimultaneous detection and degradation of tebuconazole (TBZ) for the first time.TheGCE was consecutively modified by multi-walled carbon nanotubes (MWCNTs), bismuth oxybromide (BiOBr), ꞵ-cyclodextrin (ꞵ-CD), and in situ addition of tetrabutylammonium bromide (TBABr). The detection was based on the decreasing of Bi signal at its anodic potential (Epa) of 0.05V. Under the optimum conditions, the modified electrode exhibited a linear response to TBZ in the concentration range 1-100μg L-1 with a detection limit of 0.9μg L-1. TBZ was firstly adsorbed on the surface of the modified electrode through host-guest molecule interactions of the ꞵ-CD. The adsorption was further enhanced by the large surface area of BiOBr and MWCNTs. The adsorbed TBZ on the electrode surface hindered the electron transfer of Bi, thus decreasing the oxidation of Bi. In addition, the in situ addition of tetrabutylammonium bromide (TBABr) enriched TBZ via electrostatic interactions, increasing its detection sensitivity. The fabricated electrochemical sensor was applied to determine TBZ in water and soil samples from rice fields with recoveries of 80.5-100.5% and 87.6-112%, respectively. Furthermore, the degradation of TBZ on the modified electrode was studied under a solar light simulator. The degradation percentage (100%) of TBZ (50µg L-1) was achieved in5min owing to the excellent photocatalytic properties of BiOBr.

High‐Throughput Experimentation (HTE) Applied to the Synthesis of API Impurities: A Case Study in Oxidative Decarboxylation of Aryl Acetic Acids

AbstractHigh‐throughput experimentation (HTE) has dramatically impacted experimental reaction development by enabling the rapid exploration of a diverse set of reaction conditions. During the past few decades, HTE has evolved as a tool to expedite reaction discovery and optimization. This work details the application of HTE to synthesize impurities of active pharmaceutical ingredients (APIs) with ketone/aldehyde functionality, specially focusing on ibuprofen impurity E. Initial experiments using K2S2O8 as oxidant yielded moderate results. Subsequent HTE screens identified cerium ammonium nitrate (CAN) and RuCl3‐NaIO4 as new effective decarboxylative oxidants, with RuCl3‐NaIO4 in the presence of tetrabutylammonium bromide (TBAB) achieving the highest yield of 65 %. This optimized method was successfully applied to synthesize ibuprofen impurity E on a gram scale. Additionally, the applicability of these methods to obtain other API related substances, such as naproxen impurity L and ketoprofen impurity A, was demonstrated. This research highlights the potential of HTE to streamline the synthesis of API impurities, making them widely accessible for pharmaceutical development purposes.

Enhanced Study of CO2 Hydrate Formation in Marine Oil–Gas Based on Additive Effect

During marine oil–gas extraction, significant amounts of carbon dioxide (CO2) gas are often produced. Effectively separating these associated CO2 gases during extraction has become a critical technical challenge. Therefore, this paper aims to enhance the efficiency of CO2 hydrate-based capture technology and conduct relevant research. The goal is to increase the driving force for hydrate formation by combining the traditional thermodynamic additive TBAB with pressure modulation and to improve the hydrate formation rate through the use of multiple kinetic promoters. This paper presents the initial investigation into the effect of the thermodynamic accelerator tetrabutylammonium bromide (TBAB) on the characteristics of CO2 hydrate formation. The promotion effects of TBAB solutions with varying mass concentrations (3%, 5%, 7.5%, 10%) and reaction pressures (3 MPa, 4 MPa) were subjected to a systematic analysis, and the optimal conditions were identified as 4 MPa and a 5 wt% TBAB concentration. Subsequently, the impact of combining TBAB with kinetic promoters (SDS, nano Al2O3, L-methionine, L-leucine) on CO2 hydrate generation characteristics was further investigated. In this paper, the effect of a single promoter on the generation characteristics of CO2 hydrate was investigated, and the efficient carbon trapping ability of the complex promoter was verified, which provides theoretical support for the application of CO2 trapping technology using the hydrate method.

Electricity-Driven Strain-Release Cascade Cyclization of Bicyclo[1.1.0]butane (BCB): Stereoselective Synthesis of Functionalized Spirocyclobutyl Oxindoles.

Spirocyclobutyl oxindoles, characterized by their unique three-dimensional structures, are valuable building blocks for many pharmacophores and drug units. However, stereoselective synthetic strategies for these scaffolds remain underdeveloped, with most existing methods relying on transition metal catalysts and stoichiometric redox reagents. In this work, we introduce an electrochemical strain-release driven cascade spirocyclization of bicyclo[1.1.0]butane (BCB) derivatives for the stereoselective synthesis of functionalized spirocyclobutyl oxindoles. Tetrabutylammonium bromide serves a dual purpose as both a supporting electrolyte and brominating agent. The method offers a broad substrate scope, high atom economy, and excellent diastereoselectivity. The stereoselectivity of the product is controlled by minimizing the dipolar repulsion between the amide C=O and the C-Br bonds. We also explored the methodology's versatility by applying it to various functionalizations and demonstrated its scalability for practical use. The efficient derivatization of the products allowed for the rapid creation of a diverse library of functionalized spirocyclobutyl oxindoles.

Rheological behavior of deep eutectic solvent promoted methane hydrate formation

Natural gas hydrates are recognized as a crucial and sustainable energy resource. The formation, dissociation, and flow properties of CH4 hydrate from deep eutectic solvents (DESs) are investigated using a high-pressure rheometer. In this work, rheological experiments are performed using two DESs namely, tetrabutylammonium bromide + ethylene Glycol (TBAB + EG, DES1) and methyltriphenylphosphonium bromide + ethylene Glycol (MTPB + EG, DES2) at 1 wt% concentration, 274 K temperature and 8 MPa pressure. The hydrate formation starts around 1.7 h for DES1 and around 4 h for DES2. Pressure and viscosity of the slurry are analyzed while methane hydrate forms and dissociates. The pressure drop experienced during hydrate formation is roughly 1.4 MPa for DES1 and 1.7 MPa for DES2. Further, viscosity profiles are analyzed for both DESs with varying shear rate. The viscosity gradually decreases as the shear rate increases. At equilibrium conditions of pure CH4, a spike is observed during dissociation. The rheological data is further analyzed with Cross model to validate the shear-thinning behavior of methane hydrate.

Effect of water on the excess properties of eutectic solvents

Three eutectic solvents were created utilizing a heating and stirring process. The solvents consist of tetrabutylammonium bromide and levulinic acid, as well as tetrabutylammonium chloride with either levulinic acid or lactic acid. The characterization of the samples was conducted using 1H NMR and IR techniques. The density and viscosity of three different low eutectic solvent and water binary mixture systems were determined within the temperature range of 293.15 to 333.15 K. The volume properties (excess molar volume, coefficient of expansion, coefficient of excess expansion) of the binary mixtures with different amounts of water were thoroughly investigated across the complete range of mole fraction. The study also investigated the impact of viscosity parameters, such as viscosity deviation and Excess activation Gibbs free energy of viscous flow. Furthermore, an analysis was conducted on the interaction between the eutectic solvent and the solvent molecules in the binary mixture. This analysis revealed the presence of hydrogen bonds between the eutectic solvent and water molecules. Moreover, it was confirmed that the excess properties could be fitted with the Redlich-Kister equation with r2 ≥ 0.99,demonstrating high suitability for binary mixes consisting of low eutectic solvents and water.

Synthesis of Aryl Alkyl Thioethers via a Copper-Catalyzed Three-Component Reaction with DABSO, Aryldiazonium Salts, and Alkyl Bromides.

We developed a method for synthesizing aryl alkyl thioether compounds via a three-component reaction involving aryldiazonium salts, 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide), and alkyl bromides. Optimal yields were achieved when a copper catalyst was used in conjunction with zinc and tetrabutylammonium bromide in an acetonitrile solvent at 130 °C for 10 h. This methodology demonstrates good functional group tolerance and enables the successful synthesis of various aryl alkyl thioethers with moderate to high yields.

Construction of the Co3O4/Nb2O5 Composite Catalyst with a Prickly Spherelike Architecture for CO2 Cycloaddition with Styrene Oxide.

A high-performance Nb2O5-based catalyst for the cycloaddition of CO2 with SO is designed by properly unifying the concepts of compositional regulation and architectural engineering. The Co3O4/Nb2O5 composite catalyst shows an intriguing prickly spherelike morphology. It exhibits a high styrene carbonate (SC) yield of 94.3% within 4 h (0.0824 mol g-1 h-1) under mild reaction conditions (0.4 MPa of CO2 and a reaction temperature of 90 °C) assisted by tetrabutylammonium bromide (TBAB). The coupling of Co3O4, which chemically interacts with Nb2O5, can effectively modulate the electronic structures of Nb2O5, constructing abundant acid/base sites for effectively activating the reactants and boosting the intrinsic activity. The high activity, cost-effectiveness, and good recyclability make the tailor-made Co3O4/Nb2O5 prickly spheres more appealing for commercial applications. This work offers new insights into designing and constructing well-integrated metal oxide composites for the cycloaddition of CO2 with an epoxide.

Investigation on the Adhesion Force between Tetrabutylammonium Bromide Hydrate Particles Using Atomic Force Microscopy.

This work investigates the adhesion force between tetrabutylammonium bromide (TBAB) hydrate particles dispersed in decane at different temperatures and TBAB concentrations using an atomic force microscopy. The thickness of the quasi-liquid layer (QLL) on the surface of the hydrate particles is calculated based on an adhesion force model. The results of force measurements indicate that the adhesion force between the hydrate particles increases with increasing temperature when TBAB concentration is 30 wt %. The increment of adhesion force between particles could be due to the increase in the QLL thickness on the particle surfaces. Furthermore, the force results also reveal that the adhesion force between hydrate particles(ice) at 253 K decreases when TBAB concentration increases from 0 to 30 wt %. The calculation indicates that QLL on the surface of formed hydrate particles becomes thinner at higher TBAB concentrations, which could be due to the conversion rate of water to hydrate within particles. The thickness of QLL is directly influenced by the temperature and TBAB concentration, which contributes to the adhesion force between hydrate particles.

Silicon surface texturing via TBAB-SDS composite additives enhanced copper-assisted chemical etching

Uneven etching and low fabrication efficiency impede the large-scale applications of copper-assisted chemical etching (Cu-ACE) for texturing light-trapping structures on the surface of silicon wafers. To address this, a composite additive composed of tetrabutylammonium bromide (TBAB) and sodium dodecyl sulfate (SDS) was introduced into the Cu-ACE system. The results indicated that TBAB accelerated the etching rate and improved the texturing uniformity, while SDS enlarged the size of the formed structures and enhanced their ultraviolet light absorption efficiency. The prepared inverted pyramid structure reduced the reflectivity of the silicon wafer surface to 3.8 %, thus exhibiting efficient light-trapping capabilities. The etching evolution under various TBAB concentrations and different HF/H2O2 ratios was studied by characterizing the surface contact angle and copper deposition morphology. The results indicated that electrostatic attraction between TBAB and dangling bonds on the silicon wafer surface enhanced material transfer at the reaction interface and changed the electron distribution around dangling bonds, thus facilitating the catalytic metal attack on these bonds. The copper ion reactivity was decreased due to complexation between the dissociated alkyl sulfate ions of SDS and copper ions, which favored the deposition of larger copper nanoparticles during etching, thereby increasing the size of structures. This research offers valuable insights to enable the large-scale applications of Cu-ACE.

Functionalization of pyrolyzed hydrochar with nitrogen containing deep eutectic solvent for carbon capture at low and high pressure

The purpose of this research is to evaluate the effectiveness of pyrolyzed hydrochar functionalized with nitrogen containing deep eutectic solvent (DES) in the absorption of CO2 under low- and high-pressure conditions. Pyrolyzed hydrochars were synthesized by hydrothermally carbonizing pine at the temperature of 200°C and 260°C, followed by pyrolysis at 600°C. These pyrolyzed hydrochars were impregnated with 3 different nitrogen containing DES namely choline chloride: urea, choline chloride: glycerol, and tetrabutylammonium bromide: glycerol all in 1:2 molar ratio. It was found that the functionalized pyrolyzed hydrochars were enhanced with nitrogen and oxygen functionalities (N-H, C-N, and CO). The results also show a substantial reduction in surface area for the functionalized pyrolyzed hydrochars, ranging from 10.19 to 227.74 m2g−1, compared to the surface areas of pyrolyzed hydrochars of 306–337 m2g−1. On the other hand, an increase in N content up to 38 % was identified after functionalization of pyrolyzed hydrochars. Upon conducting CO2 uptake at low (0.1–1 bar) and high (2.5–3.5 bar) pressure, the functionalized pyrolyzed hydrochars exhibited an CO2 uptake of up to 9.5 mmol/g at high pressure, which was attributed to the increased total nitrogen content, enhanced surface functionalities, and available micropore volume. The low-pressure isotherm for functionalized pyrolyzed hydrochars showed Langmuir-type isotherm, suggesting a monolayer adsorption. In contrast, the high-pressure isotherms were better fitted to the Freundlich isotherm, suggesting a multilayer adsorption behavior. It was concluded that the enhanced CO2 uptake is the result of the combined impact of increased surface functionalities and porosity, which results in improved physical and chemical adsorption mechanisms at the high pressure.

Spectrophotometric determination for green hydrophobic deep eutectic solvent-based microextraction of Brilliant Blue FCF (E133) from beverages

In this study, a simple, sensitive, and rapid method called green hydrophobic deep eutectic solvent-based liquid-liquid microextraction was developed to extract Brilliant Blue FCF dye from beverages. This method utilizes hydrophobic DES obtained by forming tetrabutylammonium bromide and 1-octanol in a 1:5 ratio as green extraction solvent. The transition of Brilliant Blue FCF to the DES phase occurred on its own, without the need for any reagents such as added salt or tetrahydrofuran. Several crucial factors were tried to get the best extraction efficiency, including species, DES volume and molar ratio, solution pH, ultrasonication, and centrifugation time. Under optimum conditions, extraction recoveries were achieved in the range of 95.1–101.3 % with the method developed for Brilliant Blue FCF. The detection and determination limits were observed to be 4.1 μg l-1 and 12.1 μg l-1, respectively. In addition, the relative standard deviation values for the method's accuracy were found to be 2.23 % and 3.48 % within and between days, respectively. It has been established that the developed method is highly environmentally friendly thanks to the application of the Analytical GREENness (AGREE) and Green Analytical Procedure Index (GAPI) tools. This study shows that DES applications can be carried out without the use of emulsifiers and dispersants by prioritizing the use of hydrophobic DES compounds as environmentally friendly and green extraction solvents in food samples.

Additive-free synthesis of house-of-card NaX zeolite for supporting amine: An efficient adsorbent for SO2 removal

The efficient adsorption of sulfur dioxide (SO2) is crucial for purifying exhaust gases, and zeolites are promising adsorbents due to their low cost and excellent stability. However, developing FAU-type zeolites with high adsorption capacities and selectivities remains challenging due to their narrow pores and limited adsorption sites. Herein, an additive-free synthesis strategy is proposed to facilely obtain NaX zeolites (X-HCL) with the house-of-card-like morphology. The hierarchical structure of X-HCL not only benefits the removal of SO2 through favorable spatial diffusion, but also promotes the loading of basic adsorption sites- [caprolactam] [tetrabutylammonium bromide] (CT) ionic liquid. The obtained CT/X-HCL adsorbent demonstrates remarkable SO2 adsorption capacity (10.58 mmol/g) and cyclic stability, as well as great selectivity of SO2/N2 (1673) and SO2/CO2 (219) due to the strong affinity of CT towards SO2. Moreover, co-feeding with water vapor benefits the adsorption of SO2 on CT/X-HCL owing to the enhanced chemisorption of hydrated CT for SO2. This research provides new insights into the construction of hierarchical zeolite for efficient adsorption and separation of SO2.

Synthesis of metal-phenanthroline-modified hypercrosslinked polymer for enhanced CO2 capture and conversion via chemical and photocatalytic methods under ambient conditions

Catalytic conversion of CO2 into valuable chemicals is a promising approach to mitigate the greenhouse effect and alleviate energy shortages. Hypercrosslinked polymers (HCPs) offer a scalable and stable platform for this conversion, but they often suffer from low CO2 adsorption and activation capabilities, necessitating high temperatures and pressures for effectiveness. To overcome these limitations, nitrogen-based CO2-philic active sites have been integrated into the structure of HCPs, enhancing CO2 attraction and leading to superior adsorption performance. The incorporation of cobalt ions further bolsters CO2 affinity, with HCP-PNTL-Co-B achieving the highest observed adsorption heat of 33.0 kJ·mol-1 alongside a substantial 2.0 mmol·g-1 CO2 uptake. These modified HCPs exhibit higher yields and reaction rates in cycloaddition reactions with cocatalyst tetrabutylammonium bromide at room temperature and atmospheric pressure, while HCP-1,10-phenanthroline (PNTL)-Co-B demonstrates a higher CO production rate (2,173 μmol·g-1·h-1) and selectivity (84%) in photocatalytic reduction reaction. This research has successfully achieved outstanding carbon dioxide capture and conversion performance at room temperature and atmospheric pressure by introducing CO2-philic active sites and cobalt ions into HCPs via facile one-step polymerization. This study provides a new method to design highly efficient organic catalysts for CO2 conversion.

Absorption-Desorption Characteristics of the Synthesized Deep Eutectic Solvents for Carbon Dioxide Capture

The development of an environmentally friendly CO2 absorbent with significant energy utilization which can be an alternative to CO2 capture by an ethanolamine solution is presently an obligatory issue. In this work, binary and ternary deep eutectic solvents (DESs) were prepared according to their CO2 absorption/desorption performances. A series of DESs comprise different hydrogen bonding donor (HBD)- acceptor (HBA) pairs as CO2 capturing solvents; HBAs include choline chloride (ChCl) and tetrabutylammonium bromide (TBAB), and selected amines are represented as HBDs and include monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA). Binary DESs synthesized of ChCl/MEA, ChCl/DEA, ChCl/TEA, TBAB/MEA, TBAB/DEA, and TBAB/TEA in a CO2 absorption cell at a mole ratio of 1:4. While selected amidines were represented as super-based (SB) and included 1,5-Diazabicyclo [4.3.0] non-5-ene (DBN) and 1,8-Diazabicyclo [5.4.0] undec-7-ene (DBU). The ternary DESs were prepared by adding DBN or DBU to the binary DESs system in a (1:4:3) molar ratio. CO2 absorption experiments were attained at atmospheric pressure and a temperature of 30 °C using 15 vol.% CO2 with 85 vol.% N2. On the other hand, the regeneration process for DESs was conducted at 90 oC. Binary DES synthesized from ChCl/MEA gives a higher absorption rate of CO2 of 0.0177 mole/kg. min, CO2 absorption loading of 2.9092 mole CO2/kg solvent, cyclic loading of 2.0001 mole CO2/kg solvent, and a regeneration efficiency of 68.75%. The synthesis DESs showed a better performance compare with a common Ionic liquids.

Study on extraction desulfurization of road-paving asphalt by deep eutectic solvents

During the hot mixing process of road-paving asphalt, odorous substances are released, primarily consisting of sulfur-containing compounds that are regarded as atmospheric pollutants, negatively impacting both human quality of life and the eco-environment. In the paper, a kind of simulated asphalt solution was designed with two sulfur-containing compounds, dibenzothiophene (DBT) and benzothiophene (BT), as well as n-eicosane dissolved in cyclohexane. DBT and BT were extracted with deep eutectic solvent (DES) of tetrabutylammonium bromide and polyethylene glycol (TBAB/PEG). The effects of different molecular weight of PEG as donor on desulfurization efficiency were investigated. The effects of DES donor/receptor ratio, extraction temperature and time, solvent oil ratio, mixing speed, recycling performance of DES on desulfurization efficiency were also studied and optimized. The results indicated that the maximum desulfurization efficiency of BT reached 89.40 % at room temperature with a ratio of agent to oil of 2:1, reaction time of 30 min, and mixing speed of 600 rpm. Similarly, the desulfurization efficiency of DBT achieved 95.54 % when the ratio of agent to oil was 3.5:1, with reaction time of 30 min and mixing speed of 600 rpm. After being recycled eight times, the extraction efficiencies of DBT and BT remained at 85.3 % and 65.2 %, respectively. Under optimized conditions, the extraction efficiency of petroleum asphalt exceeded 23 %. Fourier Transform Infrared (FTIR) analysis indicated that the sulfur-containing compounds found in the saturates and aromatics of road-paving asphalt were extracted by DESs, which are generally more volatile than those found in asphaltenes during hot-mixing. Additionally, minimal changes were observed in the structural composition of the four fractions of desulfurized asphalt.

Tetra Butyl Ammonium Bromide Catalyzed Synthesis of Thiols and Thioethers

A simple and commercially feasible route of synthesis of thiols and thioethers was developed using a simple phase transfer catalyst, i.e., Tetra Butyl Ammonium Bromide (TBAB). Sodium hydrogen sulfide (NaSH) is used as a sulfurization agent which is easily available and cost-effective. Thiols are obtained by treating alkyl or benzyl halides with sodium hydrogen sulfide (NaSH) in the presence of a phase transfer catalyst (TBAB) at 10 to 15℃. Thioethers are obtained by benzyl thiols treated with corresponding benzyl halides in the presence of a phase transfer catalyst (TBAB) at 10 to 15℃. Synthesis of thiols and thioethers is achieved by substitution reaction of benzyl or alkyl halides with sulfide in the presence of phase transfer catalyst (TBAB) and monochlorobenzene as a solvent at 10 to 15℃. Milder reaction conditions, excellent yield, shorter reaction time and operational simplicity are the key features of this procedure.