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Three new binary acidic deep eutectic solvents (DESs) were derived from tetrabutylammonium bromide (TBAB) as a hydrogen bond acceptor (HBA) coupled with azelaic acid (AzA), benzilic acid (BeA) and boric acid (BoA) as hydrogen bond donors (HBD). In order to draw the complete phase diagram and find the molar ratios in which the DESs are formed, HBA and HBDs were mixed together in the full range of molar ratios and their thermal behavior (by differential scanning calorimetry method) and stability were investigated. The activity coefficient models including Wilson, NRTL and regular solution were applied to correlate the measured solid–liquid equilibrium data. FT–IR and NMR analysis were used to investigate the chemical structures, occurrence the hydrogen bond formation between the DESs constituents and purity of the prepared DESs. Physicochemical properties of these DESs including melting point, density, and speed of sound, conductivity and refractive index were measured at different temperatures. The performance of these new DESs were successfully evaluated for the dissolution of four metal oxides including PbO, CuO, Fe2O3 and ZnO and the obtained solubility values were compared with the reported literature data. [ABSTRACT FROM AUTHOR]

Extraction of plant polysaccharides often results in a large amount of proteins, which is hard to eliminate from the crude extract, and conventional approaches for deproteinization are time-consuming and often involve hazardous organic solvents. In this study, ionic liquid tetrabutylammonium bromide (TBABr) was used to create an ionic liquid aqueous two-phase system (ILATPS) for the separation of the polysaccharide (PcP) and protein extracted from the rhizome of Polygonatum cyrtonema. Bovine serum albumin (BSA) was first applied to assess the feasibility of the ILATPS, and MgS�€�4 was determined to be the most suitable inorganic salt. By adopting the Taguchi experiment with an L9 (34) orthogonal array, it was found that the best condition for the efficient separation of crude PcP was at 25°C, with 1.5 g of TBABr, 15 mg of PcP, and 2.0 g of MgS�€�4, with the extraction efficiency for the protein and polysaccharide as 98.6% and 93.5%, respectively. The purified PcP was homogeneous, and its weight average molecular weight (Mw) was 7,554 Da. Monosaccharide composition analysis indicated the PcP comprised mannose, galactose, glucose, galacturonic acid, arabinose, and rhamnose at a molar ratio of 33:13: 8:3.5:2:1. This approach offers a practical tactic to purify polysaccharides of plant origin. [ABSTRACT FROM AUTHOR]

Tetrabutylammonium bromide (TBAB) is considered a promising alternative cold energy storage material. Due to the high dissociation heat of phase transition at an atmospheric pressure of 278–293 K, which reaches 200–500 kJ/kg, this substance is considered an effective cold energy storage medium for air conditioning systems. In this paper, the cold storage crystallization process of TBAB solution with different concentrations was tested by conducting experiments and the phase transition's temperature and latent heat were measured. Finally, the growth characteristics of TBAB hydrate crystals with different concentrations (10%, 20%, 30% and 40%) were analyzed. Considering the cold storage temperature, phase transformation temperature and latent heat, the cold storage effect is the best when 40% TBAB solution is used. Although single substance phase change materials have a long service life, they have problems with low thermal conductivity and high undercooling. Therefore, researchers usually improve the performance of phase change materials by adding other auxiliary materials, thereby enhancing their application prospects. Among these auxiliary materials, adding nano additives to phase change materials can significantly improve latent heat, thermal conductivity and nucleation ability, while also reducing undercooling. Therefore, we studied the influence of different nano-additives (Al2O3, SiC, TiO2 and ZnO) on phase change materials. The composites with excellent properties were screened by cooling step cooling curve and differential scanning calorimeter (DSC). Compared with pure TBAB solution, the phase transition latent heat of the composite phase change materials (PCMs) prepared by adding nanoparticles were significantly increased. The results show that adding nano-SiC into 40% TBAB solution can obtain better performance. This work not only provides reference for the further research, but also a sight to design the phase change materials for the application of new phase change cold storage materials. [ABSTRACT FROM AUTHOR]

BACKGROUND: The large‐scale practical application of CO2 capture using carbonate solutions is mainly limited by their low CO2 absorption rate. In view of this, it is feasible to improve CO2 capture performance of carbonate solution by adding additives. In this paper, low‐cost sodium carbonate (Na2CO3) solution was selected as the main CO2 absorbent, and the effects of different organic additives on CO2 capture performance of Na2CO3 solutions were systematically investigated. RESULTS: The results showed that 0.04 mol/L tetrabutylammonium bromide (TBAB) could achieve a better enhancement effect on CO2 capture performance of Na2CO3 solution. After addition of TBAB, the maximum CO2 absorption rate of Na2CO3 solution was improved to 2.52 × 10−3 mol/min, which increased by 105%. And the maximum CO2 desorption rate could also be improved by 45%. TBAB/Na2CO3 system not only realized a high CO2 absorption capacity of 0.769 mol/mol, but also maintained 82% of the initial CO2 absorption capacity after three cyclic tests. The regeneration heat duty of TBAB/Na2CO3 solution was calculated to be 1136.6 kJ/mol, which was significantly lower than that of single Na2CO3 solution and conventional MEA aqueous solution. The promotion mechanism of TBAB in Na2CO3 solution was explored using Fourier transform infrared spectra (FTIR) and 13C nuclear magnetic resonance (NMR) analysis. CONCLUSION: The introduction of TBAB additive could significantly improve CO2 capture performance of Na2CO3 solution and reduce regeneration heat duty, making it a possible option in the field of post‐combustion CO2 capture. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

In this work, a novel series of N and S-alkylated derivatives of 1-phenyl tetrazole-5-thione were synthesized by Michael addition in organic salt media TBAB (Tetrabutylammonium bromide) using inorganic base K2CO3 under solvent-free conditions. The new and conveniently synthesized products showed unusual regioselectivity during the reaction. S-Michael adducts via reaction between 1-phenyl tetrazole-5-thione and acrylic esters as well as acrylonitrile were afforded at room temperature and N-Michael adducts obtained at 70°C. Both reactions occurred within 24 h. Surprisingly, using fumarate esters as Michael acceptor proceeded a SN2 reaction at 100°C due to steric effects. The structures of products all were confirmed by 1H and 13C NMR spectra and target compound yields were good to excellent. [ABSTRACT FROM AUTHOR]

Extraction of plant polysaccharides often results in a large amount of proteins, which is hard to eliminate from the crude extract, and conventional approaches for deproteinization are time-consuming and often involve hazardous organic solvents. In this study, ionic liquid tetrabutylammonium bromide (TBABr) was used to create an ionic liquid aqueous two-phase system (ILATPS) for the separation of the polysaccharide (PcP) and protein extracted from the rhizome of Polygonatum cyrtonema. Bovine serum albumin (BSA) was first applied to assess the feasibility of the ILATPS, and MgSO4 was determined to be the most suitable inorganic salt. By adopting the Taguchi experiment with an L9 (3^4) orthogonal array, it was found that the best condition for the efficient separation of crude PcP was at 25°C, with 1.5 g of TBABr, 15 mg of PcP, and 2.0 g of MgSO4, with the extraction efficiency for the protein and polysaccharide as 98.6% and 93.5%, respectively. The purified PcP was homogeneous, and its weight average molecular weight (Mw) was 7,554 Da. Monosaccharide composition analysis indicated the PcP comprised mannose, galactose, glucose, galacturonic acid, arabinose, and rhamnose at a molar ratio of 33:13:8:3.5:2:1. This approach offers a practical tactic to purify polysaccharides of plant origin.

2D Ti3C2Tx MXene, possessing facile preparation, high electrical conductivity, flexibility, and solution processability, shows good application potential for enhancing device performance of perovskite solar cells (PVSCs). In this study, tetrabutylammonium bromide functionalized Ti3C2Tx (TBAB‐Ti3C2Tx) is developed as cathode buffer layer (CBL) to regulate the PCBM/Ag cathode interfacial property for the first time. By virtue of the charge transfer from TBAB to Ti3C2Tx demonstrated by electron paramagnetic resonance and density functional theory, the TBAB‐Ti3C2Tx CBL with high electrical conductivity exhibits significantly reduced work function of 3.9 eV, which enables optimization of energy level alignment and enhancement of charge extraction. Moreover, the TBAB‐Ti3C2Tx CBL can effectively inhibit the migration of iodine ions from perovskite layer to Ag cathode, which synergistically suppresses defect states and reduce charge recombination. Consequently, utilizing MAPbI3 perovskite without post‐treatment, the TBAB‐Ti3C2Tx based device exhibits a dramatically improved power conversion efficiency of 21.65% with significantly improved operational stability, which is one of the best efficiencies reported for the devices based on MAPbI3/PCBM with different CBLs. These results indicate that TBAB‐Ti3C2Tx shall be a promising CBL for high‐performance inverted PVSCs and inspire the further applications of quaternary ammonium functionalized MXenes in PVSCs. [ABSTRACT FROM AUTHOR]

LaPO4 synthesis through the sol-gel method and synthesis of LaPO4 with the addition of templates through the hydrothermal method have been successfully carried out. The templates used are hexamethylenetetramine (HMT) and tetrabutylammonium bromide (TBABr). The concentration of precursor, pH, and aging time in the sol-gel method can affect the structure and morphology of LaPO4. In this study, the ratio of La3+: PO43-, pH, and aging were varied to obtain the optimal condition in used sol-gel method. The optimization results show that LaPO4 is formed at pH 9, the ratio of moles La3+:PO43- is 1:1, and the aging time is 72 h. The obtained solids were characterized by X-ray diffraction, FTIR, SEM-EDX, and adsorption-desorption N2. The XRD results showed that LaPO4 without templates (LaP) and LaPO4 with TBABr templates (LaPT) had a hexagonal crystal structure, meanwhile, LaPO4 with HMT templates (LaPH) had a monoclinic crystalline structure. The surface area of LaP, LaPH, and LaPT was 93.28; 69.37; and 107.00 m²/g, respectively, while the pore diameters were 7.04; 16.91; and 8.30 nm, respectively. SEM morphological observations of LaP, LaPH, and LaPT solids are in the form of aggregates that have not been evenly distributed and pore sizes that have not been uniform, and differences are seen between LaP, LaPH, and LaPT. [ABSTRACT FROM AUTHOR]

Tetrabutylammonium bromide (TBAB) is considered a promising alternative cold energy storage material. Due to the high dissociation heat of phase transition at an atmospheric pressure of 278–293 K, which reaches 200–500 kJ/kg, this substance is considered an effective cold energy storage medium for air conditioning systems. In this paper, the cold storage crystallization process of TBAB solution with different concentrations was tested by conducting experiments and the phase transition’s temperature and latent heat were measured. Finally, the growth characteristics of TBAB hydrate crystals with different concentrations (10%, 20%, 30% and 40%) were analyzed. Considering the cold storage temperature, phase transformation temperature and latent heat, the cold storage effect is the best when 40% TBAB solution is used. Although single substance phase change materials have a long service life, they have problems with low thermal conductivity and high undercooling. Therefore, researchers usually improve the performance of phase change materials by adding other auxiliary materials, thereby enhancing their application prospects. Among these auxiliary materials, adding nano additives to phase change materials can significantly improve latent heat, thermal conductivity and nucleation ability, while also reducing undercooling. Therefore, we studied the influence of different nano-additives (Al2O3, SiC, TiO2 and ZnO) on phase change materials. The composites with excellent properties were screened by cooling step cooling curve and differential scanning calorimeter (DSC). Compared with pure TBAB solution, the phase transition latent heat of the composite phase change materials (PCMs) prepared by adding nanoparticles were significantly increased. The results show that adding nano-SiC into 40% TBAB solution can obtain better performance. This work not only provides reference for the further research, but also a sight to design the phase change materials for the application of new phase change cold storage materials.

This paper aims to contribute to the search for sustainable solutions for CO 2 capture from industrial processes such as steelmaking. This is realized by exploring possibilities of a CO 2 capture from blast furnace gas using clathrates and comparing this technique to conventional absorption with monoethanolamine (MEA). First a design with pure clathrate hydrates was made to act as a reference and aid to construct a more detailed model for the semiclathrate tetra-n-butyl ammonium bromide (TBAB). Herein the capture process was modeled as a crystallization process in a bubble column like crystallization vessel. It was found that the TBAB process suffers mostly from the low capacity which requires high volume flows. Because of the low temperature, large amounts of expensive refrigerants are required (>300 MW). Because of the high pressure, a large amount of electrical power is required as well (>80 MW). Overall, the process as designed here cannot compete with the conventional MEA process. However, several options were identified that could improve the process in such a way that it could become more feasible. These include an apparently higher capacity than estimated and the use of more stable semiclathrates, hence reducing the need for expensive refrigerants. [Display omitted] • Low temperature and high pressure requirements make for a complex design. • Due to low stability, pure water hydrates are not feasible. • Due to high energy requirements TBAB semiclathres are not feasible. • TBAB semiclathrates cannot compete with the MEA process. • A higher capacity and stability are needed to compete with the MEA process. [ABSTRACT FROM AUTHOR]

In this work, nanoporous antireflective coatings on silicate glass were obtained from silicon dioxide sol compositions by the sol-gel method in the presence of quaternary ammonium salt (tetrabutylammonium bromide) at different annealing temperatures (200–250 °C). Varying the salt concentration from 3 to 5 wt.%, we achieved the transmittance of the coatings of about 97% at 250 °C in comparison with 91% for clean glass in the wavelength range from 400 to 1100 nm. The addition of gold nanoparticles to the composition containing 5 wt.% tetrabutylammonium bromide allowed us to decrease the annealing temperature to 200 °C, preserving the transmittance at the level of 96.5%. For this case, the optimal concentration of gold nanoparticles is determined (2.6 × 10−9 mol/mL). According to the SEM analysis, the obtained antireflective coatings contain pores with a minimum area size up to 4 nm2. [ABSTRACT FROM AUTHOR]

Aiming at shedding light on the molecular interactions in deep eutectic solvents (DESs), the DESs based on tetrabutylammonium bromide (TBAB) as hydrogen bond acceptor (HBA) and carboxylic acids (CAs) (formic acid (FA), oxalic acid (OA), and malonic acid (MA)) as hydrogen bond donor (HBD) were investigated by both experimental and theoretical techniques. The thermal behaviors of the prepared DESs were investigated by differential scanning calorimetry (DSC) method. In order to study the hydrogen bond formation between the DESs constituents, the FT-IR analysis was carried out. The large positive deviations of the iso solvent activity lines of ternary HBA + HBD + 2-propanol mixtures determined by the isopiestic technique from the semi-ideal behavior indicate that CAs interact strongly with TBAB and therefore they can form DESs. Molecular dynamics (MD) simulations were performed to present an atomic-scale image of the components and describe the microstructure of DESs. From the MD simulations, the radial distribution functions (RDFs), coordination numbers (CNs), combined distribution functions (CDFs), and spatial distribution functions (SDFs) were calculated to investigate the interaction between the components and three-dimensional visualization of the DESs. The obtained results confirmed the importance of hydrogen bonds in the formation of TBAB/CAs DESs. [Display omitted] • DESs composed of TBAB and carboxylic acids were studied theoretically and experimentally. • RDFs, CDFs, SDFs, and CNs were used to analyze the DESs microstructure. • Thermal behavior of the prepared DESs was investigated by DSC measurements. • Isopiestic and FT-IR measurements were used to study the interaction between DESs techniques. [ABSTRACT FROM AUTHOR]

An aqueous biphasic system (ABS) based on tetrabutylammonium bromide (TBABr) with ammonium sulfate as a salting-out agent was used to extract synthetic food dyes from aqueous solutions. Conditions for the preparation of the TBABr–H2O–(NH4)2SO4 ABS for microextraction preconcentration of Allura Red, Tartrazine, Azorubine, Sunset Yellow, and Fast Green were optimized: tetrabutylammonium bromide, 0.075 M and ammonium sulfate, 33 wt %. The recovery of all of the dyes was no lower than 97% at pH 2.3–9.5 for 1 min. Filtration through nonwoven polypropylene was used to facilitate phase separation and extract isolation. The concentrate was eluted with distilled water, and the dyes in the eluate were determined by spectrophotometry. The limits of detection were 0.02, 0.03, 0.03, 0.04, and 0.02 mg/L for Allura Red, Azorubine, Tartrazine, Sunset Yellow, and Fast Green, respectively. The procedure was applied to determine dyes in drinks, a mouthwash, an Easter kit for dyeing eggs, and the drug Ibuprofen. [ABSTRACT FROM AUTHOR]

• Tetrabutylammonium bromide (TBAB) was used as a template for the first time. • TBAB/G-TiO 2 synthesized with strong response to visible and IR light via sol–gel method. • The titania catalyst, synthesized, has a higher surface area and pore volume. • The electron-hole separation ability of the catalyst was improved. In this study, we, for the first time, employed tetrabutylammonium bromide (TBAB) as a template to synthesize black TiO 2 (TBAB/G-TiO 2) with a robust response to both visible and infrared light using the sol–gel method. This novel catalyst demonstrates the ability to degrade organic pollutants even without light. The characterization results of the catalyst indicate that the hydrogen bonding force of Deep Eutectic Solvent (DES) on TiO 2 plays a crucial role in shaping the structure and influencing the performance of TiO 2. Specifically, a stronger hydrogen bonding force results in an improved photocatalytic performance of TiO 2. Influenced by the DES template, TiO 2 generates numerous oxygen defects, reducing bandgap width from 3.20 eV to 1.34 eV and a specific surface area of 65.65 m2/g. Moreover, the material exhibits a remarkable response to both visible and infrared light. The evaluation of photocatalytic performance demonstrates that TBAB/G-TiO 2 exhibits significantly higher activity than pure TiO 2. The pseudo-first-order kinetic constant for the photocatalytic degradation of methylene blue solution is 3.39 times higher than that of pure TiO 2. [ABSTRACT FROM AUTHOR]

K, B co-doped carbon nitride with enhanced CO 2 adsorption exhibited efficiently catalytic activity in the presence of Bu 4 NBr cocatalyst. [Display omitted] • K, B-CN-X was prepared through one-step calcination of melamine and KBH 4. • The optimum doped site of K and B was confirmed by XPS and DFT calculation. • The basic property was increased due to the K and B co-doped verified by CO 2 -TPD. • K, B-CN-X showed efficiently catalytic activity under 110 o C conditions. Much endeavor has been devoted to efficient heterogeneous catalysts for carbon dioxide (CO 2) conversion to high-value chemicals. Meanwhile, the cycloaddition of CO 2 to epoxides is considered as a green and atom-economy reaction to produce cyclic carbonates. Herein, a series of K, B co-doped CN with various doping contents (K, B-CN-X) were developed by simple one-step calcination of melamine and KBH 4. B was confirmed to replace the C site and K N bond was formed, which was verified by XPS (X-ray photoelectron spectroscopy) and DFT (density functional theory) calculation. Particularly, K, B-CN-4 displayed the optimal catalytic performance in the presence of Bu 4 NBr (tetrabutylammonium bromide) cocatalyst for the CO 2 cycloaddition with propylene oxide. Besides, K, B-CN-4/Bu 4 NBr catalyst exhibited good substrate versatility to various epoxides and excellent recycling performance. According to the DFT calculation on CO 2 adsorption and experimental results, K, B-CN-4 presented satisfactory catalytic activity due to the enhanced CO 2 adsorption after K and B dopings then the possible reaction mechanism was proposed. The promising K, B-CN-X catalyst presented an attractive application due to the simple, eco-friendly synthesis route for the efficient fixation of CO 2. [ABSTRACT FROM AUTHOR]

The potential effects of deep eutectic solvents (DESs) based on eutectic mixtures of amino acids (AAs) and tetrabutylammonium bromide (TBABr) in combination with beta-cyclodextrin (β-CD) were first evaluated as chiral systems in capillary electrophoresis (CE). Three DESs: tetrabutylammonium bromide/l-arginine (TBABr/l-Arg), tetrabutylammonium bromide/l-alanine (TBABr/l-Ala) and tetrabutylammonium bromide/l-proline (TBABr/l-Pro)) were used. Markedly improved chiral discrimination for four native amino acids (dl-methionine, dl-valine, dl-serine and dl-threonine) were obtained with high resolutions ranging from 4.78 to 9.84 in the presence of TBABr/l-Arg/β-CD chiral selector. Optimal CE conditions were a BGE containing 15 mmol L−1 β-CD and 10% (v/v) TBABr/l-Arg mixed with 50 mmol L−1 borate at pH 9.5, 20 kV applied voltage and 25 °C capillary temperature. The relative standard deviations (RSDs) of intra- and inter-day variations of migration times were less than 2.2% and 3.5%, respectively. l-Arg has the highest isoelectric point (pI = 10.7 at 25 °C) among protein amino acids which is appropriate for formation of stable DES at an alkaline separation medium. Moreover, TBABr/l-Arg/β-CD possessed the lowest electroosmotic flow velocity (0.018 cm2 min−1 V−1) among the investigated chiral systems providing more opportunities for chiral recognition of analytes within 14 min. Analytical characteristics of the CE/UV developed method were evaluated and demonstrated to be adequate to apply the methodology to enantiomeric analysis of methionine in commercial dietary supplements including enantiomeric impurity of d-methionine at 0.03% level (m/m). Therefore, the proposed TBABr/l-Arg/β-CD could be used as a versatile, simple and effective selector for baseline chiral recognition in CE. [ABSTRACT FROM AUTHOR]

In this work, nanoporous antireflective coatings on silicate glass were obtained from silicon dioxide sol compositions by the sol-gel method in the presence of quaternary ammonium salt (tetrabutylammonium bromide) at different annealing temperatures (200–250 °C). Varying the salt concentration from 3 to 5 wt.%, we achieved the transmittance of the coatings of about 97% at 250 °C in comparison with 91% for clean glass in the wavelength range from 400 to 1100 nm. The addition of gold nanoparticles to the composition containing 5 wt.% tetrabutylammonium bromide allowed us to decrease the annealing temperature to 200 °C, preserving the transmittance at the level of 96.5%. For this case, the optimal concentration of gold nanoparticles is determined (2.6 × 10−9 mol/mL). According to the SEM analysis, the obtained antireflective coatings contain pores with a minimum area size up to 4 nm2.

Supramolecular solvents are nanostructured liquids that are separated from colloidal solutions of amphiphilic compounds as a result of self-assembly of amphiphiles and coacervation under changing conditions. They are considered to be designer solvents as their properties can be tailored to a specific analytical task by controlling the conditions of their formation (amphiphile, coacervation inducer, medium, concentration of components). The discovery of new extraction systems based on supramolecular solvents and their application to relevant analytical tasks are of great importance for the advancement of environmentally-friendly sample preparation. A novel green liquid-phase microextraction approach involving in situ formation of 1-octylamine citrate followed by preconcentration of ochratoxin A from aqueous extract of food sample in supramolecular solvent droplets was developed. The extraction system was carefully characterized. The density of the solvent allowed it to be to retrieved from the extraction system by its solidification. The alkaline nature of the obtained extract allowed the use of acetic acid for its dissolution instead of more toxic organic solvents followed by high-performance liquid chromatography with fluorometric detection. An excellent extraction recovery of 99 % and a satisfactory enrichment factor of 8.3 were achieved. The limit of detection was 0.5 μg kg−1, while the calibration plot was linear over the range of 1.5–50 μg kg−1. Cereal and roasted coffee bean samples were successfully analyzed with a relative bias less than 20 %. In the present work, a phenomenon of supramolecular solvent formation based on primary amine citrate was presented for the first time. Tetrabutylammonium bromide was investigated as a coacervation agent in an extraction system, and possible interactions responsible for its ability to induce phase separation in a micellar solution of primary amine citrate were described. The critical micelle concentration of 1-octylamine citrate in aqueous solution of tetrabutylammonium bromide was firstly determined. [Display omitted] • Primary amine citrate as amphiphilic molecules for SUPRAS phase formation. • Tetrabutylammonium bromide-induced coacervation in primary amine citrate system. • SUPRAS based on 1-octylamine citrate as efficient media for microextraction. • Microextraction of ochratoxin A from food samples followed by HPLC-FLD analysis. • Solidification of SUPRAS phase based on 1-octylamine citrate for extract collection. [ABSTRACT FROM AUTHOR]

The title compounds, tetrabutylammonium chloride–1,1′-(1,2-phenylene)bis(3-m-tolylurea) (1/1), C16H36N+·Cl−·C22H22N4O2 or [(n-Bu4N+·Cl−)(C22H22N4O2)] (I) and tetrabutylammonium bromide–1,1′-(1,2-phenylene)bis(3-m-tolylurea) (1/1), C16H36N+·Br−·C22H22N4O2 or [(n-Bu4N+·Br−)(C22H22N4O2)] (II), both comprise a tetrabutylammonium cation, a halide anion and an ortho-phenylene bis-urea molecule. Each halide ion shows four N—H...X (X = Cl or Br) interactions with two urea receptor sites of different bis-urea moieties. A crystallographic inversion centre leads to the formation of a 2:2 arrangement of two halide anions and two bis-urea molecules. In the crystals, the dihedral angle between the two urea groups of the bis-urea molecule in (I) [defined by the four N atoms, 165.4 (2)°] is slightly smaller than that in (II) [167.4 (2)°], which is probably due to the smaller ionic radius of chloride compared to bromide.

In this paper, we offered a green, environment-friendly, novel and inexpensive method for the synthesis of a series of pyrazole derivatives. The reaction took place in the presence of tetrabutylammonium bromide, a commercially available organic ionic salt, at room temperature under solvent-free conditions. All products were confirmed by infrared radiation, nuclear magnetic resonance and elemental analysis. Yields of products were 75–86%.

In this paper, we describe a new, simple and efficient strategy for the formation of novel and valuable acyl hydrazide derivatives from reaction between diverse acyl hydrazides and α,β-unsaturated esters in the presence of 1,4-diaza-bicyclo[2,2,2]octane (DABCO) – an inexpensive base – and tetrabutylammonium bromide (TBAB) – an ionic organic salt – under solvent-free conditions. In the reaction, double Michael adducts were produced in good yields in 7 h when acrylic esters were used as Michael acceptors. Surprisingly, no double Michael adducts were produced with fumaric esters, and single Michael adducts were the only products of these reactions in 10 h.

A new series of spiro[[1,3]dithiolane-2,3′-indolines]-2′-one derivatives was synthesized using Michael addition reaction of spiro[[1,3]dithiolane-2,3′-indolin]-2′-one to various α,β-unsaturated esters as well as direct alkylation of this compound with alkyl dihalides. Michael reaction of spiro[[1,3]dithiolane-2,3′-indolin]-2′-one and α,β-unsaturated esters produced related Michael adduct in the presence of tetrabutylammonium bromide and base 1,4-diazabicyclo[2.2.2]octane in good to excellent yields at 80°C under solvent-free conditions. Also, direct alkylation of spiro[[1,3]dithiolane-2,3′-indolin]-2′-one by dihaloalkanes in the presence of base K2CO3 afforded the corresponding products in good yields under the same conditions.

Electrochemical regioselective bromination of electron-rich aromatic rings using stoichiometric tetrabutylammonium bromide (n Bu4 NBr) has been accomplished under mild conditions. This protocol provides an environmentally friendly and simple way for the construction of C–Br bond in moderate to high yields with wide functional group tolerance. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Alkylation of 5-nitrotetrazole sodium salt with dimethyl sulfate was carried out. • Mass-transfer coefficient kL in microreactor is 15–208 times higher than in batch. • kLa in microreactor is 6.8–15.2 times higher than in batch without the use of TBAB. • kLa in microreactor is 1.2–3.24 times higher than in batch with the use of TBAB. Abstract Alkylation of 5-nitrotetrazole sodium salt with dimethyl sulfate was carried out under two-phase Taylor flow conditions in a system "dichloromethane-water" in a microreactor of 1.22 mm diameter. A comparative analysis was performed of the specific interfacial area, the surface and volume mass transfer coefficients with respect to results obtained in the presence of phase transfer catalysis in a batch reactor with a magnetic stirrer (MM) or a high speed rotor disperser (HSD). It was shown that regardless of the larger drops formed in the microreactor (and an essentially less value of the specific interfacial area a) as compared to the HSD reactor the surface mass-transfer coefficient (k L) attained in the microreactor is 15 and 208 times higher (in MM and HSD reactors correspondingly) in the absence of the phase transfer catalyst and 3.17 (MM) and 36.2 (HSD) times higher at the application of the latter. Without phase transfer catalyst the volume mass transfer coefficient (k L a) in the microreactor is 15.2 (MM) and 6.8 (HSD) times larger than in batch reactors. At the use of the phase transfer catalyst the volume mass transfer coefficient (k L a) in the microreactor is 3.24 (MM) and 1.2 (HSD) times larger than in batch reactors, even though interfacial area in HSD 30 times higher than that in the microreactor. The application of microreactors in future may provide a possibility to eliminate the use of phase transfer catalysts and high speed mixing devices and would lower the hazard level of the corresponding processes. [ABSTRACT FROM AUTHOR]

A series of nickel‐aluminium, cobalt‐aluminium and zinc‐aluminum layered double hydroxides were synthesized by urea hydrolysis (UH) and reverse micelle (RM) methods and then applied for the cycloaddition of carbon dioxide to propylene oxide (PO) under solvent‐free and ambient conditions. The most efficient catalyst was zinc‐aluminum layered double hydroxide prepared by RM (denoted as ZnAl‐RM) and it showed, in the presence of a co‐catalyst of tetrabutylammonium bromide, 96% propylene carbonate (PC) yield in 12 h at 25 °C and 1 MPa carbon dioxide. It is noteworthy for the same catalyst system that 74% PC yield was achieved in 24 h at room temperature (about 25 °C) and atmospheric carbon dioxide pressure. The high catalytic performance of the ZnAl‐RM and tetrabutylammonium bromide system should result from cooperative effects between zinc ion and bromine ion. Moreover, the ZnAl‐RM and tetrabutylammonium bromide system showed excellent versatility, which was also an active catalyst to the transformation of carbon dioxide and other epoxides into corresponding cyclic carbonates under mild temperature and pressure conditions. [ABSTRACT FROM AUTHOR]

During the last two decades, tetrabutylammonium bromide (TBAB) has gained significant attention as an efficient metal-free homogeneous phase-transfer catalyst. A catalytic amount of TBAB is sufficient to catalyze various alkylation, oxidation, reduction, and esterification processes. It is also employed as an efficient co-catalyst for numerous coupling reactions. It has also acted as an efficient zwitterionic solvent in many organic transformations under molten conditions. In this review, we have summarized the recent developments on TBAB-catalyzed protocols for the efficient synthesis of various biologically promising heterocyclic scaffolds.

In the present manuscript, the facile synthesis of tri-Schiff's bases, containing the core-thiophosphate moiety by using O,O,O-tris(4-formylphenyl) phosphorothioate, 3 and substituted anilines as a precursor has been reported. The key precursor 3 has been prepared under mild conditions in presence of (C4H9)4NBr as a phase transfer catalyst. All the synthesized compounds (5a-5h) were screened for their antibacterial and antifungal activities and were found to show good to excellent antibacterial and antifungal activities as compared to the standards. [ABSTRACT FROM AUTHOR]

Efficient TBHP/R 4 N + X – promoted hydroaroylations of dialkyl azo-1,2-dicarboxylates with methyl arenes, aldehydes, aryl methanols and arylmethyl chlorides are described. These oxidation/oxygenation and hydroaroylation processes were carried out by tert -butyl hydroperoxide as terminal oxidant/oxygen source, and were catalyzed by tetrabutylammonium bromide and tricaprylmethylammonium chloride as the driving force. During this investigation, all these hydroaroylating sources were found to be highly efficient reagents without the need of any transition-metal. [ABSTRACT FROM AUTHOR]

The effect of combining a thermodynamic promoter, tetrabutylammonium bromide (TBAB), with a kinetic promoter, sodium dodecyl sulphate (SDS), to a methane clathrate system was investigated. Kinetic growth experiments were conducted in a semi‐batch stirred tank crystallizer at driving forces of 1500 kPa using a range of 100 to 1500 ppm SDS and 200 to 200 000 ppm TBAB. Solutions containing low concentrations of TBAB in water reduced methane hydrate growth rates up to 55 % for 1250 ppm TBAB compared to pure water. Solutions containing 900 ppm SDS in water enhanced the growth rate by 880 % compared to pure water. Solutions were then tested combining both promoters. The gradual addition of SDS from concentrations between 100 to 1250 ppm to low‐concentration TBAB systems between 200 to 1250 ppm was initially found to reduce growth kinetics, but eventually increased the growth rates once a threshold SDS concentration was reached. In all cases, the promoting effect of the SDS was more pronounced in the absence of the TBAB. The growth kinetics of systems containing 5 and 20 wt% TBAB also followed a similar inhibition‐promotion trend with the SDS concentration. An increase of 177 % in the gas consumption rate was observed when 1500 ppm SDS was added to the 20 wt% TBAB clathrate system. This work demonstrates that SDS can be added to a TBAB‐water‐methane system to enhance gas consumption rates, but care must be taken to ensure that the concentration of the additives places the system in a promotion regime. [ABSTRACT FROM AUTHOR]

Association constants and single-ion conductivities of the bromide salts of five isomeric tetrabutylammonium ions were determined with dilute-solution conductivity measurements for aqueous solutions at 298.15 K. In addition, for two of the isomers dielectric relaxation experiments were performed. It was found that, despite similar size of all cations, the hydrodynamic radii of the branched isomers were significantly smaller than that of the un-branched Bu 4 N + species. It appears that the more compact branched cations exert only a minor perturbation on the H-bond network of the surrounding solvent and easily strip off their hydration shell. This effect, and the —on average— closer approach between anions and cations in ion pairs of Bu 2 iso Bu 2 NBr and iso Bu 4 NBr probably explain the rather large association constants of the latter salts. [ABSTRACT FROM AUTHOR]

Properties of three types of universal acid-base indicator paper (IP) obtained by means of noncovalent immobilization of five indicators (methyl yellow, methyl red, phenolphthalein, thymol blue, bromothymol blue) in the presence of tetraethylammonium chloride (TEAC) or tetrabutylammonium bromide (TBAB) and in the absence of salts were compared. It was proved that IP-TBAB has advantages in time stability of paper color, reliability of indicators retention in sorbent phase, and accuracy of visual determination of pH values using color scale. Values of acidity constants of indicators were determined by spectrophotometric method in water-ethanol solutions (mass fraction of ethanol is 50%) in the presence and absence of TBAB salt. It was found that modifying action of TBAB on properties of indicators in water-ethanol solutions and on paper is similar to influence of cationic surfactants. Examples of application of the indicator paper are given. [ABSTRACT FROM AUTHOR]

Density, viscosity and ionic conductivity data sets of deep eutectic solvents (DESs) formed by tetrabutylammonium bromide (TBABr) paired with ethlyene glycol, 1,3-propanediol, 1,5-pentanediol and glycerol hydrogen bond donors (HBDs) are reported. The properties of DES were measured at temperatures between 303 K and 333 K for HBD percentages of 66.7% to 90%. The effects of HBDs under different temperature and percentages are systematically analyzed. As expected, the measured density and viscosity of the studied DESs decreased with an increase in temperature, while ionic conductivity increases with temperature. In general, DESs made of TBABr and glycerol showed the highest density and viscosity and the lowest ionic conductivity when compared to other DESs. The presence of an extra hydroxyl group on glycerol in a DES affected the properties of the DES.

Since reporting the Reline (choline chloride and urea at 1:2 M ratio) deep eutectic solvent (DES) few years ago, a diversity of similar solvents have been prepared, characterized and used in different practical applications. The need is still available for converting some conventional solvents into a eutectic formulation for different reasons. In this work, the monoethanolamine (MEA) is combined with three different quaternary salts to form DES at different molar compositions. The resulting DESs were characterized by measuring their main physical properties including melting point, density, viscosity, surface tension, and refractive index within the temperature range of 298.15–358.15 K. An FTIR analysis was also conducted to provide an evidence of any chemical structural changes. These new eutectic fluids have melting points below 279.15 K and of relatively low density and viscosity values. The molar composition of these DESs have significant effect on their physical properties. These new fluids can be utilized for a variety of applications involving adsorptive gas separation and particularly carbon dioxide capture. [ABSTRACT FROM AUTHOR]

In this paper, we offered a green, environment-friendly, novel and inexpensive method for the synthesis of a series of pyrazole derivatives. The reaction took place in the presence of tetrabutylammonium bromide, a commercially available organic ionic salt, at room temperature under solvent-free conditions. All products were confirmed by infrared radiation, nuclear magnetic resonance and elemental analysis. Yields of products were 75–86%. [ABSTRACT FROM AUTHOR]

The ion conductivity of the salts [(CH)N]BF and [(CH)N]Br was studied in vacuum at temperatures from room temperature to 190 and 135°C, respectively. The salts have phase transitions to disordered high-temperature phases accompanied by an increase in conductivity. [(CH)N]Br has higher conductivity than [(CH)N]BF. As the conductivity decreases with the increasing size of the anion, the BF and Br anions are the most probable current carriers in the salts. [ABSTRACT FROM AUTHOR]

The alkylation of 5-nitrotetrazole sodium salt with dimethyl sulfate was studied in a two-phase water-dichloromethane system in the presence of tetrabutylammonium bromide as a phase-transfer catalyst. The reaction produced a mixture of regioisomers - 1-methyl- and 2-methyl-5-nitrotetrazoles in 1:3 ratio. 2-Methyl-5-nitrotetrazole was obtained from this mixture as individual compound in 52% yield. The application of phase-transfer catalysis allowed to obtain 5-nitrotetrazole N-alkyl derivatives under conditions that did not require preliminary isolation of highly impact and friction sensitive 5-nitrotetrazole salts from aqueous solutions. [ABSTRACT FROM AUTHOR]

The effects of oxygen-functionalized multi-walled carbon nanotubes (MWCNTs) on tetrabutylammonium bromide (TBAB)-water-carbon dioxide semi-clathrate system was investigated. A system comprised of 9.5 ppmw MWCNTs and 40 wt % TBAB was chosen and the average gas consumption rate was calculated for different conditions. At 14 °C, the average gas consumption rate during growth decreased to a plateau with increasing induction time at 3.0 °C subcooling for systems with and without MWCNTs. The addition of MWCNTs increased the gas consumption rate during growth for induction times less than one hour but did not affect it at longer induction times. The maximum gas consumption enhancement from the added MWCNTs was 15%. Dissolution runs at equilibrium conditions indicated that the presence of MWCNTs improved the dissolution rate of carbon dioxide gas into the liquid by lowering the time constant τ by 5%. This suggests that the gas-liquid interfacial resistance of carbon dioxide gas mass transfer is not the limiting factor for hydrate growth in this TBAB semi-clathrate system with and without nanoparticles. At a lower subcooling of 1.5 °C, there was no significant difference in the gas consumption rates with the addition of MWCNTs, due to prolonged induction times. [ABSTRACT FROM AUTHOR]

The direct conversion of simple and sterically hindered N-protected amino/peptide hydroxamic acids to O-benzyl hydroxamates employing KCO, tetrabutylammonium bromide and benzyl bromide is described. In addition, Cbz-Ala-CONHOH and Cbz-Phe-CONHOH derived acylaminoxy peptides 3j and 3k have also been prepared. The method is of importance in the view of easy availability of precursors, catalyst and reaction conditions. All the products are obtained in moderate to good yields. Graphical Abstract: [ABSTRACT FROM AUTHOR]

In this paper, we describe a new, simple and efficient strategy for the formation of novel and valuable acyl hydrazide derivatives from reaction between diverse acyl hydrazides andα,β-unsaturated esters in the presence of 1,4-diaza-bicyclo[2,2,2]octane (DABCO) – an inexpensive base – and tetrabutylammonium bromide (TBAB) – an ionic organic salt – under solvent-free conditions. In the reaction, double Michael adducts were produced in good yields in 7 h when acrylic esters were used as Michael acceptors. Surprisingly, no double Michael adducts were produced with fumaric esters, and single Michael adducts were the only products of these reactions in 10 h. [ABSTRACT FROM PUBLISHER]