655 results on '"Tetrabutylammonium bromide"'
Search Results
152. Removal of arsenic in the form of anions from solid matrices by supercritical CO2 extraction with ion-pairing
- Author
-
Wang, Tao and Guan, Yanfen
- Subjects
- *
ARSENIC , *ANIONS - Abstract
A new method for the removal of the arsenic in the form of anions such as arsenite and arsenate, from solid samples by supercritical CO2 extraction coupled with ion pairing was investigated. Tetrabutylammonium bromide (Bu4NBr) was used as the ion-pairing reagent. As a result of the insolubility of Bu4NBr in supercritical CO2, the extraction of the anions by supercritical CO2 with the in situ ion-pairing is not effective. The arsenic in the form of anions in the solid samples can be effectively removed by supercritical CO2 extraction with pre-ion-pairing. For the case of the pre-ion-pairing, the extraction efficiency was strongly dependent on the dosage of Bu4NBr. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
153. An efficient synthesis of pyrroles by a one-pot, three-component condensation of a carbonyl compound, an amine and a nitroalkene in a molten ammonium salt
- Author
-
Ranu, Brindaban C. and Dey, Suvendu S.
- Subjects
- *
PYRROLES , *NITROALKENES - Abstract
A one-pot, three-component condensation of a carbonyl compound, an amine and a nitroalkene leading to an efficient synthesis of alkyl-substituted pyrroles has been carried out in molten tetrabutylammonium bromide. Neither a catalyst nor an organic solvent is required for this reaction and the molten ammonium salt is recyclable. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
154. Catalysis by an ionic liquid: efficient conjugate addition of thiols to electron deficient alkenes catalyzed by molten tetrabutylammonium bromide under solvent-free conditions
- Author
-
Ranu, Brindaban C., Dey, Suvendu S., and Hajra, Alakananda
- Subjects
- *
THIOLS , *ADDITION reactions - Abstract
An inexpensive and readily available ionic liquid, tetrabutylammonium bromide in the molten state, efficiently catalyzes the conjugate addition of thiols to α,β-unsaturated nitriles, carboxylic ester, ketones and aldehydes as well as nitro olefins. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
155. High performance method for O-methylation of phenol with dimethyl carbonate
- Author
-
Ouk, Samedy, Thiébaud, Sophie, Borredon, Elisabeth, and Le Gars, Pierre
- Subjects
- *
CARBONATES , *PHENOLS - Abstract
The O-methylation of phenols, including the sterically hindered phenols, with dimethyl carbonate (DMC) under mild conditions of temperature and pressure was described. The reaction was carried out in the presence of tetrabutylammonium bromide (TBAB), in a semi-continuous process. Aryl methyl ethers were rapidly and selectively obtained in good yields. [Copyright &y& Elsevier]
- Published
- 2003
- Full Text
- View/download PDF
156. STUDIES OF INTERACTION BETWEEN TETRABUTYLAMMONIUM BROMIDE BASED DEEP EUTECTIC SOLVENT AND DNA USING FLUORESCENCE QUENCHING METHOD AND CIRCULAR DICHROISM SPECTROSCOPY
- Author
-
Mohd Basyaruddin Abdul Rahman and Rizana Yusof
- Subjects
Circular dichroism ,chemistry.chemical_compound ,010405 organic chemistry ,Chemistry ,Tetrabutylammonium bromide ,Inorganic chemistry ,010402 general chemistry ,Photochemistry ,01 natural sciences ,DNA ,0104 chemical sciences ,Analytical Chemistry ,Deep eutectic solvent - Published
- 2016
157. Molecular interactions in ternary mixtures tetra-n-butylammonium bromide–inorganic salts–water according to ultrasonic data at T = 293.15–318.15 K
- Author
-
Rahmat Sadeghi, Behrooz Khezri, and Hossein Hooshyar
- Subjects
Molecular interactions ,Chemistry ,Inorganic chemistry ,02 engineering and technology ,Electrolyte ,Atmospheric temperature range ,021001 nanoscience & nanotechnology ,Condensed Matter::Soft Condensed Matter ,Inorganic salts ,020401 chemical engineering ,Tetrabutylammonium bromide ,Ultrasonic velocity ,Organic chemistry ,Ultrasonic sensor ,Physics::Chemical Physics ,0204 chemical engineering ,Physical and Theoretical Chemistry ,0210 nano-technology ,Ternary operation - Abstract
The ultrasonic velocity and density for ternary liquid mixtures containing tetrabutylammonium bromide and some inorganic salts in water as a function of electrolyte concentration were measured in the temperature range 293–318 K. These data have been used to estimate the acoustical parameters. The observed variation of these parameters helps in understanding the nature of ion-solvent and ion-ion interactions in the liquid mixtures. The results are discussed in terms of structure-making tendency of additive inorganic salts in the mixtures.
- Published
- 2016
158. Green synthesis of novel isatin thioketal derivatives under solvent-free conditions
- Author
-
Gholamhassan Imanzadeh, Taarof Fathi, Zahra Soltanzadeh, and Alireza Banaei
- Subjects
Thioketal ,Base (chemistry) ,Alkylation ,030226 pharmacology & pharmacy ,01 natural sciences ,Adduct ,Green synthesis ,dihaloalkanes ,lcsh:Chemistry ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Environmental Chemistry ,Organic chemistry ,lcsh:Science ,Alkyl ,Octane ,α,β-unsaturated esters ,chemistry.chemical_classification ,010405 organic chemistry ,Isatin ,General Chemistry ,0104 chemical sciences ,lcsh:QD1-999 ,chemistry ,tetrabutylammonium bromide ,Michael reaction ,lcsh:Q ,spiro[[1,3]dithiolane-2,3′-indolines]-2′-one - Abstract
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.
- Published
- 2016
159. Facile synthesis of isomerically pure fullerenols C 60 (OH) 5 Br and 1,4-C 60 (OH) 2 from chlorofullerene C 60 Cl 6
- Author
-
Alexander S. Peregudov, Olga A. Kraevaya, Vyacheslav M. Martynenko, and Pavel A. Troshin
- Subjects
Fullerene ,010405 organic chemistry ,Organic Chemistry ,Nuclear magnetic resonance spectroscopy ,010402 general chemistry ,Mass spectrometry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chlorobenzene ,Yield (chemistry) ,Tetrabutylammonium bromide ,Drug Discovery ,Organic chemistry - Abstract
The chlorofullerene C60Cl6 was demonstrated as a versatile precursor for the synthesis of two isomerically pure fullerenols via tetrabutylammonium bromide promoted reactions with water. Performing the synthesis in wet chlorobenzene produced 1,4-C60(OH)2 as the only isolable product along with substantial amounts of non-functionalized C60. However, the addition of DMSO as a co-solvent altered the reaction pathway, leading to the formation of C60(OH)5Br as the main product. Both isolated compounds were novel and their molecular compositions and structures were confirmed by mass spectrometry and NMR spectroscopy. The fullerenol C60(OH)5Br, which was formed in a moderate yield, represents the first isomerically pure polyhydroxylated fullerene available on a large scale.
- Published
- 2018
160. Oxidative Bromination Reactions in Aqueous Media by Using Bu4NBr/TFA/H2O2 System
- Author
-
Toshiyuki Moriuchi, Toshikazu Hirao, Takashi Sakuramoto, and Yasuhiro Fukui
- Subjects
Aqueous medium ,010405 organic chemistry ,Halogenation ,General Chemistry ,Oxidative phosphorylation ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Tetrabutylammonium bromide ,Trifluoroacetic acid ,Organic chemistry ,Hydrogen peroxide - Abstract
Metal-free oxidative bromination reactions in aqueous media were performed using tetrabutylammonium bromide, trifluoroacetic acid, and hydrogen peroxide under mild conditions. Oxidative bromination reaction of alkenes was found to afford the corresponding vic-bromides. Furthermore, this oxidative bromination system is applicable to the oxidative bromination of alkynes, arenes, and 3,4-dihydronaphthalen-1(2H)-one. A gram-scale bromination reaction was also performed successfully.
- Published
- 2017
161. An insight into the effects of ratios and temperatures on a tetrabutylammonium bromide and ethylene glycol deep eutectic solvent.
- Author
-
Yusof, Rizana, Jumbri, Khairulazhar, and Abdul Rahman, Mohd Basyaruddin
- Subjects
- *
ETHYLENE dibromide , *CHOLINE chloride , *RADIAL distribution function , *ETHYLENE glycol , *TEMPERATURE effect , *MOLECULAR dynamics , *DIFFUSION coefficients - Abstract
• Tetrabutylammonium-based deep eutectic solvent was studied by computer simulation. • Interactions between ions change eutectic properties. • High numbers of hydrogen bonds were at a high ethylene glycol ratio. • The simulation rationalizes the importance of eutectic as DNA solvating medium. Molecular dynamics (MD) simulations were performed to study the structures and properties of a deep eutectic solvent (DES) synthesised from tetrabutylammonium bromide (TBAB) paired with ethylene glycol (EG). Measurements were performed at different mol ratios of TBAB:EG (1:2 to 1:6) and temperatures (303 to 333 K). Upon validation, MD simulations of DES's density confirmed results to be in good agreement with previously validated experimental density (Maximum Deviation = 3.91%). The effects of different ratios and temperatures on radial distribution function (RDF), spatial distribution function (SDF), hydrogen bonding, mean square displacement (MSD) and self-diffusion coefficient of the TBAB:EG system were investigated. From RDF analysis, it was observed that Br− moved further away from TBA+ and formed a hydrogen bond with the hydroxyl group (OH) on EG at the closest distance of 0.270 nm. The self-diffusion coefficient of TBA+, Br− and EG increased proportionately to EG. High numbers of hydrogen bonds were observed at a high EG ratio as more intermolecular bondings between EG-Br were established. Hence, the introduction of EG molecules significantly affected ionic interaction within the resulting DES and changed its properties. Experimental data from infrared (IR) spectra and NMR were used to show a correlation between the formation of hydrogen-bonded EG-Br as observed in RDF. Increasing temperatures also altered the RDF, MSD and hydrogen bonding properties of the DES. Meanwhile, the main factor determining ionic movement was found to be the presence of TBA, as the ability of its cation's long alkyl side chain to form clustering ions dictated the behaviour of the liquid. Therefore, the changes in ratios and temperatures in DESs are essential in predicting their properties and subsequently, in ascertaining the industrial applicability of a particular DES. The presented results showed that the studied DES can be used for many applications and suit the requirement for DNA technology, especially for DNA solvating medium. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
162. Closer look into the structures of tetrabutylammonium bromide–glycerol-based deep eutectic solvents and their mixtures with water.
- Author
-
Makoś-Chełstowska, Patrycja, Chromá, Renáta, and Andruch, Vasil
- Subjects
- *
CHOLINE chloride , *MELTING points , *EUTECTICS , *SOLVENTS , *MOLECULAR dynamics , *MIXTURES , *HYDROGEN bonding - Abstract
• Studies on the mechanisms of DES and DES-water complex formation. • Influence of water addition on DES structures. • Destruction of DES structure after 50% (v/v) water addition. In recent years, deep eutectic solvents (DES) and it's mixture with water have become more and more attention as green solvents used in chemistry. However, there are only a few theoretical studies on the mechanisms of pure DES and DES-water complex formation. Therefore, the structural properties of tetrabutylammonium bromide–glycerol-based deep eutectic solvents and their mixtures with water have been investigated by means of Molecular Dynamics simulations. The obtained results indicate that three types of H-bonds exist in the pure DES structures, and all of these interactions play an important role in DES formation. In addition, between hydrogen bond donors (HBDs) and hydrogen bond acceptor (HBA) weaker non-bonded interactions, i.e. van der Waals exist, which also contribute to the formation of stable DES structures and to lower the melting point of DES compared to pure substances. The small addition of water to DES provides the formation of a stable complex, however, a further increase in water content (higher than 50% v/v) provide to the destruction of the most important hydrogen bonds (O–H···Br) in DES structure. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
163. Lewis acid/base pair as a catalytic system for α-stereoselective synthesis of 2-deoxyglycosides through the addition of alcohols to glycals
- Author
-
Zhaojun Hang, Zhaoyan Wang, Weihua Xue, Qinjian Xie, Haijing Liang, and Chen Wang
- Subjects
Reaction conditions ,Nucleophilic addition ,010405 organic chemistry ,Base pair ,Chemistry ,Organic Chemistry ,Substrate (chemistry) ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Combinatorial chemistry ,0104 chemical sciences ,Catalysis ,Tetrabutylammonium bromide ,Drug Discovery ,Stereoselectivity ,Lewis acids and bases - Abstract
This report describes the α-stereoselective addition of alcohols to glycals promoted by a cooperative Lewis acid/base pair catalytic system composed of B(C6F5)3 and tetrabutylammonium bromide (TBAB), which provides access to 2-deoxylglycosides in high yields. A mechanistic investigation supported by NMR analysis highlights the possible involvement of nucleophilic addition through boron-induced activation of alcohols under the assistance of TBAB. The protocol discussed here features the high stereoselectivity, mild reaction conditions, inexpensive and stable catalysts, and a broad substrate scopes.
- Published
- 2020
164. Metal-free tetra-n-butylammonium bromide-mediated aerobic oxidative synthesis of β-ketosulfones from styrenes
- Author
-
Kai Sun, Guisheng Zhang, and Xin Wan
- Subjects
Metal free ,010405 organic chemistry ,Chemistry ,Tetrabutylammonium bromide ,Organic chemistry ,General Chemistry ,Oxidative phosphorylation ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,0104 chemical sciences - Abstract
An efficient and broadly applicable protocol for the aerobic coupling of styrenes with sulfonylhydrazides has been developed that affords β-ketosulfones bearing various functional groups in moderate to excellent yields. The preliminary experimental results support the involvement of active benzyl radical species, and a radical pathway was therefore proposed for the reaction.
- Published
- 2016
165. A Convenient and Efficient One-Pot Synthesis of Arylacetones from (E)-3-Aryl-2-methylacrylic Acids by Curtius Rearrangement
- Author
-
He Xin, Chong Cao, Xin-yang Li, Fan-hao Meng, Zhang Tingjian, and Jing-wei Liang
- Subjects
010405 organic chemistry ,Aryl ,010401 analytical chemistry ,Organic Chemistry ,One-pot synthesis ,01 natural sciences ,0104 chemical sciences ,Catalysis ,Hydrolysis ,chemistry.chemical_compound ,chemistry ,Tetrabutylammonium bromide ,Yield (chemistry) ,Organic chemistry ,Curtius rearrangement - Abstract
A convenient and efficient method was developed for the synthesis of arylacetones from (E)-3-aryl-2-methylacrylic acids through a Curtius rearrangement. The Curtius rearrangement of (E)-3-aryl-2-methylacryloyl azides and subsequent hydrolysis proceeded at mild temperatures in a two-phase medium of carbon tetrachloride and water containing a catalytic amount of tetrabutylammonium bromide to give the corresponding derivatives in 82–93% yield.
- Published
- 2016
166. A Bimetallic Aluminium(Salphen) Complex for the Synthesis of Cyclic Carbonates from Epoxides and Carbon Dioxide
- Author
-
Michael North and Xiao Wu
- Subjects
General Chemical Engineering ,Carbonates ,Epoxide ,chemistry.chemical_element ,Chemistry Techniques, Synthetic ,Phenylenediamines ,010402 general chemistry ,01 natural sciences ,Chloride ,Catalysis ,chemistry.chemical_compound ,Aluminium ,Organometallic Compounds ,medicine ,Environmental Chemistry ,Organic chemistry ,General Materials Science ,Bimetallic strip ,010405 organic chemistry ,Carbon Dioxide ,0104 chemical sciences ,General Energy ,chemistry ,Tetrabutylammonium bromide ,Intramolecular force ,Carbon dioxide ,Epoxy Compounds ,Aluminum ,medicine.drug - Abstract
A bimetallic aluminium(salphen) complex is reported as a sustainable, efficient and inexpensive catalyst for the synthesis of cyclic carbonates from epoxides and carbon dioxide. In the presence of this complex and tetrabutylammonium bromide, terminal and internal epoxides reacted at 50 °C and 10 bar carbon dioxide pressure to afford their corresponding cyclic carbonates in yields of 50-94 % and 30-71 % for terminal and internal cyclic carbonates, respectively. Mechanistic studies using deuterated epoxides and an analogous monometallic aluminium(salphen) chloride complex support a mechanism for catalysis by the bimetallic complex, which involves intramolecular cooperative catalysis between the two aluminium centres.
- Published
- 2016
167. CO2 Capture from CH4/CO2 Mixture Gas with Tetra-n-butylammonium Bromide Semi-clathrate Hydrate through a Pressure Recovery Method
- Author
-
Long Xiaojun, Jun Chen, Yanhong Wang, Xuemei Lang, and Shuanshi Fan
- Subjects
Chromatography ,Chemistry ,Mixed gas ,020209 energy ,General Chemical Engineering ,Clathrate hydrate ,Analytical chemistry ,Energy Engineering and Power Technology ,02 engineering and technology ,chemistry.chemical_compound ,Fuel Technology ,020401 chemical engineering ,Recovery method ,Bromide ,Tetrabutylammonium bromide ,0202 electrical engineering, electronic engineering, information engineering ,Separation method ,Gas separation ,0204 chemical engineering ,Hydrate - Abstract
In this study, CO2 capture from (67.00 mol %) CH4/CO2 mixed gas with tetra-n-butylammonium bromide (TBAB) solution at 281.3 K through a pressure recovery of hydrate separation method were studied. During the experiment, pressure was recovered by TBAB solution injected into the cell to improve the separation efficiencies of CO2, and the effects of the concentration of TBAB solution and the operating conditions was investigated. The results showed that the CH4 concentration in the gas phase could achieve 93.52 mol % with a pressure recovery method at 1.14 MPa and 0.293 mol % TBAB. Under the pressure of 1.14 MPa and 0.1 mol % TBAB, the maximum CO2 separation factor was 52.87 and the CH4 separation and recovery factor was 2.050. The results demonstrated that the pressure recovery method can significant enhance the separation efficiency of hydrate separation. It is an effective method to cut down energy consumption of hydrate-based gas separation.
- Published
- 2016
168. One-Pot Synthesis of Nα-Protected Amino/Peptide O-benzyl Hydroxamates and Acylaminoxy Dipeptides Employing Hydroxamic Acid
- Author
-
M. S. Krishnamurthy, N. R. Sagar, and Vommina V. Sureshbabu
- Subjects
chemistry.chemical_classification ,Reaction conditions ,Steric effects ,Hydroxamic acid ,010405 organic chemistry ,One-pot synthesis ,Bioengineering ,Peptide ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Analytical Chemistry ,Catalysis ,chemistry.chemical_compound ,chemistry ,Benzyl bromide ,Tetrabutylammonium bromide ,Drug Discovery ,Molecular Medicine ,Organic chemistry - Abstract
The direct conversion of simple and sterically hindered Nα-protected amino/peptide hydroxamic acids to O-benzyl hydroxamates employing K2CO3, 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.
- Published
- 2016
169. New insights on Natural Rubber microgel structure thanks to a new method for microaggregates extraction
- Author
-
Chantal Cazevieille, Jérôme Sainte-Beuve, Sébastien Rolere, and Frédéric Bonfils
- Subjects
Polymers and Plastics ,Size-exclusion chromatography ,General Physics and Astronomy ,Extraction ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Natural rubber ,Materials Chemistry ,Q60 - Traitement des produits agricoles non alimentaires ,Propriété physicochimique ,Caoutchouc ,Chromatography ,biology ,Chemistry ,Organic Chemistry ,Extraction (chemistry) ,021001 nanoscience & nanotechnology ,biology.organism_classification ,0104 chemical sciences ,Hevea brasiliensis ,Chromatographie ,Tetrabutylammonium bromide ,visual_art ,Propriété technologique ,visual_art.visual_art_medium ,0210 nano-technology - Abstract
Size exclusion chromatography (SEC) columns pre-treated with a tetrabutylammonium bromide (TBABr) solution were used to develop a new method for extracting the microgel of Natural Rubber (NR). A solution of microaggregates smaller than 1 μm (Microgel
- Published
- 2016
170. Interfacial tension between (CO 2 + N 2 ) gas and tetrabutylammonium bromide aqueous solution
- Author
-
Hotaka Akiba and Ryo Ohmura
- Subjects
Flue gas ,Aqueous solution ,Chemistry ,Inorganic chemistry ,Clathrate hydrate ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Ion ,Surface tension ,020401 chemical engineering ,Tetrabutylammonium bromide ,General Materials Science ,0204 chemical engineering ,Physical and Theoretical Chemistry ,Mass fraction ,Pressure gradient - Abstract
This paper reports experimental values of the interfacial tension between (CO2 + N2) gas and tetrabutylammonium bromide aqueous solution (TBABaq). The experiments were performed by the pendant drop method in conditions from P = (1.00 to 4.00) MPa, from T = (288.15 to 303.15) K and from wTBAB = (0.10 to 0.40), where wTBAB denotes the mass fraction of TBAB in the aqueous solution. The interfacial tension decreased with increasing wTBAB and pressure. The depletion of the interfacial tension with increasing wTBAB in the (CO2 + N2 + TBABaq) system was consistent with that in (CO2 + TBABaq) system. The depletion ratio of the pressure gradient of the interfacial tension caused by the addition of TBAB in (CO2 + N2 + water) system was almost the same as that in (CO2 + water) system. There might be little effect on the interfacial tension caused by the interaction between gases and tetrabutylammonium ions. The temperature dependence of γ was not observed as well as in the (CO2 + TBABaq) system.
- Published
- 2016
171. Chemical fixation of CO2 to cyclic carbonates using Al(III) β-aminoalcohol based efficient catalysts: An experimental and computational studies
- Author
-
Bishwajit Ganguly, Noor-ul H. Khan, Hari C. Bajaj, Rukhsana I. Kureshy, Manish Kumar, Sayed H.R. Abdi, Mrinal Kanti Si, Mohd Nazish, and Shailesh Verma
- Subjects
010405 organic chemistry ,Metalation ,Process Chemistry and Technology ,Ether ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Catalysis ,Cycloaddition ,0104 chemical sciences ,chemistry.chemical_compound ,Benzylamine ,chemistry ,Styrene oxide ,Tetrabutylammonium bromide ,Organic chemistry ,Physical and Theoretical Chemistry ,Selectivity - Abstract
A series of Al(III) unsymmetrical β-aminoalcohol based complexes 1–6 were synthesized via metalation of the corresponding ligands 1′–6′ those were prepared by the reaction of benzylamine with readily available epoxides viz., styrene oxide, 1,2-epoxy-3-phenoxypropane, 4-tertbutylphenyl glycidyl ether, 4-chlorophenyl glycidyl ether, glycidyl 2-methylphenyl ether and 1,2-epoxyhexane. Among these complexes, the complex 2 was found to be most effective in the cycloaddition of aryloxy/aliphatic terminal epoxides with CO 2 under atmospheric pressure to get corresponding cyclic carbonates with high conversion and selectivity (up to >99%) in the presence of tetrabutylammonium bromide as a co-catalyst. The DFT calculations revealed the important role played by counter-ion in the co-catalyst during cycloaddition reaction of CO 2 with the substituted epoxides.
- Published
- 2016
172. Copper(II)-Mediated Intermolecular C(sp2)–H Amination of Benzamides with Electron-Rich Anilines
- Author
-
Bijaya Kumar Singh, Ranjan Jana, and Arghya Polley
- Subjects
Nonsteroidal ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Intermolecular force ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Copper ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,Tetrabutylammonium bromide ,Organic chemistry ,Amination - Abstract
Despite significant progress, copper-catalyzed/mediated C-H amination reactions with electron-rich anilines remain an unsolved problem due to catalyst deactivation and deleterious side reactions. Herein, we report a copper(II)-mediated C(sp(2))-H amination of benzamides with electronically neutral or electron-rich anilines. A dramatic influence of silver(I) and tetrabutylammonium bromide was observed on the reaction outcome. The present protocol also demonstrates the synthesis of a number of nonsteroidal anti-inflammatory drugs.
- Published
- 2016
173. Dissociation Temperatures of Mixed Semiclathrate Hydrates Formed with Tetrabutylammonium Bromide Plus Tetrabutylammonium Chloride
- Author
-
Lingli Shi, Wen-Zhi Wu, Lizhi Yi, Deqing Liang, and Xiaodong Shen
- Subjects
Chemistry ,General Chemical Engineering ,Inorganic chemistry ,Clathrate hydrate ,Cold storage ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,Mole fraction ,01 natural sciences ,Dissociation (chemistry) ,0104 chemical sciences ,020401 chemical engineering ,Tetrabutylammonium bromide ,0204 chemical engineering ,Hydrate ,Tetrabutylammonium chloride ,Tetrabutylphosphonium bromide - Abstract
Dissociation temperatures of mixed tetrabutylammonium bromide (TBAB) + tetrabutylammonium chloride (TBAC) semiclathrate hydrates were determined by using the DSC technique. The system was measured in five groups with a fixed total mole fraction (x = 0.0100, 0.0200, and 0.0337), TBAB mole fraction (xTBAB = 0.0370) or TBAC mole fraction (xTBAC = 0.0337). The obtained results demonstrated that at a given x, the dissociation temperatures of mixed (TBAB + TBAC) semiclathrate hydrates were all higher than that of pure TBAB hydrate, and the maximum dissociation temperature appeared at xTBAB/x = 0.25 instead of xTBAB/x = 0 or 1 (corresponding to pure TBAC or TBAB hydrate). In addition, for systems with fixed xTBAB or xTBAC, TBAC gained the control of forming TBAC semiclathrate hydrate preferentially.
- Published
- 2016
174. Unexpected formation of 5-alkylidene derivatives of hydantoin from the Michael addition of 4-phenylurazole to fumaric esters
- Author
-
Nader Noroozi-Pesyan, Gholamhassan Imanzadeh, Hemayat Hooshmand, Ertan Şahin, and Zahra Soltanzadeh
- Subjects
010405 organic chemistry ,Organic Chemistry ,Hydantoin ,DABCO ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Medicinal chemistry ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Tetrabutylammonium bromide ,Drug Discovery ,Michael reaction ,Hydantoin derivatives ,Octane - Abstract
An unexpected reaction between 4-phenylurazole and fumaric esters which led to the formation of 5-alkylidene derivatives of hydantoin is described in this paper. The reaction takes place in the presence of tetrabutylammonium bromide (TBAB), and 1,4-diaza-bicyclo[2,2,2]octane (DABCO) at 70 °C under solvent-free conditions.
- Published
- 2016
175. Direct α-acyloxylation of organic sulfides with the hypervalent (diacyloxyiodo)benzene/tetra-n-butylammonium bromide (TBAB) reagent combination
- Author
-
Denghu Chang, Shaoyan Gan, Dan Zhu, and Lei Shi
- Subjects
chemistry.chemical_classification ,010405 organic chemistry ,General Chemical Engineering ,Hypervalent molecule ,Substrate (chemistry) ,General Chemistry ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Tetrabutylammonium bromide ,Reagent ,Functional group ,Organic chemistry ,Benzene ,Alkyl - Abstract
A novel metal-free approach to directly synthesize α-acyloxy sulfides from readily available alkyl sulfides utilizing the hypervalent (diacyloxyiodo)benzene and TBAB reagent combination is reported. This transformation is characterized by its broad substrate scope in moderate to excellent yields, convenient operating conditions and outstanding functional group tolerance.
- Published
- 2016
176. Surface tension between CO 2 gas and tetra- n -butylammonium bromide aqueous solution
- Author
-
Hotaka Akiba and Ryo Ohmura
- Subjects
Aqueous solution ,Clathrate hydrate ,Inorganic chemistry ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Atomic and Molecular Physics, and Optics ,Drop method ,Surface tension ,chemistry.chemical_compound ,020401 chemical engineering ,chemistry ,Bromide ,Tetrabutylammonium bromide ,General Materials Science ,0204 chemical engineering ,Physical and Theoretical Chemistry ,0210 nano-technology ,Hydrate ,Mass fraction - Abstract
This paper reports experimental values of the surface tension between CO2 gas and tetra-n-butylammonium bromide (TBAB) aqueous solution measured by the pendant drop method. The experimental conditions were pressures from 1.00 MPa to 4.00 MPa, temperatures from 288.15 K to 303.15 K and wTBAB from 0.10 to 0.40, where wTBAB denotes the mass fraction of TBAB in the aqueous solution. These pressure–temperature-composition conditions partially fall into the stability zone of (CO2 + TBAB) semiclathrate hydrate but all data were obtained without any hydrate in the system. Surface tension decreased with increasing wTBAB and pressure but temperature dependency was not observed. Compared to the air–TBAB aqueous solution system and CO2–water system, the values of the surface tension were smaller.
- Published
- 2016
177. Investigation of tetrabutylammonium bromide-glycerol-based deep eutectic solvents and their mixtures with water by spectroscopic techniques.
- Author
-
Chromá, Renáta, Vilková, Mária, Shepa, Ivan, Makoś-Chełstowska, Patrycja, and Andruch, Vasil
- Subjects
- *
CHOLINE chloride , *ANALYTICAL chemistry , *RAMAN spectroscopy , *MIXTURES , *SOLVENTS , *HYDROGEN bonding , *EUTECTICS - Abstract
Deep eutectic solvents (DES) are formed by an acceptor and a donor of hydrogen bonds. They are generally considered as a possible alternative to hazardous organic solvents in various fields. Very recently they have also appeared in analytical chemistry, used mainly for the separation of analytes before instrumental quantification. For the development of new extraction procedures, it is important, among other things, to understand the mechanism of the extraction process itself. In this study we present NMR, IR and Raman spectroscopy studies of TBAB-Gly-based DESs at various HBA:HBD molar ratios for the neat DES as well as the DES mixed with various amounts of added water to better understand the mechanism of DES formation, intermolecular interactions in DES and the interaction of the DES with water, which have not yet been studied in detail. The obtained results indicate that hydrogen bonds between TBAB and Gly exist in the DESs at all molar ratios (1:2; 1:3; 1:4). A small amount of water added to the DES structure provides the establishment of an H-bond network, which does not weaken the existing H-bonds between the HBA and HBD, thus creating a stable supramolecular structure. However, further increasing of water amount provide to weakened of hydrogen bonds between TBAB and Gly. • Detailed spectroscopic studies on DES formation. • Influence of water addition on DES structures. • Supramolecular structure of DES and water was obtained. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
178. Гідрофобні добавки на основі амінів для полідисперсних в'яжучих матеріалів
- Author
-
Гарбуз, Анастасія Сергіївна and Гарбуз, Анастасія Сергіївна
- Abstract
Магістерська дисертація на тему: «Гідрофобні добавки на основі амінів для полідисперсних в’яжучих матеріалів» містить 94 с., 20 рис., 13 табл., 45 джерел, 3 додатки. Хімічні добавки широко використовуються у виробництві цементів та бетонів. Основною причиною їх використання є зниження економічних та енергетичних затрат (саме на помел клінкеру), а також покращення властивостей цементів і бетонів та надання їм спеціальних властивостей. Наразі важливою проблемою є зберігання цементу. Під час транспортування та зберігання цемент поглинає вологу з навколишнього середовища, в результаті чого втрачає свою активність. Також при помелі клінкеру адсорбована волога сприяє налипанню частинок цементу на стінки млина, що погіршує процес помелу. З метою подовження терміну зберігання цементу та уникнення негативного впливу води до його складу вводять спеціальний вид добавок – гідрофобізуючі. Добавки на основі амінів широко використовуються у виробництві цементу, насамперед, як інтенсифікатори помелу та прискорювачі тужавлення та тверднення. Метою науково-дослідної роботи є дослідження впливу добавок на основі амінів різної будови та складу на процес помелу клінкеру, гідратацію цементного каменю, а також встановлення можливості їх використання в якості гідрофобізуючих добавок. Об’єкт дослідження – цемент, модифікований добавками на основі амінів. Предмет дослідження – оцінка впливу вибраних добавок на основі амінів на фізико-механічні та гідрофобні властивості отриманих цементів. Методи дослідження: визначення залишку на ситі та питомої поверхні матеріалів; визначення фізико-механічних властивостей: нормальної густини, термінів тужавлення та міцності; проба на гідрофобність; визначення крайового кута змочування; дослідження сипучості та гігроскопічності матеріалів. Публікації: наукові результати магістерської дисертації опубліковано у збірнику матеріалів XVIII Всеукраїнської студентської науково-практичної конференції «Science and Technology of the XXI Century» та у збірнику тез доп, Master's dissertation on the subject: "The amines-based hydrophobic admixtures for poly-dispersive binders" contains 94 pages., 20 fig, 13 tabl., 45 sources, 3 appendixes. Chemical admixtures are widely used in the manufacture of cements and concretes. The main reason for their use is the reduction of economic and energy costs (namely clinker milling), as well as the improvement of the properties of cements and concrete and giving them special properties. Nowadays, cement storage is an important issue. Cement absorbs the humidity of the environment, which is leading to, activity loss during transportation and storage. Also, the adsorbed moisture contributes to sticking particles of cement to the walls of the mill, during milling process, which worsens the grinding process. In order to extend the storage of cement and to avoid the negative influence of water on its composition, a special type of admixtures is added. Amine-based admixtures are widely used in the production of cement, primarily as grinding intensifiers and boosters and curing agents. The purpose of the research work is the influence of amines-based admixtures of different structure and composition in the process of milling of clinker, hydration of cement stone investigation, and the research of possibility of their use as hydrophobic admixtures. The object of the study is cement modified with amine-based admixtures. The subject of the study is the evaluation of the influence of selected additives amines-based on the physical, mechanical and hydrophobic properties of the cements obtained. Research methods are determination dispersity of the materials; determination of physical and mechanical properties: normal density, setting time; hydrophobic test; definition of the contact angle; study of the flowability and hygroscopicity of materials. Publications: scientific results of the master's dissertation are published in the collection of materials of the XVIII All-Ukrainian Student Scientific and Practical
- Published
- 2018
179. Osmotic Coefficients and Activity Coefficients of Nonaqueous Electrolyte Solutions. Part 4. Lithium Bromide, Tetrabutylammonium Bromide, and Tetrabutylammonium Perchlorate in Acetone.
- Author
-
Barthel, Josef, Neueder, Roland, Poepke, Herbert, and Wittmann, Harald
- Abstract
Vapor pressure lowering by the addition of lithium bromide (0.03–0.8 m), tetrabutylammonium bromide (0.01–0.8 m), and tetrabutylammonium perchlorate (0.02–3.6 m) to acetone was measured at 25°C with high precision. The experimental data of the corresponding osmotic coefficients are compared to those obtained by the use of Pitzer equations and chemical model calculations. Mean activity coefficients are derived from the osmotic coefficients. [ABSTRACT FROM AUTHOR]
- Published
- 1999
- Full Text
- View/download PDF
180. How copper corrosion can be retarded – New ways investigating a chronic problem for cellulose in paper
- Author
-
Kyujin Ahn, Monika Horsky, Antje Potthast, and Christa Hofmann
- Subjects
Paper ,food.ingredient ,Polymers and Plastics ,Organic Chemistry ,Inorganic chemistry ,chemistry.chemical_element ,Triazoles ,Accelerated aging ,Copper ,Gelatin ,Corrosion ,Quaternary Ammonium Compounds ,chemistry.chemical_compound ,food ,chemistry ,Tetrabutylammonium bromide ,Materials Chemistry ,Degradation (geology) ,Cellulose ,Erosion corrosion of copper water tubes ,Nuclear chemistry - Abstract
To better assess the stabilization effects of chemical treatments on Cu(II)-catalyzed cellulose degradation, we developed Cu(II)-containing model rag paper with typical copper corrosion characteristics using e-beam radiation. The paper can be prepared homogeneously and quickly compared to tedious pre-aging methods. Using the Cu(II)-containing model rag paper, the stabilization effects of various chemicals on Cu(II)-catalyzed degradation of cellulose were tested. Benzotriazol was highly effective in retarding the degradation of the Cu(II)-containing model rag paper under hot and humid aging condition, as well as under photo-oxidative stress. Tetrabutylammonium bromide reduced Cu(II)-catalyzed degradation of cellulose, but its efficacy was dependent on the accelerated aging conditions. The results with the alkaline treatments and gelatin treatment suggested that their roles in the degradation mechanisms of cellulose in the presence of Cu(II) differ from those of benzotriazol and tetrabutylammonium bromide.
- Published
- 2015
181. Reaction of Diazo Compounds with Difluorocarbene: An Efficient Approach towards 1,1-Difluoroolefins
- Author
-
Yan Zhang, Chengpeng Wang, Chenggui Wu, Weizhi Yu, Jianbo Wang, and Zhikun Zhang
- Subjects
chemistry.chemical_classification ,Difluorocarbene ,010405 organic chemistry ,Carbene dimerization ,Hydrazone ,chemistry.chemical_element ,General Medicine ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Combinatorial chemistry ,Catalysis ,Relative stability ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Tetrabutylammonium bromide ,Fluorine ,Organic chemistry ,Diazo ,Carbene - Abstract
A transition-metal-free difluoromethylenation of diazo compounds that proceeds under mild conditions has been developed and is based on the use of TMSCF2 Br as the difluoromethylene source and tetrabutylammonium bromide (TBAB) as the promoter. The chemoselective formal carbene dimerization reaction is achieved owing to the electronic properties and the relative stability of the difluorocarbene intermediate.
- Published
- 2015
182. The first synthesis of peracetyl glycosyl aurone derivatives and aurone glucosides
- Author
-
Shrijana Bhattarai, Arjun Kafle, and Scott T. Handy
- Subjects
chemistry.chemical_classification ,animal structures ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,Glycoside ,macromolecular substances ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,carbohydrates (lipids) ,chemistry.chemical_compound ,Bromide ,Tetrabutylammonium bromide ,Yield (chemistry) ,Drug Discovery ,Aurone ,Organic chemistry ,lipids (amino acids, peptides, and proteins) ,Glycosyl ,Phase-transfer catalyst - Abstract
Aurones, a sub-class of the flavonoids with proven therapeutic importance, also exist in variously glycosylated forms. Although a large number of glycosylated aurone derivatives have been isolated from plant sources, no syntheses have been reported yet. Inspired from this gap, here we report the first synthesis of peracetylated glycosyl derivatives of synthetic aurones. The direct O-glycosylation was achieved by reacting 6-hydroxy aurones with 2, 3, 4, 6-tetra-O-acetyl-α-D glucopyranosyl bromide in the presence of a phase transfer catalyst tetrabutylammonium bromide (TBAB). The successful synthesis of aurone glycosides (33 examples) in 60–92% yield will benefit the synthesis of combinatorial libraries of glycosylated aurones for their biological study and comparison with non-glycosylated aurones.
- Published
- 2020
183. Dimerizations of 2-bromo-3-methyl-1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone in tetra-n-butylammonium bromide
- Author
-
Mai Onuki, Shusuke Tomoshige, Motohiro Ota, Shogo Kamo, Shoya Otokozawa, Kouji Kuramochi, and Kazunori Tsubaki
- Subjects
Organic solvent ,Organic Chemistry ,2 methyl 1 4 naphthoquinone ,Ionic bonding ,1,4-Naphthoquinone ,Biochemistry ,Medicinal chemistry ,Solvent ,chemistry.chemical_compound ,chemistry ,Bromide ,Tetrabutylammonium bromide ,Drug Discovery ,Ionic liquid - Abstract
2-Bromo-3-methyl-1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone are highly reactive species known to dimerize in various ways. The product obtained in the dimerization of each compound is primarily dependent upon the solvent used. Ionic liquids represent a new class of solvents having non-molecular (ionic) character. Replacement of a conventional organic solvent with an ionic solvent frequently changes the mechanism of a reaction. In this study, reactions of 2-bromo-3-methyl-1,4-naphthoquinone and 2-methyl-1,4-naphthoquinone in ionic liquids were examined. Dimerization of 2-bromo-3-methyl-1,4-naphthoquinone or 2-methyl-1,4-naphthoquinone with N-methylcyclohexylamine in tetra-n-butylammonium bromide (TBAB), an ionic liquid, under an aerobic atmosphere afforded 5,7,12,14-pentacenetetrone and 1-methylKuQuinone, respectively. The use of TBAB as a solvent improved the yields of the products as compared with previously reported methods. The mechanism of each dimerization was also investigated.
- Published
- 2020
184. Copper-catalyzed fragmentation-rearrangement sequence of cycloketoxime esters
- Author
-
Binlin Zhao, Yu Yuan, Zhuangzhi Shi, and Yixiao Wu
- Subjects
Primary (chemistry) ,010405 organic chemistry ,Organic Chemistry ,Sequence (biology) ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Combinatorial chemistry ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Fragmentation (mass spectrometry) ,Reagent ,Tetrabutylammonium bromide ,Atom economy ,Drug Discovery ,Functional group ,Copper catalyzed - Abstract
Copper-catalyzed fragmentation-rearrangement sequence of cycloketoxime esters is reported. This strategy provides direct access to diverse ring-opening acyloxylation nitriles avoiding the use of toxic cyanic reagents with good atom economy and well functional group tolerance. Experimental exploration showed that tetrabutylammonium bromide (TBAB) played an irreplaceable role in this transformation. Based on the primary mechanistic experiments, a plausible mechanism was also proposed.
- Published
- 2020
185. Application of the Bjerrum Association Model to Electrolyte Solutions. II. Enthalpies of Dilution in Water and Nonaqueous Solvents.
- Author
-
Côté, Jean-François, Perron, Gérald, Desnoyers, Jacques, Benson, George, and Lu, Benjamin
- Abstract
The association theory based on the Bjerrum model, which had been developed for the treatment of apparent and partial molar volumes of electrolyte solutions, is extended to apparent molar relative enthalpies L
2,φ . Experimental enthalpies of dilution for tetrabutylammonium bromide in acetonitrile, propylene carbonate, and γ-butyrolactone and for lithium perchlorate and sodium thiocyanate in acetonitrile were obtained and analyzed with this model. Literature data for various electrolytes in water, acetonitrile, and n-propanol were also reanalyzed. Through the Bjerrum equations, enthalpies of dilution can be extrapolated to infinite dilution and reliable L2,φ obtained for associated electrolytes. The model can be used to estimate the association constant KA of the electrolyte and these KA are compared with literature values (generally obtained from conductivity). Considering the difference in the concentration ranges investigated in L2,φ and Λ measurements, KA extracted from L2,φ generally fall within an expected range of deviation from the ones obtained by conductivity, provided that no specific interactions are present in solution. [ABSTRACT FROM AUTHOR]- Published
- 1998
- Full Text
- View/download PDF
186. Polarographic determination of extraction constants.
- Author
-
Dingjan, H., Bennekom, W., and Bult, A.
- Abstract
The extraction contants of three organic compounds containing nitrogen as a picrate ion pair in a water-chloroform system were determined by following polarographically the picrate concentration in the aqueous phase as a function of the added amount of reagent. The extraction constants were also determined spectrophotometrically (via batch extraction). The obtained results are in good agreement. The proposed method is applicable for extraction constants with values between 10 and 10. [ABSTRACT FROM AUTHOR]
- Published
- 1987
- Full Text
- View/download PDF
187. Theoretical investigation of thermodynamic properties of tetrabutylammonium bromide ionic clathrate hydrate
- Author
-
R. K. Zhdanov, Yu Yu Bozhko, V. R. Belosludov, Oleg S. Subbotin, and K. V. Gets
- Subjects
History ,Chemistry ,Tetrabutylammonium bromide ,Clathrate hydrate ,Inorganic chemistry ,Ionic bonding ,Physics::Chemical Physics ,Computer Science Applications ,Education - Abstract
In the framework of the lattice dynamics method, the densities of the phonon states of tetrabutylammonium bromide ionic clathrate hydrate have been found. The dynamic stability of the hydrate is shown for a number of temperatures. Using the developed statistical-thermodynamic theory, the free energy curves have been constructed for a wide range of temperatures at different unit cell volumes and, based on the calculated data, the lines of thermal expansion of the hydrate have been constructed.
- Published
- 2019
188. Гідрофобні добавки на основі амінів для полідисперсних в'яжучих матеріалів
- Author
-
Токарчук, Володимир Володимирович
- Subjects
organic admixtures ,666.942 ,diethylenetriamine ,органічні добавки ,етилдиізопропіламін ,диетилентриамін ,triethylamine ,тетрабутиламонію бромід ,triethanolamine ,hydrophobic cement ,ethyldiisopropylamine ,tetrabutylammonium bromide ,триетаноламін ,триетиламін ,гідрофобний цемент - Abstract
Магістерська дисертація на тему: «Гідрофобні добавки на основі амінів для полідисперсних в’яжучих матеріалів» містить 94 с., 20 рис., 13 табл., 45 джерел, 3 додатки. Хімічні добавки широко використовуються у виробництві цементів та бетонів. Основною причиною їх використання є зниження економічних та енергетичних затрат (саме на помел клінкеру), а також покращення властивостей цементів і бетонів та надання їм спеціальних властивостей. Наразі важливою проблемою є зберігання цементу. Під час транспортування та зберігання цемент поглинає вологу з навколишнього середовища, в результаті чого втрачає свою активність. Також при помелі клінкеру адсорбована волога сприяє налипанню частинок цементу на стінки млина, що погіршує процес помелу. З метою подовження терміну зберігання цементу та уникнення негативного впливу води до його складу вводять спеціальний вид добавок – гідрофобізуючі. Добавки на основі амінів широко використовуються у виробництві цементу, насамперед, як інтенсифікатори помелу та прискорювачі тужавлення та тверднення. Метою науково-дослідної роботи є дослідження впливу добавок на основі амінів різної будови та складу на процес помелу клінкеру, гідратацію цементного каменю, а також встановлення можливості їх використання в якості гідрофобізуючих добавок. Об’єкт дослідження – цемент, модифікований добавками на основі амінів. Предмет дослідження – оцінка впливу вибраних добавок на основі амінів на фізико-механічні та гідрофобні властивості отриманих цементів. Методи дослідження: визначення залишку на ситі та питомої поверхні матеріалів; визначення фізико-механічних властивостей: нормальної густини, термінів тужавлення та міцності; проба на гідрофобність; визначення крайового кута змочування; дослідження сипучості та гігроскопічності матеріалів. Публікації: наукові результати магістерської дисертації опубліковано у збірнику матеріалів XVIII Всеукраїнської студентської науково-практичної конференції «Science and Technology of the XXI Century» та у збірнику тез доповідей І Міжнародної наукової конференції студентів, аспірантів та молодих учених «Хімічні проблеми сьогодення». Також була взята участь в очній VII Міжнародній конференції студентів, аспірантів та молодих учених «Неорганічне матеріалознавство». Master's dissertation on the subject: "The amines-based hydrophobic admixtures for poly-dispersive binders" contains 94 pages., 20 fig, 13 tabl., 45 sources, 3 appendixes. Chemical admixtures are widely used in the manufacture of cements and concretes. The main reason for their use is the reduction of economic and energy costs (namely clinker milling), as well as the improvement of the properties of cements and concrete and giving them special properties. Nowadays, cement storage is an important issue. Cement absorbs the humidity of the environment, which is leading to, activity loss during transportation and storage. Also, the adsorbed moisture contributes to sticking particles of cement to the walls of the mill, during milling process, which worsens the grinding process. In order to extend the storage of cement and to avoid the negative influence of water on its composition, a special type of admixtures is added. Amine-based admixtures are widely used in the production of cement, primarily as grinding intensifiers and boosters and curing agents. The purpose of the research work is the influence of amines-based admixtures of different structure and composition in the process of milling of clinker, hydration of cement stone investigation, and the research of possibility of their use as hydrophobic admixtures. The object of the study is cement modified with amine-based admixtures. The subject of the study is the evaluation of the influence of selected additives amines-based on the physical, mechanical and hydrophobic properties of the cements obtained. Research methods are determination dispersity of the materials; determination of physical and mechanical properties: normal density, setting time; hydrophobic test; definition of the contact angle; study of the flowability and hygroscopicity of materials. Publications: scientific results of the master's dissertation are published in the collection of materials of the XVIII All-Ukrainian Student Scientific and Practical Conference "Science and Technology of the XXI Century" and in the collection of abstracts of the I International Scientific Conference for students and young researchers "Current Chemical Problems". Participation in the VII International Conference of Students and Young Scientists "Inorganic Materials Science" was also attended.
- Published
- 2018
189. The synthesis of 5-substituted 1H-tetrazoles in molten tetrabutylammonium bromide.
- Author
-
Xie, Aming, Cao, Meiping, Feng, Liandong, and Dong, Wei
- Subjects
- *
TETRAZOLES , *ENANTIOSELECTIVE catalysis , *METAL catalysts , *TRIMETHYLSILYL compounds , *ION pairs - Abstract
An economical and environmentally benign method for the synthesis of 5-substituted 1H-tetrazoles has been established. In this protocol, molten tetrabutylammonium bromide (TBAB) is used as both the solvent and catalyst. A mechanism involving the intermediacy of tetrabutylammonium azide (TBAN3) is proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
190. Thermal conductivities of methane–methylcyclohexane and tetrabutylammonium bromide clathrate hydrate
- Author
-
Lihua Wan, Dongliang Li, Deqing Liang, and Hao Peng
- Subjects
Chemistry ,Inorganic chemistry ,Clathrate hydrate ,Compaction ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Methane ,0104 chemical sciences ,chemistry.chemical_compound ,Thermal conductivity ,Tetrabutylammonium bromide ,Thermal ,Physical chemistry ,Physical and Theoretical Chemistry ,Methylcyclohexane ,0210 nano-technology ,Hydrate - Abstract
Thermal conductivities of structure H (sH) methane–methylcyclohexane hydrate and type A tetrabutylammonium bromide (TBAB) clathrate hydrate were measured using a single-sided transient plane source technique. The thermal conductivity of sH hydrate exhibited a positive trend with temperature and the average thermal conductivity was found to be 0.44 W m−1 K−1 at a compaction pressure of 12 MPa. The thermal conductivity of sH hydrate was lower than those of structure I and structure II hydrates at the same temperature and was found to depend not only on guest–host interactions but also on the rigidity of the framework. Unlike sH hydrates, the thermal conductivity of type A TBAB hydrates exhibited a negative trend with temperature. One possible reason for this strange phenomenon could be that the TBAB hydrate has a semi-clathrate structure, which retains the crystal heat transmission characteristics. The structures of the hydrates studied were different from those of normal gas hydrates. In addition, the thermal conductivity values for TBAB hydrates were also affected by interactions between the cations and anions.
- Published
- 2015
191. Efficient Synthesis of Conjugated 1,3,4-Thiadiazole Hybrids through Palladium-Catalyzed Cross-Coupling of 2,5-Bis(4-bromophenyl)-1,3,4-thiadiazole with Boronic Acids
- Author
-
Monika Wróblowska, Mieczysław Łapkowski, and Agnieszka Kudelko
- Subjects
Solvent system ,chemistry.chemical_classification ,chemistry.chemical_compound ,chemistry ,Base (chemistry) ,Tetrabutylammonium bromide ,Organic Chemistry ,Polymer chemistry ,chemistry.chemical_element ,Triphenylphosphine ,Conjugated system ,Palladium ,Catalysis - Abstract
New derivatives of 2,5-bis(4-heteroarylphenyl)-1,3,4-thiadiazole were synthesized under Suzuki cross-coupling reactions from 2,5-bis(4-bromophenyl)-1,3,4-thiadiazole and commercially available boronic acids. Reactions were conducted in a two-phase solvent system in the presence of catalytic amounts of tetrakis(triphenylphosphine)palladium(0), cesium carbonate as a base, and tetrabutylammonium bromide playing a role of a phase-transfer catalyst.
- Published
- 2015
192. Experimental measurements of carbon dioxide solubility in aqueous tetra-n-butylammonium bromide solutions
- Author
-
Ryo Ohmura, Sanehiro Muromachi, H. Miyamoto, and Atsushi Shijima
- Subjects
Aqueous solution ,Carbon dioxide solubility ,biology ,Chemistry ,Inorganic chemistry ,biology.organism_classification ,Atomic and Molecular Physics, and Optics ,chemistry.chemical_compound ,Bromide ,Tetrabutylammonium bromide ,Carbon dioxide ,Tetra ,General Materials Science ,Physical and Theoretical Chemistry ,Solubility ,Mass fraction - Abstract
In this paper, we report the absolute measurements of CO2 solubility in aqueous tetra-n-butylammonium bromide (TBAB) solution. The measurement range was 0.2 MPa 3 MPa and T > 292 K with wTBAB ⩾ 0.4 mass fraction of TBAB.
- Published
- 2015
193. Mild Oxidation of Alcohols with o-Iodoxybenzoic Acid in Liquid Tetrabutylammonium Bromide
- Author
-
Boliang Wang, Yangyang Liu, Meiping Cao, Feng Liandong, and Xie Aming
- Subjects
O-iodoxybenzoic acid ,Chemistry ,Tetrabutylammonium bromide ,Alcohol oxidation ,Organic chemistry ,General Chemistry - Published
- 2015
194. Preparation of 3,5-Dibromo-2-pyrone from Coumalic Acid
- Author
-
Hyun Kyu Cho and Cheon Gyu Cho
- Subjects
Chloroform ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,0104 chemical sciences ,chemistry.chemical_compound ,Coumalic acid ,2-Pyrone ,Tetrabutylammonium bromide ,Physical and Theoretical Chemistry ,N-Bromosuccinimide - Published
- 2015
195. Amide synthesis from alcohols and amines catalyzed by a RuII–N-heterocyclic carbene (NHC)–carbonyl complex
- Author
-
Abir Sarbajna, Biswajit Saha, Gargi Sengupta, Indranil Dutta, and Jitendra K. Bera
- Subjects
Chemistry ,Organic Chemistry ,Substrate (chemistry) ,Biochemistry ,Medicinal chemistry ,Catalysis ,Inorganic Chemistry ,chemistry.chemical_compound ,Catalytic cycle ,Bromide ,Amide ,Tetrabutylammonium bromide ,Materials Chemistry ,Organic chemistry ,Physical and Theoretical Chemistry ,Carbene ,Dichloromethane - Abstract
Treatment of [Ru2(CO)4(CH3CN)6](BF4)2 with 3-methyl-1-(pyridin-2-yl)-imidazolium bromide in the presence of tetrabutylammonium bromide at room temperature in dichloromethane affords a RuII–N-heterocyclic carbene–carbonyl complex [Ru(py-NHC)(CO)2Br2] (1). Catalyst 1 displays diverse substrate scope for phosphine-free acceptorless coupling between alcohols and amines to amides at low catalyst loading. A RuII-dihydride/Ru0 sequence is proposed in the catalytic cycle.
- Published
- 2014
196. Tetrabutylammonium Bromide (TBAB) Catalyzed Synthesis of Bioactive Heterocycles.
- Author
-
Banik, Bimal Krishna, Banerjee, Bubun, Kaur, Gurpreet, Saroch, Shivam, Kumar, Rajat, Dohi, Toshifumi, Zhang, Cheng-Pan, and Keglevich, György
- Subjects
- *
PHASE-transfer catalysts , *HETEROCYCLIC compounds , *BROMIDES , *ORGANIC solvents , *ALKYLATION , *ZWITTERIONS , *HETEROCYCLIC chemistry - Abstract
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. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
197. Lewis acid/base pair as a catalytic system for α-stereoselective synthesis of 2-deoxyglycosides through the addition of alcohols to glycals.
- Author
-
Wang, Chen, Liang, Haijing, Hang, Zhaojun, Wang, Zhao-yan, Xie, Qinjian, and Xue, Weihua
- Subjects
- *
BASE pairs , *LEWIS acids , *GLYCALS , *ALCOHOL , *DNA , *STEREOSELECTIVE reactions - Abstract
• • α-Stereoselective 2-deoxyglycosidation. • • Inexpensive and stable catalysts. • • A wide substrate scope, the simple operation, and an interesting mechanism. This report describes the α-stereoselective addition of alcohols to glycals promoted by a cooperative Lewis acid/base pair catalytic system composed of B(C 6 F 5) 3 and tetrabutylammonium bromide (TBAB), which provides access to 2-deoxylglycosides in high yields. A mechanistic investigation supported by NMR analysis highlights the possible involvement of nucleophilic addition through boron-induced activation of alcohols under the assistance of TBAB. The protocol discussed here features the high stereoselectivity, mild reaction conditions, inexpensive and stable catalysts, and a broad substrate scopes. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
198. Investigation of the stabilization of verdigris-containing rag paper by wet chemical treatments
- Author
-
Ahn, Kyujin, Hartl, Andreas, Hofmann, Christa, Henniges, Ute, and Potthast, Antje
- Published
- 2014
- Full Text
- View/download PDF
199. Ligand-free palladium catalyzed phosphorylation of aryl iodides
- Author
-
Najmeh Nowrouzi, Saba Keshtgar, and Enayatollah Bahman Jahromi
- Subjects
inorganic chemicals ,010405 organic chemistry ,Ligand ,Aryl ,Organic Chemistry ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Combinatorial chemistry ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,Tetrabutylammonium bromide ,Drug Discovery ,Organic chemistry ,Phosphorylation ,Palladium - Abstract
A reusable ligand-free palladium catalyzed phosphorylation of aryl iodides using PdCl2/tetrabutylammonium bromide is described. Functionalized triarylphosphines were obtained in good to excellent yields in the absence of external reductants and supporting ligands.
- Published
- 2016
200. INFLUENCE OF TETRABUTYLAMMONIUM BROMIDE AND SODIUM BROMIDE ON ACID-BASE PROPERTIES OF THYMOL BLUE IN WATER-ETHANOL MEDIUM
- Author
-
N.N. Kamneva, K.V. Goloviznina, A.I. Rysukhina, and E.A. Reshetnyak
- Subjects
chemistry.chemical_classification ,Sodium bromide ,chemistry.chemical_compound ,Ethanol ,chemistry ,Base (chemistry) ,Tetrabutylammonium bromide ,Thymol blue ,Nuclear chemistry - Published
- 2017
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.