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Tetra-n-butylammonium
Tetrabutylammonium bromide (TBAB) is a quaternary ammonium salt with a bromide commonly used as a phase transfer catalyst. It is used to prepare many other tetrabutylammonium salts by salt metathesis reactions. The anhydrous form is a white solid. In addition to being cheap, tetrabutylammonium bromide is also environmentally friendly, has a greater degree of selectivity, is operationally simple, non-corrosive, and can be recycled easily as well. Preparation and reactions Tetrabutylammonium bromide can be prepared by the alkylation of tributylamine with 1-bromobutane. Tetrabutylammonium bromide is used to prepare other salts of the tetrabutylammonium cation by salt metathesis reactions. It serves as a source of bromide ions for substitution reactions. It is a commonly used phase transfer catalyst. As its melting point is just over 100 °C and decreases in the presence of other reagents, it can be considered an ionic liquid. Role in semi-clathrate formation TBAB is being ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrabutylammonium Tribromide
Tetrabutylammonium tribromide, abbreviated to TBATB, is a pale orange solid with the formula (C4H9)4r3. It is a salt of the lipophilic tetrabutylammonium cation and the linear tribromide anion. The salt is sometimes used as a reagent used in organic synthesis as a conveniently weighable, solid source of bromine. Preparation The compound is prepared by treatment of solid tetra-''n''-butylammonium bromide with bromine vapor: : (C4H9)4r + Br2 → (C4H9)4r3 Instead of bromine, tetra-''n''-butylammonium bromide can also be reacted with vanadium pentoxide and aqueous hydrogen peroxide, or alternatively with ceric ammonium nitrate Ceric ammonium nitrate (CAN) is the inorganic compound with the formula . This orange-red, water-soluble cerium salt is a specialised oxidizing agent in organic synthesis and a standard oxidant in quantitative analysis. Preparation, properties, .... See also * Tribromide * Tetrabutylammonium triiodide References Reagents for organic chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase Transfer Catalyst
In chemistry, a phase-transfer catalyst or PTC is a catalyst that facilitates the transition of a reactant from one phase into another phase where reaction occurs. Phase-transfer catalysis is a special form of catalysis and can act through homogeneous catalysis or heterogeneous catalysis methods depending on the catalyst used. Ionic reactants are often soluble in an aqueous phase but insoluble in an organic phase in the absence of the phase-transfer catalyst. The catalyst functions like a detergent for solubilizing the salts into the organic phase. Phase-transfer catalysis refers to the acceleration of the reaction upon the addition of the phase-transfer catalyst. PTC is widely exploited industrially.Marc Halpern "Phase-Transfer Catalysis" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. Polyesters for example are prepared from acyl chlorides and bisphenol-A. Phosphothioate-based pesticides are generated by PTC-catalyzed alkylation of phosphothioates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetra-n-butylammonium Iodide
Tetra-''n''-butylammonium iodide (TBAI) is a quaternary ammonium salt with an iodide counterion. It is used for synthesizing tetra-''n''-butylammonium triiodide by mixing with iodine. TBAI is also commonly used as a catalyst for the protection of alcohols as benzyl ethers with benzyl bromide. Properties The solid crystal of tetra-''n''-butylammonium iodide is in the monoclinic crystal system. It has space group ''C''2/''c''. The unit cell has dimensions a=14.2806 b=14.1864 c=19.5951 β=111.149. There are eight formulae in the unit cell (Z=8), which has volume 3702.4 Å3. The enthalpy of formation ΔfH0 of tetra-''n''-butylammonium iodide is −499 kJ/mol, which is lower than that for the bromide or chloride (−540, −564 kJ/mol). At lower temperatures with water tetra-''n''-butylammonium iodide forms a clathrate hydrate. The tetra-''n''-butylammonium cation is large and hydrophobic. The absolute enthalpy of hydration (from gas phase) is −260 kJ/mol. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichloromethane
Dichloromethane (DCM, methylene chloride, or methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odor is widely used as a solvent. Although it is not miscible with water, it is slightly polar, and miscible with many organic solvents.Rossberg, M. ''et al.'' (2006) "Chlorinated Hydrocarbons" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. . Occurrence Natural sources of dichloromethane include oceanic sources, macroalgae, wetlands, and volcanoes. However, the majority of dichloromethane in the environment is the result of industrial emissions. Production DCM is produced by treating either chloromethane or methane with chlorine gas at 400–500 °C. At these temperatures, both methane and chloromethane undergo a series of reactions producing progressively more chlorinated products. In this way, an estimated 400,000 tons were produced in the US, Europe, and Japan in 199 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clathrate
A clathrate is a chemical substance consisting of a lattice (group), lattice that traps or contains molecules. The word ''clathrate'' is derived from the Latin language, Latin (), meaning 'with bars, Crystal structure, latticed'. Most clathrate compounds are polymeric and completely envelop the guest molecule, but in modern usage clathrates also include host–guest complexes and inclusion compounds.Atwood, J. L. (2012) "Inclusion Compounds" in ''Ullmann's Encyclopedia of Industrial Chemistry''. Wiley-VCH, Weinheim. According to International Union of Pure and Applied Chemistry, IUPAC, clathrates are inclusion compounds "in which the guest molecule is in a cage formed by the host molecule or by a lattice of host molecules." The term refers to many molecular hosts, including calixarenes and cyclodextrins and even some inorganic polymers such as zeolites. Clathrates can be divided into two categories: clathrate hydrates and inorganic clathrates. Each clathrate is made up of a fram ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionic Liquid
An ionic liquid (IL) is a salt (chemistry), salt in the liquid state at ambient conditions. In some contexts, the term has been restricted to salts whose melting point is below a specific temperature, such as . While ordinary liquids such as water and gasoline are predominantly made of electric charge, electrically neutral molecules, ionic liquids are largely made of ions. These substances are variously called liquid electrolytes, ionic melts, ionic fluids, fused salts, liquid salts, or ionic glasses. Ionic liquids have many potential applications. They are powerful solvents and can be used as electrolytes. Salts that are liquid at near-ambient temperature are important for electric battery applications, and have been considered as sealants due to their very low vapor pressure. Any salt that melts without pyrolysis, decomposing or vaporizing usually yields an ionic liquid. Sodium chloride (NaCl), for example, melts at into a liquid that consists largely of sodium cations () and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salt Metathesis Reaction
A salt metathesis reaction (also called a double displacement reaction, double replacement reaction, or double decomposition) is a type of chemical reaction in which two ionic compounds in aqueous solution exchange their component ions to form two new compounds. Often, one of these new compounds is a precipitate, gas, or weak electrolyte, driving the reaction forward. :AB + CD -> AD + CB \mathitA_\mathitD_\mathit + \mathitC_\mathitB_\mathit --> In older literature, the term double decomposition is common. The term double decomposition is more specifically used when at least one of the substances does not dissolve in the solvent, as the ligand or ion exchange takes place in the solid state of the reactant. For example: :AX(aq) + BY(s) → AY(aq) + BX(s). Types of reactions Counterion exchange Salt metathesis is a common technique for exchanging counterions. The choice of reactants is guided by a solubility chart or lattice energy. HSAB theory can also be used to predict ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tributylamine
Tributylamine (TBA) is an organic compound with the molecular formula (C4H9)3N. It is a colorless liquid with an amine-like odor. Uses Tributylamine is used as a catalyst (proton acceptor) and as a solvent in organic syntheses and polymerization (including polyurethane Polyurethane (; often abbreviated PUR and PU) is a class of polymers composed of organic chemistry, organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane term ...s). References {{reflist Amine solvents Alkylamines Tertiary amines Butyl compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encyclopedia Of Reagents For Organic Synthesis
The ''Encyclopedia of Reagents for Organic Synthesis'' is published in print and online by John Wiley & Sons Ltd. The online version is also known as e-EROS. The encyclopedia contains a description of the use of reagents used in organic chemistry. The eight-volume print version includes 3500 alphabetically arranged articles and the online version is regularly updated to include new reagents and catalyst Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...s. References External links *Print version Encyclopedias of science Chemistry books {{encyclopedia-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salt Metathesis
A salt metathesis reaction (also called a double displacement reaction, double replacement reaction, or double decomposition) is a type of chemical reaction in which two ionic compounds in aqueous solution exchange their component ions to form two new compounds. Often, one of these new compounds is a precipitate, gas, or weak electrolyte, driving the reaction forward. :AB + CD -> AD + CB \mathitA_\mathitD_\mathit + \mathitC_\mathitB_\mathit --> In older literature, the term double decomposition is common. The term double decomposition is more specifically used when at least one of the substances does not dissolve in the solvent, as the ligand or ion exchange takes place in the solid state of the reactant. For example: :AX(aq) + BY(s) → AY(aq) + BX(s). Types of reactions Counterion exchange Salt metathesis is a common technique for exchanging counterions. The choice of reactants is guided by a solubility chart or lattice energy. HSAB theory can also be used to predict ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrabutylammonium
Tetrabutylammonium is a quaternary ammonium cation with the formula , also denoted (where Bu = butyl group). It is used in the research laboratory to prepare lipophilic salts of inorganic anions. Relative to tetraethylammonium derivatives, tetrabutylammonium salts are more lipophilic but crystallize less readily. Derivatives Some tetrabutylammonium salts of simple anions include: * tetrabutylammonium fluoride, a desilylation reagent. * tetrabutylammonium bromide, a precursor to other tetrabutylammonium salts via salt metathesis reactions. * tetrabutylammonium iodide, a low cost catalyst. * tetrabutylammonium triiodide, a common carrier of the triiodide anion used in chemical synthesis. * tetrabutylammonium hydroxide, a precursor to other tetrabutylammonium salts via acid-base reactions. * tetrabutylammonium hexafluorophosphate, an electrolyte for nonaqueous electrochemistry. Some tetrabutylammonium salts of more complex examples include: *polyoxometalate In chemistry, a poly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
