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Tetrabutylammonium Hydroxide
Tetrabutylammonium hydroxide is the chemical compound with the formula (C4H9)4NOH, abbreviated Bu4NOH with the acronym TBAOH or TBAH. This species is employed as a solution in water or alcohols. It is a common base in organic chemistry. Relative to more conventional inorganic bases, such as KOH and NaOH, Bu4NOH is more soluble in organic solvents.. Preparation and reactions Solutions of Bu4NOH are usually prepared ''in situ'' from butylammonium halides, Bu4NX, for example by reacting them with silver oxide or using an ion exchange resin. Attempts to isolate Bu4NOH induces Hofmann elimination, leading to Bu3N and 1-butene. Solutions of Bu4NOH are typically contaminated with Bu3N for this reason. Treatment of Bu4NOH with a wide range of acids gives water and the other tetrabutylammonium salts: Bu4NOH + HX -> Bu4NX + H2O Applications Bu4NOH is a strong base that is used often under phase-transfer conditions to effect alkylations and deprotonations. Typical reactions include benz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element is therefore not a compound. A compound can be transformed into a different substance by a chemical reaction, which may involve interactions with other substances. In this process, bonds between atoms may be broken and/or new bonds formed. There are four major types of compounds, distinguished by how the constituent atoms are bonded together. Molecular compounds are held together by covalent bonds; ionic compounds are held together by ionic bonds; intermetallic compounds are held together by metallic bonds; coordination complexes are held together by coordinate covalent bonds. Non-stoichiometric compounds form a disputed marginal case. A chemical formula specifies the number of atoms of each element in a compound molecule, usi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deprotonation
Deprotonation (or dehydronation) is the removal (transfer) of a proton (or hydron, or hydrogen cation), (H+) from a Brønsted–Lowry acid in an acid–base reaction.Henry Jakubowski, Biochemistry Online Chapter 2A3, https://employees.csbsju.edu/hjakubowski/classes/ch331/protstructure/PS_2A3_AA_Charges.html, accessed 12/2/2020 The species formed is the conjugate base of that acid. The complementary process, when a proton is added (transferred) to a Brønsted–Lowry base, is protonation (or hydronation). The species formed is the conjugate acid of that base. A species that can either accept or donate a proton is referred to as amphiprotic. An example is the H2O (water) molecule, which can gain a proton to form the hydronium ion, H3O+, or lose a proton, leaving the hydroxide ion, OH−. The relative ability of a molecule to give up a proton is measured by its p''K''a value. A low p''K''a value indicates that the compound is acidic and will easily give up its proton to a bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desilylation
Silylation is the introduction of one or more (usually) substituted silyl groups (R3Si) to a molecule. The process is the basis of organosilicon chemistry. Of organic compounds Alcohols, carboxylic acids, amines, thiols, and phosphates can be silylated. The process involves the replacement of a proton with a trialkylsilyl group, typically trimethylsilyl (-SiMe3). Generally the substrate is deprotonated with a suitable strong base followed by treatment with a silyl chloride (e.g. trimethylsilyl chloride). Often strong bases such butyl lithium or a Grignard reagent are used, as illustrated by the synthesis of a trimethylsilyl ethers as protecting groups from an alcohol: :ROH + BuLi → ROLi + BuH :ROLi + Me3SiCl → ROSiMe3 + LiCl Bis(trimethylsilyl)acetamide ("BSA", Me3SiNC(OSiMe3)Me is an efficient silylation agent used for the derivatisation of compounds. The reaction of BSA with alcohols gives the corresponding trimethylsilyl ether, together with N-(trimethylsilyl)acetamide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetra-n-butylammonium Fluoride
Tetra-''n''-butylammonium fluoride, commonly abbreviated to TBAF and ''n''-Bu4NF, is a quaternary ammonium salt with the chemical formula (CH3CH2CH2CH2)4N+F−. It is commercially available as the white solid trihydrate and as a solution in tetrahydrofuran. TBAF is used as a source of fluoride ion in organic solvents. Preparation and properties TBAF can be prepared by passing hydrofluoric acid through an ion-exchange resin, followed by tetrabutylammonium bromide. Upon evaporation of the water, TBAF can be collected as an oil in quantitative yield. Preparing anhydrous samples is of interest as the basicity of fluoride increases by more than 20 p''K'' units on passing from aqueous to aprotic solvent. However, heating samples of the hydrated material to 77 °C under vacuum causes decomposition to the hydrogen difluoride salt. Similarly, samples dried at 40 °C under high vacuum still contain 10-30 mol% of water and some 10% of difluoride. Instead, anhydrous TBAF ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrofluoric Acid
Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly corrosive. It is used to make most fluorine-containing compounds; examples include the commonly used pharmaceutical antidepressant medication fluoxetine (Prozac) and the material PTFE (Teflon). Elemental fluorine is produced from it. It is commonly used to etch glass and silicon wafers. Uses Production of organofluorine compounds The principal use of hydrofluoric acid is in organofluorine chemistry. Many organofluorine compounds are prepared using HF as the fluorine source, including Teflon, fluoropolymers, fluorocarbons, and refrigerants such as freon. Many pharmaceuticals contain fluorine. Production of inorganic fluorides Most high-volume inorganic fluoride compounds are prepared from hydrofluoric acid. Foremost are Na3AlF6, cryolite, and AlF3, aluminium trifluoride. A molten mixture of these solids serves as a high-temperature solvent for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disodium Pyrophosphate
Disodium pyrophosphate or sodium acid pyrophosphate (SAPP) is an inorganic compound consisting of sodium cations and pyrophosphate anion. It is a white, water-soluble solid that serves as a buffering and chelating agent, with many applications in the food industry. When crystallized from water, it forms a hexahydrate, but it dehydrates above room temperature. Pyrophosphate is a polyvalent anion with a high affinity for polyvalent cations, e.g. Ca2+. Disodium pyrophosphate is produced by heating sodium dihydrogen phosphate: :2 NaH2PO4 → Na2H2P2O7 + H2O Food uses Disodium pyrophosphate is a popular leavening agent found in baking powders. It combines with sodium bicarbonate to release carbon dioxide: : Na2H2P2O7 + NaHCO3 → Na3HP2O7 + CO2 + H2O It is available in a variety of grades that affect the speed of its action. Because the resulting phosphate residue has an off-taste, SAPP is usually used in very sweet cakes which mask the off-taste. Disodium pyroph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conjugate Base
A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid donates a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a hydrogen ion. On the other hand, a conjugate base is what is left over after an acid has donated a proton during a chemical reaction. Hence, a conjugate base is a species formed by the removal of a proton from an acid, as in the reverse reaction it is able to gain a hydrogen ion. Because some acids are capable of releasing multiple protons, the conjugate base of an acid may itself be acidic. In summary, this can be represented as the following chemical reaction: :acid + base conjugate\ base + conjugate\ acid Johannes Nicolaus Brønsted and Martin Lowry introduced the Brønsted–Lowry theory, which proposed that any compound that can transfer a proton to any other compound is an acid, and the compound that accepts the proton is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mineral Acid
A mineral acid (or inorganic acid) is an acid derived from one or more inorganic compounds, as opposed to organic acids which are acidic, organic compounds. All mineral acids form hydrogen ions and the conjugate base when dissolved in water. Characteristics Commonly used mineral acids are sulfuric acid (H2SO4), hydrochloric acid (HCl) and nitric acid (HNO3, they are also known as bench acids). Mineral acids range from superacids ( perchloric acid) to very weak ones ( boric acid). Mineral acids tend to be very soluble in water and insoluble in organic solvents. Mineral acids are used in many sectors of the chemical industry as feedstocks for the synthesis of other chemicals, both organic and inorganic. Large quantities of these acids – especially sulfuric acid, nitric acid, and hydrochloric acid – are manufactured for commercial use in large plants. Mineral acids are also used directly for their corrosive properties. For example, a dilute solution of hydrochloric acid is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutralization (chemistry)
In chemistry, neutralization or neutralisation (see spelling differences) is a chemical reaction in which acid and a base react quantitatively with each other. In a reaction in water, neutralization results in there being no excess of hydrogen or hydroxide ions present in the solution. The pH of the neutralized solution depends on the acid strength of the reactants. Meaning of "neutralization" In the context of a chemical reaction the term neutralization is used for a reaction between an acid and a base or alkali. Historically, this reaction was represented as :acid + base (alkali) → salt + water For example: :HCl + NaOH → NaCl + H2O The statement is still valid as long as it is understood that in an aqueous solution the substances involved are subject to dissociation, which changes the ionization state of the substances. The arrow sign, →, is used because the reaction is complete, that is, neutralization is a quantitative reaction. A more general definition is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroform
Chloroform, or trichloromethane, is an organic compound with formula C H Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to PTFE. It is also a precursor to various refrigerants. It is trihalomethane. It is a powerful anesthetic, euphoriant, anxiolytic, and sedative when inhaled or ingested. Structure The molecule adopts a tetrahedral molecular geometry with C3v symmetry. Natural occurrence The total global flux of chloroform through the environment is approximately tonnes per year, and about 90% of emissions are natural in origin. Many kinds of seaweed produce chloroform, and fungi are believed to produce chloroform in soil. Abiotic processes are also believed to contribute to natural chloroform productions in soils although the mechanism is still unclear. Chloroform volatilizes readily from soil and surface water and undergoes degradation in air to produce phosgene, dichloromethane, formyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichlorocarbene
Dichlorocarbene is the reactive intermediate with chemical formula CCl2. Although this chemical species has not been isolated, it is a common intermediate in organic chemistry, being generated from chloroform. This bent diamagnetic molecule rapidly inserts into other bonds. Preparation Dichlorocarbene is most commonly generated by reaction of chloroform and a base such as potassium ''tert''-butoxide or aqueous sodium hydroxide. A phase transfer catalyst, for instance benzyltriethylammonium bromide, facilitates the migration of the hydroxide in the organic phase. :HCCl3 + NaOH → CCl2 + NaCl + H2O Other reagents and routes Another precursor to dichlorocarbene is ethyl trichloroacetate. Upon treatment with sodium methoxide it releases CCl2. Phenyl(trichloromethyl)mercury decomposes thermally to release CCl2. :PhHgCCl3 → CCl2 + PhHgCl Dichlorodiazirine, which is stable in the dark, decomposes into dichlorocarbene and nitrogen via photolysis. Dichlorocarbene can also be ob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzyl
In organic chemistry, benzyl is the substituent or molecular fragment possessing the structure . Benzyl features a benzene ring () attached to a methylene group () group. Nomenclature In IUPAC nomenclature, the prefix benzyl refers to a substituent, for example benzyl chloride or benzyl benzoate. Benzyl is not to be confused with phenyl with the formula . The term benzylic is used to describe the position of the first carbon bonded to a benzene or other aromatic ring. For example, is referred to as a "benzylic" carbocation. The benzyl free radical has the formula . The benzyl cation or phenylcarbenium ion is the carbocation with formula ; the benzyl anion or phenylmethanide ion is the carbanion with the formula . None of these species can be formed in significant amounts in the solution phase under normal conditions, but they are useful referents for discussion of reaction mechanisms and may exist as reactive intermediates. Abbreviations The abbreviation "Bn" denotes be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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