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Triacetoxyborohydride
Sodium triacetoxyborohydride, also known as sodium triacetoxyhydroborate, commonly abbreviated STAB, is a chemical compound with the formula Na(CH3COO)3BH. Like other borohydrides, it is used as a reducing agent in organic synthesis. This colourless salt is prepared by protonolysis of sodium borohydride with acetic acid: :NaBH4 + 3 HO2CCH3 → NaBH(O2CCH3)3 + 3 H2 Comparison with related reagents Sodium triacetoxyborohydride is a milder reducing agent than sodium borohydride or even sodium cyanoborohydride. It reduces aldehydes but not most ketones. It is especially suitable for reductive aminations of aldehydes and ketones. However, unlike sodium cyanoborohydride, the triacetoxyborohydride hydrolyzes readily, nor is it compatible with methanol. It reacts only slowly with ethanol and isopropanol and can be used with these. NaBH(OAc)3 may also be used for reductive alkylation of secondary amines with aldehyde-bisulfite adducts. Monoacetoxyborohydride The combinat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protonolysis
Protonolysis is the cleavage of a chemical bond by acids. Many examples are found in organometallic chemistry since the reaction requires polar Mδ+-Rδ- bonds, where δ+ and δ- signify partial positive and negative charges associated with the bonding atoms. When compounds containing these bonds are treated with acid (HX), these bonds cleave: :M-R + HX → M-X + H-R Hydrolysis (X− = OH−) is a special case of protonolysis. Compounds susceptible to hydrolysis often undergo protonolysis. Hydrides The borohydride anion is susceptible to reaction with even weak acids, resulting protonolysis of one or more B-H bonds. Protonolysis of sodium borohydride with acetic acid gives triacetoxyborohydride: :NaBH4 + 3 HO2CCH3 → NaBH(O2CCH3)3 + 3 H2 Related reactions occur for hydrides of other electropositive elements, e.g. lithium aluminium hydride. Alkyls The alkyl derivatives of many metals undergo protonolysis. For the alkyls of very electropositive metals (zinc, magnesium, and lithium), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Cyanoborohydride
Sodium cyanoborohydride is the chemical compound with the formula Sodium, NaBoron, BHydrogen, H3cyanide, CN. It is a colourless salt, but commercial samples can appear tan. It is widely used in organic synthesis for the reduction of imines. The salt tolerates aqueous conditions. Use Owing to the presence of the electron-withdrawing cyanide substituent, [B(CN)H3]− is less reducing than is sodium borohydride, [BH4]−. As a mild reducing agent, it is used to convert imines to amines. It is especially favored for reductive aminations, wherein aldehydes or ketones are treated with an amine in the presence of this reagent: : R2CO + R'NH2 + NaBH3CN + CH3OH → R2CH-NHR' + "NaCH3OBH2CN" The reagent is typically used in excess. Selectivity is achieved at mildly basic solutions (pH 7–10). The reagent is ideal for reductive aminations ("Borch Reaction"). In conjunction with tosylhydrazine, sodium cyanoborohydride is used in the reductive deoxygenation of ketones. Structure and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a light, volatile, colourless, flammable liquid with a distinctive alcoholic odour similar to that of ethanol (potable alcohol). A polar solvent, methanol acquired the name wood alcohol because it was once produced chiefly by the destructive distillation of wood. Today, methanol is mainly produced industrially by hydrogenation of carbon monoxide. Methanol consists of a methyl group linked to a polar hydroxyl group. With more than 20 million tons produced annually, it is used as a precursor to other commodity chemicals, including formaldehyde, acetic acid, methyl tert-butyl ether, methyl benzoate, anisole, peroxyacids, as well as a host of more specialised chemicals. Occurrence Small amounts of methanol are present in normal, healthy hu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Borohydrides
Borohydride refers to the anion , which is also called tetrahydroborate, and its salts. Borohydride or hydroborate is also the term used for compounds containing , where ''n'' is an integer from 0 to 3, for example cyanoborohydride or cyanotrihydroborate and triethylborohydride or triethylhydroborate . Borohydrides find wide use as reducing agents in organic synthesis. The most important borohydrides are lithium borohydride and sodium borohydride, but other salts are well known (see Table). Tetrahydroborates are also of academic and industrial interest in inorganic chemistry. History Alkali metal borohydrides were first described in 1940 by Hermann Irving Schlesinger and Herbert C. Brown. They synthesized lithium borohydride from diborane : :, where M = Li, Na, K, Rb, Cs, etc. Current methods involve reduction of trimethyl borate with sodium hydride. Structure In the borohydride anion and most of its modifications, boron has a tetrahedral structure. The reactivity of the B−H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Compounds
Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. As a result, sodium usually forms ionic compounds involving the Na+ cation. Sodium is a reactive alkali metal and is much more stable in ionic compounds. It can also form intermetallic compounds and organosodium compounds. Sodium compounds are often soluble in water. Metallic sodium Metallic sodium is generally less reactive than potassium and more reactive than lithium. Sodium metal is highly reducing, with the standard reduction potential for the Na+/Na couple being −2.71 volts, though potassium and lithium have even more negative potentials. The thermal, fluidic, chemical, and nuclear properties of molten sodium metal have caused it to be one of the main coolants of choice for the fast breeder reactor. Such nuclear reactors are seen as a crucial step for the production of clean energy. Salts and oxides Sodium compounds are of immense commercial importance, being particularly centra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Borohydride
Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, is an inorganic compound with the formula Na BH4. This white solid, usually encountered as an aqueous basic solution, is a reducing agent that finds application in papermaking and dye industries. It is also used as a reagent in organic synthesis. The compound was discovered in the 1940s by H. I. Schlesinger, who led a team seeking volatile uranium compounds.Hermann I Schlesinger and Herbert C Brown (1945)Preparation of alkali metal compounds. US Patent 2461661. Granted on 1949-02-15; expired on 1966-02-15. Results of this wartime research were declassified and published in 1953. Properties The compound is soluble in alcohols, certain ethers, and water, although it slowly hydrolyzes. Sodium borohydride is an odorless white to gray-white microcrystalline powder that often forms lumps. It can be purified by recrystallization from warm (50 °C) diglyme. Sodium borohydride is soluble ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboxylic Acid
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion. Examples and nomenclature Carboxylic acids are commonly identified by their trivial names. They at oftentimes have the suffix ''-ic acid''. IUPAC-recommended names also exist; in this system, carboxylic acids have an ''-oic acid'' suffix. For example, butyric acid (C3H7CO2H) is butanoic acid by IUPAC guidelines. For nomenclature of complex molecules containing a carboxylic acid, the carboxyl can be considered position one of the parent chain even if there are other substituents, such as 3-chloropropanoic acid. Alternately, it can be named as a "carboxy" or "carboxylic acid" substituent on another ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synthesis (journal)
''Synthesis'' is a scientific journal published from 1969 to the present day by Thieme Medical Publishers, Thieme. Its stated purpose is the "advancement of the science of synthetic chemistry". From August 2006, selected articles are offered free of charge. The impact factor of this journal is 2.867 (2018).Journal Citation Reports, 2018 References [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reductive Amination Of A Ketone With An Amine Using STAB
Reduction, reduced, or reduce may refer to: Science and technology Chemistry * Reduction (chemistry), part of a reduction-oxidation (redox) reaction in which atoms have their oxidation state changed. ** Organic redox reaction, a redox reaction that takes place with organic compounds ** Ore reduction: see smelting Computing and algorithms * Reduction (complexity), a transformation of one problem into another problem * Reduction (recursion theory), given sets A and B of natural numbers, is it possible to effectively convert a method for deciding membership in B into a method for deciding membership in A? * Bit Rate Reduction, an audio compression method * Data reduction, simplifying data in order to facilitate analysis * Graph reduction, an efficient version of non-strict evaluation * L-reduction, a transformation of optimization problems which keeps the approximability features * Partial order reduction, a technique for reducing the size of the state-space to be searched by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reductive Amination
Reductive amination (also known as reductive alkylation) is a form of amination that involves the conversion of a carbonyl group to an amine via an intermediate imine. The carbonyl group is most commonly a ketone or an aldehyde. It is considered the most important way to make amines, and a majority of amines made in the pharmaceutical industry are made this way. Reaction process In this organic reaction, the amine first reacts with the carbonyl group to form a hemiaminal species, which subsequently loses one molecule of water in a reversible manner by alkylimino-de-oxo-bisubstitution, to form the imine. The equilibrium between aldehyde/ketone and imine can be shifted toward imine formation by removal of the formed water through physical or chemical means. This intermediate imine can then be isolated and reduced with a suitable reducing agent (e.g., sodium borohydride). This method is sometimes called indirect reductive amination. In a separate approach, imine formation and redu ... [...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, using the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Cyanoborohydride
Sodium cyanoborohydride is the chemical compound with the formula Sodium, NaBoron, BHydrogen, H3cyanide, CN. It is a colourless salt, but commercial samples can appear tan. It is widely used in organic synthesis for the reduction of imines. The salt tolerates aqueous conditions. Use Owing to the presence of the electron-withdrawing cyanide substituent, [B(CN)H3]− is less reducing than is sodium borohydride, [BH4]−. As a mild reducing agent, it is used to convert imines to amines. It is especially favored for reductive aminations, wherein aldehydes or ketones are treated with an amine in the presence of this reagent: : R2CO + R'NH2 + NaBH3CN + CH3OH → R2CH-NHR' + "NaCH3OBH2CN" The reagent is typically used in excess. Selectivity is achieved at mildly basic solutions (pH 7–10). The reagent is ideal for reductive aminations ("Borch Reaction"). In conjunction with tosylhydrazine, sodium cyanoborohydride is used in the reductive deoxygenation of ketones. Structure and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
