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Ketone Reduction
In organic chemistry, carbonyl reduction is the conversion of any carbonyl group, usually to an alcohol. It is a common transformation that is practiced in many ways. Ketones, aldehydes, carboxylic acids, esters, amides, and acid halides - some of the most pervasive functional groups, -comprise carbonyl compounds. Carboxylic acids, esters, and acid halides can be reduced to either aldehydes or a step further to primary alcohols, depending on the strength of the reducing agent. Aldehydes and ketones can be reduced respectively to primary and secondary alcohols. In deoxygenation, the alcohol group can be further reduced and removed altogether by replacement with H. Two broad strategies exist for carbonyl reduction. One method, which is favored in industry, uses hydrogen as the reductant. This approach is called hydrogenation and requires metal catalysts. The other broad approach employs stoichiometric reagents that deliver H− and H+ separately. This article focuses on the use o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redox Ladder
A redox gradient is a series of reduction-oxidation (redox) reactions sorted according to Reduction potential, redox potential. The redox ladder displays the order in which redox reactions occur based on the free energy gained from redox pairs. These redox gradients form both spatially and temporally as a result of differences in microbial processes, chemical composition of the environment, and oxidative potential. Common environments where redox gradients exist are Marsh, coastal marshes, lakes, contaminant plumes, and soils. The Earth has a global redox gradient with an oxidizing environment at the surface and increasingly reducing conditions below the surface. Redox gradients are generally understood at the macro level, but characterization of redox reactions in heterogeneous environments at the micro-scale require further research and more sophisticated measurement techniques. Measuring redox conditions Redox conditions are measured according to the redox potential (Eh) i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Hydride
A metal () is a material that, when polished or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. These properties are all associated with having electrons available at the Fermi level, as against nonmetallic materials which do not. Metals are typically ductile (can be drawn into a wire) and malleable (can be shaped via hammering or pressing). A metal may be a chemical element such as iron; an alloy such as stainless steel; or a molecular compound such as polymeric sulfur nitride. The general science of metals is called metallurgy, a subtopic of materials science; aspects of the electronic and thermal properties are also within the scope of condensed matter physics and solid-state chemistry, it is a multidisciplinary topic. In colloquial use materials such as steel alloys are referred to as metals, while others such as polymers, wood or ceramics are nonmetallic materials. A metal conducts electricity at a temperature of absolute zero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Esterification
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods. Esters can be formed from oxoacids (e.g. esters of acetic acid, carbonic acid, sulfu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fukuyama Reduction
The Fukuyama reduction is an organic reaction and an organic reduction in which a thioester is reduced to an aldehyde by a silyl hydride in presence of a catalytic amount of palladium. This reaction was invented in 1990 by Tohru Fukuyama. In the original scope of the reaction the silyl hydride was triethylsilane and the catalyst palladium on carbon: : Fukuyama reductions are used for the conversion of carboxylic acids (as thioester precursor) to aldehydes which is considered a difficult procedure because of the ease of secondary reduction to an Alcohol (chemistry), alcohol. Reaction mechanism The basic reaction mechanism for this reaction takes place as a catalytic cycle: * Oxidative addition: *: + Pd^0 -> RC(O)-Pd^-SR * Transmetallation: *: + R3SiH -> + R3Si-SR * Reductive elimination: *: RC(O)-Pd^-H -> + Pd^0 Scope In a variation of the Fukuyama reduction the core BODIPY molecule has been synthesized from the SMe-substituted derivative:''The Smallest and One of the Brighte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fukuyama Scheme
Fukuyama may refer to: People * Francis Fukuyama, Japanese-American philosopher and political economist * Fukuyama (surname), other people with the name Places *Fukuyama, Hiroshima, city in Japan *Fukuyama, Kagoshima was a town located in Aira District, Kagoshima Prefecture, Japan. As of 2003, the town had an estimated population of 7,209 and the density of 105.21 persons per km2. The total area was 68.52 km2. On November 7, 2005, Fukuyama, along with the ci ..., former town in Japan, now part of Kirishima city Other uses *Fukuyama congenital muscular dystrophy ( FCMD) {{disambiguation, geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydride Reduction Table
In chemistry, a hydride is formally the anion of hydrogen (H−), a hydrogen ion with two electrons. In modern usage, this is typically only used for ionic bonds, but it is sometimes (and has been more frequently in the past) applied to all compounds containing covalently bound H atoms. In this broad and potentially archaic sense, water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. In covalent compounds, it implies hydrogen is attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed. Almost all of the elements form binary compounds with hydrogen, the exceptions being He, Ne, Ar, Kr, Pm, Os, Ir, Rn, Fr, and Ra. Exotic molecules such as positronium hydride have also been made. Bonds Bonds between hydrogen and the other elements range from being highly ionic to somewhat covalent. Some hydrides, e.g. boron hy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
L-selectride
L-selectride is a organoboron compound with the chemical formula . A colorless salt, it is usually dispensed as a solution in THF. As a particularly basic and bulky borohydride, it is used for stereoselective reduction of ketones. Use in synthesis Like other borohydrides, reductions are effected in two steps: delivery of the hydride equivalent to give the lithium alkoxide followed by hydrolytic workup: : : The selectivity of this reagent is illustrated by its reduction of all three methylcyclohexanones to the less stable methylcyclohexanols in >98% yield. Under certain conditions, L-selectride can selectively reduce enones by conjugate addition of hydride, owing to the greater steric hindrance the bulky hydride reagent experiences at the carbonyl carbon relative to the (also-electrophilic) β-position. L-Selectride can also stereoselectively reduce carbonyl groups in a 1,2-fashion, again due to the steric nature of the hydride reagent. It reduces ketones to alcohols. Related ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithium Triethylborohydride
Lithium triethylborohydride is the organoboron compound with the formula Li Et3 BH. Commonly referred to as LiTEBH or Superhydride, it is a powerful reducing agent used in organometallic and organic chemistry. It is a colorless or white liquid but is typically marketed and used as a THF solution. The related reducing agent sodium triethylborohydride is commercially available as toluene solutions. LiBHEt3 is a stronger reducing agent than lithium borohydride and lithium aluminium hydride. Preparation LiBHEt3 is prepared by the reaction of lithium hydride (LiH) and triethylborane (Et3B) in tetrahydrofuran (THF): :LiH + Et3B → LiEt3BH The resulting THF complex is stable indefinitely in the absence of moisture and air. Reactions Alkyl halides are reduced to the alkanes by LiBHEt3. LiBHEt3 reduces a wide range of functional groups, but so do many other hydride reagents. Instead, LiBHEt3 is reserved for difficult substrates, such as sterically hindered carbonyls, as illustrated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyano
In chemistry, cyanide () is an inorganic chemical compound that contains a functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom. Ionic cyanides contain the cyanide anion . This anion is extremely poisonous. Soluble cyanide salts such as sodium cyanide (NaCN), potassium cyanide (KCN) and tetraethylammonium cyanide () are highly toxic. Covalent cyanides contain the group, and are usually called nitriles if the group is linked by a single covalent bond to carbon atom. For example, in acetonitrile , the cyanide group is bonded to methyl . In tetracyanomethane , four cyano groups are bonded to carbon. Although nitriles generally do not release cyanide ions, the cyanohydrins do and are thus toxic. The cyano group may be covalently bonded to atoms different than carbon, e.g., in cyanogen azide , phosphorus tricyanide and trimethylsilyl cyanide . Hydrogen cyanide, or , is a highly volatile toxic liquid that is produ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetoxy Group
In organic chemistry, the acetoxy group (abbr. AcO– or –OAc; IUPAC name: acetyloxy), is a functional group with the formula and the structure . As the ''-oxy'' suffix implies, it differs from the acetyl group () by the presence of an additional oxygen atom. The name acetoxy is the short form of ''acetyl-oxy''. Functionality An acetoxy group may be used as a protection for an alcohol functionality in a synthetic route although the protecting group itself is called an acetyl group. Alcohol protection There are several options of introducing an acetoxy functionality in a molecule from an alcohol (in effect protecting the alcohol by acetylation): * Acetyl halide, such as acetyl chloride in the presence of a base like triethylamine * Activated ester form of acetic acid, such as a N-hydroxysuccinimide ester, although this is not advisable due to higher costs and difficulties. * Acetic anhydride in the presence of base with a catalyst such as pyridine with a bit of DMAP added. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron-withdrawing Group
An electron-withdrawing group (EWG) is a Functional group, group or atom that has the ability to draw electron density toward itself and away from other adjacent atoms. This electron density transfer is often achieved by resonance or inductive effects. Electron-withdrawing groups have significant impacts on fundamental chemical processes such as acid-base reactions, redox potentials, and substitution reactions. Consequences of EWGs Effects on Brønsted–Lowry acidity Electron-withdrawing groups exert an "Inductive effect, inductive" or "electron-pulling" effect on covalent bonds. The strength of the electron-withdrawing group is inversely proportional to the Acid dissociation constant, pKa of the carboxylic acid. : The inductive effect is cumulative: trichloroacetic acid is 1000× stronger than chloroacetic acid. : :The impact of the EWG on pKa decreases with distances from the carboxylic group. For benzoic acids, the effect is quantified by the Hammett equation: :\log ... [...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 (sometimes written as ). It is a white crystalline solid, usually encountered as an aqueous basic solution. Sodium borohydride 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
