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Metal-catalysed Hydroboration
In chemistry, metal-catalysed hydroboration is a reaction used in organic synthesis. It is one of several examples of homogeneous catalysis. History In 1975, Kono and Ito reported that Wilkinson's catalyst (Rh(PPh3)3Cl) can undergo oxidative addition with catecholborane (HBcat) or 4,4,6-trimethyl-1,3,2-dioxaborinane. These two borane compounds are otherwise slow to participate in hydroboration. In 1985, Männig and Nöth demonstrated for the first time that Wilkinson’s catalyst indeed catalyzes hydroboration of alkenes with HBcat. : Whereas uncatalyzed hydroboration using HBcat leads to reduction of the carbonyl group, the catalyzed version is selective for the alkene. : As indicated by subsequent research, transition metal-catalyzed hydroboration proceeds with attractive functional group-, regio-, stereo-, and chemo- selectivity. Mechanism The rhodium-catalyzed hydroboration reaction is thought to be initiated with the dissociation of a triphenylphosphine from the Rh(I) ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one of the most important branches of organic chemistry. There are several main areas of research within the general area of organic synthesis: ''total synthesis'', ''semisynthesis'', and ''methodology''. Total synthesis A total synthesis is the complete chemical synthesis of complex organic molecules from simple, commercially available petrochemical or natural precursors. Total synthesis may be accomplished either via a linear or convergent approach. In a ''linear'' synthesis—often adequate for simple structures—several steps are performed one after another until the molecule is complete; the chemical compounds made in each step are called synthetic intermediates. Most often, each step in a synthesis refers to a separate rea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalytic Hydroboration Regioselectivity
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usually gaseous or liquid) as the reactant, or heterogeneous, whose components are not in the same phase. Enzymes and other biocatalysts are often considered as a third category. Catalysis is ubiquitous in chemical industry of all kinds. Estimates are that 90% of all commercially produced chemical products involve catalysts at some stage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzylamine Synthesis
Benzylamine is an organic chemical compound with the condensed structural formula C6H5CH2NH2 (sometimes abbreviated as PhCH2NH2 or BnNH2). It consists of a benzyl group, C6H5CH2, attached to an amine functional group, NH2. This colorless water-soluble liquid is a common precursor in organic chemistry and used in the industrial production of many pharmaceuticals. The hydrochloride salt was used to treat motion sickness on the Mercury-Atlas 6 mission in which NASA astronaut John Glenn became the first American to orbit the Earth. Manufacturing Benzylamine can be produced by several methods, the main industrial route being the reaction of benzyl chloride and ammonia. It is also produced by the reduction of benzonitrile and reductive amination of benzaldehyde, both done over Raney nickel. : It was first produced accidentally by Rudolf Leuckart in the reaction of benzaldehyde with formamide in a process now known as the Leuckart reaction, a general process in which reduct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloramine
Chloramines refer to derivatives of ammonia and organic amines wherein one or more N-H bonds have been replaced by N-Cl bonds. Two classes of compounds are considered: inorganic chloramines and organic chloramines. Inorganic chloramines Inorganic chloramines comprise three compounds: monochloramine (NH2Cl), dichloramine (NHCl2), and nitrogen trichloride (NCl3). Monochloramine is of broad significance as a disinfectant for water. Organic chloramines 144px, ''N''-Chloropiperidine is a rare example of an organic chloramine. 144px, Chloramine-T is often referred to as a chloramine, but it is really a salt (CH3C6H4SO2NClNa) derived from a chloramine. Organic chloramines feature the NCl functional group attached to an organic substituent. Examples include ''N''-chloromorpholine (ClN(CH2CH2)2O), ''N''-chloropiperidine, and ''N''-chloroquinuclidinium chloride. Chloramines are commonly produced by the action of bleach on secondary amines: :R2NH + NaOCl → R2NCl + NaOH ''Te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzylamine
Benzylamine is an organic chemical compound with the condensed structural formula C6H5CH2NH2 (sometimes abbreviated as PhCH2NH2 or BnNH2). It consists of a benzyl group, C6H5CH2, attached to an amine functional group, NH2. This colorless water-soluble liquid is a common precursor in organic chemistry and used in the industrial production of many pharmaceuticals. The hydrochloride salt was used to treat motion sickness on the Mercury-Atlas 6 mission in which NASA astronaut John Glenn became the first American to orbit the Earth. Manufacturing Benzylamine can be produced by several methods, the main industrial route being the reaction of benzyl chloride and ammonia. It is also produced by the reduction of benzonitrile and reductive amination of benzaldehyde, both done over Raney nickel. : It was first produced accidentally by Rudolf Leuckart in the reaction of benzaldehyde with formamide in a process now known as the Leuckart reaction, a general process in which reductive am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PN Ligand For Catalytic Asymmetric Hydroboration Chart
PN may refer to: Arts and entertainment * ''Purple Noon'', a 1960 film * Patriotic Nigras, a griefing group in the game ''Second Life'' Business and economics * Pacific National, a rail freight company in Australia * Participatory notes, issued to unregistered overseas investors in Indian stock markets * Pennsylvania Northeastern Railroad (reporting mark PN) * Promissory note, a contract where one party makes an unconditional promise in writing to pay a sum of money to another * West Air (China) (IATA airline code PN) Organizations Navies * Pakistan Navy * Peruvian Navy * Philippine Navy * Portuguese Navy Political parties * National Renaissance Front, Partidul Naţiunii, a political party in Romania * Partit Nazzjonalista, a political party in Malta * Perikatan Nasional, a political coalition in Malaysia * Partido Nacional (Uruguay), a political party in Uruguay Places * Penang * Pitcairn Islands (ISO 3166-1 country code) * Palmerston North, a city in New Zealand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PP Ligands For Asymmetric Hydroboration
PP, pp or Pp may refer to: Arts and entertainment * ''Pianissimo'', a music term meaning ''very quiet'', from musical dynamics * Production code for the 1967–1968 ''Doctor Who'' serial '' The Enemy of the World'' *Police Procedural - a subgenre of procedural drama and detective fiction Businesses and organisations Political parties * Patriotic Party (Guatemala) * People's Party (Spain) (''Partido Popular'') * Pirate Party (Global) * Progressistas (Brazil) (''Progressistas'') * Progressive Party (Iceland) * People's Partnership (Trinidad and Tobago) * We Continue the Change (Bulgaria) ("Prodalzhavame promyanata") Other businesses and organizations * Pancasila Youth (''Pemuda Pancasila''), an Indonesian paramilitary organization * PediaPress, a German software company * Planned Parenthood, a reproductive health organization * Philipp Plein, logo * PayPal, an online payments company Religion * pp, ''Papa Pontifex'', post-nominal used by popes Science, technology, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Styrene
Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concentrations have a less pleasant odor. Styrene is the precursor to polystyrene and several copolymers. Approximately 25 million tonnes of styrene were produced in 2010, increasing to around 35 million tonnes by 2018. Natural occurrence Styrene is named after storax balsam (often commercially sold as ''styrax''), the resin of Liquidambar trees of the Altingiaceae plant family. Styrene occurs naturally in small quantities in some plants and foods (cinnamon, coffee beans, balsam tree (other), balsam trees and peanuts) and is also found in coal tar. History In 1839, the German apothecary Eduard Simon isolated a volatile liquid from the resin (called ''storax'' or ''styrax'' (Latin)) of the Liquidambar styraciflua, American sweetgu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BINAP
BINAP (2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) is an organophosphorus compound. This chiral diphosphine ligand is widely used in asymmetric synthesis. It consists of a pair of 2-diphenylphosphinonaphthyl groups linked at the 1 and 1′ positions. This C2-symmetric framework lacks a stereogenic atom, but has axial chirality due to restricted rotation ( atropisomerism). The barrier to racemization is high due to steric hindrance, which limits rotation about the bond linking the naphthyl rings. The dihedral angle between the naphthyl groups is approximately 90°. The natural bite angle is 93°. Use as ligand in asymmetric catalysis BINAP is used in organic synthesis for enantioselective transformations catalyzed by its complexes of ruthenium, rhodium, and palladium. As pioneered by Ryōji Noyori and his co-workers, rhodium complexes of BINAP are useful for the synthesis of (–)-menthol. Silver complexes are also important; BINAP- AgF can be used to enantioselect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown Asymmetric Hydroboration
Brown is a color. It can be considered a composite color, but it is mainly a darker shade of orange. In the CMYK color model used in printing or painting, brown is usually made by combining the colors orange and black. In the RGB color model used to project colors onto television screens and computer monitors, brown combines red and green. The color brown is seen widely in nature, wood, soil, human hair color, eye color and skin pigmentation. Brown is the color of dark wood or rich soil. According to public opinion surveys in Europe and the United States, brown is the least favorite color of the public; it is often associated with plainness, the rustic, feces, and poverty. More positive associations include baking, warmth, wildlife, and the autumn. Etymology The term is from Old English , in origin for any dusky or dark shade of color. The first recorded use of ''brown'' as a color name in English was in 1000. The Common Germanic adjectives ''*brûnoz and *brûnâ'' meant b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Markovnikov's Rule
In organic chemistry, Markovnikov's rule or Markownikoff's rule describes the outcome of some addition reactions. The rule was formulated by Russian chemist Vladimir Markovnikov in 1870. Explanation The rule states that with the addition of a protic acid HX or other polar reagent to an asymmetric alkene, the acid hydrogen (H) or electropositive part gets attached to the carbon with more hydrogen substituents, and the halide (X) group or electronegative part gets attached to the carbon with more alkyl substituents. This is in contrast to Markovnikov's original definition, in which the rule is stated that the X component is added to the carbon with the fewest hydrogen atoms while the hydrogen atom is added to the carbon with the greatest number of hydrogen atoms. The same is true when an alkene reacts with water in an addition reaction to form an alcohol which involve formation of carbocations. The hydroxyl group (OH) bonds to the carbon that has the greater number of carbon– ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homogeneous Catalysis
In chemistry, homogeneous catalysis is catalysis by a soluble catalyst in a solution. Homogeneous catalysis refers to reactions where the catalyst is in the same phase as the reactants, principally in solution. In contrast, heterogeneous catalysis describes processes where the catalysts and substrate are in distinct phases, typically solid-gas, respectively. The term is used almost exclusively to describe solutions and implies catalysis by organometallic compounds. Homogeneous catalysis is an established technology that continues to evolve. An illustrative major application is the production of acetic acid. Enzymes are examples of homogeneous catalysts. Examples Acid catalysis The proton is a pervasive homogeneous catalyst because water is the most common solvent. Water forms protons by the process of self-ionization of water. In an illustrative case, acids accelerate (catalyze) the hydrolysis of esters: :CH3CO2CH3 + H2O CH3CO2H + CH3OH At neutral pH, aqueous solutions of most e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
