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Doyle–Kirmse Reaction
The Doyle–Kirmse reaction is an organic reaction in which a metal carbene reacts with an allyl compound with transposition of the alkene and transfer of the electronegative group from the allyl onto the carbene carbon. As originally developed, an allyl sulfide reacts with trimethylsilyldiazomethane to form the homoallyl sulfide compound. The reaction was first reported by in 1968 and modified by Michael P. Doyle in 1981. The Kirmse protocol required a copper salt. The reaction mechanism involves nucleophilic addition of the sulfur to the metal carbene formed from the diazoalkane followed by a Stevens-like rearrangement. Doyle expanded the scope of the reaction to include other diazo compounds, such as ethyl diazoacetate, other allyl compounds, such as allyl amines and allyl halides, and use of with rhodium catalysts, such as hexadecacarbonylhexarhodium. An example is the reaction of ethyl diazoacetate with allyl iodide: The reaction can also be catalyzed by iron, pall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Reaction
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, mechanistic organic photochemistry, photochemical reactions and organic redox reaction, redox reactions. In organic synthesis, organic reactions are used in the construction of new organic molecules. The production of many man-made chemicals such as drugs, plastics, food additives, fabrics depend on organic reactions. The oldest organic reactions are combustion of organic fuels and saponification of fats to make soap. Modern organic chemistry starts with the Wöhler synthesis in 1828. In the history of the Nobel Prize in Chemistry awards have been given for the invention of specific organic reactions such as the Grignard reaction in 1912, the Diels–Alder reaction in 1950, the Wittig reaction in 1979 and olefin metathesis in 2005. Classifications Organ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexadecacarbonylhexarhodium
Hexadecacarbonylhexarhodium is a metal carbonyl cluster with the formula Rh6(CO)16. It exists as purple-brown crystals that are slightly soluble in dichloromethane and chloroform. It is the principal binary carbonyl of rhodium. Discovery and synthesis Rh6(CO)16 was first prepared by Walter Hieber in 1943 by carbonylation of RhCl3·3H2O at 80–230 °C and 200 atm carbon monoxide with silver or copper as a halide acceptor. Hieber correctly formulated the compound as a binary carbonyl, but suggested the formula Rh4(CO)11, i.e., CO/Rh ratio of 2.75. The correct formula and structure was subsequently established by Dahl et al. using X-ray crystallography. The correct CO/Rh ratio is 2.66. Relative to the original preparation, the carbonylation of a mixture of anhydrous rhodium trichloride and iron pentacarbonyl was shown to give good yields of Rh6(CO)16. Other compounds of rhodium are also effective precursors such as 2">CO)2Rh(μ-Cl)sub>2 and rhodium(II) acetat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Name Reactions
A name reaction (or named reaction) is a chemical reaction named after its discoverer(s) or developer(s). Among the tens of thousands of organic reactions that are known, hundreds of such reactions are typically identified by the eponym. Well-known examples include the Grignard reaction, the Sabatier reaction, the Wittig reaction, the Claisen condensation, the Friedel–Crafts acylation, and the Diels–Alder reaction. Books have been published devoted exclusively to name reactions;Alfred Hassner, C. Stumer. ''Organic syntheses based on name reactions''. Elsevier, 2002. Li, Jie Jack. ''Name Reactions: A Collection of Detailed Reaction Mechanisms''. Springer, 2003. the ''Merck Index ''The Merck Index'' is an encyclopedia of chemical substance, chemicals, pharmaceutical drug, drugs and biomolecule, biologicals with over 10,000 monographs on single substances or groups of related chemical compound, compounds published online ...'', a chemical encyclopedia, also includes an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stereoselectivity
In chemistry, stereoselectivity is the property of a chemical reaction in which a single reactant forms an unequal mixture of stereoisomers during a non- stereospecific creation of a new stereocenter or during a non-stereospecific transformation of a pre-existing one. The selectivity arises from differences in steric and electronic effects in the mechanistic pathways leading to the different products. Stereoselectivity can vary in degree but it can never be total since the activation energy difference between the two pathways is finite: both products are at least possible and merely differ in amount. However, in favorable cases, the minor stereoisomer may not be detectable by the analytic methods used. An enantioselective reaction is one in which one enantiomer is formed in preference to the other, in a reaction that creates an optically active product from an achiral starting material, using either a chiral catalyst, an enzyme or a chiral reagent. The degree of selectivity is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chiral
Chirality () is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek language, Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from its mirror image; that is, it cannot be wikt:superpose, superposed (not to be confused with wikt:superimpose, superimposed) onto it. Conversely, a mirror image of an ''achiral'' object, such as a sphere, cannot be distinguished from the object. A chiral object and its mirror image are called ''enantiomorphs'' (Greek, "opposite forms") or, when referring to molecules, ''enantiomers''. A non-chiral object is called ''achiral'' (sometimes also ''amphichiral'') and can be superposed on its mirror image. The term was first used by Lord Kelvin in 1893 in the second Robert Boyle Lecture at the Oxford University Junior Scientific Club which was published in 1894: Human hands are perhaps the most recognized example of chirality ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allene
In organic chemistry, allenes are organic compounds in which one carbon atom has double bonds with each of its two adjacent carbon atoms (, where R is hydrogen, H or some organyl group). Allenes are classified as diene#Classes, cumulated dienes. The parent compound of this class is propadiene (), which is itself also called ''allene''. A group of the structure is called allenyl, while a substituent attached to an allene is referred to as an allenic substituent (R is H or some alkyl group). In analogy to Allyl group, allylic and Propargyl group, propargylic, a substituent attached to a saturated carbon α (i.e., directly adjacent) to an allene is referred to as an allenylic substituent. While allenes have two consecutive ('cumulated') double bonds, compounds with three or more cumulated double bonds are called cumulenes. History For many years, allenes were viewed as curiosities but thought to be synthetically useless and difficult to prepare and to work with.The Chemistry of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propargyl
In organic chemistry, the propargyl group is a functional group of 2- propynyl with the structure . It is an alkyl group derived from propyne (). The term propargylic refers to a saturated position ( ''sp''3-hybridized) on a molecular framework next to an alkynyl group. The name comes from mix of ''propene'' and ''argentum'', which refers to the typical reaction of the terminal alkynes with silver salts. The term homopropargylic designates in the same manner * a saturated position on a molecular framework next to a propargylic group and thus two bonds from an alkyne moiety. * a 3-butynyl fragment, , or substituted homologue. See also * Alkenyl groups ** Allyl ** Vinyl group * Ethynyl In organic chemistry, an ethynyl group is a functional group with the formula −C≡CH, representing an acetylene molecule with one fewer hydrogen atom. * Ethynyl group (HC≡C–), also designated as an acetylenic group (from acetylene), is refer ... * Propargyl chloride * Propargyl alcoh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nickel
Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slow to react with air under standard conditions because a passivation layer of nickel oxide forms on the surface that prevents further corrosion. Even so, pure native nickel is found in Earth's crust only in tiny amounts, usually in ultramafic rocks, and in the interiors of larger nickel–iron meteorites that were not exposed to oxygen when outside Earth's atmosphere. Meteoric nickel is found in combination with iron, a reflection of the origin of those elements as major end products of supernova nucleosynthesis. An iron–nickel mixture is thought to compose Earth's outer and inner cores. Use of nickel (as natural meteoric nickel–iron alloy) has been traced as far back as 3500 BCE. Nickel was first isolated and classifie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver
Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. Silver is found in the Earth's crust in the pure, free elemental form ("native metal, native silver"), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc Refining (metallurgy), refining. Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes bimetallism, alongside gold: while it is more abundant than gold, it is much less abundant as a native metal. Its purity is typically measured on a per-mille basis; a 94%-pure alloy is described as "0.940 fine". As one of the seven metals of antiquity, silver has had an enduring role in most human cultures. Other than in currency and as an in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palladium
Palladium is a chemical element; it has symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1802 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas (formally 2 Pallas), which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form together a group of elements referred to as the platinum group metals (PGMs). They have similar chemical properties, but palladium has the lowest melting point and is the least dense of them. More than half the supply of palladium and its congener platinum is used in catalytic converters, which convert as much as 90% of the harmful gases in automobile exhaust (hydrocarbons, carbon monoxide, and nitrogen dioxide) into nontoxic substances (nitrogen, carbon dioxide and water vapor). Palladium is also used in electronics, dentistry, medicine, hydrogen purification ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron
Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most abundant element in the Earth's crust, being mainly deposited by meteorites in its metallic state. Extracting usable metal from iron ores requires kilns or furnaces capable of reaching , about 500 °C (900 °F) higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BC and the use of iron tools and weapons began to displace copper alloys – in some regions, only around 1200 BC. That event is considered the transition from the Bronze Age to the Iron Age. In the modern world, iron alloys, such as steel, stainless steel, cast iron and special steels, are by far the most common industrial metals, due to their mechan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Doyle Diazo Compound Reaction
Doyle is a surname of Irish origin. The name is a back-formation from O'Doyle, which is an Anglicisation of the Irish (), meaning "descendant of ''Dubhghall''". There is another possible etymology: the Anglo-Norman surname ''D'Oyley'' with agglutination of the French article ''de'' (cf. Disney). It means 'from Ouilly', the name of a knight who originated from one of the places named Ouilly in Normandy, such as Ouilly-le-Tesson (Calvados, ''Oylley'' 1050), Ouilly-le-Vicomte (Calvados, ''de Oilleio'' 1279), etc. The relationship with the family D'Oyly is unknown. The personal name ''Dubhghall'' contains the elements ''dubh'' "black" + ''gall'' "stranger". Similar Scottish and Irish surnames, derived from the same personal name are: ''MacDougall'' / ''McDougall'' and '' MacDowell'' / '' McDowell''. During the Viking Age the term '' Dubhghoill'' was used to describe the Vikings—usually Danes—and the term ''Fionnghoill'' ("fair foreigners") was used to describe Norwegians. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
