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Wagner–Meerwein Rearrangement
A Wagner–Meerwein rearrangement is a class of carbocation 1,2-rearrangement rearrangement reaction, reactions in which a hydrogen, alkyl or aryl group migrates from one carbon to a neighboring carbon. They can be described as cationic [1,2]-sigmatropic rearrangements, proceeding suprafacially and with stereochemical retention. As such, a Wagner–Meerwein shift is a thermally allowed pericyclic process with the Woodward-Hoffmann symbol [ω0s + σ2s]. They are usually facile, and in many cases, they can take place at temperatures as low as –120 °C. The reaction is named after the Russian chemist Yegor Yegorovich Vagner; he had German origin and published in German journals as Georg Wagner; and Hans Meerwein. Several reviews have been published. The rearrangement was first discovered in bicyclic terpenes for example the conversion of isoborneol to camphene: The story of the rearrangement reveals that many scientists were puzzled with this and related reactions and it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbocation
Carbocation is a general term for ions with a positively charged carbon atom. In the present-day definition given by the IUPAC, a carbocation is any even-electron cation with significant partial positive charge on a carbon atom. They are further classified in two main categories according to the coordination number of the charged carbon: three in the carbenium ions and five in the carbonium ions. Among the simplest carbocations are the methenium (a carbenium ion), methanium (a carbonium ion), acylium ions , and Vinyl cation, vinyl cations. Until the early 1970s, carbocations were called ''carbonium ions''. This nomenclature was proposed by George Andrew Olah, G. A. Olah. Carbonium ions, as originally defined by Olah, are characterized by a Three-center two-electron bond, three-center two-electron delocalized bonding scheme and are essentially synonymous with so-called 'non-classical carbocations', which are carbocations that contain bridging C–C or C–H σ-bonds. However ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camphene
Camphene is a bicyclic organic compound. It is one of the most pervasive monoterpenes. As with other terpenes, it is insoluble in water, flammable, colorless, and has a pungent smell. It is a minor constituent of many essential oils such as turpentine, cypress oil, camphor oil, citronella oil, neroli, ginger oil, valerian, and mango. It is produced industrially by isomerization of the more common alpha-pinene using a solid acid catalyst such as titanium dioxide. Camphene is used in the preparation of fragrances and as a food additive for flavoring. These include isobornyl acetate. Biosynthesis Camphene is biosynthesized from linalyl pyrophosphate via a sequence of carbocation Carbocation is a general term for ions with a positively charged carbon atom. In the present-day definition given by the IUPAC, a carbocation is any even-electron cation with significant partial positive charge on a carbon atom. They are further ...ic intermediates. : References {{Authority ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sergey Namyotkin
Sergey Semyonovich Nametkin (; – 5 August 1950) was a Soviet and Russian organic chemist, a prominent researcher in terpene chemistry, the cracking of petrochemicals, and rearrangement of camphenes. Academician of the USSR Academy of Sciences. Winner of two Stalin Prizes. Biography Nametkin was born into a merchant family in the village of Kaymary, Kazan Uyezd, Kazan Governorate. He received his primary education at the first Progymnasium in Kazan. In 1886, the family moved to Moscow, and soon, at the age of 12, Sergei Nametkin was left an orphan. In 1892 he graduated from the second Moscow Progymnasium, and in 1896 – from the first Moscow Men's Gymnasium. During his high school years, he earned his living by giving private lessons. In 1896-1902 he studied at the Faculty of Physics and Mathematics of the Imperial Moscow University (soon after entering the mathematics department, in 1897 he changed it to the department of natural sciences), from which he graduated with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbocation Rearrangement Polito 2010
Carbocation is a general term for ions with a positively charged carbon atom. In the present-day definition given by the IUPAC, a carbocation is any even-electron cation with significant partial positive charge on a carbon atom. They are further classified in two main categories according to the coordination number of the charged carbon: three in the carbenium ions and five in the carbonium ions. Among the simplest carbocations are the methenium (a carbenium ion), methanium (a carbonium ion), acylium ions , and vinyl cations. Until the early 1970s, carbocations were called ''carbonium ions''. This nomenclature was proposed by G. A. Olah. Carbonium ions, as originally defined by Olah, are characterized by a three-center two-electron delocalized bonding scheme and are essentially synonymous with so-called ' non-classical carbocations', which are carbocations that contain bridging C–C or C–H σ-bonds. However, others have more narrowly defined the term 'carbonium ion' as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetic Acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. Historically, vinegar was produced from the third century BC and was likely the first acid to be produced in large quantities. Acetic acid is the second simplest carboxylic acid (after formic acid). It is an important Reagent, chemical reagent and industrial chemical across various fields, used primarily in the production of cellulose acetate for photographic film, polyvinyl acetate for wood Adhesive, glue, and synthetic fibres and fabrics. In households, diluted acetic acid is often used in descaling agents. In the food industry, acetic acid is controlled by the E number, food additive code E260 as an acidity regulator and as a condiment. In biochemistry, the acetyl group, derived from acetic acid, is funda ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfuric Acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, and hydrogen, with the molecular formula . It is a colorless, odorless, and Viscosity, viscous liquid that is Miscibility, miscible with water. Pure sulfuric acid does not occur naturally due to its Dehydration reaction, strong affinity to water vapor; it is Hygroscopy, hygroscopic and readily absorbs water vapor from the Atmosphere of Earth, air. Concentrated sulfuric acid is a strong oxidant with powerful dehydrating properties, making it highly corrosive towards other materials, from rocks to metals. Phosphorus pentoxide is a notable exception in that it is not dehydrated by sulfuric acid but, to the contrary, dehydrates sulfuric acid to sulfur trioxide. Upon addition of sulfuric acid to water, a considerable amount of heat is releas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2-methyl-2-butanol
''tert''-Amyl alcohol (TAA) or 2-methylbutan-2-ol (2M2B), is a branched pentanol. Historically, TAA has been used as an anesthetic and more recently as a recreational drug. TAA is mostly a positive allosteric modulator for GABAA receptors in the same way as ethanol. The psychotropic effects of TAA and ethanol are similar, though distinct. Impact on coordination and balance are proportionately more prominent with TAA, which is significantly more potent by weight than ethanol. Its appeal as an alternative to ethanol may stem from its lack of a hangover (due to different metabolic pathways) and the fact that it is often not detected on standard drug test. TAA is a colorless liquid with a burning flavor and an unpleasant odor similar to paraldehyde with a hint of camphor. TAA remains liquid at room temperature, making it a useful alternative solvent to ''tert''-butyl alcohol. Production TAA is primarily made by the hydration of 2-methyl-2-butene in the presence of an acidic catal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
