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Enone–alkene Cycloadditions
In organic chemistry, enone–alkene cycloadditions are a version of the +2cycloaddition This reaction involves an enone and alkene as substrates. Although the concerted photochemical +2cycloaddition is allowed, the reaction between enones and alkenes is stepwise and involves discrete diradical intermediates. History In 1908, it was reported that exposure of carvone to "Italian sunlight" for one year gives carvone- camphor. Subsequent investigations demonstrated the utility of the photochemical +2cycloaddition of enones to alkenes. Mechanism In spite of the stepwise, radical mechanism, both stereoselective intra- and intermolecular variants have emerged. Cyclic enones are employed, otherwise competitive cis-trans isomerization ensues. The mechanism of +2photocyclization is proposed to begin with photoexcitation of the enone to a singlet excited state. The singlet state is typically very short lived, and decays by intersystem crossing to the triplet state. At this point, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; Greeves, N. and Warren, S. (2012) ''Organic Chemistry''. Oxford University Press. pp. 1–15. . Study of structure determines their structural formula. Study of properties includes physical and chemical properties, and evaluation of chemical reactivity to understand their behavior. The study of organic reactions includes the chemical synthesis of natural products, drugs, and polymers, and study of individual organic molecules in the laboratory and via theoretical ( in silico) study. The range of chemicals studied in organic chemistry includes hydrocarbons (compounds containing only carbon and hydrogen) as well as compounds based on carbon, but also containing other elements, especially oxygen, nitrogen, sulfur, phosphorus (included in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pericyclic
In organic chemistry, a pericyclic reaction is the type of organic reaction wherein the transition state of the molecule has a cyclic geometry, the reaction progresses in a concerted fashion, and the bond orbitals involved in the reaction overlap in a continuous cycle at the transition state. Pericyclic reactions stand in contrast to ''linear reactions'', encompassing most organic transformations and proceeding through an acyclic transition state, on the one hand and '' coarctate reactions'', which proceed through a doubly cyclic, concerted transition state on the other hand. Pericyclic reactions are usually rearrangement or addition reactions. The major classes of pericyclic reactions are given in the table below (the three most important classes are shown in bold). Ene reactions and cheletropic reactions are often classed as group transfer reactions and cycloadditions/cycloeliminations, respectively, while dyotropic reactions and group transfer reactions (if ene reactions are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Favorskii Rearrangement
The Favorskii rearrangement is principally a rearrangement of cyclopropanones and α-halo ketones that leads to carboxylic acid derivatives. In the case of cyclic α-halo ketones, the Favorskii rearrangement constitutes a ring contraction. This rearrangement takes place in the presence of a base, sometimes hydroxide, to yield a carboxylic acid but most of the time either an alkoxide base or an amine to yield an ester or an amide, respectively. α,α'-Dihaloketones eliminate HX under the reaction conditions to give α,β-unsaturated carbonyl compounds. History The reaction is named for the Russian chemist Alexei Yevgrafovich Favorskii Reaction mechanism The reaction mechanism is thought to involve the formation of an enolate on the side of the ketone away from the chlorine atom. This enolate cyclizes to a cyclopropanone intermediate which is then attacked by the hydroxide nucleophile. The second step has also been proposed to be stepwise process, with chloride anion le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahedron Lett
''Tetrahedron Letters'' is a weekly international journal for rapid publication of full original research papers in the field of organic chemistry. According to the ''Journal Citation Reports'', the journal has a 2020 impact factor of 2.415. Indexing ''Tetrahedron Letters'' is indexed in: References See also *''Tetrahedron In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the o ...'' *'' Tetrahedron: Asymmetry'' Chemistry journals Weekly journals Publications established in 1959 Elsevier academic journals {{chem-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
22Scope2
Scope or scopes may refer to: People with the surname * Jamie Scope (born 1986), English footballer * John T. Scopes (1900–1970), central figure in the Scopes Trial regarding the teaching of evolution Arts, media, and entertainment * CinemaScope or Scope prints, anamorphic film prints * ''Scope'' (magazine), a South African men's magazine * ''The Scope (alternative weekly)'', a newspaper in St. John's, Newfoundland * ''Scope'' (Australian TV series) * ''Scope'' (Irish TV series) * ''Scope'' (album), a 1979 studio album by Buck Hill Quartet Computing * Scope (computer science), the range in which a variable can be referenced * scope (scopeArchiv), an archival information program * CDC SCOPE, a series of Control Data Corporation operating systems Concepts * Scope (logic), the range influenced by the quantification in logic * Scope (formal semantics), the natural language counterpart of logical scope * Scope (project management), the sum of all projects, products and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
22Gen
Gen may refer to: * ''Gen'' (film), 2006 Turkish horror film directed by Togan Gökbakar * Gen (Street Fighter), a video game character from the ''Street Fighter'' series * Gen Fu, a video game character from the ''Dead or Alive'' series * Gen language, the language of Togo * Gen-san, a character in the anime series '' Sky Girls'' *, Japanese Nordic combined skier *, Japanese singer-songwriter, musician, actor, and writer *, Japanese footballer *, Japanese novelist, visual novel writer and anime screenwriter *, Japanese engineer and businessman *, Japanese politician *, Japanese ballet dancer and choreographer * Generation as in GenX, GenZ, etc. Gen. or GEN may refer to: * General officer, a high senior rank in the military * GEN Corporation, of Japan * Gen Digital, a computer security software company in United States * GEN Energija, a state-owned power company in Slovenia * GEN, a website published by Medium * Global Ecovillage Network * Global Editors Network * '' Gew ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
22Mech
In science fiction, or mechs are giant robots or machines controlled by people, typically depicted as humanoid walking vehicles. The term was first used in Japanese after shortening the English loanword or , but the meaning in Japanese is more inclusive, and or 'giant robot' is the narrower term. Fictional mecha vary greatly in size and shape, but are distinguished from vehicles by their humanoid or biomorphic appearance, although they are bigger, often much bigger, than human beings. Different subgenres exist, with varying connotations of realism. The concept of Super Robot and Real Robot are two such examples found in Japanese anime and manga. Real-world piloted humanoid or non-humanoid robotic platforms, existing or planned, may also be called "mecha". In Japanese, "mecha" may refer to mobile machinery or vehicles (including aircraft) in general, manned or otherwise. Characteristics 'Mecha' is an abbreviation, first used in Japanese, of 'mechanical'. In Japan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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