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Meyer–Schuster Rearrangement
The Meyer–Schuster rearrangement is the chemical reaction described as an acid-catalysis, catalyzed rearrangement reaction, rearrangement of secondary and tertiary propargyl alcohols to α,β-unsaturated ketones if the alkyne group is internal and α,β-unsaturated aldehydes if the alkyne group is terminal.Swaminathan, S.; Narayan, K. V. "The Rupe and Meyer-Schuster Rearrangements" ''Chem. Rev.'' 1971, ''71'', 429–438.Review Mechanism The reaction proceeds by three major steps: (1) the rapid protonation of oxygen, (2) the slow, rate-determining step comprising the sigmatropic reaction, 1,3-shift of the protonated hydroxy group, and (3) the keto-enol tautomerism followed by rapid deprotonation. Formation of the unsaturated carbonyl compound is irreversible. Solvent is important and cage effect (chemistry), solvent caging is proposed to stabilize the transition state. Rupe rearrangement The reaction of tertiary alcohols containing an α-acetylenic group does not produce the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kurt Heinrich Meyer
Kurt Heinrich Meyer or Kurt Otto Hans Meyer (29 September 1883 – 14 April 1952) was a German chemist. Life and work Born in Tartu, Estonia, Meyer was the son of the pharmacologist Hans Horst Meyer. He was a student from 1892 until 1901 in the “Gymnasium Philippinum” in Marburg, Germany. This was followed at first by studies in medicine, later in chemistry in Marburg (where Theodor Zincke was the professor), and in Leipzig, Freiburg, London, and Munich. In Leipzig, Meyer obtained his PhD in 1907 with the dissertation “Untersuchungen über Halochromie” (Research on Halochromie) under the direction of Arthur Hantzsch. Afterwards, following the advice of his father, he travelled to England to complement his education and worked for several months in the laboratory of Ernest Rutherford. After his return to Germany in 1891, he obtained the highest academic degree, the Habilitation, working under the direction of Adolf von Baeyer in Munich on the determination of the equilibrium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetylenic
In organic chemistry, the term acetylenic designates *A doubly unsaturated position (''sp''-hybridized) on a molecular framework, for instance in an alkyne such as acetylene Acetylene (Chemical nomenclature, systematic name: ethyne) is a chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is u ...; *An ethynyl fragment, HC\equivC–, or substituted homologue. See also * Allylic * Propargylic * Vinylic Organic chemistry ... [...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 2022 impact factor of 1.8 Indexing ''Tetrahedron Letters'' is indexed in: References See also *''Tetrahedron In geometry, a tetrahedron (: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular Face (geometry), faces, six straight Edge (geometry), edges, and four vertex (geometry), vertices. The tet ...'' *'' Tetrahedron: Asymmetry'' Chemistry journals Weekly journals Academic journals established in 1959 Elsevier academic journals {{chem-journal-stub ... [...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] |
Microwave Chemistry
Microwave chemistry is the science of applying microwave radiation to chemical reactions. Microwaves act as high frequency electric fields and will generally heat any material containing mobile electric charges, such as polar molecules in a solvent or conducting ions in a solid. Microwave heating occurs primarily through two mechanisms: dipolar polarization and ionic conduction. Polar solvents because their dipole moments attempt to realign with the oscillating electric field, creating molecular friction and dielectric loss. The phase difference between the dipole orientation and the alternating field leads to energy dissipation as heat. Semiconducting and conducting samples heat when ions or electrons within them form an electric current and energy is lost due to the electrical resistance of the material .Commercial microwave systems typically operate at a frequency of 2.45 GHz, which allows effective energy transfer to polar molecules without quantum mechanical resonance effects. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synlett
''Synlett'' is an international scientific journal for accounts and rapid communications of original contributions of fundamental research in synthetic organic chemistry. The impact factor of this journal is 2.419 (2017). ''Nature'' featured a brief piece by the editor-in-chief of the journal in 2017, Benjamin List Benjamin List (; born 11 January 1968) is a German chemist who is one of the directors of the Max Planck Institute for Coal Research and professor of organic chemistry at the University of Cologne. He co-developed organocatalysis, a method of acc ..., where he discussed the journal's experience with the non-traditional peer review system. References Chemistry journals Thieme academic journals Academic journals established in 1989 {{chem-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewis Acid
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any species that has a filled orbital containing an electron pair which is not involved in bonding but may form a dative bond with a Lewis acid to form a Lewis adduct. For example, NH3 is a Lewis base, because it can donate its lone pair of electrons. Trimethylborane CH3)3Bis a Lewis acid as it is capable of accepting a lone pair. In a Lewis adduct, the Lewis acid and base share an electron pair furnished by the Lewis base, forming a dative bond. In the context of a specific chemical reaction between NH3 and Me3B, a lone pair from NH3 will form a dative bond with the empty orbital of Me3B to form an adduct NH3•BMe3. The terminology refers to the contributions of Gilbert N. Lewis. From p. 142: "We are inclined to think of substances as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Metal
In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. The lanthanide and actinide elements (the f-block) are called inner transition metals and are sometimes considered to be transition metals as well. They are lustrous metals with good electrical and thermal conductivity. Most (with the exception of group 11 and group 12) are hard and strong, and have high melting and boiling temperatures. They form compounds in any of two or more different oxidation states and bind to a variety of ligands to form coordination complexes that are often coloured. They form many useful alloys and are often employed as catalysts in elemental form or in compounds such as coordination complexes and oxides. Most are strongly paramagnetic because of their unpaired d electrons, as are many of their compounds. All of the elements that are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
