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Japp–Maitland Condensation
The Japp–Maitland condensation is an organic reaction and a type of Aldol reaction and a tandem reaction. In a reaction between the ketone 3-pentanone and the aldehyde benzaldehyde catalyzed by base the bis Aldol adduct is formed first. The second step is a ring-closing reaction when one hydroxyl group displaces the other in a nucleophilic substitution forming an oxo-tetrahydropyran. : The reaction was first described by Francis Robert Japp and William Maitland in 1904. The Japp–Maitland reaction is of some importance to synthetic organic chemistry for example as part of the synthesis of biomolecule ''centrolobine'':2-step procedure, step one is a Mukaiyama aldol reaction. The catalyst in step two is boron trifluoride TMS = trimethylsilyl A trimethylsilyl group (abbreviated TMS) is a functional group in organic chemistry. This group consists of three methyl groups bonded to a silicon atom minus;Si(CH3)3 which is in turn bonded to the rest of a molecule. This structur ... [...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] |
Tert-butyldimethylsilyl
Silyl ethers are a group of chemical compounds which contain a silicon atom covalent bond, covalently bonded to an alkoxy group. The general structure is R1R2R3Si−O−R4 where R4 is an alkyl group or an aryl group. Silyl ethers are usually used as protecting groups for alcohols in organic synthesis. Since R1R2R3 can be combinations of differing groups which can be varied in order to provide a number of silyl ethers, this group of chemical compounds provides a wide spectrum of selectivity for protecting group chemistry. Common silyl ethers are: trimethylsilyl (TMS), Tert-Butyldiphenylsilyl, ''tert''-butyldiphenylsilyl (TBDPS), ''tert''-butyldimethylsilyl (TBS/TBDMS) and triisopropylsilyl (TIPS). They are particularly useful because they can be installed and removed very selectively under mild conditions. Common silyl ethers Formation Commonly silylation of alcohols requires a silyl chloride and an amine base. One reliable and rapid procedure is the Corey protocol in which th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trimethylsilyl
A trimethylsilyl group (abbreviated TMS) is a functional group in organic chemistry. This group consists of three methyl groups bonded to a silicon atom [−Si(CH3)3], which is in turn bonded to the rest of a molecule. This structural group is characterized by Chemically inert, chemical inertness and a large molecular volume, which makes it useful in a number of applications. A trimethylsilyl group bonded to a methyl group forms tetramethylsilane, which is abbreviated as TMS as well. Compounds with trimethylsilyl groups are not normally found in nature. Chemists sometimes use a trimethylsilylating reagent to derivatize rather non-volatile compounds such as certain Alcohol (chemistry), alcohols, phenols, or carboxylic acids by substituting a trimethylsilyl group for a hydrogen in the hydroxyl groups on the compounds. This way Silyl ether, trimethylsiloxy groups [−O-Si(CH3)3] are formed on the molecule. A couple of examples of trimethylsilylating agents include trimethyls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boron Trifluoride
Boron trifluoride is the inorganic compound with the formula . This pungent, colourless, and toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds. Structure and bonding The geometry of a molecule of is Trigonal planar molecular geometry, trigonal planar. Its D3h symmetry group, symmetry conforms with the prediction of VSEPR theory. The molecule has no dipole moment by virtue of its high symmetry. The molecule is isoelectronic with the carbonate anion, . is commonly referred to as "electron deficiency, electron deficient," a description that is reinforced by its exothermic reactivity toward Lewis bases. In the boron trihalides, , the length of the B–X bonds (1.30 Å) is shorter than would be expected for single bonds, and this shortness may indicate stronger B–X pi bond, π-bonding in the fluoride. A facile explanation invokes the symmetry-allowed overlap of a p orbital on the boron atom with the in-phas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mukaiyama Aldol Reaction
In organic chemistry, the Mukaiyama aldol addition is an organic reaction and a type of aldol reaction between a silyl enol ether () and an aldehyde () or formate (). The reaction was discovered by Teruaki Mukaiyama in 1973. His choice of reactants allows for a crossed aldol reaction between an aldehyde and a ketone (), or a different aldehyde without self-condensation of the aldehyde. For this reason the reaction is used extensively in organic synthesis. General reaction scheme The Mukaiyama aldol addition is a Lewis acid-mediated Addition reaction, addition of enol silanes to carbonyl () compounds. In this reaction, compounds with various organic groups can be used (see educts). A basic version ( = H) without the presence of Chiral auxiliary, chiral catalysts is shown below. A Racemic mixture, racemic mix of enantiomers is built. If E–Z notation, Z- or E-enol silanes are used in this reaction a mixture of four products occurs, yielding two racemates. Whether the ''anti''-di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahedron (journal)
''Tetrahedron'' is a weekly peer-reviewed scientific journal covering the field of organic chemistry. According to the ''Journal Citation Reports'', ''Tetrahedron'' has a 2020 impact factor of 2.1. ''Tetrahedron'' and Elsevier, its publisher, support an annual symposium. In 2010, complaints were raised over its high subscription cost. Notable papers , the Web of Science lists ten papers from ''Tetrahedron'' that have more than 1000 citations. The four articles that have been cited more than 2000 times are: * – cited 2228 times * – cited 2162 times * – cited 2124 times * – cited 2107 times See also * ''Tetrahedron Letters'' * '' Tetrahedron Computer Methodology'' * ''Polyhedron In geometry, a polyhedron (: polyhedra or polyhedrons; ) is a three-dimensional figure with flat polygonal Face (geometry), faces, straight Edge (geometry), edges and sharp corners or Vertex (geometry), vertices. The term "polyhedron" may refer ...'' (journal) Reference ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomolecule
A biomolecule or biological molecule is loosely defined as a molecule produced by a living organism and essential to one or more typically biological processes. Biomolecules include large macromolecules such as proteins, carbohydrates, lipids, and nucleic acids, as well as small molecules such as vitamins and hormones. A general name for this class of material is ''biological materials''. Biomolecules are an important element of living organisms. They are often endogeny (biology), endogenous, i.e. produced within the organism, but organisms usually also need exogeny, exogenous biomolecules, for example certain nutrients, to survive. Biomolecules and their organic reaction, reactions are studied in biology and its subfields of biochemistry and molecular biology. Most biomolecules are organic compounds, and just four chemical element, elements—oxygen, carbon, hydrogen, and nitrogen—make up 96% of the human body's mass. But many other elements, such as the various biometal (b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Maitland (chemist) (1847–1919), British civil servant in India, and cricketer
{{hndis, Maitland, William ...
William Maitland may refer to: * William Maitland of Lethington (1525–1573), Scottish politician and reformer * William Maitland (historian) (1693–1757), Scottish merchant, historian and topographer * William Fuller Maitland (1813–1876), English picture collector * William Whitaker Maitland (1794–1861), British landowner and High Sheriff of Essex * William Maitland (civil servant) William James Maitland (22 July 1847 – 8 May 1919) was a British civil servant in India and a Scottish first-class cricketer. The son of Augustus Maitland and his wife, Elizabeth Jane Richards, he was born at Edinburgh in July 1847. He was e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Francis Robert Japp
Francis Robert Japp FRS (8 February 1848 – 1 August 1925) was a British chemist who discovered the Japp-Klingemann reaction in 1887. He was born in Dundee, Scotland, the son of James Japp, a minister of the Catholic Apostolic Church. He graduated from St Andrews with an Master of Arts (Scotland), M.A. in 1868 and entered the University of Edinburgh as a student of law. He left the university because of health problems and stayed in Germany for two years from 1871 until 1873. After returning to England he decided to study chemistry. He started his studies at the University of Heidelberg with Robert Bunsen, where he received his PhD in 1875. He joined the laboratory of August Kekulé at the University of Bonn the following year and after returning to Scotland in 1878 worked with Alexander Crum Brown at the University of Edinburgh. In 1881 Japp became assistant professor at the Royal School of Mines and Normal School of Science South Kensington and in 1890 Professor of Chemistry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahydropyran
Tetrahydropyran (THP) is the organic compound consisting of a saturated six-membered ring containing five carbon atoms and one oxygen atom. It is named by reference to pyran, which contains two double bonds, and may be produced from it by adding four hydrogens. In 2013, its preferred IUPAC name was established as oxane. The compound is a colourless volatile liquid. Derivatives of tetrahydropyran are, however, more common. 2-Tetrahydropyranyl (THP-) ethers derived from the reaction of alcohols and 3,4-dihydropyran are commonly used as protecting groups in organic synthesis. Furthermore, a tetrahydropyran ''ring system'', i.e., five carbon atoms and an oxygen, is the core of pyranose sugars, such as glucose. Structure and preparation In gas phase, the THP exists in its lowest energy Cs symmetry chair conformation. One classic procedure for the organic synthesis of tetrahydropyran is by hydrogenation of the 3,4-isomer of dihydropyran with Raney nickel. Tetrahydropyranyl deri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
