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Perkin Synthesis
The Perkin reaction is an organic reaction developed by English chemist William Henry Perkin in 1868 that is used to make cinnamic acids. It gives an α,β-unsaturated aromatic acid or α-substituted β-aryl acrylic acid by the aldol condensation of an aromatic aldehyde and an acid anhydride, in the presence of an alkali salt of the acid. The alkali salt acts as a base catalyst, and other bases can be used instead. Several reviews have been written. Reaction mechanism Clear from the reaction mechanism, the anhydride of aliphatic acid must contain at least 2 α-H for the reaction to occur. The above mechanism is not universally accepted, as several other versions exist, including decarboxylation without acetic group transfer.Bansal, Raj K. (1998) ''Organic Reaction Mechanisms'', Tata McGraw Hill, 3rd Edition , pp. 199–201, . Applications * Salicylaldehyde converted to coumarin using acetic anhydride with acetate as base. * cinnamic acid is prepared from benzaldehyde, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Henry Perkin
Sir William Henry Perkin (12 March 1838 – 14 July 1907) was a British chemist and entrepreneur best known for his serendipitous discovery of the first commercial synthetic organic dye, mauveine, made from aniline. Though he failed in trying to synthesise quinine for the treatment of malaria, he became successful in the field of dyes after his first discovery at the age of 18. Perkin set up a factory to produce the dye industrially. Lee Blaszczyk, professor of business history at the University of Leeds, states, "By laying the foundation for the synthetic organic chemicals industry, Perkin helped to revolutionize the world of fashion." Early years William Perkin was born in the East End of London, the youngest of the seven children of George Perkin, a successful carpenter. His mother, Sarah, was of Scottish descent and moved to East London as a child.UXL Encyclopedia of World Biography (2003). Accessed 18 March 2008. He was baptized in the Anglican parish church of St ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalyst
Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. The rate increase occurs because the catalyst allows the reaction to occur by an alternative mechanism which may be much faster than the noncatalyzed mechanism. However the noncatalyzed mechanism does remain possible, so that the total rate (catalyzed plus noncatalyzed) can only increase in the presence of the catalyst and never decrease. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pechmann Condensation
The Pechmann condensation is a synthesis of Coumarin derivatives, coumarins, starting from a phenol and a carboxylic acid or ester containing a β-carbonyl group. The condensation is performed under acidic conditions. The mechanism involves an esterification/transesterification followed by attack of the activated carbonyl ortho to the oxygen to generate the new ring. The final step is a dehydration, as seen following an aldol condensation. It was discovered by the Germany, German chemist Hans von Pechmann . Mechanism To synthesize coumarin derivatives, β-ketoesters can be condensed with phenols under acidic conditions. In this case, a transesterification reaction occurs first with the formation of the phenol ester. This is then followed by ring closure, similar to Friedel–Crafts reaction#Acylation, Friedel-Crafts alkylation. Examples With simple phenols, the conditions are harsh, although yields may still be good. With highly activated phenols such as resorcinol, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stobbe Condensation
The Stobbe condensation entails the reaction of an aldehyde or ketone with an ester of succinic acid to generate alkylidene succinic acid or related derivatives. The reaction consumes one equivalent of metal alkoxide. Commonly, diethylsuccinate is a component of the reaction. The usual product is salt of the half-ester. The Stobbe condensation is named after its discoverer, , whose work involved the sodium ethoxide-induced condensation of acetone and diethyl succinate. An example is the reaction of benzophenone with diethyl succinate: : A reaction mechanism that explains the formation of both an ester group and a carboxylic acid group is centered on a lactone intermediate (5): : The Stobbe condensation is also illustrated by the synthesis of the drug tametraline. See also *Aldol condensation *Polyketide synthase *Dieckmann condensation *Claisen condensation The Claisen condensation is a carbon–carbon bond forming reaction that occurs between two esters or one ester and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stilbene
Stilbene may refer to one of the two stereoisomers of 1,2-diphenylethene: * (''E'')-Stilbene (''trans'' isomer) * (''Z'')-Stilbene (''cis'' isomer) See also * Stilbenoid Stilbenoids are hydroxylated derivatives of stilbene. They have a C6–C2–C6 structure. In biochemical terms, they belong to the family of phenylpropanoids and share most of their biosynthesis pathway with Chalconoid, chalcones. Most stilbenoids ...s, a class of molecules found in plants * 1,1-Diphenylethylene {{Chemistry index Stilbenoids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytoestrogens
A phytoestrogen is a plant-derived xenoestrogen (a type of estrogen produced by organisms other than humans) not generated within the endocrine system, but consumed by eating plants or manufactured foods. Also called a "dietary estrogen", it is a diverse group of naturally occurring nonsteroidal plant compounds that, because of its structural similarity to estradiol (17-β-estradiol), have the ability to cause both estrogenic or antiestrogenic effects. Phytoestrogens are not essential nutrients because their absence from the diet does not cause a disease, nor are they known to participate in any normal biological function. Common foods containing phytoestrogens are soybeans and soy protein concentrate, miso, tempeh, and tofu. Some soy-based infant formulas manufactured with soy protein contain isoflavones. Its name comes from the Greek language, Greek ''phyto'' ("plant") and ''estrogen'', the hormone which gives fertility to female mammals. The word "estrus" (Greek οίστ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fo-ti
''Reynoutria multiflora'' ( syn. ''Fallopia multiflora'' and ''Polygonum multiflorum'') is a species of flowering plant in the buckwheat family Polygonaceae native to central and southern China. It is known by the English common names tuber fleeceflower and Chinese (climbing) knotweed. It is known as ''he shou wu'' (何首烏) in China and East Asia. Another name for the species is ''fo-ti'', which is a misnomer. It can be difficult to prevent the spread of this vine and to remove it once established. The leaves are thin and fragile but the stems, although narrow in diameter, can be very strong. Description ''Reynoutria multiflora'' is a herbaceous perennial vine growing to tall from a woody tuber. The leaves are long and broad, broad arrowhead-shaped, with an entire margin. The flowers are diameter, white or greenish-white, produced on short, dense panicles up to long in summer to mid-autumn. The fruit is an achene long. In folk belief In Chinese folklore, it is believed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resveratrol
Resveratrol (3,5,4′-trihydroxy-''trans''-stilbene) is a stilbenoid, a type of natural phenol or polyphenol and a phytoalexin produced by several plants in response to injury or when the plant is under attack by pathogens, such as bacterium, bacteria or fungus, fungi. Sources of resveratrol in food include the skin of grapes, blueberries, raspberries, mulberries, and peanuts. Although commonly used as a dietary supplement and studied in laboratory models of human diseases, there is no evidence-based medicine, high-quality evidence that resveratrol improves longevity, lifespan or has a substantial effect on any human disease. Research Resveratrol has been studied for its potential therapeutic use, with little evidence of anti-disease effects or health benefits in humans. Cardiovascular disease There is no evidence of benefit from resveratrol in people who already have heart disease. A 2018 meta-analysis found no effect on systolic blood pressure, systolic or diastolic blood pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzaldehyde
Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is among the simplest aromatic aldehydes and one of the most industrially useful. It is a colorless liquid with a characteristic almond-like odor, and is commonly used in cherry-flavored sodas. A component of bitter almond oil, benzaldehyde can be extracted from a number of other natural sources. Synthetic benzaldehyde is the flavoring agent in imitation almond extract, which is used to flavor cakes and other baked goods. History Benzaldehyde was first extracted in 1803 by the French pharmacist Martrès. His experiments focused on elucidating the nature of amygdalin, the poisonous compound found in bitter almonds, the fruit of '' Prunus dulcis''. Further work on the oil by Pierre Robiquet and Antoine Boutron Charlard, two French chemists, produced benzaldehyde. In 1832, Friedrich Wöhler and Justus von Liebig first synthesized benzaldehyde. Production Benzaldeh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coumarin
Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by an unsaturated lactone ring , forming a second six-membered heterocycle that shares two carbons with the benzene ring. It belongs to the benzopyrone chemical class and is considered a lactone. Coumarin is a colorless crystalline solid with a sweet odor resembling the scent of vanilla and a bitter taste. It is found in many plants, where it may serve as a chemical defense against predators. While coumarin is not an anticoagulant, its 3-alkyl-4-hydroxy derivatives, such as the fungal metabolite dicoumarol, inhibit synthesis of vitamin K, a key component in blood clotting. A related compound, the prescription drug anticoagulant warfarin, is used to inhibit formation of blood clots, deep vein thrombosis, and pulmonary embolism. Etymology Coumarin is derived from , the French word for the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perkin Reaction Mechanism , an American-origin global corporation
{{disambiguation ...
Perkin may refer to: People * Perkin (surname) * Perkin Warbeck (c. 1474 – 1499), imposter and pretender to the English throne Other uses * Perkin (crater), on the Moon * 2482 Perkin, an asteroid * Perkin Medal, awarded annually by the American section of the Society of Chemical Industry * Perkin, a character in ''The Flumps'' See also * Perkins (other) * Parkin (other) * PerkinElmer PerkinElmer, Inc., previously styled Perkin-Elmer, is an American global corporation that was founded in 1937 and originally focused on precision optics. Over the years it went into and out of several different businesses via acquisitions and di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
