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Aldol Scheme 3
In organic chemistry, an aldol is a structure consisting of a hydroxy group (-OH) two carbons away from either an aldehyde or a ketone. The name combines the suffix 'ol' from the alcohol and the prefix depending on the carbonyl group, either 'ald' for an aldehyde, or 'ket' for a ketone, in which case it referred to as a 'ketol'. An aldol may also use the term β-hydroxy aldehyde (or β-hydroxy ketone for a ketol). The term "aldol" may refer to 3-hydroxybutanal. Aldols are the product of a Carbon–carbon bond, carbon-carbon bond-formation reaction, giving them wide applicability as a precursor for a variety of other compounds. Synthesis and reactions Aldols are usually synthesized from an aldol reaction, aldol addition reaction using two aldehydes or an aldehyde and a ketone for a ketol. These reactions may also be done intramolecularly to form 5 or 6 member rings or for stereoselective syntheses in the active area of asymmetric synthesis. Aldols may also undergo a condensation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diol
A diol is a chemical compound containing two hydroxyl groups ( groups). An aliphatic diol may also be called a glycol. This pairing of functional groups is pervasive, and many subcategories have been identified. They are used as protecting groups of carbonyl groups, making them essential in synthesis of organic chemistry. The most common industrial diol is ethylene glycol. Examples of diols in which the hydroxyl functional groups are more widely separated include 1,4-butanediol and propylene-1,3-diol, or beta propylene glycol, . Synthesis of classes of diols Geminal diols A geminal diol has two hydroxyl groups bonded to the same atom. These species arise by hydration of the carbonyl compounds. The hydration is usually unfavorable, but a notable exception is formaldehyde which, in water, exists in equilibrium with methanediol H2C(OH)2. Another example is (F3C)2C(OH)2, the hydrated form of hexafluoroacetone. Many gem-diols undergo further condensation to give dimer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldol Reactions
In organic chemistry, aldol reactions are acid- or base-catalyzed reactions of aldehydes or ketones. Aldol addition or aldolization refers to the addition of an enolate or enolation as a nucleophile to a Carbonyl group, carbonyl Moiety (chemistry), moiety as an electrophile. This produces a β-hydroxyaldehyde or β-hydroxyketone. In an aldol condensation, water is subsequently eliminated and an α,β-unsaturated carbonyl is formed. The aldol cleavage or Retro-aldol reaction is the reverse reaction into the starting compounds. The name ''aldehyde'' -alcohol ''reaction'' derives from the reaction product in the case of a reaction among aldehydes, a Aldol, β-hydroxy aldehyde. Aldol reactions are important reactions for carbon-carbon bond formation and a fundamental reaction principle in organic chemistry. Mechanisms Aldol reactions may proceed by two distinct mechanisms. Carbonyl compounds, such as aldehydes and ketones, can be converted to enols or enol ethers. These species, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epothilone
Epothilones are a class of potential cancer drugs. Like taxanes, they prevent cancer cells from dividing by interfering with tubulin, but in early trials, epothilones have better efficacy and milder adverse effects than taxanes. Epothilones were originally identified as metabolites produced by the soil-dwelling myxobacterium ''Sorangium cellulosum''. , epothilones A to F have been identified and characterized. Early studies in cancer cell lines and human cancer patients indicate superior efficacy to the taxanes. Their mechanism of action is similar, but their chemical structure is simpler. Due to their better water solubility, cremophors (solubilizing agents used for paclitaxel which can affect cardiac function and cause severe hypersensitivity) are not needed. Endotoxin-like properties known from paclitaxel, like activation of macrophages synthesizing inflammatory cytokines and nitric oxide, are not observed for epothilone B. History The structure of epothilone A was determin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oseltamivir
Oseltamivir, sold under the brand name Tamiflu among others, is an antiviral medication used to treat and prevent influenza A and influenza B, viruses that cause the flu. Many medical organizations recommend it in people who have complications or are at high risk of complications within 48 hours of first symptoms of infection. They recommend it to prevent infection in those at high risk, but not the general population. The Centers for Disease Control and Prevention (CDC) recommends that clinicians use their discretion to treat those at lower risk who present within 48 hours of first symptoms of infection. It is taken by mouth, either as a pill or liquid. Recommendations regarding oseltamivir are controversial as are criticisms of the recommendations. A 2014 Cochrane Review concluded that oseltamivir does not reduce hospitalizations, and that there is no evidence of reduction in complications of influenza. Two meta-analyses have concluded that benefits in those who are other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyketide
In organic chemistry, polyketides are a class of natural products derived from a Precursor (chemistry), precursor molecule consisting of a Polymer backbone, chain of alternating ketone (, or Carbonyl reduction, its reduced forms) and Methylene group, methylene () groups: . First studied in the early 20th century, discovery, biosynthesis, and application of polyketides has evolved. It is a large and diverse group of secondary metabolites caused by its complex biosynthesis which resembles that of fatty acid synthesis. Because of this diversity, polyketides can have various medicinal, agricultural, and industrial applications. Many polyketides are medicinal or exhibit acute toxicity. Biotechnology has enabled discovery of more naturally-occurring polyketides and evolution of new polyketides with novel or improved bioactivity. History Naturally produced polyketides by various plants and organisms have been used by humans since before studies on them began in the 19th and 20th century ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quinoline Yellow SS
Quinoline Yellow SS is a bright yellow dye with green shade. It is insoluble in water, but soluble in nonpolar organic solvents. Quinoline yellow is representative of a large class of quinophthalone pigments. It is suggested that quinoline yellow exhibits excited-state intramolecular proton transfer (ESIPT) behavior and the behavior might be the cause of its decent photostability, by recent spectroscopic study. Synthesis and reactions As first described in 1878, the dye is prepared by the fusion of phthalic anhydride and quinaldine. The compound exists as a mixture of two tautomers. Using other anhydrides and other quinaldine derivatives other dyes in the quinophthalone family can be prepared. When sulfonated, it converts to a water-soluble derivative, Quinoline Yellow WS. Uses and safety Quinoline Yellow SS is used in spirit lacquers, polystyrene, polycarbonates, polyamides, acrylic resins, and to color hydrocarbon solvents. It is also used in externally applied drugs and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quinaldine
Quinaldine or 2-methylquinoline is an organic compound with the formula CH3C9H6N. It is one of the methyl derivatives of the heterocyclic compound quinoline. It is bioactive and is used in the preparation of various dyes. It is a colorless oil but commercial samples can appear colored. Production and reactions Quinaldine is recovered from coal tar. It can be prepared from aniline and paraldehyde via Skraup synthesis or from aniline and crotonaldehyde via Doebner-von Miller variation of the Skraup reaction. Hydrogenation of quinaldine gives 2-methyltetrahydroquinoline. This reduction can be conducted enantioselectively. Properties Quinaldine has critical point at 787 K and 4.9 MPa and its refractive index In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ... is 1.8116. Uses Qui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-Hydroxybutanal
In organic chemistry, 3-hydroxybutanal (acetaldol, aldol) is an organic compound with the formula and the structure . It is classified as an aldol () and the word "aldol" can refer specifically to 3-hydroxybutanal. It is formally the product of the dimerization of acetaldehyde (). A thick colorless or pale-yellow liquid, it is a versatile and valuable intermediate with diverse impacts. The compound is chiral although this aspect is not often exploited. Production Acetaldehyde dimerizes upon treatment with aqueous sodium hydroxide: : This is the prototypical aldol reaction. Reactions and uses Dehydration of 3-hydroxybutanal gives crotonaldehyde. Distillation of 3-hydroxybutanal is sufficiently forcing to effect this conversion: : Hydrogenation of 3-hydroxybutanal gives 1,3-butanediol: : This diol is a precursor to 1,3-butadiene, precursor to diverse polymers. Polymerization of 3-hydroxybutanal is also spontaneous, but can be stopped with the addition of water. Aldol has be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distillation
Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances; the separation process is realized by way of the selective boiling of the mixture and the condensation of the vapors in a still. Distillation can operate over a wide range of pressures from 0.14 bar (e.g., ethylbenzene/ styrene) to nearly 21 bar (e.g., propylene/propane) and is capable of separating feeds with high volumetric flowrates and various components that cover a range of relative volatilities from only 1.17 ( o-xylene/ m-xylene) to 81.2 (water/ ethylene glycol). Distillation provides a convenient and time-tested solution to separate a diversity of chemicals in a continuous manner with high purity. However, distillation has an enormous environmental footprint, resulting in the consumption of approximately 25% of all industrial energy use. The key issue is that distillation operates based on phase changes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydroxypivaldehyde
Hydroxypivaldehyde is the organic compound with the formula HOCH2(CH3)2CCHO. A colorless liquid, it is produced by condensation of formaldehyde and isobutyraldehyde: :CH2O + (CH3)2CHCHO → HOCH2(CH3)2CCHO The compound is a rare example of a distillable aldol (3-hydroxyaldehyde). Upon standing, it dimerizes reversibly to the dioxane derivative. Applications Hydroxypivaldehyde is a precursor to vitamin B5 as is practiced commercially.{{cite journal , doi=10.1002/anie.201205886 , title=One Hundred Years of Vitamins-A Success Story of the Natural Sciences , year=2012 , last1=Eggersdorfer , first1=Manfred , last2=Laudert , first2=Dietmar , last3=Létinois , first3=Ulla , last4=McClymont , first4=Tom , last5=Medlock , first5=Jonathan , last6=Netscher , first6=Thomas , last7=Bonrath , first7=Werner , journal=Angewandte Chemie International Edition , volume=51 , issue=52 , page=12975 , pmid=23208776 : Hydroxypivaldehyde is also a precursor to neopentyl glycol by hydrogenation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alcohol (chemistry)
In chemistry, an alcohol (), is a type of organic compound that carries at least one hydroxyl () functional group bound to a Saturated and unsaturated compounds, saturated carbon atom. Alcohols range from the simple, like methanol and ethanol, to complex, like sugar alcohols and cholesterol. The presence of an OH group strongly modifies the properties of Hydrocarbon, hydrocarbons, conferring Hydrophile, hydrophilic (water-loving) properties. The OH group provides a site at which many reactions can occur. History The flammable nature of the exhalations of wine was already known to ancient natural philosophers such as Aristotle (384–322 BCE), Theophrastus (–287 BCE), and Pliny the Elder (23/24–79 CE). However, this did not immediately lead to the isolation of alcohol, even despite the development of more advanced distillation techniques in second- and third-century Roman Egypt. An important recognition, first found in one of the writings attributed to Jabir ibn Hayyan, JÄ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
