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Diethylaminosulfur Trifluoride
Diethylaminosulfur trifluoride (DAST) is the organosulfur compound with the formula Et2NSF3. This liquid is a fluorinating reagent used for the synthesis of organofluorine compounds. The compound is colourless; older samples assume an orange colour. Use in organic synthesis DAST converts alcohols to the corresponding alkyl fluorides as well as aldehydes and unhindered ketones to geminal difluorides. Carboxylic acids react no further than the acyl fluoride (sulfur tetrafluoride effects the transformation —CO2H → —CF3). DAST is used in preference to the more classical gaseous SF4, since as a liquid it is more easily handled. A slightly thermally more stable compound is morpho-DAST. Acid-labile substrates are less likely to undergo rearrangement and elimination since DAST is less prone to contamination with acids. Reaction temperatures are milder as well – alcohols typically react at −78 °C and ketones around 0 °C. Synthesis DAST is prepared by the reaction of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a hydroxyl group). Ethanol is a Volatility (chemistry), volatile, Combustibility and flammability, flammable, colorless liquid with a characteristic wine-like odor and pungent taste. It is a psychoactive recreational drug, the active ingredient in alcoholic drinks. Ethanol is naturally produced by the fermentation process of Carbohydrate, sugars by yeasts or via Petrochemistry, petrochemical processes such as ethylene hydration. It has medical applications as an antiseptic and disinfectant. It is used as a chemical solvent and in the Chemical synthesis, synthesis of organic compounds, and as a Alcohol fuel, fuel source. Ethanol also can be dehydrated to make ethylene, an important chemical feedstock. As of 2006, world produ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green Chemistry
Green chemistry, also called sustainable chemistry, is an area of chemistry and chemical engineering focused on the design of products and processes that minimize or eliminate the use and generation of hazardous substances. While environmental chemistry focuses on the effects of polluting chemicals on nature, green chemistry focuses on the environmental impact of chemistry, including lowering consumption of nonrenewable resources and technological approaches for preventing pollution. The overarching goals of green chemistry—namely, more resource-efficient and inherently safer design of molecules, materials, products, and processes—can be pursued in a wide range of contexts. History Green chemistry emerged from a variety of existing ideas and research efforts (such as atom economy and catalysis) in the period leading up to the 1990s, in the context of increasing attention to problems of chemical pollution and resource depletion. The development of green chemistry in Europe a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reagents For Organic Chemistry
In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a substance ''consumed'' in the course of a chemical reaction. ''Solvents'', though involved in the reaction mechanism, are usually not called reactants. Similarly, ''catalysts'' are not consumed by the reaction, so they are not reactants. In biochemistry, especially in connection with enzyme-catalyzed reactions, the reactants are commonly called substrates. Definitions Organic chemistry In organic chemistry, the term "reagent" denotes a chemical ingredient (a compound or mixture, typically of inorganic or small organic molecules) introduced to cause the desired transformation of an organic substance. Examples include the Collins reagent, Fenton's reagent, and Grignard reagents. Analytical chemistry In analytical chemistry, a reagent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organofluorides
Organofluorine chemistry describes the chemistry of the organofluorines, organic compounds that contain the carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from Lipophobicity, oil and hydrophobe, water repellents to pharmaceuticals, refrigerants, and reagents in catalysis. In addition to these applications, some organofluorine compounds are pollutants because of their contributions to ozone depletion, global warming, bioaccumulation, and toxicity. The area of organofluorine chemistry often requires special techniques associated with the handling of fluorinating agents. The carbon–fluorine bond Fluorine has several distinctive differences from all other substituents encountered in organic molecules. As a result, the physical and chemical properties of organofluorines can be distinctive in comparison to other organohalogens. # The carbon–fluorine bond is one of the strongest in organic chemistry (an average bond energy around 480 kJ/molKirsch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorination With Aminosulfuranes
Fluorination with aminosulfuranes is a chemical reaction that transforms oxidized organic compounds into organofluorine compounds. Aminosulfuranes selectively exchange hydroxyl groups for fluorine, but are also capable of converting carbonyl groups, halides, silyl ethers, and other functionality into organofluorides. Introduction Prior to the introduction of diethylaminosulfur trifluoride (DAST) in 1970 for the replacement of hydroxyl groups with fluoride, sulfur tetrafluoride was the reagent most commonly used to accomplish this transformation. However, sulfur tetrafluoride only reacts with the most acidic hydroxyl groups (its substrate scope is limited), and is difficult to handle, toxic, and capable of generating hydrogen fluoride upon hydrolysis. Thus, aminosulfurane reagents such as diethylaminosulfur trifluoride have largely replaced SF4 as the reagents of choice for replacement of hydroxyl groups with fluoride.von Halasz, P.; Glemser, O. ''Chem. Ber.'' 1970, ''103'', 594. Ami ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ishikawa Reagent
Ishikawa's reagent is a fluorinating reagent used in organic chemistry. It is used to convert alcohols into alkyl fluorides and carboxylic acids into acyl fluorides. Aldehydes and ketones do not react with it. The reagent consists of a mixture of ''N'',''N''-diethyl-(1,1,2,3,3,3-hexafluoropropyl)amine and ''N'',''N''-diethyl-(''E'')-pentafluoropropenylamine in varying proportions. The active species is the hexafluoropropylamine; any enamine is converted into this by the hydrogen fluoride byproduct as the reaction proceeds. Ishikawa's reagent is a popular alternative to the DAST reagent, since it is shelf-stable and easily prepared from inexpensive and innocuous reagents. It is an improvement on Yarovenko's reagent, the adduct of chlorotrifluoroethylene and diethylamine, which must be prepared in a sealed vessel and once prepared keeps only for a few days, even in the refrigerator. The reagent is mostly used to convert primary alcohols to alkyl fluorides under mild conditions wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrafluoroborate
Tetrafluoroborate is the anion . This tetrahedral species is isoelectronic with tetrafluoroberyllate (), tetrafluoromethane (CF4), and tetrafluoroammonium () and is valence isoelectronic with many stable and important species including the perchlorate anion, , which is used in similar ways in the laboratory. It arises by the reaction of fluoride salts with the Lewis acid BF3, treatment of tetrafluoroboric acid with base, or by treatment of boric acid with hydrofluoric acid. As an anion in inorganic and organic chemistry The popularization of has led to decreased use of in the laboratory as a weakly coordinating anion. With organic compounds, especially amine derivatives, forms potentially explosive derivatives. Disadvantages to include its slight sensitivity to hydrolysis and decomposition via loss of a fluoride ligand, whereas does not suffer from these problems. Safety considerations, however, overshadow this inconvenience. With a formula weight of 86.8, BF is also conveni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbolabs
Carbolabs, Inc., is an American chemistry company specializing in reactions utilizing phosgene, founded by Joe Karabinos in 1967. Originally located in the basement of his home in Bethany, Connecticut, it wasn't until the following year that the business was moved into its own dedicated building. The company was purchased by Sigma Aldrich in 1998. In 2008 operations at the Bethany site were discontinued and were subsequently moved to the Sheboygan Falls, Wisconsin Sigma Aldrich manufacturing facility. Carbolabs uses phosgene to produce a wide array of chemicals including isocyanates, chloroformates, and isonitriles, although some reactions not involving phosgene such as the production of the fluorinating reagent DAST are also part of their established chemistries. As a subsidiary of Sigma Aldrich Sigma-Aldrich (formally MilliporeSigma) is an American chemical, life science, and biotechnology company that is owned by the German chemical conglomerate Merck Group. Sigma-Aldrich ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diethyl Ether
Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable liquid. It is commonly used as a solvent in laboratories and as a starting fluid for some engines. It was formerly used as a general anesthetic, until non-flammable drugs were developed, such as halothane. It has been used as a recreational drug to cause intoxication. Production Most diethyl ether is produced as a byproduct of the vapor-phase hydration of ethylene to make ethanol. This process uses solid-supported phosphoric acid catalysts and can be adjusted to make more ether if the need arises. Vapor-phase dehydration of ethanol over some alumina catalysts can give diethyl ether yields of up to 95%. Diethyl ether can be prepared both in laboratories and on an industrial scale by the acid ether synthesis. Ethanol is mixed with a stro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acetonitrile
Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula and structure . This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not classed as organic). It is produced mainly as a byproduct of acrylonitrile manufacture. It is used as a polar aprotic solvent in organic synthesis and in the purification of butadiene. The skeleton is linear with a short distance of 1.16 Å. Acetonitrile was first prepared in 1847 by the French chemist Jean-Baptiste Dumas. Applications Acetonitrile is used mainly as a solvent in the purification of butadiene in refineries. Specifically, acetonitrile is fed into the top of a distillation column filled with hydrocarbons including butadiene, and as the acetonitrile falls down through the column, it absorbs the butadiene which is then sent from the bottom of the tower to a second separating tower. Heat is then employed in the separatin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Montreal Protocol
The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone l .... It was agreed on 16 September 1987, and entered into force on 1 January 1989. Since then, it has undergone nine revisions, in 1990 (London), 1991 (Nairobi), 1992 (Copenhagen), 1993 (Bangkok), 1995 (Vienna), 1997 (Montreal), 1998 (Australia), 1999 (Beijing) and 2016 (Kigali) As a result of the international agreement, the ozone hole in Antarctica is slowly recovering. Climate projections indicate that the ozone layer will return to 1980 levels between 2050 and 2070. Due to its widespread adoption and implementation, it has been hailed as an example of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
