|
Trifluoroacetic Anhydride
Trifluoroacetic anhydride (TFAA) is the acid anhydride of trifluoroacetic acid. It is the perfluorinated derivative of acetic anhydride. Preparation Trifluoroacetic anhydride was originally prepared by the dehydration of trifluoroacetic acid with phosphorus pentoxide. The dehydration might also be carried out with excess α-halogenated acid chlorides. For example, with dichloroacetyl chloride: : 2 CF3COOH + Cl2CHCOCl → (CF3CO)2O + Cl2CHCOOH + HCl Uses Trifluoroacetic anhydride has various uses in organic synthesis. It may be used to introduce the corresponding trifluoroacetyl group, for which it is more convenient than the corresponding acyl chloride, trifluoroacetyl chloride, which is a gas. It can be used to promote reactions of carboxylic acids, including Friedel-Crafts acylation and acylation of other unsaturated compounds. Other electrophilic aromatic substitution reactions can also be promoted with trifluoroacetic anhydride, including nitration, sulfonation and ni ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benzene
Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, benzene is classed as a hydrocarbon. Benzene is a natural constituent of petroleum and is one of the elementary petrochemicals. Due to the cyclic continuous pi bonds between the carbon atoms, benzene is classed as an aromatic hydrocarbon. Benzene is a colorless and highly Combustibility and flammability, flammable liquid with a sweet smell, and is partially responsible for the aroma of gasoline. It is used primarily as a Precursor (chemistry), precursor to the manufacture of chemicals with more complex structures, such as ethylbenzene and cumene, of which billions of kilograms are produced annually. Although benzene is a major Chemical industry, industrial che ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acyl Chloride
In organic chemistry, an acyl chloride (or acid chloride) is an organic compound with the functional group . Their formula is usually written , where R is a side chain. They are reactive derivatives of carboxylic acids (). A specific example of an acyl chloride is acetyl chloride, . Acyl chlorides are the most important subset of acyl halides. Nomenclature Where the acyl chloride moiety takes priority, acyl chlorides are named by taking the name of the parent carboxylic acid, and substituting ''-yl chloride'' for ''-ic acid''. Thus: : : : butyr''ic acid'' (C3H7COOH) → butyr''yl chloride'' (C3H7COCl) (Idiosyncratically, for some trivial names, ''-oyl chloride'' substitutes ''-ic acid''. For example, pival''ic acid'' becomes pival''oyl chloride'' and acryl''ic acid'' becomes acryl''oyl chloride.'' The names pivalyl chloride and acrylyl chloride are less commonly used, although they are arguably more logical.) When other functional groups take priority, acyl chlorides a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Google Books
Google Books (previously known as Google Book Search, Google Print, and by its code-name Project Ocean) is a service from Google that searches the full text of books and magazines that Google has scanned, converted to text using optical character recognition (OCR), and stored in its digital database.The basic Google book link is found at: https://books.google.com/ . The "advanced" interface allowing more specific searches is found at: https://books.google.com/advanced_book_search Books are provided either by publishers and authors through the Google Books Partner Program, or by Google's library partners through the Library Project. Additionally, Google has partnered with a number of magazine publishers to digitize their archives. The Publisher Program was first known as Google Print when it was introduced at the Frankfurt Book Fair in October 2004. The Google Books Library Project, which scans works in the collections of library partners and adds them to the digital inventory, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Desiccant
A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccants for specialized purposes may be in forms other than solid, and may work through other principles, such as chemical bonding of water molecules. They are commonly encountered in foods to retain crispness. Industrially, desiccants are widely used to control the level of water in gas streams. Types of desiccants Although some desiccants are chemically inert, others are extremely reactive and require specialized handling techniques. The most common desiccant is silica gel, an otherwise inert, nontoxic, water-insoluble white solid. Tens of thousands of tons are produced annually for this purpose. Other common desiccants include activated charcoal, calcium sulfate, calcium chloride, and molecular sieves (typically, zeolites). Desicc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfide (organic)
In organic chemistry, a sulfide (British English sulphide) or thioether is an organosulfur functional group with the connectivity as shown on right. Like many other sulfur-containing compounds, volatile sulfides have foul odors. A sulfide is similar to an ether except that it contains a sulfur atom in place of the oxygen. The grouping of oxygen and sulfur in the periodic table suggests that the chemical properties of ethers and sulfides are somewhat similar, though the extent to which this is true in practice varies depending on the application. Nomenclature Sulfides are sometimes called thioethers, especially in the old literature. The two organic substituents are indicated by the prefixes. (CH3)2S is called dimethylsulfide. Some sulfides are named by modifying the common name for the corresponding ether. For example, C6H5SCH3 is methyl phenyl sulfide, but is more commonly called thioanisole, since its structure is related to that for anisole, C6H5OCH3. The modern systemati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfoxide
In organic chemistry, a sulfoxide, also called a sulphoxide, is an organosulfur compound containing a sulfinyl () functional group attached to two carbon atoms. It is a polar functional group. Sulfoxides are oxidized derivatives of sulfides. Examples of important sulfoxides are alliin, a precursor to the compound that gives freshly crushed garlic its aroma, and dimethyl sulfoxide (DMSO), a common solvent. Structure and bonding Sulfoxides feature relatively short S–O distances. In DMSO, the S–O distance is 1.531 Å. The sulfur center is pyramidal; the sum of the angles at sulfur is about 306°.. Sulfoxides are generally represented with the structural formula R−S(=O)−R', where R and R' are organic groups. The bond between the sulfur and oxygen atoms is intermediate of a dative bond and a polarized double bond. The double-bond resonance form implies 10 electrons around sulfur (10-S-3 in N-X-L notation). The double-bond character of the S−O bond may be accou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Iodide
Sodium iodide (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions (I−) in a crystal lattice. It is used mainly as a nutritional supplement and in organic chemistry. It is produced industrially as the salt formed when acidic iodides react with sodium hydroxide. It is a chaotropic salt. Uses Food supplement Sodium iodide, as well as potassium iodide, is commonly used to treat and prevent iodine deficiency. Iodized table salt contains 10 ppm iodide. Organic synthesis Sodium iodide is used for conversion of alkyl chlorides into alkyl iodides. This method, the Finkelstein reaction, relies on the insolubility of sodium chloride in acetone to drive the reaction: ::R–Cl + NaI → R–I + NaCl Nuclear medicine Some radioactive iodide salts of sodium, including Na 125I and Na 131I, have rad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swern Oxidation
In organic chemistry, the Swern oxidation also known as Moffatt-Swern, named after Daniel Swern, is a chemical reaction whereby a primary or secondary Alcohol (chemistry), alcohol () is redox, oxidized to an aldehyde () or ketone () using oxalyl chloride, dimethyl sulfoxide (DMSO) and an organic Base (chemistry), base, such as triethylamine. It is one of the many oxidation reactions commonly referred to as 'activated DMSO' oxidations. The reaction is known for its mild character and wide tolerance of functional groups. The by-products are dimethyl sulfide ((CH3)2S), carbon monoxide (CO), carbon dioxide (CO2) and—when triethylamine is used as base—triethylammonium chloride (Et3NHCl). Of the volatile by-products, dimethyl sulfide has a strong, pervasive odour and carbon monoxide is acutely toxic, so the reaction and the work-up needs to be performed in a fume hood. Dimethyl sulfide is a volatile liquid (B.P. 37 °C) with an unpleasant odour at even low concentrations. Me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxalyl Chloride
Oxalyl chloride is an organic chemical compound with the formula . This colorless, sharp-smelling liquid, the diacyl chloride of oxalic acid, is a useful reagent in organic synthesis. Preparation Oxalyl chloride was first prepared in 1892 by the French chemist Adrien Fauconnier, who treated diethyl oxalate with phosphorus pentachloride. It can also be prepared by treating oxalic acid with phosphorus pentachloride. Oxalyl chloride is produced commercially from ethylene carbonate. Photochlorination gives the perchloroethylene carbonate and hydrogen chloride HCl, which is subsequently degraded to oxalyl chloride and phosgene : : : Reactions As originally determined by Staudinger, oxalyl chloride reacts with water giving off gaseous products only: hydrogen chloride (HCl), carbon dioxide (), and carbon monoxide (CO). : Other acyl chlorides hydrolyze with formation of hydrogen chloride and the original carboxylic acid. Applications in organic synthesis Oxidation of alcohols Addit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pummerer Rearrangement
The Pummerer rearrangement is an organic reaction whereby an alkyl sulfoxide rearranges to an α- acyloxy–thioether (monothioacetal-ester) in the presence of acetic anhydride. The stoichiometry of the reaction is: :RS(O)CHR'2 + Ac2O → RSC(OAc)R'2 + AcOH Synthetic implementation Aside from acetic anhydride, trifluoroacetic anhydride and trifluoromethanesulfonic anhydride have been employed as activators. Common nucleophiles besides acetates are arenes, alkenes, amides, and phenols. The usage of α-acyl sulfoxides and Lewis acids, such as TiCl4 and SnCl4, allow the reaction to proceed at lower temperatures (0 °C). Thionyl chloride can be used in place of acetic anhydride to trigger the elimination for forming the electrophilic intermediate and supplying chloride as the nucleophile to give an α-chloro-thioether: Other anhydrides and acyl halides can give similar products. Inorganic acids can also give this reaction. This product can be converted to alde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrophilic Aromatic Substitution
Electrophilic aromatic substitution (SEAr) is an organic reaction in which an atom that is attached to an aromatic ring, aromatic system (usually hydrogen) is replaced by an electrophile. Some of the most important electrophilic aromatic substitutions are aromatic nitration, aromatic halogenation, aromatic sulfonation, alkylation Friedel–Crafts reaction and acylation Friedel–Crafts reaction. Illustrative reactions The most widely practised example of this reaction is the ethylation of benzene. :: Approximately 24,700,000 tons were produced in 1999. (After dehydrogenation and polymerization, the commodity plastic polystyrene is produced.) In this process, acids are used as catalyst to generate the incipient carbocation. Many other electrophilic reactions of benzene are conducted, although on a much smaller scale; they are valuable routes to key intermediates. The nitration of benzene is achieved via the action of the nitronium ion as the electrophile. The Aromatic sulfonation, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Friedel–Crafts Reaction
The Friedel–Crafts reactions are a set of organic reaction, reactions developed by Charles Friedel and James Crafts in 1877 to attach substituents to an Aromatic hydrocarbon, aromatic ring. Friedel–Crafts reactions are of two main types: alkylation reactions and acylation reactions. Both proceed by electrophilic aromatic substitution. Alkylation With alkenes In commercial applications, the alkylating agents are generally alkenes, some of the largest scale reactions practiced in industry. Such alkylations are of major industrial importance, e.g. for the production of ethylbenzene, the precursor to polystyrene, from benzene and ethylene and for the production of cumene from benzene and propene in cumene process: : : Industrial production typically uses solid acids derived from a zeolite as the catalyst. With alkyl halides Friedel–Crafts alkylation involves the alkylation of an aromatic ring. Traditionally, the alkylating agents are alkyl halides. Many alkylating ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
