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Chloropyridine
Chloropyridines are a group of aryl chlorides consisting of a pyridine ring with chlorine atoms as substituents. This may refer to: * 2-Chloropyridine *3-Chloropyridine * 4-Chloropyridine * 2,6-Dichloropyridine Production Direct halogenation of pyridine with chlorine gas above 270 °C gives a mixture of 2-chloropyridine and 2,6-dichloropyridine. 2- and 4-chloropyridine are prepared from the corresponding pyridinols using phosphoryl chloride: : Uses Chloropyridines are important intermediates to pharmaceuticals and agrochemicals. A major use of 2-chloropyridine is the production of production of the fungicide pyrithione. Reaction of 4-chloropyridine with thioglycolic acid gives pyridylmercaptoacetic acid, a step in the production of cephalosporin The cephalosporins (sg. ) are a class of β-lactam antibiotics originally derived from the fungus ''Acremonium'', which was previously known as ''Cephalosporium''. Together with cephamycins, they constitute a subgroup of β-l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrithione
Pyrithione is the common name of an organosulfur compound with molecular formula , chosen as an abbreviation of pyridinethione, and found in the Persian shallot. It exists as a pair of tautomers, the major form being the thione 1-hydroxy-2(1''H'')-pyridinethione and the minor form being the thiol 2-mercaptopyridine ''N''-oxide; it crystallises in the thione form. It is usually prepared from either 2-bromopyridine, 2-chloropyridine, or 2-chloropyridine ''N''-oxide, and is commercially available as both the neutral compound and its sodium salt. It is used to prepare zinc pyrithione, which is used primarily to treat dandruff and seborrhoeic dermatitis in medicated shampoos, though is also an anti-fouling agent in paints. Preparation The preparation of pyrithione was first reported in 1950 by Shaw and was prepared by reaction of 2-chloropyridine ''N''-oxide with sodium hydrosulfide followed by acidification, or more recently with sodium sulfide. 2-chloropyridine ''N''-oxi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2,6-Dichloropyridine
2,6-Dichloropyridine is a chloropyridine with the formula C5H3Cl2N. A white solid, it is one of six isomers of dichloropyridine. It serves as a precursor to the antibiotic enoxacin, as well as the drug and anpirtoline and the antifungal liranaftate. Synthesis 2,6-Dichoropyridine is produced by reaction of pyridine with chlorine. 2-Chloropyridine is an intermediate. Toxicity The is 115 mg/kg (oral, mice). References Chloropyridines {{organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyridine
Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is colorless, but older or impure samples can appear yellow, due to the formation of extended, unsaturated polymeric chains, which show significant electrical conductivity. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Historically, pyridine was produced from coal tar. As of 2016, it is synthesized on the scale of about 20,000 tons per year worldwide. Properties Physical properties The molecular electric dipole moment is 2.2 debyes. Pyridine is diamagnetism, diamagnetic and has a Magnetic susceptibility, diamagnetic susceptibility of −48.7 × 10−6 cm3·mol−1. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphoryl Chloride
Phosphoryl chloride (commonly called phosphorus oxychloride) is a colourless liquid with the formula . It hydrolyses in moist air releasing phosphoric acid and fumes of hydrogen chloride. It is manufactured industrially on a large scale from phosphorus trichloride and oxygen or phosphorus pentoxide. It is mainly used to make phosphate esters such as tricresyl phosphate. Structure Like phosphate, is tetrahedral in shape. It features three P−Cl bonds and one strong P=O double bond, with an estimated bond dissociation energy of 533.5 kJ/mol. On the basis of bond length and electronegativity, the Schomaker-Stevenson rule suggests that the double bond form is dominant, in contrast with the case of . The P=O bond involves the donation of the lone pair electrons on oxygen ''p''-orbitals to the antibonding combinations associated with phosphorus-chlorine bonds, thus constituting ''π'' bonding. Phosphoryl chloride exists as neutral molecules in the solid, liquid and gas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-Chloropyridine
3-Chloropyridine is an organohalide with the formula C5H4ClN. It is a colorless liquid that is mainly used as a building block in organic synthesis. The compound is a substrate for many coupling processes including the Heck reaction, Suzuki reaction, and Ullmann reaction The Ullmann reaction or Ullmann coupling is a coupling reaction between aryl halides. Traditionally this reaction is effected by copper, but palladium and nickel are also effective catalysts. The reaction is named after Fritz Ullmann. Mechanism .... Related compounds * 3-Bromopyridine * 2-Chloropyridine References {{DEFAULTSORT:Chloropyridine, 3- Chloropyridines 3-Pyridyl compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fungicide
Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, and profit. Fungicides are used both in agriculture and to fight fungal infections in animals. Chemicals used to control oomycetes, which are not fungi, are also referred to as fungicides, as oomycetes use the same mechanisms as fungi to infect plants. Fungicides can either be contact, translaminar or systemic. Contact fungicides are not taken up into the plant tissue and protect only the plant where the spray is deposited. Translaminar fungicides redistribute the fungicide from the upper, sprayed leaf surface to the lower, unsprayed surface. Systemic fungicides are taken up and redistributed through the xylem vessels. Few fungicides move to all parts of a plant. Some are locally systemic, and some move upwardly. Most fungicides that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cephalosporin
The cephalosporins (sg. ) are a class of β-lactam antibiotics originally derived from the fungus '' Acremonium'', which was previously known as ''Cephalosporium''. Together with cephamycins, they constitute a subgroup of β-lactam antibiotics called cephems. Cephalosporins were discovered in 1945, and first sold in 1964. Discovery The aerobic mold which yielded cephalosporin C was found in the sea near a sewage outfall in Su Siccu, by Cagliari harbour in Sardinia, by the Italian pharmacologist Giuseppe Brotzu in July 1945. Structure Cephalosporin contains a 6-membered dihydrothiazine ring. Substitutions at position 3 generally affect pharmacology; substitutions at position 7 affect antibacterial activity, but these cases are not always true. Medical uses Cephalosporins can be indicated for the prophylaxis and treatment of infections caused by bacteria susceptible to this particular form of antibiotic. First-generation cephalosporins are active predominantly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thioglycolic Acid
Thioglycolic acid (TGA) is the organic compound HSCH2CO2H. TGA is often called mercaptoacetic acid (MAA). It contains both a thiol (mercaptan) and carboxylic acid functional groups. It is a colorless liquid with a strongly unpleasant odor. TGA is miscible with polar organic solvents.''The Merck index'', 14th ed.; O’Neil, Maryadele J., Ed.; Merck & Co., Inc.: Whitehouse Station, NJ, 2006; p. 9342.Robert Rippel "Mercaptoacetic Acid and Derivatives" in ''Ullmann's Encyclopedia of Industrial Chemistry'', 2012, Wiley-VCH, Weinheim. . Uses TGA is used as a chemical depilatory and is still used as such, especially in salt forms, including calcium thioglycolate and sodium thioglycolate. TGA is the precursor to ammonium thioglycolate, which is used for permanents. TGA and its derivatives break the disulfide bonds in the cortex of hair. One reforms these broken bonds in giving hair a "perm". Alternatively and more commonly, the process leads to depilation, as is done commonly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aryl Chloride
In organic chemistry, an aryl halide (also known as haloarene) is an aromatic compound in which one or more hydrogen atoms, directly bonded to an aromatic ring are replaced by a halide. The haloarene are different from haloalkanes because they exhibit many differences in methods of preparation and properties. The most important members are the aryl chlorides, but the class of compounds is so broad that there are many derivatives and applications. Preparation The two main preparatory routes to aryl halides are direct halogenation and via diazonium salts. Direct halogenation In the Friedel-Crafts halogenation, Lewis acids serve as catalysts. Many metal chlorides are used, examples include iron(III) chloride or aluminium chloride. The most important aryl halide, chlorobenzene is produced by this route. Monochlorination of benzene is always accompanied by formation of the dichlorobenzene derivatives. Arenes with electron donating groups react with halogens even in the absence of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agrochemical
An agrochemical or agrichemical, a contraction of ''agricultural chemical'', is a chemical product used in industrial agriculture. Agrichemical refers to biocides (pesticides including insecticides, herbicides, fungicides and nematicides) and synthetic fertilizers. It may also include hormones and other chemical growth agents. Agrochemicals are counted among speciality chemicals. Categories Biological action In most of the cases, agrochemicals refer to pesticides. *Pesticides ** Insecticides ** Herbicides ** Fungicides ** Algaecides ** Rodenticides ** Molluscicides ** Nematicides * Fertilisers * Soil conditioners * Liming and acidifying agents *Plant growth regulators Application method * Fumigants * Penetrant Ecology Many agrochemicals are toxic, and agrichemicals in bulk storage may pose significant environmental and/or health risks, particularly in the event of accidental spills. In many countries, use of agrichemicals is highly regulated. Government-issued permi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
