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Pyrethrines
The pyrethrins are a class of organic compounds normally derived from ''Chrysanthemum cinerariifolium'' that have potent insecticidal activity by targeting the nervous systems of insects. Pyrethrin naturally occurs in chrysanthemum flowers and is often considered an organic insecticide when it is not combined with piperonyl butoxide or other synthetic adjuvants.Mader, Eric, and Nancy Lee Adamson. "Organic-Approved Pesticides."Organic-Approved Pesticides (n.d.): n. pag. The Xerxes Society. The Xerces Society for Invertebrate Conservation, Oct. 2012. Web. 10 Mar. 2015. Their insecticidal and insect-repellent properties have been known and used for thousands of years. Pyrethrins are gradually replacing organophosphates and organochlorides as the pesticides of choice as the latter compounds have been shown to have significant and persistent toxic effects to humans. They first appeared on markets in the 1900s and have been continually used since then in products such as bug bombs, bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrethrin
The pyrethrins are a class of organic compounds normally derived from ''Chrysanthemum cinerariifolium'' that have potent Insecticide, insecticidal activity by targeting the nervous systems of insects. Pyrethrin naturally occurs in chrysanthemum flowers and is often considered an organic horticulture, organic insecticide when it is not combined with piperonyl butoxide or other synthetic agricultural spray adjuvant, adjuvants.Mader, Eric, and Nancy Lee Adamson. "Organic-Approved Pesticides."Organic-Approved Pesticides (n.d.): n. pag. The Xerxes Society. The Xerces Society for Invertebrate Conservation, Oct. 2012. Web. 10 Mar. 2015. Their insecticidal and insect-repellent properties have been known and used for thousands of years. Pyrethrins are gradually replacing organophosphates and organochlorides as the pesticides of choice as the latter compounds have been shown to have significant and persistent toxic effects to humans. They first appeared on markets in the 1900s and have bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrethrum
''Pyrethrum'' was a genus of several Old World plants now classified in either '' Chrysanthemum'' or '' Tanacetum'' which are cultivated as ornamentals for their showy flower heads. Pyrethrum continues to be used as a common name for plants formerly included in the genus ''Pyrethrum''. Pyrethrum is also the name of a natural insecticide made from the dried flower heads of '' Chrysanthemum cinerariifolium'' and '' Chrysanthemum coccineum''. The insecticidal compounds present in these species are pyrethrins. Description Some members of the genus ''Chrysanthemum'', such as the following two, are placed in the genus '' Tanacetum'' instead by some botanists. Both genera are members of the daisy (or aster) family, Asteraceae. They are all perennial plants with a daisy-like appearance and white petals. * '' Tanacetum cinerariifolium'' is called the Dalmatian chrysanthemum, denoting its origin in that region of the Balkans (Dalmatia). It looks more like the common daisy than other py ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrysanthemic Acid
Chrysanthemic acid is an organic compound that is related to a variety of natural and synthetic insecticides. It is related to the pyrethrin I and II, as well as the pyrethroids. One of the four stereoisomers, (1''R'',3''R'')- or (+)-''trans''-chrysanthemic acid (pictured), is the acid part of the ester pyrethrin I, which occurs naturally in the seed cases of ''Chrysanthemum cinerariaefolium''. Many synthetic pyrethroids, for example the allethrins, are esters of all four stereoisomers. Staudinger and Ružička named chrysanthemic acid in 1924.H. Staudinger, L. Ružička: "Insektentotende Stoffe H. Zur Konstitution der Chrysanthemummonocarbonsiiure und -dicarbonsiiure", Helv. Chem. Acta 7 (1924) 201 Biosynthesis Chrysanthemic acid is derived from its pyrophosphate ester, which in turn is produced naturally from two molecules of dimethylallyl diphosphate. Industrial synthesis Chrysanthemic acid is produced industrially in a cyclopropanation reaction of a diene In or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopropane
Cyclopropane is the cycloalkane with the molecular formula (CH2)3, consisting of three methylene groups (CH2) linked to each other to form a triangular ring. The small size of the ring creates substantial ring strain in the structure. Cyclopropane itself is mainly of theoretical interest but many of its derivatives - cyclopropanes - are of commercial or biological significance. Cyclopropane was used as a clinical inhalational anesthetic from the 1930s through the 1980s. The substance's high flammability poses a risk of fire and explosions in operating rooms due to its tendency to accumulate in confined spaces, as its density is higher than that of air. History Cyclopropane was discovered in 1881 by August Freund, who also proposed the correct structure for the substance in his first paper. Freund treated 1,3-Dibromopropane, 1,3-dibromopropane with sodium, causing an intramolecular Wurtz reaction leading directly to cyclopropane. The yield of the reaction was improved by Gustavson ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Esters
In chemistry, an ester is a chemical compound, compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a Functional group#Groups containing oxygen , distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods. Esters can be formed from oxoa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrethrin II
Pyrethrin II is an organic compound that is a potent insecticide. It is one of the two pyrethrins, the other being pyrethrin I. Thousands of tons this mixture are produced annually from chrysanthemum plants, which are cultivated in warm climates.Robert L. Metcalf “Insect Control” in Ullmann’s Encyclopedia of Industrial Chemistry” Wiley-VCH, Weinheim, 2002. Structure and related compounds Whereas pyrethrin I is a derivative of (+)-''trans''- chrysanthemic acid, in pyrethrin II one methyl group is oxidized to a carboxymethyl group, the resulting core being called pyrethric acid. Knowledge of their chemical structures opened the way for the production of synthetic analogues, which are called pyrethroids. In terms of their biosynthesis, pyrethrins are classified as terpenoid The terpenoids, also known as isoprenoids, are a class of naturally occurring organic compound, organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrethrin I
Pyrethrin I is one of the two pyrethrins, natural organic compounds with potent insecticidal activity. It is an ester of (+)-''trans''- chrysanthemic acid with (''S'')-(''Z'')- pyrethrolone. Total synthesis The synthesis of pyrethrin I involves the esterification of (+)-''trans''-chrysanthemic acid with (S)-(Z)-pyrethrolone. One synthetic method for each of these is shown in the images below. Sobti and Dev of the Malti-Chem Research Centre in Nadesari, vadodara, India published this method for chrysanthemic acid in 1974. The starting material for the synthesis uses commercially available (+)-3α, 4α-epoxycarane (1). A lactone is eventually formed and the ring is opened by the use of a Grignard reagent to give (+)-trans-chrysanthemic acid. The preparation of (''S'')-pyrethrolone is essentially a 2 step synthesis. The starting material (S)-4-hydroxy-3-methyl-2-(2-propynyl)-2-cyclopenten-1-one (7) is also commercially available as the alcohol moiety of ETOC. Tetrakis(triphenylphosph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermann Staudinger
Hermann Staudinger (; 23 March 1881 – 8 September 1965) was a German organic chemist who demonstrated the existence of macromolecules, which he characterized as polymers. For this work he received the 1953 Nobel Prize in Chemistry. He is also known for his discovery of ketenes and of the Staudinger reaction. Staudinger, together with Leopold Ružička, also elucidated the molecular structures of pyrethrin I and II in the 1920s, enabling the development of pyrethroid insecticides in the 1960s and 1970s. Early work Staudinger was born in 1881 in Worms. Staudinger, who initially wanted to become a botanist, studied chemistry at the University of Halle, at the TH Darmstadt and at the LMU Munich. He received his "Verbandsexamen" (comparable to Master's degree) from TH Darmstadt. After receiving his Ph.D. from the University of Halle in 1903, Staudinger qualified as an academic lecturer at the University of Strasbourg in 1907. He was supported in his work by his new wife Dora ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Napoleonic Wars
{{Infobox military conflict , conflict = Napoleonic Wars , partof = the French Revolutionary and Napoleonic Wars , image = Napoleonic Wars (revision).jpg , caption = Left to right, top to bottom:Battles of Battle of Austerlitz, Austerlitz, Fall of Berlin (1806), Berlin, Battle of Friedland, Friedland, Battle of Aspern-Essling, Aspern-Essling, French occupation of Moscow, Moscow, Battle of Leipzig, Leipzig and Battle of Paris (1814), Paris , date = {{start and end dates, 1803, 5, 18, 1815, 11, 20, df=yes({{Age in years, months, weeks and days, month1=05, day1=18, year1=1803, month2=11, day2=20, year2=1815) , place = Atlantic Ocean, Caucasus, Europe, French Guiana, Mediterranean Sea, North Sea, West Indies, Ottoman Egypt, Egypt, East Indies. , result = Coalition victory , combatant1 = Coalition forces of the Napoleonic Wars, Coalition forces:{{flagcountry, United Kingdom of Great Britain and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Persian Powder
Persian powder is an insecticide powder with natural pyrethrin as the active agent. It is also known as Persian pellitory, insect powder and internationally as pyrethrum. Biological pest control Persian powder is a green pesticide that has been used for centuries for the biological pest extermination of household insects, garden pests, and agricultural pests.''Bioaromatica'The history of pyrethrum It may first have been exported from Persia to Ancient Rome. Pyrethrin and pyrethroids are used indoors, in gardens and the horticulture industry, and in agriculture. It is produced from the powdered flowers of certain species of pyrethrum, plants in the genera ''Chrysanthemum'' and '' Tanacetum''. In more recent times it has had formulations with brand names such as Zacherlin. Synthetic forms Pyrethroids are synthetic insecticides based on natural pyrethrum (pyrethrins), such as permethrin. A common formulation of pyrethrin is in preparations containing the synthetic chemic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
