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Pyrethrin
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 1900's and have been continually used since then in products such as bug bombs, bui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrethrin II
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 1900's and have bee ... [...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(triphenylphos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrethrum
''Pyrethrum'' was a genus of several Old World plants now classified as ''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 pyrethrums d ... [...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. It was here that he discovered the ketenes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrysanthemum
Chrysanthemums (), sometimes called mums or chrysanths, are flowering plants of the genus ''Chrysanthemum'' in the family Asteraceae. They are native to East Asia and northeastern Europe. Most species originate from East Asia and the center of diversity is in China.Liu, P. L., et al. (2012)Phylogeny of the genus ''Chrysanthemum'' L.: Evidence from single-copy nuclear gene and chloroplast DNA sequences.''PLOS One'' 7(11), e48970. . Countless horticultural varieties and cultivars exist. Description The genus ''Chrysanthemum'' are perennial herbaceous flowering plants, sometimes subshrubs. The leaves are alternate, divided into leaflets and may be pinnatisect, lobed, or serrate (toothed) but rarely entire. The compound inflorescence is an array of several flower heads, or sometimes a solitary head. The head has a base covered in layers of phyllaries. The simple row of ray florets is white, yellow, or red. The disc florets are yellow. Pollen grains are approximately 34 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrethroids
A pyrethroid is an organic compound similar to the natural pyrethrins, which are produced by the flowers of pyrethrums ('' Chrysanthemum cinerariaefolium'' and '' C. coccineum''). Pyrethroids are used as commercial and household insecticides. In household concentrations pyrethroids are generally harmless to humans. However, pyrethroids are toxic to insects such as bees, dragonflies, mayflies, gadflies, and some other invertebrates, including those that constitute the base of aquatic and terrestrial food webs. Pyrethroids are toxic to aquatic organisms, especially fish.Pyrethroids fact sheet from the Illinois Department of Public Health. They have been shown to be an effective control measure for malaria outbreaks, through indoor applications. Mode of action Pyrethr ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrysanthemum Cinerariifolium
''Tanacetum cinerariifolium'' is a species of flowering plant in the aster family, Asteraceae, and formerly part of the genus ''Pyrethrum'', but now placed in the genus ''Chrysanthemum'', or the genus ''Tanacetum'' by some biologists. It is called the Dalmatian chrysanthemum, denoting its origin in that region of Europe (Dalmatia). It looks more like the common daisy than other pyrethrums do. Its flowers, typically white with yellow centers, grow from numerous fairly rigid stems. Plants have blue-green leaves and grow to 45 to 100 cm (18 to 39 in) in height. As an insecticide The plant is economically important as a natural source of an insecticide called "pyrethrum." The flowers are pulverized and the active components, called pyrethrins, contained in the seed cases, are extracted and sold in the form of an oleoresin. This is applied as a suspension in water or oil, or as a powder. Pyrethrins attack the nervous systems of all insects, and inhibit female mosquitoes from bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agricultural Spray Adjuvant
Agricultural spray adjuvants are part of integrated pest management, and during pesticide application are used to enhance the effectiveness of pesticides, herbicides, insecticides, fungicides and other agents that control or eliminate unwanted pests. As with medical adjuvants, agricultural spray adjuvants are not themselves active in controlling or killing pests. Instead, these additives modify some property of the spray solution, which improves the ability of the pesticide to penetrate, target or protect the target organism. Among the typical types of ingredients used are surfactants, emulsifiers, oils and salts. Each of these ingredients, and others, modifies the spray solution itself to improve such properties as spreading, penetration, droplet size or other characteristics. These additives may be included in a formulation with a pesticide or may be added separately to a tank. When they are included in the pesticide formulations themselves, they are called ''in-can'' adjuvants. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chou Dynasty
The Zhou dynasty ( ; Old Chinese ( B&S): *''tiw'') was a royal dynasty of China that followed the Shang dynasty. Having lasted 789 years, the Zhou dynasty was the longest dynastic regime in Chinese history. The military control of China by the royal house, surnamed Ji, lasted initially from 1046 until 771 BC for a period known as the Western Zhou, and the political sphere of influence it created continued well into the Eastern Zhou period for another 500 years. The establishment date of 1046 BC is supported by the Xia–Shang–Zhou Chronology Project and David Pankenier, but David Nivison and Edward L. Shaughnessy date the establishment to 1045 BC. During the Zhou dynasty, centralized power decreased throughout the Spring and Autumn period until the Warring States period in the last two centuries of the dynasty. In the latter period, the Zhou court had little control over its constituent states that were at war with each other until the Qin state consolidated power and for ... [...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 org ... [...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 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 are of commercial or biological significance. 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 with sodium, causing an intramolecular Wurtz reaction leading directly to cyclopropane. The yield of the reaction was improved by Gustavson in 1887 with the use of zinc instead of sodium. Cyclopropane had no commercial application until Henderson and Lucas discovered its anaesthetic properties in 1929; industrial production had begun by 1936. In modern anaesthetic practice, it has been superseded by other agents. Anaesthesia Cyclopropane was introduced into cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
