|
Organoarsenic
Organoarsenic chemistry is the chemistry of compounds containing a chemical bond between arsenic and carbon. A few organoarsenic compounds, also called "organoarsenicals," are produced industrially with uses as insecticides, herbicides, and fungicides. In general these applications are declining in step with growing concerns about their impact on the environment and human health. The parent compounds are arsane and arsenic acid. Despite their toxicity, organoarsenic biomolecules are well known. History 140px, Cacodyl (tetramethyldiarsine) was one of the first organoarsenic compounds. Surprising for an area now considered of minor importance, organoarsenic chemistry played a prominent role in chemistry's history. The oldest known organoarsenic compound, the foul smelling cacodyl was reported in "cacodyl" (1760) and is sometimes classified as the first synthetic organometallic compound. The compound Salvarsan was one of the first pharmaceuticals, earning a Nobel prize for Paul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organometallic Compound
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide ( metal carbonyls), cyanide, or carbide, are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term " metalorganic compound" refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. Metal β-diketonates, alkoxides, dialkylamides, and metal phosphine complexes are r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salvarsan
Arsphenamine, also known as Salvarsan or compound 606, is an antibiotic drug that was introduced at the beginning of the 1910s as the first effective treatment for the deadly infectious diseases syphilis, relapsing fever, and African trypanosomiasis. This organoarsenic compound was the first modern antimicrobial agent. History Arsphenamine was first synthesized in 1907 in Paul Ehrlich's lab by Alfred Bertheim. The antisyphilitic activity of this compound was discovered by Sahachiro Hata in 1909, during a survey of hundreds of newly synthesized organic arsenical compounds. Ehrlich had theorized that by screening many compounds, a drug could be discovered that would have anti-microbial activity but not kill the human patient. Ehrlich's team began their search for such a " magic bullet" among chemical derivatives of the dangerously toxic drug atoxyl. Arsphenamine was used to treat the disease syphilis because it is toxic to the bacterium ''Treponema pallidum'', a spirochete tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenic
Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is notoriously toxic. It occurs naturally in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. It has various Allotropes of arsenic, allotropes, but only the grey form, which has a metallic appearance, is important to industry. The primary use of arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is also a common n-type dopant in semiconductor electronic devices, and a component of the III–V compound semiconductor gallium arsenide. Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining with the increasing recognition of the persistent tox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cacodyl
Cacodyl, also known as dicacodyl or tetramethyldiarsine, (CH3)2As–As(CH3)2, is an organoarsenic compound that constitutes a major part of " Cadet's fuming liquid" (named after the French chemist Louis Claude Cadet de Gassicourt). It is a poisonous oily liquid with an extremely unpleasant garlicky odor. Cacodyl undergoes spontaneous combustion in dry air. Cacodyl is also the name of the functional group or radical (CH3)2As. Preparation A mixture of dicacodyl and cacodyl oxide ((CH3)2As–O–As(CH3)2) was first prepared by Cadet by the reaction of potassium acetate with arsenic trioxide. A subsequent reduction yields a mixture of several methylated arsenic compounds including dicacodyl. The global reaction (mass balance) corresponding to the oxide formation is the following: : A more efficient synthesis was later developed which started from the dimethyl arsine chloride and dimethyl arsine: : History Robert Wilhelm Bunsen coined the name kakodyl (later modified to cacodyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyldichloroarsine
Methyldichloroarsine, sometimes abbreviated "MD" and also known as methyl Dick, is an organoarsenic compound with the formula CH3AsCl2. This colourless volatile liquid is a highly toxic vesicant that has been used in chemical warfare. History German chemists weaponized methyldichloroarsine during World War I, between 1917 and 1918. It was the first organoarsenic compound to be weaponized. Structure, synthesis, reactivity Focusing on the arsenic center, the molecule geometry is trigonal pyramidal with the Cl-As-Cl and C-As-Cl angles approaching 90° (see image). Virtually all related arsenic(III) compounds adopt similar structures. Methyldichloroarsine is produced by the reaction of methylmagnesium chloride and arsenic trichloride: :AsCl3 + CH3MgCl → CH3AsCl2 + MgCl2 Typically such syntheses are conducted in ether or THF solutions and typically the product is isolated by distillation. Use of larger amounts of the magnesium reagent affords greater amounts of dimeth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bechamp Reaction
In organic synthesis the Béchamp reaction is used for producing arsonic acids from activated aromatic substrates. The reaction is an electrophilic aromatic substitution, using arsenic acid as the electrophile. The reaction proceeds according to this idealized stoichiometry for the preparation of arsanilic acid: : Reaction scope The reaction was first reported in 1863 by Antoine Béchamp. It is very analogous to the sulfonation of arenes. The Béchamp reaction was employed in the Nobel Prize The Nobel Prizes ( ; ; ) are awards administered by the Nobel Foundation and granted in accordance with the principle of "for the greatest benefit to humankind". The prizes were first awarded in 1901, marking the fifth anniversary of Alfred N ...-winning work on organoarsenicals by Paul Erlich. In one commercial application, the Béchamp reaction is reaction is used to produce roxarsone, which exhibits an anticoccidial action and promotes growth in animals. Further reading * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cacodylic Acid
Cacodylic acid is an organoarsenic compound with the formula (CH3)2 AsO2H. With the formula R2As(O)OH, it is the simplest of the arsinic acids. It is a colorless solid that is soluble in water. Neutralization of cacodylic acid with base gives cacodylate salts, e.g. sodium cacodylate. They are potent herbicides. Cacodylic acid/sodium cacodylate is a buffering agent in the preparation and fixation of biological samples for electron microscopy and in protein crystallography. History In the 18th century it was found that combining arsenic trioxide () and four equivalents of potassium acetate () gives a product called " Cadet's fuming liquid" which contains cacodyl oxide, and cacodyl, . Early research into "cacodyls" was reported by Robert Bunsen at the University of Marburg. Bunsen said of the compounds, "The smell of this body produces instantaneous tingling of the hands and feet, and even giddiness and insensibility... It is remarkable that when one is exposed to the sme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsane
Arsine (IUPAC name: arsane) is an inorganic compound with the formula As H3. This flammable, pyrophoric, and highly toxic pnictogen hydride gas is one of the simplest compounds of arsenic. Despite its lethality, it finds some applications in the semiconductor industry and for the synthesis of organoarsenic compounds. The term ''arsine'' is commonly used to describe a class of organoarsenic compounds of the formula AsH3−''x''R''x'', where R = aryl or alkyl. For example, As(C6H5)3, called triphenylarsine, is referred to as "an arsine". General properties In its standard state arsine is a colorless, denser-than-air gas that is slightly soluble in water (2% at 20 °C) and in many organic solvents as well. Arsine itself is odorless, but it oxidizes in air and this creates a slight garlic or fish-like scent when the compound is present above 0.5 ppm. This compound is kinetically stable: at room temperature it decomposes only slowly. At temperatures of ca. 230 °C, decompo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsinic Acids
Arsinic acids are organoarsenic compounds with the formula R2AsO2H. They are formally, but not actually, related to arsinic acid, a hypothetical compound of the formula H2AsO2H. Arsinic acids are monoprotic, weak acids. They react with sodium sulfide to give the dithioarinates R2AsS2Na. Arsinic acids are related to phosphinic acids (R2PO2H.). Well known arsinic acids include diphenylarsinic acid and cacodylic acid Cacodylic acid is an organoarsenic compound with the formula (CH3)2 AsO2H. With the formula R2As(O)OH, it is the simplest of the arsinic acids. It is a colorless solid that is soluble in water. Neutralization of cacodylic acid with base gives ca ..., R2AsO2H (R = Ph, Me, respectively). References {{Reflist Organoarsenic compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4-Hydroxy-3-nitrobenzenearsonic Acid
Roxarsone is an organoarsenic compound that has been used in poultry production as a feed additive to increase weight gain and improve feed efficiency, and as a coccidiostat. As of June 2011, it was approved for chicken feed in the United States, Canada, Australia, and 12 other countries. The drug was also approved in the United States and elsewhere for use in pigs. Its use in the United States was voluntarily ended by the manufacturers in June 2011 and has been illegal since 2013. Its use was immediately suspended in Malaysia. It was banned in Canada in August 2011. In Australia, its use in chicken feed was discontinued in 2012. Roxarsone has been banned in the European Union since 1999. Production and applications Roxarsone is a derivative of phenylarsonic acid (C6H5As(O)(OH)2). It was first reported in a 1923 British patent that described the nitration and diazotization of arsanilic acid. When blended with calcite powder, it is used in poultry feed premixes in some parts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsanilic Acid
Arsanilic acid, also known as aminophenyl arsenic acid or aminophenyl arsonic acid, is an organoarsenic compound, an amino derivative of phenylarsonic acid whose amine group is in the 4-position. A crystalline powder introduced medically in the late 19th century as Atoxyl, its sodium salt was used by injection in the early 20th century as the first organic arsenical drug, but it was soon found prohibitively toxic for human use. Arsanilic acid saw long use as a veterinary feed additive promoting growth and to prevent or treat dysentery in poultry and swine. In 2013, its approval by US government as an animal drug was voluntarily withdrawn by its sponsors. Still sometimes used in laboratories, arsanilic acid's legacy is principally through its influence on Paul Ehrlich in launching the antimicrobial chemotherapy approach to treating infectious diseases of humans. Chemistry Synthesis was first reported in 1863 by Antoine Béchamp and became the basis of the Bechamp reaction. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
