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Methylmercury
Methylmercury is an organometallic cation with the formula . It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is a bioaccumulative environmental toxicant with a 50-day half-life. Methylmercury (derived biologically from dimethylmercury) is the causative agent of the infamous Minamata disease. Methylmercury is designated as a "priority hazardous substance" according to the Directive on Environmental Quality Standards (Directive 2013/39/EU). Structure and chemistry "Methylmercury" is a shorthand for the hypothetical "methylmercury cation", sometimes written ''methylmercury(1+) cation'' or ''methylmercury(II) cation''. This functional group is composed of a methyl group Chemical bond, bonded to an atom of Mercury (element), mercury. Its chemical formula is (sometimes written as ). The Methylmercury compound has an overall charge of +1, with Hg in the +2 oxidation state. Methylmer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethylmercury
Dimethylmercury is an extremely toxic organomercury compound with the formula ( CH3)2 Hg. A volatile, flammable, dense and colorless liquid, dimethylmercury is one of the strongest known neurotoxins. Less than 0.1 mL is capable of inducing severe mercury poisoning resulting in death. Synthesis, structure, and reactions The compound was one of the earliest organometallics reported, reflecting its considerable stability. The compound was first prepared by George Buckton in 1857 by a reaction of methylmercury iodide with potassium cyanide: : 2 CH3HgI + 2 KCN → Hg(CH3)2 + 2 KI + (CN)2 + Hg Later, Edward Frankland discovered that it could be synthesized by treating sodium amalgam with methyl halides: : Hg + 2 Na + 2 CH3I → Hg(CH3)2 + 2 NaI It can also be obtained by alkylation of mercuric chloride with methyllithium: : HgCl2 + 2 LiCH3 → Hg(CH3)2 + 2 LiCl The molecule adopts a linear structure with Hg–C bond lengths of 2.083 Å. Reactivity and physical propert ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minamata Disease
is a neurological disease caused by severe mercury poisoning. Signs and symptoms include ataxia, numbness in the hands and feet, general muscle weakness, loss of peripheral vision, and damage to hearing and speech. In extreme cases, insanity, paralysis, coma, and death follow within weeks of the onset of symptoms. A congenital form of the disease affects fetuses, causing microcephaly, extensive cerebral damage, and symptoms similar to those seen in cerebral palsy. Minamata disease was first discovered in the city of Minamata, Kumamoto Prefecture, Japan, in 1956. It was caused by the release of methylmercury in the industrial wastewater from a chemical factory owned by the Chisso Corporation, which continued from 1932 to 1968. It has also been suggested that some of the mercury sulfate in the wastewater was also metabolized to methylmercury by bacteria in the sediment. This highly toxic chemical bioaccumulated and biomagnified in shellfish and fish in Minamata Bay and th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury (element)
Mercury is a chemical element; it has Symbol (chemistry), symbol Hg and atomic number 80. It is commonly known as quicksilver. A Heavy metal element, heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature. Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is obtained by Mill (grinding), grinding natural cinnabar or synthetic mercuric sulfide. Exposure to mercury and mercury-containing organic compounds is toxic to the nervous system, immune system and kidneys of humans and other animals; mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury) either directly or through mechanisms of biomagnification. Mercu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ethylmercury
Ethylmercury (sometimes ethyl mercury) is a cation composed of an organic CH3CH2— species (an ethyl group) bound to a mercury(II) centre, making it a type of organometallic cation, and giving it a chemical formula C2H5Hg+. The main source of ethylmercury is thimerosal. Synthesis and structure Ethylmercury (C2H5Hg+) is a substituent of compounds: it occurs as a component of compounds of the formula C2H5HgX where X = chloride, thiolate, or another organic group. Most famously X = the mercaptide group of thiosalicylic acid as in thiomersal. In the body, ethylmercury is most commonly encountered as derivatives with a thiolate attached to the mercury. In these compounds, Hg(II) has a linear or sometimes trigonal coordination geometry. Given the comparable electronegativities of mercury and carbon, the mercury-carbon bond is described as covalent. Toxicity The toxicity of ethylmercury is well studied. Like methylmercury, ethylmercury distributes to all body tissues, crossi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organomercury
Organomercury chemistry refers to the study of organometallic compounds that contain mercury. Many organomercury compounds are highly toxic, but some are used in medicine, e.g., merbromin ("Mercurochrome") and the vaccine preservative thiomersal. Structure and bonding Most organomercury compounds feature diamagnetic Hg(II) and adopt a linear C-Hg-X structure. Indeed, no organic derivatives of Hg are known, as Hg requires electronegative subtituents for condensed-phase stability. Hg(II) derivatives are neither Lewis basic or Lewis acidic. They are stable to oxygen and water, indicating the low polarity of the Hg-C bond. Mercury forms a compound with two cyclopentadiene ligands, but the resulting complex may not be a metallocene. When made in the 1950s, it was too sensitive for structural determination. Toxicity The toxicity of organomercury compounds presents both dangers and benefits. Dimethylmercury in particular is notoriously toxic, but found use as an antifungal a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bioaccumulative
Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance faster than it can be lost or eliminated by catabolism and excretion. Thus, the longer the biological half-life of a toxic substance, the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high. Bioaccumulation, for example in fish, can be predicted by models. Hypothesis for molecular size cutoff criteria for use as bioaccumulation potential indicators are not supported by data. Biotransformation can strongly modify bioaccumulation of chemicals in an organism. Toxicity induced by metals is associated with bioaccumulation and biomagnification. Storage or uptake of a metal faster than it is metabolized and excreted leads to the accumulation of that metal. The presence of various chemicals and harmful substances in the environment can be analyzed and assessed with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrate
Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in water. An example of an insoluble nitrate is bismuth oxynitrate. Chemical structure The nitrate anion is the conjugate acid, conjugate base of nitric acid, consisting of one central nitrogen atom surrounded by three identically bonded oxygen atoms in a trigonal planar arrangement. The nitrate ion carries a formal charge of −1. This charge results from a combination formal charge in which each of the three oxygens carries a − charge, whereas the nitrogen carries a +1 charge, all these adding up to formal charge of the polyatomic nitrate ion. This arrangement is commonly used as an example of Resonance (chemistry), resonance. Like the isoelectronic carbonate ion, the nitrate ion can be represented by three resonance structures: Che ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfur
Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with the chemical formula S8. Elemental sulfur is a bright yellow, crystalline solid at room temperature. Sulfur is the tenth most abundant element by mass in the universe and the fifth most common on Earth. Though sometimes found in pure, native form, sulfur on Earth usually occurs as sulfide and sulfate minerals. Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India, ancient Greece, China, and ancient Egypt. Historically and in literature sulfur is also called brimstone, which means "burning stone". Almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum.. Downloahere Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thiol
In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl group, or a sulfanyl group. Thiols are the sulfur analogue of alcohols (that is, sulfur takes the place of oxygen in the hydroxyl () group of an alcohol), and the word is a blend of "''thio-''" with "alcohol". Many thiols have strong odors resembling that of garlic, cabbage or rotten eggs. Thiols are used as odorants to assist in the detection of natural gas (which in pure form is odorless), and the smell of natural gas is due to the smell of the thiol used as the odorant. Nomenclature Thiols are sometimes referred to as mercaptans () or mercapto compounds, a term introduced in 1832 by William Christopher Zeise and is derived from the Latin ('capturing mercury')''Oxford American Dictionaries'' (Mac OS X Leopard). because the thiolate grou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amino Acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 appear in the genetic code of life. Amino acids can be classified according to the locations of the core structural functional groups ( alpha- , beta- , gamma- amino acids, etc.); other categories relate to polarity, ionization, and side-chain group type ( aliphatic, acyclic, aromatic, polar, etc.). In the form of proteins, amino-acid '' residues'' form the second-largest component (water being the largest) of human muscles and other tissues. Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis. It is thought that they played a key role in enabling life on Earth and its emergence. Amino acids are formally named by the IUPAC- IUBMB Joint Commi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloride
The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pronunciation of the word "chloride" is . Chloride salts such as sodium chloride are often soluble in water.Green, John, and Sadru Damji. "Chapter 3." ''Chemistry''. Camberwell, Vic.: IBID, 2001. Print. It is an essential electrolyte located in all body fluids responsible for maintaining acid/base balance, transmitting nerve impulses and regulating liquid flow in and out of cells. Other examples of ionic chlorides include potassium chloride (), calcium chloride (), and ammonium chloride (). Examples of covalent chlorides include methyl chloride (), carbon tetrachloride (), sulfuryl chloride (), and monochloramine (). Electronic properties A chloride ion (diameter 167 pm) is much larger than a chlorine atom (diameter 99 pm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
