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Trimethylarsine
Trimethylarsine (abbreviated TMA or TMAs) is the chemical compound with the formula (CH3)3As, commonly abbreviated As Me3 or TMAs. This organic derivative of arsine has been used as a source of arsenic in microelectronics industry, a building block to other organoarsenic compounds, and serves as a ligand in coordination chemistry. It has distinct "garlic"-like smell. Trimethylarsine had been discovered as early as 1854. Structure and preparation AsMe3 is a pyramidal molecule. The As-C distances average 1.519 Å, and the C-As-C angles are 91.83° Trimethylarsine can be prepared by treatment of arsenic oxide with trimethylaluminium: :As2O3 + 1.5 lMe3sub>2 → 2 AsMe3 + 3/n (MeAl-O)n Occurrence and reactions Trimethylarsine is the volatile byproduct of microbial action on inorganic forms of arsenic which are naturally occurring in rocks and soils at the parts-per-million level. Trimethylarsine has been reported only at trace levels (parts per billion) in landfill gas from Germany, C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organoarsenic Compounds
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 the history of the field of chemistry. 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 Nobe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scheele's Green
Scheele's Green, also called Schloss Green, is chemically a cupric hydrogen arsenite (also called copper arsenite or acidic copper arsenite), . It is chemically related to Paris Green. Scheele's Green was invented in 1775 by Carl Wilhelm Scheele. By the end of the 19th century, it had virtually replaced the older green pigments based on copper carbonate. It is a yellowish-green pigment commonly used during the early to mid-19th century in paints as well as being directly incorporated into a variety of products as a colorant. It began to fall out of favor after the 1860s because of its toxicity and the instability of its color in the presence of sulfides and various chemical pollutants. The acutely toxic nature of Scheele's green as well as other arsenic-containing green pigments such as Paris Green may have contributed to the sharp decline in the popularity of the color green in late Victorian society. By the dawn of the 20th century, Scheele's green had completely fallen out o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organoarsenic Compound
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 the history of the field of chemistry. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentamethylarsenic
Pentamethylarsenic (or pentamethylarsorane)is an organometalllic compound containing five methyl groups bound to an arsenic atom with formula As(CH3)5. It is an example of a hypervalent compound. The molecular shape is trigonal bipyramid. History The first claim to make pentamethylarsenic was in 1862 in a reaction of tetramethylarsonium iodide with dimethylzinc by A. Cahours. For many years all the reproductions of this proved fruitless, so the production proved not to be genuine. It was actually discovered by Karl-Heinz Mitschke and Hubert Schmidbaur in 1973. Production Trimethylarsine is chlorinated to trimethylarsine dichloride, which then reacts with methyl lithium to yield pentamethylarsenic. :As(CH3)3 + Cl2 → As(CH3)3Cl2 :As(CH3)3Cl2 + 2LiCH3 → As(CH3)5 + 2LiCl Side products include As(CH3)4Cl and As(CH3)3=CH2. Pentamethylarsenic is not produced by biological organisms. Properties Pentamethylarsenic smells the same as pentamethylantimony, but is otherwise uniqu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microascus Brevicaulis
''Microascus brevicaulis'' is a microfungus in the Ascomycota. It is the teleomorph form of ''Scopulariopsis brevicaulis.'' ''Microascus brevicaulis'' occurs world-wide as a saprotroph in soil, a common agent of biodeterioration, an irregular plant pathogen, and an occasional agent of human nail infection. Name Most of the discussion of this fungus in the scientific and medical literature has referred to the fungus using the name of its asexual form, or anamorph, ''Scopulariopsis brevicaulis''. However, a sexual form (teleomorph) named ''Microascus brevicaulis'' was recently described. Under the current revision of '' International Code of Nomenclature for Algae, Fungi, and Plants'', as articulated in thShenzhen Code 2018 it remains unclear which name this fungus will ultimately take. Until further clarification, ''Microascus brevicaulis'' is considered the most recent, accepted name. Bartolomeo Gosio discovered in 1890 that under wet conditions ''M. brevicaulis'' produces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bartolomeo Gosio
Bartolomeo Gosio (17 March 1863 – 13 April 1944) was an Italian medical scientist. He discovered a toxic fume, eponymously named "Gosio gas", which is produced by microorganisms, that killed many people. He identified the chemical nature of the gas as an arsenic compound (arsine), but incorrectly named it as diethylarsine. He also discovered an antibacterial compound called mycophenolic acid from the mould '' Penicillium brevicompactum''. He demonstrated that the novel compound was effective against the deadly anthrax bacterium, ''Bacillus anthracis''. This was the first antibiotic compound isolated in pure and crystallised form. Though the original compound was abandoned in clinical practice due to its adverse effects, its chemical derivative mycophenolate mofetil became the drug of choice as an immunosuppressant in kidney, heart, and liver transplantations. Biography Gosio was born in Magliano Alfieri, Piedmont, Italy. His father Giacomo Gosio, a veterinarian, died just when ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenic
Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the gray 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 a common n-type dopant in semiconductor electronic devices. It is also 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 toxicity of arsenic and its compounds. A few species of bacteria are able to use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in rats, ham ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenic Trioxide
Arsenic trioxide, sold under the brand name Trisenox among others, is an inorganic compound and medication. As an industrial chemical, whose major uses include in the manufacture of wood preservatives, pesticides, and glass. As a medication, it is used to treat a type of cancer known as acute promyelocytic leukemia. For this use it is given by injection into a vein. Common side effects include vomiting, diarrhea, swelling, shortness of breath, and headaches. Severe side effects may include APL differentiation syndrome and heart problems. Use during pregnancy or breastfeeding may harm the baby. Arsenic trioxide has the formula . Its mechanism in treating cancer is not entirely clear. Arsenic trioxide was approved for medical use in the United States in 2000. It is on the World Health Organization's List of Essential Medicines. Approximately 50,000 tonnes are produced a year. Due to its toxicity, a number of countries have regulations around its manufacture and sale. Uses M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylarsine
Triphenylarsine is the chemical compound with the formula As(C6H5)3. This organoarsenic compound, often abbreviated As Ph3, is a colorless crystalline solid that is used as a ligand and a reagent in coordination chemistry and organic synthesis. The molecule is pyramidal with As-C distances of 1.942–1.956 Å and C-As-C angles of 99.6–100.5°. This compound is prepared by the reaction of arsenic trichloride with chlorobenzene using sodium as the reducing agent: :AsCl3 + 3 PhCl + 6 Na → AsPh3 + 6 NaCl Reactions Reaction of triphenylarsine with lithium gives lithium diphenylarsenide: :AsPh3 + 2 Li → LiAsPh2 + LiPh Triphenylarsine is the precursor to tetraphenylarsonium chloride, sPh4l, a popular precipitating agent. AsPh3 forms metal complexes with metals. Most are analogues of the corresponding triphenylphosphine derivatives. Examples include IrCl(CO)(AsPh3)2, RhCl(AsPh3)3, and Fe(CO)4(AsPh3). Tetraphenylarsonium chloride Tetraphenylarsonium chloride is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pigment
A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compounds. Pigments of prehistoric and historic value include ochre, charcoal, and lapis lazuli. Economic impact In 2006, around 7.4 million tons of inorganic, organic, and special pigments were marketed worldwide. Estimated at around US$14.86 billion in 2018 and will rise at over 4.9% CAGR from 2019 to 2026. The global demand for pigments was roughly US$20.5 billion in 2009. According to an April 2018 report by ''Bloomberg Businessweek'', the estimated value of the pigment industry globally is $30 billion. The value of titanium dioxide – used to enhance the white brightness of many products – was placed at $13.2 billion per year, while the color Ferrari red is valued at $300 million each year. Physical principles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrophoricity
A substance is pyrophoric (from grc-gre, πυροφόρος, , 'fire-bearing') if it ignites spontaneously in air at or below (for gases) or within 5 minutes after coming into contact with air (for liquids and solids). Examples are organolithium compounds and triethylborane. Pyrophoric materials are often water-reactive as well and will ignite when they contact water or humid air. They can be handled safely in atmospheres of argon or (with a few exceptions) nitrogen. Class D fire extinguishers are designated for use in fires involving pyrophoric materials. A related concept is hypergolicity, in which two compounds spontaneously ignite when mixed. Uses The creation of sparks from metals is based on the pyrophoricity of small metal particles, and pyrophoric alloys are made for this purpose. The sparking mechanisms in lighters and various toys, using ferrocerium; starting fires without matches, using a firesteel; the flintlock mechanism in firearms; and spark testing ferrou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
