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Hexafluorobenzene
Hexafluorobenzene, HFB or perfluorobenzene is an organofluorine compound with the chemical formula . In this derivative of benzene, all hydrogen atoms have been replaced by fluorine atoms. The technical uses of the compound are limited, although it has some specialized uses in the laboratory owing to distinctive spectroscopic properties. Geometry of the aromatic ring Hexafluorobenzene stands somewhat aside in the perhalogenbenzenes. If a perhalogenated benzene ring were to remain planar, then geometric constraints would force adjacent halogens closer than their associated nonbonding radius. Consequently the benzene ring buckles, reducing ''p''-orbital overlap and aromaticity to avoid the steric clash. Perfluorobenzene is an exception: as shown in the following table, two fluorines are small enough to avoid collision, retaining planarity and full aromaticity. Synthesis The direct synthesis of hexafluorobenzene from benzene and fluorine has not been useful. Instead it is pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perfluorotoluene
Perfluorotoluene or octafluorotoluene is a chemical which belongs to the class of fluorocarbons, specifically a perfluorocarbon. Fluorocarbons and their derivatives are useful fluoropolymers, refrigerants, solvents, and anesthetics. More specifically, perfluorotoluene is a perfluoroaromatic compound, which is perfluorocarbon containing an aromatic ring. Other examples include hexafluorobenzene and octafluoronaphthalene. Perfluorotoluene is commonly used as industrial solvent and can be prepared by defluorination of perfluoromethylcyclohexane by heating to 500 °C with a nickel or iron catalyst Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick .... References {{reflist Fluorocarbons Halogenated solvents Coolants Trifluoromethyl compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentafluorothiophenol
Pentafluorothiophenol is an organosulfur compound with the formula . It is a colorless volatile liquid. The compound is prepared by the reaction of sodium hydrosulfide and hexafluorobenzene. With a p''K''a of 2.68, it is one of the most acidic thiols. Its conjugate base has been used as a ligand in coordination chemistry.Torrens, Hugo "Pentafluorobenzenethiolato derivatives of the platinum group metals" Coordination Chemistry Reviews, 2000, vol. 196, pp. 331-352. {{doi, 10.1016/S0010-8545(99)00055-7 Related compounds * Pentafluorophenol Pentafluorophenol is the organofluorine compound (specifically a fluoroalcohol) with the formula . This is the perfluorinated analogue of phenol. It is a white solid that melts just above room temperature, and smells of phenol. With a pKa, p''K''a ... References Thiols Fluoroarenes Foul-smelling chemicals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poise (unit)
The poise (symbol P; ) is the unit of dynamic viscosity (absolute viscosity) in the centimetre–gram–second system of units (CGS). It is named after Jean Léonard Marie Poiseuille (see Hagen–Poiseuille equation). The centipoise (1 cP = 0.01 P) is more commonly used than the poise itself. Dynamic viscosity has dimensions of \mathrm, that is, [\mathsf^1 \mathsf^ \mathsf^]. 1~\text = 0.1~\text^ \text \text^ = 1~\text^ \text \text^ = 1~\text \text \text^. The analogous unit in the SI, International System of Units is the pascal-second (Pa⋅s): 1~\text \text = 1~\text \text \text^ = 1~\text^ \text \text^ = 10~\text. The poise is often used with the metric prefix ''centi-'' because the viscosity of water at 20 °C (standard conditions for temperature and pressure) is almost exactly 1 centipoise. A centipoise is one hundredth of a poise, or one millipascal-second (mPa⋅s) in SI units (1 cP = 10−3 Pa⋅s = 1 mPa⋅s). The CGS symbol fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antimony Fluoride
Antimony fluoride may refer to either of the following: *Antimony trifluoride, SbF3 *Antimony pentafluoride Antimony pentafluoride is the inorganic compound with the formula Sb F5. This colorless, viscous liquid is a strong Lewis acid and a component of the superacid fluoroantimonic acid, formed upon mixing liquid HF with liquid SbF5 in 1:1 ratio. It ..., SbF5 {{Short pages monitor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Institute For Occupational Safety And Health
The National Institute for Occupational Safety and Health (NIOSH, ) is the List of United States federal agencies, United States federal agency responsible for conducting research and making recommendations for the prevention of work-related occupational injury, injury, occupational disease, illness, disability, and occupational fatality, death. Its functions include gathering information, conducting scientific research both in the laboratory and in the field, and translating the knowledge gained into products and services.About NIOSH National Institute for Occupational Safety and Health. Among NIOSH's programs are determination of recommended exposure limits for toxic chemicals and other hazards, field research such as the Health Hazard Evaluation Program, epidemiology and health surveillance programs such as the National Firefighter Re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MSDS
A safety data sheet (SDS), material safety data sheet (MSDS), or product safety data sheet (PSDS) is a document that lists information relating to occupational safety and health for the use of various substances and products. SDSs are a widely used type of fact sheet used to catalogue information on chemical species including chemical compounds and chemical mixtures. SDS information may include instructions for the safe use and potential hazards associated with a particular material or product, along with spill-handling procedures. The older MSDS formats could vary from source to source within a country depending on national requirements; however, the newer SDS format is internationally standardized. An SDS for a substance is not primarily intended for use by the general consumer, focusing instead on the hazards of working with the material in an occupational setting. There is also a duty to properly label substances on the basis of physico-chemical, health, or enviro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Central Nervous System Depression
Central nervous system depression (or CNS depression) is a nervous system disorder characterized by a severely impaired physiological state in which patients may exhibit decreased rate of breathing, decreased heart rate, and loss of consciousness; in extreme cases, CNS depression can possibly lead to coma or death. Causes Central nervous system depression is generally caused by the improper or excessive use of depressant drugs such as opioids, barbiturates, benzodiazepines, general anesthetics, anticonvulsants, and certain sleep medications. These drugs, although useful for treating severe cases of depression that may manifest as CNS depression, can easily be misused. The medications above depress the functions of the spinal cord and brain, both vital components of the central nervous system. In cases of misuse due to addiction, accidents, or unregulated dosage increases, individuals can very easily slip into unconscious coma states because neural activity drops below sa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skin Irritation
Irritation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant. Irritants are typically thought of as chemical agents (for example phenol and capsaicin) but mechanical, thermal (heat), and radiative stimuli (for example ultraviolet light or ionising radiations) can also be irritants. Irritation also has non-clinical usages referring to bothersome physical or psychological pain or discomfort. Irritation can also be induced by some allergic response due to exposure of some allergens for example contact dermatitis, irritation of mucosal membranes and pruritus. Mucosal membrane is the most common site of irritation because it contains secretory glands that release mucus which attracts the allergens due to its sticky nature. Chronic irritation is a medical term signifying that afflictive health conditions have been present for a while. There are many diso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
19F NMR
Fluorine-19 nuclear magnetic resonance spectroscopy (fluorine NMR or 19F NMR) is an analytical technique used to detect and identify fluorine-containing compounds. 19F is an important nucleus for NMR spectroscopy because of its Receptivity (NMR), receptivity and large chemical shift dispersion, which is greater than that for proton nuclear magnetic resonance spectroscopy. Operational details Fluorine-19, 19F has a nuclear spin (I) of and a high gyromagnetic ratio. Consequently, this isotope is highly responsive to NMR measurements. Furthermore, 19F comprises 100% of naturally occurring fluorine. The only other highly sensitive spin NMR-active nuclei that are monoisotopic (or nearly so) are 1H and 31P. Indeed, the 19F nucleus is the third most receptive NMR nucleus, after the 3H nucleus and 1H nucleus. The 19F NMR chemical shifts span a range of about 800 ppm. For ''organo''fluorine compounds the range is narrower, being about −50 to −70 ppm (for CF3 groups) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dewar Benzene
Dewar benzene (also spelled ''dewarbenzene'') or bicyclo .2.0exa-2,5-diene is a bicyclic isomer of benzene with the molecular formula C6H6. The compound is named after James Dewar who included this structure in a list of possible C6H6 structures in 1869. However, he did not propose it as the structure of benzene, and in fact he supported the correct structure previously proposed by August Kekulé in 1865. Structure and properties Unlike benzene, Dewar benzene is not flat because the carbons where the rings join are bonded to four atoms rather than three. These carbons tend toward tetrahedral geometry, and the two cyclobutene rings make an angle where they are '' cis''- fused to each other. The compound has nevertheless considerable strain energy and reverts to benzene with a chemical half-life of two days. This thermal conversion is relatively slow because orbital symmetries forbid it. Synthesis The compound itself was first synthesized in 1962 as a ''tert''-butyl derivative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyether
In organic chemistry, ethers are a class of compounds that contain an ether group, a single oxygen atom bonded to two separate carbon atoms, each part of an organyl group (e.g., alkyl or aryl). They have the general formula , where R and R′ represent the organyl groups. Ethers can again be classified into two varieties: if the organyl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group is the solvent and anaesthetic diethyl ether, commonly referred to simply as "ether" (). Ethers are common in organic chemistry and even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin. Structure and bonding Ethers feature bent linkages. In dimethyl ether, the bond angle is 111° and C–O distances are 141 pm. The barrier to rotation about the C–O bonds is low. The bonding of oxy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perfluoro
A perfluorinated compound (PFC) or perfluoro compound is an organofluorine compound that lacks C-H bonds. Many perfluorinated compounds have properties that are quite different from their C-H containing analogues. Common functional groups in PFCs are OH, CO2H, chlorine, O, and SO3H. Electrofluorination is the predominant method for PFC production. Due to their chemical stability, some of these perfluorinated compounds bioaccumulate. Applications One class of perfluorinated compounds, the fluorosurfactants, are widely used in the production of teflon (PTFE) and related fluorinated polymers. They also have been used to confer hydrophobicity and stain-resistance to fabrics. They are components of fire-fighting foam. Fluorosurfactants (PFAS) reduce surface tension by concentrating at the liquid-air interface due to the ''lipo''phobicity of polyfluorocarbons. Chlorofluorocarbons are also perfluorinated compounds, many of which were formerly used as refrigerants (Freon) until they w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
