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Perfluorinated Compounds
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 of 5.5, it is one of the most acidic phenols. Uses Pentafluorophenol is used to prepare pentafluorophenyl esters, which are active esters useful in peptide synthesis. Environmental hazards Pentafluorophenol is considered hazardous because of oral, dermal and inhalation toxicity and because it causes severe skin burns and eye damage. References {{Reflist Fluoroarenes Perfluorinated compounds Phenols ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrofluorination
Electrochemical fluorination (ECF), or electrofluorination, is a foundational organofluorine chemistry method for the preparation of fluorocarbon-based organofluorine compounds.G. Siegemund, W. Schwertfeger, A. Feiring, B. Smart, F. Behr, H. Vogel, B. McKusick "Fluorine Compounds, Organic" in "Ullmann’s Encyclopedia of Industrial Chemistry" 2005, Wiley-VCH, Weinheim. The general approach represents an application of electrosynthesis. The fluorinated chemical compounds produced by ECF are useful because of their distinctive solvation properties and the relative inertness of carbon–fluorine bonds. Two ECF synthesis routes are commercialized and commonly applied: the Simons process and the Phillips Petroleum process. It is also possible to electrofluorinate in various organic media.Fred G. Drakesmith "Electrofluorination of Organic Compounds" Topics in Current Chemistry, Vol. 193, Springer, Berlin-Heidelberg, 1997. Prior to the development of these methods, fluorination with fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polytetrafluoroethylene
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene, and has numerous applications because it is chemically inert. The commonly known brand name of PTFE-based composition is Teflon by Chemours, a corporate spin-off, spin-off from DuPont (1802–2017), DuPont, which originally invented the compound in 1938. Polytetrafluoroethylene is a fluorocarbon solid, as it is a high-molecular-weight polymer consisting wholly of carbon and fluorine. PTFE is hydrophobic: neither water nor water-containing substances Wetting, wet PTFE, as fluorocarbons exhibit only small London dispersion forces due to the low polarizability, electric polarizability of fluorine. PTFE has one of the lowest Friction#Coefficient of friction, coefficients of friction of any solid. Polytetrafluoroethylene is used as a non-stick coating for Cookware and bakeware, pans and other Cookware and bakeware, cookware. It is Chemically inert, non-reactive, partly because of the strength of car ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrafluoroethylene
Tetrafluoroethylene (TFE) is a fluorocarbon with the chemical formula . It is a colorless gas. Its structure is . It is used primarily in the industrial preparation of fluoropolymers. It is the simplest perfluorinated alkene. It was first reported as "dicarbon tetrafluoride" in 1890. Properties Tetrafluoroethylene is a synthetic colorless, odorless gas that is insoluble in water. Like all unsaturated fluorocarbons, it is susceptible to nucleophilic attack. It is unstable towards decomposition to carbon and carbon tetrafluoride () and prone to form explosive peroxides in contact with air. Industrial use Polymerization of tetrafluoroethylene produces polytetrafluoroethylene (PTFE) polymers such as Teflon and Fluon. PTFE is one of the two fluorocarbon resins composed wholly of fluorine and carbon. The other resin composed purely of carbon and fluorine is the copolymer of TFE with typically 6–9% hexafluoropropene (HFP), which is known as FEP (fluorinated ethylene propylene c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichlorodifluoromethane
Dichlorodifluoromethane (R-12) is a colorless gas popularly known by the genericized brand name Freon (as Freon-12). It is a chlorofluorocarbon halomethane (CFC) used as a refrigerant and aerosol spray propellant. In compliance with the Montreal Protocol, its manufacture was banned in developed countries (non-article 5 countries) in 1996, and in developing countries (Article 5 countries) in 2010 out of concerns about its damaging effect on the ozone layer. Its only allowed usage is as a fire retardant in submarines and aircraft. It is soluble in many organic solvents. R-12 cylinders are colored white. Preparation It can be prepared by reacting carbon tetrachloride with hydrogen fluoride in the presence of a catalytic amount of antimony pentachloride: :CCl4 + 2HF → CCl2F2 + 2HCl This reaction can also produce trichlorofluoromethane (CCl3F), chlorotrifluoromethane (CClF3) and tetrafluoromethane (CF4). History Charles F. Kettering, vice president of General Motors Researc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Breathing
Liquid breathing is a form of Respiration (physiology), respiration in which a normally Atmosphere of Earth, air-breathing organism breathes an oxygen-rich liquid which is capable of CO2 gas exchange (such as a perfluorocarbon). The liquid involved requires certain physical properties, such as respiratory gas solubility, density, viscosity, vapor pressure and lipid solubility, which some perfluorocarbon, perfluorochemicals (PFCs) have. Thus, it is critical to choose the appropriate PFC for a specific biomedical application, such as liquid ventilation, drug delivery or blood substitutes. The physical properties of PFC liquids vary substantially; however, the one common property is their high solubility for respiratory gases. In fact, these liquids carry more oxygen and carbon dioxide than blood. In theory, liquid breathing could assist in the treatment of patients with severe human lung, pulmonary or human heart, cardiac trauma, especially in pediatric cases. Liquid breathing h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonography
Medical ultrasound includes diagnostic techniques (mainly imaging) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound. The usage of ultrasound to produce visual images for medicine is called medical ultrasonography or simply sonography, or echography. The practice of examining pregnant women using ultrasound is called obstetric ultrasonography, and was an early development of clinical ultrasonography. The machine used is called an ultrasound machine, a sonograph or an echograph. The visual image formed using this technique is called an ultrasonogram, a sonogram or an echogram. Ultrasound is composed of sound waves with frequencies greater than 20,000 Hz, which is the approximate upper threshold of human ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CT Scan
A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or radiology technologists. CT scanners use a rotating X-ray tube and a row of detectors placed in a gantry (medical), gantry to measure X-ray Attenuation#Radiography, attenuations by different tissues inside the body. The multiple X-ray measurements taken from different angles are then processed on a computer using tomographic reconstruction algorithms to produce Tomography, tomographic (cross-sectional) images (virtual "slices") of a body. CT scans can be used in patients with metallic implants or pacemakers, for whom magnetic resonance imaging (MRI) is Contraindication, contraindicated. Since its development in the 1970s, CT scanning has proven to be a versatile imaging technique. While CT is most prominently used in medical diagnosis, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to form images of the organs in the body. MRI does not involve X-rays or the use of ionizing radiation, which distinguishes it from computed tomography (CT) and positron emission tomography (PET) scans. MRI is a medical application of nuclear magnetic resonance (NMR) which can also be used for imaging in other NMR applications, such as NMR spectroscopy. MRI is widely used in hospitals and clinics for medical diagnosis, staging and follow-up of disease. Compared to CT, MRI provides better contrast in images of soft tissues, e.g. in the brain or abdomen. However, it may be perceived as less comfortable by patients, due to the usually longer and louder measurements with the subject in a long, confining tube, although ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contrast Medium
A contrast agent (or contrast medium) is a substance used to increase the contrast of structures or fluids within the body in medical imaging. Contrast agents absorb or alter external electromagnetism or ultrasound, which is different from radiopharmaceuticals, which emit radiation themselves. In X-ray imaging, contrast agents enhance the radiodensity in a target tissue or structure. In magnetic resonance imaging (MRI), contrast agents shorten (or in some instances increase) the relaxation times of nuclei within body tissues in order to alter the contrast in the image. Contrast agents are commonly used to improve the visibility of blood vessels and the gastrointestinal tract. The types of contrast agent are classified according to their intended imaging modalities. Radiocontrast media For radiography, which is based on X-rays, iodine and barium are the most common types of contrast agent. Various sorts of iodinated contrast agents exist, with variations occurring between the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perfluorooctyl Bromide
Perflubron (INN/ USAN, or perfluorooctyl bromide; brand name Imagent) is a contrast medium for magnetic resonance imaging, computer tomography and sonography. It was approved for this use in the United States by the Food and Drug Administration in 1993. Experimental research Perflubron has also been tested experimentally for use in liquid breathing Liquid breathing is a form of Respiration (physiology), respiration in which a normally Atmosphere of Earth, air-breathing organism breathes an oxygen-rich liquid which is capable of CO2 gas exchange (such as a perfluorocarbon). The liquid in ... in premature infants with respiratory distress. References MRI contrast agents Orphan drugs Chlorofluoroalkanes {{pharma-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentafluoroethyl Iodide
Pentafluoroethyl iodide is a suggested component of a fire-extinguishing composition.US patent application 20010048094 It is a very dense gas. Production Pentafluoroethyl iodide can be produced by electrochemical fluorination of 1,1,2,2-tetrafluoro-1,2-diiodoethane. : It can also be produced by react tetrafluoroethylene, iodine and iodine pentafluoride. : Properties Pentafluoroethyl iodide is a pungent colourless gas and an anesthetic An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia — in other words, to result in a temporary loss of sensation or awareness. They may be divided into t .... Uses Pentafluoroethyl iodide is an intermediate of preparing other compounds.Google PatentsUS3351671A - Preparation of pentafluoroiodoethane - Google Patents retrieved 7 January 2019.Google PatentsUS20080200735A1 - Catalyst for the synthesis of CF3I and CF3CF2I - Google Patents retrieved 7 Janua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
