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Perchloroethylene
Tetrachloroethylene, also known as perchloroethylene or under the systematic name tetrachloroethene, and abbreviations such as perc (or PERC), and PCE, is a chlorocarbon with the formula . It is a non-flammable, stable, colorless and heavy liquid widely used for dry cleaning of fabrics and occasionally as a highly effective automotive brake cleaner. It has a mildly sweet, sharp odor, detectable by most people at a concentration of 50 ppm. Tetrachloroethylene is regarded as a toxic substance, a human health hazard, and an environmental hazard. In 2020, the United States Environmental Protection Agency stated that "tetrachloroethylene exposure may harm the nervous system, liver, kidneys, and reproductive system, and may be harmful to unborn children", and reported that numerous toxicology agencies regard it as a carcinogen. History and production French chemist Henri Victor Regnault first synthesized tetrachloroethylene in 1839 by thermal decomposition of hexachloroethane fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dry Cleaning
Dry cleaning is any cleaning process for clothing and textiles using a solvent other than water. Clothes are instead soaked in a water-free liquid solvent (usually non-polar, as opposed to water which is a Solvent#Solvent classifications, polar solvent). Perchloroethylene (known in the industry as "perc") is the most commonly used solvent, although alternative solvents such as hydrocarbons, and decamethylcyclopentasiloxane are also used. Most natural fibers can be washed in water but some synthetics (e.g., viscose) react poorly with water and should be dry cleaned if possible. If not, this could result in changes in texture, strength, and shape. Additionally, certain specialty fabrics, including silk and rayon, may also benefit from dry cleaning to prevent damage. History The ancient Greeks and Romans had some waterless methods to clean textiles, involving the use of powdered chemicals and absorbent clay (fuller's earth). By the 1700s, the French were using turpentine-based s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brake Cleaner
Brake cleaner, often also called '' parts cleaner'', is a mostly colorless cleaning agent, mainly used for cleaning the brake disks, the engine compartment and underfloor of motor vehicles. An important feature is that the brake cleaner leaves no residue after the solvents evaporate.Explosionsschutz beim Umgang mit brennbaren Reinigern in der Kfz-Werkstatt (PDF; 762 kB).' Composition Chlorinated brake cleaners (often sold as non-flammable) use organochlorides like tetrachloroethylene and dichloromethane. Historically 1,1,1-Trichloroethane was used, sometimes together with Tetrachloroethylene. It was phased out because of its ozone-depleting nature. Non-chlorinated brake cleaners use hydrocarbons as a main component; it will either be a low-boiling aliphatic compound or higher-boiling hydrocarbon mixture. Aromatics like benzene, toluene or xylene may also be used. The hydrocarbons used are sometimes made by hydrogenation from naphtha. The lipophilic liquids dissolve fat-so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Ramsay
Sir William Ramsay (; 2 October 1852 – 23 July 1916) was a Scottish chemist who discovered the noble gases and received the Nobel Prize in Chemistry in 1904 "in recognition of his services in the discovery of the inert gaseous elements in air" along with his collaborator, John William Strutt, 3rd Baron Rayleigh, who received the Nobel Prize in Physics that same year for their discovery of argon. After the two men identified argon, Ramsay investigated other atmospheric gases. His work in isolating argon, helium, neon, krypton, and xenon led to the development of a new section of the periodic table. Early years Ramsay was born at 2 Clifton StreetGlasgow Post Office Directory 1852 in Glasgow on 2 October 1852, the son of civil engineer and surveyor, William C. Ramsay, and his wife, Catherine Robertson. The family lived at 2 Clifton Street in the city centre, a three-storey and basement Georgian townhouse. The family moved to 1 Oakvale Place in the Hillhead district in his ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexachlorobenzene
Hexachlorobenzene, or perchlorobenzene, is an aryl chloride and a six-substituted chlorobenzene with the molecular formula C6Cl6. It is a fungicide formerly used as a seed treatment, especially on wheat to control the fungal disease bunt. Its use has been banned globally under the Stockholm Convention on Persistent Organic Pollutants. Physical and chemical properties Hexachlorobenzene is a stable, white, crystalline chlorinated hydrocarbon. It is sparingly soluble in organic solvents such as benzene, diethyl ether and alcohol, but practically insoluble in water with no reaction. It has a flash point of 468 °F and it is stable under normal temperatures and pressures. It is combustible but it does not ignite readily. When heated to decomposition, hexachlorobenzene emits highly toxic fumes of hydrochloric acid, other chlorinated compounds (such as phosgene), carbon monoxide, and carbon dioxide. History Hexachlorobenzene was first known as "Julin's chloride of carbon" as it w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Tetrachloride
Carbon tetrachloride, also known by many other names (such as carbon tet for short and tetrachloromethane, also IUPAC nomenclature of inorganic chemistry, recognised by the IUPAC), is a chemical compound with the chemical formula CCl4. It is a non-flammable, dense, colourless liquid with a "sweet" chloroform-like odour that can be detected at low levels. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, an anthelmintic and a cleaning agent, but has since been phased out because of environmental and safety concerns. Exposure to high concentrations of carbon tetrachloride can affect the central nervous system and degenerate the liver and kidneys. Prolonged exposure can be fatal. Properties In the carbon tetrachloride molecule, four chlorine atoms are positioned symmetrically as corners in a tetrahedron, tetrahedral configuration joined to a central carbon atom by single covalent bonds. Because of this symmetric geometry, CCl4 is non-polar. methane, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorine
Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidizing agent, oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the revised Electronegativity#Pauling electronegativity, Pauling scale, behind only oxygen and fluorine. Chlorine played an important role in the experiments conducted by medieval Alchemy, alchemists, which commonly involved the heating of chloride Salt (chemistry), salts like ammonium chloride (sal ammoniac) and sodium chloride (common salt), producing various chemical substances containing chlorine such as hydrogen chloride, mercury(II) chloride (corrosive sublimate), and . However, the nature of fre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Michael Faraday
Michael Faraday (; 22 September 1791 – 25 August 1867) was an English chemist and physicist who contributed to the study of electrochemistry and electromagnetism. His main discoveries include the principles underlying electromagnetic induction, diamagnetism, and electrolysis. Although Faraday received little formal education, as a self-made man, he was one of the most influential scientists in history. It was by his research on the magnetic field around a Electrical conductor, conductor carrying a direct current that Faraday established the concept of the electromagnetic field in physics. Faraday also established that magnetism could Faraday effect, affect rays of light and that there was an underlying relationship between the two phenomena. the 1911 ''Encyclopædia Britannica''. He similarly discovered the principles of electromagnetic induction, diamagnetism, and the Faraday's laws of electrolysis, laws of electrolysis. His inventions of electric motor, electromagnetic rotar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexachloroethane
Hexachloroethane (perchloroethane) is an organochlorine compound with the chemical formula . Its structure is . It is a white or colorless solid at room temperature with a camphor-like odor. It has been used by the military in smoke compositions, such as base-eject smoke munitions ( smoke grenades). Hexachloroethane was discovered along with carbon tetrachloride by Michael Faraday in 1820. Faraday obtained it by chlorinating ethylene. Manufacture Chlorination of tetrachloroethylene at 100–140 °C with the presence of iron(III) chloride is the most commonly used commercial production method, however several other methods exist. A high purity form can be produced in a small scale by reacting chlorine together with barium carbide. In September 1997, it was reported as no longer being produced in the United States for commercial distribution, but was produced as a by-product of industrial chlorination process. : Applications Hexachloroethane has been used in the formulation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henri Victor Regnault
Henri Victor Regnault (21 July 1810 – 19 January 1878) was a French chemist and physicist best known for his careful measurements of the thermal properties of gases. He was an early thermodynamicist and was mentor to William Thomson in the late 1840s. He never used his first given name, and was known throughout his lifetime as Victor Regnault. Biography Born in Aix-la-Chapelle in 1810 (modern Aachen, Germany and at that time under French rule), he moved to Paris at the age of eight, following the death of his parents. There, he worked for an upholstery firm until he was eighteen. In 1830, he was admitted to the École Polytechnique, and in 1832 he graduated from the École des mines. Working under Justus von Liebig at Gießen, Regnault distinguished himself in the nascent field of organic chemistry by synthesizing several chlorinated hydrocarbons (e.g. vinyl chloride in 1835, dichloromethane and perchloroethylene in 1839, 1,1,1-Trichloroethane in 1838 or 1840), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemist
A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of matter and its properties. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms. Chemists carefully measure substance proportions, chemical reaction rates, and other chemical properties. In Commonwealth English, pharmacists are often called chemists. Chemists use their knowledge to learn the composition and properties of unfamiliar substances, as well as to reproduce and synthesize large quantities of useful naturally occurring substances and create new artificial substances and useful processes. Chemists may specialize in any number of Chemistry#Subdisciplines, subdisciplines of chemistry. Materials science, Materials scientists and metallurgists sha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carcinogen
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruses and bacteria. Most carcinogens act by creating mutations in DNA that disrupt a cell's normal processes for regulating growth, leading to uncontrolled cellular proliferation. This occurs when the cell's DNA repair processes fail to identify DNA damage allowing the defect to be passed down to daughter cells. The damage accumulates over time. This is typically a multi-step process during which the regulatory mechanisms within the cell are gradually dismantled allowing for unchecked cellular division. The specific mechanisms for carcinogenic activity is unique to each agent and cell type. Carcinogens can be broadly categorized, however, as activation-dependent and activation-independent which relate to the agent's ability to engage dir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toxicology
Toxicology is a scientific discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating exposures to toxins and toxicants. The relationship between dose and its effects on the exposed organism is of high significance in toxicology. Factors that influence chemical toxicity include the dosage, duration of exposure (whether it is acute or chronic), route of exposure, species, age, sex, and environment. Toxicologists are experts on poisons and poisoning. There is a movement for evidence-based toxicology as part of the larger movement towards evidence-based practices. Toxicology is currently contributing to the field of cancer research, since some toxins can be used as drugs for killing tumor cells. One prime example of this is ribosome-inactivating proteins, tested in the treatment of leukemia. The word ''toxicology'' () ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
