Solvents halogenated hydrocarbons

In spite of some of the disadvantages of silica gel, it is a very useful sorbent. Most of the early work with silica gel use a single U-tube or a train of two or more U-tubes. The U-tubes held at least 10 g of silica gel and sometimes one arm of the tube held a desiccant to reduce humidity effects The commercial tubes now available contain 150 mg to 1.5 g of silica gel sealed in glass tubes. Silica 1 has been used for a wide range of organic solvents halogenated hydrocarbons and nitrogen dioxide Often chemicals collected on silica gel require analysis by HPLC or derivatization prior to analysis. 

Typical nonsieve, polar adsorbents are siUca gel and activated alumina. Kquilihrium data have been pubUshed on many systems (11—16,46,47). The order of affinity for various chemical species is saturated hydrocarbons < aromatic hydrocarbons = halogenated hydrocarbons < ethers = esters = ketones < amines = alcohols < carboxylic acids. In general, the selectivities are parallel to those obtained by the use of selective polar solvents in hydrocarbon systems, even the magnitudes are similar. Consequendy, the commercial use of these adsorbents must compete with solvent-extraction techniques. 

Aqueous mineral acids react with BF to yield the hydrates of BF or the hydroxyfluoroboric acids, fluoroboric acid, or boric acid. Solution in aqueous alkali gives the soluble salts of the hydroxyfluoroboric acids, fluoroboric acids, or boric acid. Boron trifluoride, slightly soluble in many organic solvents including saturated hydrocarbons (qv), halogenated hydrocarbons, and aromatic compounds, easily polymerizes unsaturated compounds such as butylenes (qv), styrene (qv), or vinyl esters, as well as easily cleaved cycHc molecules such as tetrahydrofuran (see Furan derivatives). Other molecules containing electron-donating atoms such as O, S, N, P, etc, eg, alcohols, acids, amines, phosphines, and ethers, may dissolve BF to produce soluble adducts. 

Halogenated hydrocarbons that are inexpensive sometimes are used alone or in blends with phosphate esters as fire-resistant hydrauHc fluids. Other halogenated fluids are used for oxygen-compressor lubricants, lubricants for vacuum pumps that are in contact with corrosive materials, solvent-resistant lubricants, and other lubricant appHcations where highly corrosive or reactive materials are being handled. 

At room temperature, HDPE is not soluble in any known solvent, but at a temperature above 80—100°C, most HDPE resins dissolve in some aromatic, aflphatic, and halogenated hydrocarbons. The solvents most frequently used for HDPE dissolution are xylenes, tetralin, decalin 1,2,4-trimethylbenzene, o-dichlorobenzene, and 1,2,4-ttichlorobenzene. 

Chemical Properties and Reactivity. LLDPE is a saturated branched hydrocarbon. The most reactive parts of LLDPE molecules are the tertiary CH bonds in branches and the double bonds at chain ends. Although LLDPE is nonreactive with both inorganic and organic acids, it can form sulfo-compounds in concentrated solutions of H2SO4 (>70%) at elevated temperatures and can also be nitrated with concentrated HNO. LLDPE is also stable in alkaline and salt solutions. At room temperature, LLDPE resins are not soluble in any known solvent (except for those fractions with the highest branching contents) at temperatures above 80—100°C, however, the resins can be dissolved in various aromatic, aUphatic, and halogenated hydrocarbons such as xylenes, tetralin, decalin, and chlorobenzenes. 

Explosible dusts can also be changed into mixtures which are no longer explosible by the addition of inert dusts (e.g., rock salt, sodium sulrate). In general, inert dust additions of more than 50 wt % are necessary here. It is also possible to replace flammable solvents and cleaning agents by nonflammable halogenated hydrocarbons or water, or flammable pressure transmission fluids by halocarbon oils. 

The chemical resistance of the linear polymers is also very good. Resistant to most acids, aqueous bases, hydrocarbons, most halogenated hydrocarbons, alcohols and phenols, they are attacked by concentrated sulphuric acid, formic acid, some amines, benzaldehyde, nitromethane and a few other reagents. They will dissolve in 1-chloronaphthalene at elevated temperatures but in general have excellent solvent resistance. The polymer is cross-linked by air oxidation at elevated temperatures. 

Chemical compounds manufactured at petrochemical plants include methanol, formaldehyde, and halogenated hydrocarbons. Formaldehyde is used in the manufacture of plastic resins, including phenolic, urea, and melamine resins. Halogenated hydrocarbons are used in the manufacture of silicone, solvents, refrigerants, and degreasing agents. 

Compounds that Cause Kidney Damage Several drugs and some anesthetic compounds such as methoxyflurane cause kidney damage when present at high doses. Kidney-toxic compounds found in occupational environments include mycotoxins, halogenated hydrocarbons, several metals, and solvents (see Table 5.16). 

Compounds Affecting Rq>roduction Compounds that can affect reproductive function include several drugs and occupationally important chemicals such as solvents and pesticides as well as a number of environmentally relevant com-fxrunds. A group of chemical compounds that has received much attention recently is endocrine disrupters, many of which are halogenated hydrocarbons, e.g., PCBs. These are known to induce feminization in fish and other animal species.1.5/ There is intense debate about the significance of these compounds to human health. Tobacco smoke and ethyl alcohol also have major effects on human reproduction, the effects of alcohol being especially important. Table 5.17 lists compounds that may disturb the functions of female and male reproductive functions. 

Volatile solvents are fluids or gases contained in a wide variety of products (e.g., gasoline, paint thinner, butane gas) that have significant concentrations of aliphatic, aromatic, or halogenated hydrocarbons, which vaporize at room temperature. Because of their rapid absorption in the lungs, volatile solvents exert a rapid intoxicating effect. 

Hoffmaim P, Heinroth K, Richards D, et al. 1994. Depression of calcium dynamics in cardiac myoc54es - a common mechanism of halogenated hydrocarbon anesthetics and solvents. J Mol Cell Cardiol 26 579-589. 

Schnaak et al. [4] Polychlorinated terphenyls, naphthalenes, chloropesticides, halogenated hydrocarbon solvents, aromatic hydrocarbon solvents (BTEX), chlorobenzenes, poly aromatic hydrocarbons (EPA 610), phenols, chlorophenols, phthalates, petroleum hydrocarbons, LAS and nonylphenol (NP), organotin compounds and 2,4-dichloroaniline 1 pg/kg to 10 mg/kg for chlorine-contained compounds 10 pg/kg to 1 g/kg for solvent and phenols 1 mg/kg to 10 g/kg for EPA610, DEHP, LAS, and mineral oils Sewage sludge... 

Polymers having average Molecular weight of 15000 are sticky viscous liquids but those with Molecular weight 1,00,000 to 2,00,000 are rubber like. It is soluble in hydrocarbon and halogenated hydrocarbon solvents at room temperature. It is largely used as adhesive, for fibre and paper coating, etc. 

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