Halogenated hydrocarbons methylene chloride

Causes of acute chemical hepatitis include exposure to industrial solvents such as halogenated hydrocarbons (methylene chloride, trichloroethylene, and trichloroethane) carbon tetrachloride (only rarely encountered in modem industry) and dimethylformamide, dinitropropane, and di-methylacetamide. The jet and rocket fuel components hydrazine and monomethylhydrazine are also potent hepatotoxins. 

The range of solvents used can be subdivided into four main categories oxygenates (primarily ketones, alcohols and esters, but also ethers and glycol ethers) hydrocarbons (mainly aromatics such as toluene, but also some aliphatics) halogenates (primarily methylene chloride) and those containing a heteroatom (such as dimethyl sulphoxide, dimethylformamide and pyridine). 

Soluble in alcohol, ether (Weast, 1986), and many low molecular weight hydrocarbons (pentane, hexane, heptane), and halogenated hydrocarbons such as chloroform, methylene chloride, trichloroethylene. 

Isotactic Polystyrene. The familiar steam molding of pre-expanded particles has so far not been applied successfully to isotactic polystyrene. However, the polymer has been foamed, according to three disclosed methods. For example, finely divided acetone-insoluble polymer, with a melting point in excess of 200°C., is blended with a liquid selected from methylene chloride, aromatic hydrocarbons, or halogenated aromatic hydrocarbons. This blend is then heated (84). A mixture of molten polymer and methyl chloride, propane, or butane is suddenly depressurized (8). Foam may also be generated in a continuous manner directly from a butyllithium-initiated polymerization conducted in the presence of a 4/1 blend of benzene and petroleum ether (15). 

Workers come in contact with a large number of chemical substances in work areas, as does the general public. The commonly found chemical carcinogens are grouped under (1) polycyclic aromatic hydrocarbons (PAHs), (2) nitroso compounds, (3) halogenated hydrocarbons (solvents e.g., carbon tetrachloride, chloroform, trichloroethylene, and methylene chloride), (4) inorganic metals and minerals (beryllium, cadmium, nickel, cobalt, chromium, asbestos and arsenic), and (5) naturally occurring chemical substances (aflatoxins). 

Halogenated hydrocarbons. Several of these compounds are commonly used as solvents. Examples include carbon tetrachloride, chloroform, trichloroethylene, and methylene chloride. 

In the early 1980s, when it appeared that hexane was in short supply, Johnson et al. described a 56-h pilot plant extrachon of cottonseed using an alternative solvent, methylene chloride (dichloromethane) (158). This solvent extracted the oil and signihcantly reduced levels of the antinutrients gossypol and aflatoxin. However, because of environmental concerns, the commercial use of halogenated hydrocarbons in solvent extraction has not occurred. 

Silylated silica gel or low-activity (Grade III) silica gel are effective adsorbants, but even these can frequently cause decomposition of the very sensitive dioxetanes, even at — 50°C. In such cases Florisil can sometimes be useful. Eluant mixtures of halogenated hydrocarbons, for example, methylene chloride, carbon tetrachloride, fluorotrichloromethane (Freon-11), and alkanes, for example, -pentane, n-hexane, and cyclohexane, are quite effective and convenient, but their purity is critical, especially the absence of metal impurities. 

Solvents employed for such modified procedures must not affect the esterification reaction or the catalyst. Halogenated hydrocarbons are among the most interesting materials which have been used."- A process employing methylene chloride has achieved commercial use. This material is an excellent solvent for cellulose triacetate, and can be employed with low catalyst concentrations. A more unusual process is one using liquid sulfur dioxide as the esterification solvent. ... 

A blend of hydrocarbon and halogenated hydrocarbons has appeared recently in the patent literature (196). An example is a blend of pentane and methylene chloride in a weight ratio of about 50/50. 

Paints often contain solvents such as toluene, xylene, halogenated aromatic hydrocarbons, and methylene chloride, as well as heavy metals in their pigments including chromium yellow, lemon yellow (barium chromate), vermilion red (cadmium and mercuric sulfides), and flake white (lead). Both acute and chronic exposures to toluene and xylene are associated with neurotoxicity and can also damage the liver and kidneys. 

For the synthesis of 6,12-dihydro-6-hydroxy-cannabidiol as the intermediate in accordance with the invention the starting materials are the readily available olivetol (formula II) and cis-p-menth-2-ene-l,8-diol (formula III). The reaction is performed in a suitable solvent, aromatic hydrocarbons such as benzene and toluene, halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane and trichloroethane, ethers such as diethylether, diisopropylether and tetrahydrofuran having proved to be suitable. Furthermore it is possible to use mixtures of the said solvents. Toluene, benzene, methylene chloride and chloroform are the preferred solvents for use in the method of the invention. 

The dried polyarylsulfone (IV) is soluble in halogenated hydrocarbons such as chloroform, chlorobenzene, and methylene chloride. 

For methylene chloride or other halogenated lower hydrocarbons, a higher degree of sulfonation, equivalent to about 1.5 mg to 20 mg S03 per cm2 is desirable. On the... 

Halo-substituted unsaturated hydrocarbons behave like aromatic hydrocarbons towards saturated halides in the presence of aluminum chloride.93 Suitable acceptors are the halogen substitution products of ethylene in particular, chloromethanes, and best of all chloroform and methylene chloride... 

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