Tetrachloromethane toxicity

One of the chief uses of chloromethane is as a starting material from which sili cone polymers are made Dichloromethane is widely used as a paint stripper Trichloromethane was once used as an inhalation anesthetic but its toxicity caused it to be replaced by safer materials many years ago Tetrachloromethane is the starting mate rial for the preparation of several chlorofluorocarbons (CFCs) at one time widely used as refrigerant gases Most of the world s industrialized nations have agreed to phase out all uses of CFCs because these compounds have been implicated m atmospheric processes that degrade the Earth s ozone layer... 

Carbon tetrachloride [56-23-5] (tetrachloromethane), CCl, at ordinary temperature and pressure is a heavy, colorless Hquid with a characteristic nonirritant odor it is nonflammable. Carbon tetrachloride contains 92 wt % chlorine. When in contact with a flame or very hot surface, the vapor decomposes to give toxic products, such as phosgene. It is the most toxic of the chloromethanes and the most unstable upon thermal oxidation. The commercial product frequendy contains added stabilizers. Carbon tetrachloride is miscible with many common organic Hquids and is a powerhil solvent for asphalt, benzyl resin (polymerized benzyl chloride), bitumens, chlorinated mbber, ethylceUulose, fats, gums, rosin, and waxes. 

Tetrachloromethane has a higher viscosity than trichloromethane (leading to a greater pressure drop across the column). It is also toxic. 

The chlorofluorocarbon compounds of methane and ethane are collectively known as freons. They are extremely stable, unreactlve, non-toxic, non-corrosive and easily liquefiable gases. Freon 12 (CCI2F2) Is one of the most common freons In Industrial use. It Is manufactured from tetrachloromethane by Swarts reaction. These are usually produced for aerosol propellants, refrigeration and air conditioning purposes. By 1974, total freon production In the world was about 2 billion pounds annually. Most freon, even that used In refrigeration, eventually makes Its way Into the atmosphere where It diffuses unchanged Into the stratosphere. In stratosphere, freon Is able to Initiate radical chain reactions that can upset the natural ozone balance (Unit 14, Class XI). 

Tetrachloromethane (carbon tetrachloride, CC14) is a toxic industrial chemical with several natural sources (1). The solfataras and hydrothermal vents of Kamchatka... 

Note Nonpolar solvent soluble in alcohols, ethers, chloroform, benzene, and most fixed and volatile oils insoluble in water nonflammable extremely toxic by inhalation, ingestion, or skin absorption carcinogenic incompatible with allyl alcohol, silanes, triethyldialuminum, and many metals (e.g., sodium). Synonyms tetrachloromethane, perchloromethane, methane tetrachloride, Halon-104. 

BONE MEALS. These are particularly suitable for supplying phosphorus and lime to the soil. Bone meals are produced from bone waste from abattoirs. Before grinding they are treated with hot steam and the fat is removed. The fat should not be removed with tetrachloromethane or similar toxic substances, however. If it is, the bone meal is not suitable for use on organic crops. 

It has long been speculated, since the pioneering work of Muller in 1911 [1459], that phosgene may be an important intermediate in the toxicity of trichloromethane and tetrachloromethane. Experiments on rat liver microsomes have demonstrated that phosgene is generated when CHClj is metabolized both in vitro [1316,1631,1635,1636,1846] and in vivo... 

Dichloromethane (DCM), trichloroethene (TCE), tetrachloroethene (TeCE), chloroform, tetrachloromethane, and 1,2-dichIoroethane are nonflammable and powerful solvents for many compounds, and have uses such as cleaning of precision instruments, etc. Most of these solvents are harmfiil to living creatures, and therefore must be treated carefully and finally decomposed after use. The three major chemicals, DCM, TCE, and TeCE are annually produced at approximately 100 thousand tons/ year in Japan, much of which is not recovered and may be disposed of either in air, water, or soil. Ideally, these chemicals should be recovered after use. However, it is not economic when the chemicals are diluted or mixed with other materials and, therefore, the chemicals are often burned. This could produce toxic materials such as dioxin when the burning temperature is low. The reaction during the burning process is hydrolysis, which produces HCl that can cause corrosion of the reactor. 

Trichloromethane (or chloroform, CHCI3) is non-flammable and was used as an anaesthetic, before it was found to cause liver damage. Tetrachloromethane (or carbon tetrachloride, CCI4) also has anaesthetic properties, but it is even more toxic. Bromochlorotrifluoroethane (common name halothane) is now widely used. It also has anaesthetic properties and is much safer to use. 

The ionization potential of iodine is sufficiently low for it to form a number of compounds in which it is electropositive. It forms I cations, for example, by reaction of solid silver nitrate with iodine solution, and such cations are sufficiently electrophilic to substitute aromatic compounds such as phenol. Iodine also exhibits the interesting property of forming solutions that are violet colored in non-donor type solvents, such as tetrachloromethane, but in donor solvents, such as ethanol or dioxan, there is a strong iodine-solvent interaction, which gives the solution a deep brown color. Even though iodine solutions were commonly used as antiseptic agents, the element is classified as toxic, and care should be taken to avoid eye intrusions or excessive skin contact. 

Carbon tetrachloride (CCI4, tetrachloromethane) was once widely used as a dry cleaning solvent, degreaser, spot remover, fire extinguisher agent, and anthelmintic. Because of its liver toxicity and known carcinogenicity in animals, its role has become limited it is now used mainly as an intermediate in chemical manufacturing. 

Tetrachloromethane [56-23-5] (carbon tetrachloride, Tetra ), is a colorless, neutral, nonflammable liquid. It is toxic and forms phosgene, hydrogen chloride, and... 

Compared with MCDE, tetrachloromethane is also a good crosslinker with less toxicity. Hradil and Kralova reported a series of crosslinked resins with surface areas up to 1000 m g , which were obtained by post-crosslinking styrene-divinylbenzene eopolymer precursors with tetrachloromethane via a Friedel-Crafts reaction in the presence of aluminium or ferrie ehloride. 

The extracting solvent can be diethyl ether or carbon tetrachloride (tetrachloromethane). The former is advised in the method given here, because of its lower toxicity. ASTM Method D 4224-89 [3] is similar, but uses a 13.6% solution of the reagent, permits only carbon tetrachloride and directs that the initial extraction should be done by shaking for 10 min. It uses ortho-cresol red (o-cresol sulphonephthalein) as indicator, and adds the correction for extracted p-toluidine hydrochloride (step 10), which was not part of the original method. 

Caution The reagent tetrachloromethane and the by-product [ osgene are toxic and environmentally undesirable. 

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