From chlorinated hydrocarbon solvents

Owing to their low flammability and excellent degreasing properties, the chlorinated hydrocarbons are commonly used as solvents in the laboratory, office and industrial workplaces. These materials, however, are particularly susceptible to thermal or photochemical decomposition to phosgene in normal environments. 

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Polyearbonates were prepared by a two-phase eondensation of TCP with bisphenol S. They preeipitate from chlorinated hydrocarbon solvents such as DCM, TCM and DCE. According to bofli flie yield and the inherent viscosity ofthese polymers, the use of BTEAC as a phase-transfer catalyst, sodium hydroxide as a base and DCE as an organic solvent was suitable to prepare a polycondensate having a large molar mass and a high yield. 

Tetrachloroethane (TeCA) was the first chlorinated hydrocarbon solvent produced in large quantities before World War I [371]. It was used as a solvent for cellulose acetate, fat, waxes, greases, rubber, and sulfur. In a few cases, TeCA is used as a carrier or reaction solvent in manufacturing processes for other chemicals and as an analytical reagent for polymers [371]. TeCA was largely replaced by less toxic solvents after 1945. TeCA release in the United States varied from 44,000 pounds in 1988 to 66,000 pounds in 1991 [372]. 

Fractional Precipitation of Cellulose Triacetate. The reported partial or non-fractionation of cellulose triacetate from chlorinated hydrocarbons or acetic acid may be explained in terms of the polymer-solvent Interaction parameter x (1-11) The x values for cellulose triacetate-tetrachloroethane and cellulose triacetate-chloroform systems are reported (10,21) as 0.29 and 0.34 respectively. The lower values of x for such systems will result in a smaller or negative heat of mixing (AHm) and therefore partial or non-fractionation of the polymer in question results. 

Solvent dyes are dyes that are soluble in alcohols, chlorinated hydrocarbon solvents, or liquid ammonia, and there appears to be considerable promise in dyeing the difficult-to-dye synthetics, polyesters, polyacrylates, and triacetates, from such solutions. 

For PIPO, the time for complete conversion increased from 20 to 45 minutes. The silica-supported TEMPO system reported by Bolm et al.13 gave 74% conversion in 2 hours, whereas using the Anelli protocol (dichloromethane/bromide) this activity was already reached within 30 minutes. With homogeneous TEMPO, the differences were even more dramatic, i.e. complete conversion was reached within 10 minutes using the Anelli protocol,3 whereas only 45% conversion was observed in 2 hours under the chlorinated hydrocarbon solvent- and bromide-free conditions. 

In summary, we have developed a recyclable heterogeneous catalyst for the bleach oxidation of alcohols and polyols. In contrast to previously reported systems, neither a chlorinated hydrocarbon solvent nor a bromide cocatalyst is necessary to achieve good activity. Besides bleach-oxidation, PIPO is also effective in the CuCl/nitroxyl catalysed aerobic oxidation of benzyl alcohol. A further advantage of our system is that PIPO is readily prepared from inexpensive and commercially available raw materials. We believe that it will find wide application in organic synthesis. 

The polyimides derived from the dianhydrides had high Tg s of 238 to 466 °C and they were soluble in chlorinated hydrocarbon solvents. Because of their solubility, copolyimides containing the following acetylene substituted diamine monomere were readily prepared by homogeneous high temperature solution polycondensation in m-cresol. 

They may be differentiated from other chlorinated hydrocarbon compounds (e.g., solvents) by molecular weight. Organochlorine insecticides, by virtue of their cyclic structure, have molecular weights ranging from 291 to 545, whereas chlorinated hydrocarbon solvents and fumigants have molecular weights that generally are less than 236. 

Phosgene is widely used as a chemical intermediate. It is used in metallurgy and in the production of pesticides, herbicides, and many other compounds. It is a by-product of chloroform biotransformation and can be generated from some chlorinated hydrocarbon solvents under intense heats. Phosgene has been used as a chemical warfare agent. 

It is important to use sulfuric acid at this point to ensure efficient extraction. The sulfate salt of the alkaloid is more soluble in water and less soluble in organic solvents than the hydrochloride salt. In the ADH of other alkenes the preferred system is sulfuric acid/diethyl ether. However stilbene diol Is only sparingly soluble in diethyl ether, which necessitates the use of ethyl acetate. Chlorinated hydrocarbon solvents should be avoided since both alkaloid salts have appreciable solubility in them. When diethyl ether is used as the organic phase, not all of the reaction mixture dissolves in it, but the material that remains undissolved is derived solely from 4-methylmorpholine. 

The products of peracid oxidation of limonene have also been re-examined. Wylde and Teulon have shown that the best method for making pure cis-or trans- limonene 1,2-epoxides, a mixture of which is obtained by direct peracid oxidation in chlorinated hydrocarbon solvents, is to treat this mixture with hydrogen chloride in ether, when the two diaxial chlorohydrins (122) and (123) are obtained with practically no equatorially substituted isomers. Of these two isomers only (122) forms a p-nitrobenzoate, allowing (123) to be distilled from the residue. Treatment of the nitrobenzoate of (122) with methanolic potassium hydroxide now leads to the c/s-epoxide (120) similar treatment of... 

TiX4,n(3-cyanopyridine) (X = Cl or Br and n = 1 or 2) complexes have been prepared from their constituent molecules by mixing in a chlorinated hydrocarbon solvent. I.r. spectra suggest that, for the n = 2 complexes, the ligands are co-ordinated via the pyridine nitrogen only, but that when n — 1 the cyano-nitrogen is also involved. The complexes TiCl4L2 have been characterized, where L is a unidentate, aromatic Schiff base derived from benzaldehyde, anisaldehyde, or salicylaldehyde and amines such as aniline, 0-, m-, or p-toluidine or other substituted anilines. The electronic and i.r. spectra of these complexes are consistent with octahedral stereochemistry... 

Chlorinated hydrocarbon solvents are also pure materials but the routes to most of the important ones are fewer. Most are derived from methane, ethylene, hydrogen chloride and chlorine. The more important routes are shown in Table 1.4. 

Azides, both organic and inorganic, and some azo compounds can be heat- and shock-sensitive. Azides such as sodium azide can displace halide from chlorinated hydrocarbons such as dichloromethane to form highly explosive organic polyazides this substitution reaction is facilitated in solvents such as dimethyl sulfoxide (DMSO). 

The TP olefin elastomers are available in several grades having a room-temperature hardness from 60 Shore A to 60 Shore D. They have the lowest density of all the TPEs, and their cost is in the mid-range of the TPEs. Olefins flexibility remains down to — 5TC (- 60°F), and they are not brittle at 32°C (90°F). They are autoclavable and can be used up to 135°C (275°F) in air. These TPOs have good resistance to some acids and most bases. They are attacked by chlorinated hydrocarbon solvents. Olefin compounds rated V-0 by UL 94 are available. 

As with other electrophiles, halogenation can occur to give 1,2- or 1,4-addition product from conjugated dienes. When molecular bromine is used as the brominating agent in chlorinated hydrocarbon solvent, the 1,4-addition product dominates by 7 1 in the case of butadiene." ... 

There have been a number of subsitutions of chemicals in recent years, many of them driven by environmental concerns and regulations resulting from those concerns. One of the greater of these has been the substitution of hydrochloro-fluorocarbons (HCFCs) and hydrofluorocarbons (MFCs) for chlorofluorocarbons (Freons or CFCs) driven by concerns over stratospheric ozone depletion. Substitutions of nonhalogenated solvents, supercritical fluid carbon dioxide, and even water with appropriate additives for chlorinated hydrocarbon solvents will continue as environmental concerns over these solvents increase. 

Some contaminants can be removed from surfaces by solvents, which dissolve (take into solution) the contaminant. Polar solvents such as water and water-alcohol mixtures are used to dissolve ionic materials (salts) that are polar contaminants. Non-polar solvents such as the chlorinated hydrocarbon solvents are used to remove non-polar contaminants such as oil. Often there is a mixture of solvents used to dissolve both polar and non-polar contaminants. Solvents can vary greatly as to their ability to dissolve contaminants and their effectiveness needs to be determined by determining the solubility parameter (e.g. Kauri-Butanol value) for specific contaminants. 

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