Tetrachloroethane, reaction

Thermal Cracking. Thermal chlorination of ethylene yields the two isomers of tetrachloroethane, 1,1,1,2 and 1,1,2,2. Introduction of these tetrachloroethane derivatives into a tubular-type furnace at temperatures of 425—455°C gives good yields of trichloroethylene (33). In the cracking of the tetrachloroethane stream, introduction of ferric chloride into the 460°C vapor-phase reaction zone improves the yield of trichloroethylene product. 

The ultraviolet lamps used in the photochlorination process serve to dissociate the chlorine into free radicals and start the radical-chain reaction. Other radical sources, such as 2,2 -a2obisisobutyronitrile, have been used (63,64). Primary by-products of the photochlorination process include 1,1,2-trichloroethane (15—20%), tetrachloroethanes, and pentachloroethane. Selectivity to 1,1,1-trichloroethane is higher in vapor-phase chlorination. Various additives, most containing iodine or an aromatic ring in the molecule, have been used to increase the selectivity of the reaction to... 

From Acetylene. The acetjdene-based process consists of two steps. Eirst acetylene is chlorinated to 1,1,2,2-tetrachloroethane [79-34-5]. The reaction is exothermic (402 kJ/mol = 96 kcal/mol but is maintained at 80—90°C by the vaporization of solvent and product. Catalysts include ferric chloride and sometimes phosphoms chloride and antimony chloride (24). 

Oxychlorination of Ethylene or Dichloroethane. Ethylene or dichloroethane can be chlorinated to a mixture of tetrachoroethylene and trichloroethylene in the presence of oxygen and catalysts. The reaction is carried out in a fluidized-bed reactor at 425°C and 138—207 kPa (20—30 psi). The most common catalysts ate mixtures of potassium and cupric chlorides. Conversion to chlotocatbons ranges from 85—90%, with 10—15% lost as carbon monoxide and carbon dioxide (24). Temperature control is critical. Below 425°C, tetrachloroethane becomes the dominant product, 57.3 wt % of cmde product at 330°C (30). Above 480°C, excessive burning and decomposition reactions occur. Product ratios can be controlled but less readily than in the chlorination process. Reaction vessels must be constmcted of corrosion-resistant alloys. 

If phosphorus pentachloride is reacted with ammonium chloride in an inert solvent such as sym-tetrachloroethane, polymers will be formed by the following reaction... 

Ir. the second step, the diethylaminoethyl 2-chloro-4-aminobenzoate hydrochloride is prepared by refluxing equimolar proportions of the hydrochloride of (3-diethylaminoethanol in a suitable inert solvent such as a mixture of dry toluene and tetrachloroethane and the hydrochloride of 2-chloro-4-aminobenzoyl chloride until the reaction as indicated by the cessation of hydrogen chloride evolution is complete. The supernatant solvents are decanted from the reaction product which can be conveniently purified by crystallization from absolute ethanol. 

To cold diionyl chloride (1.31 g, 11 mmol) in an ice-water bath, pyridine (10 mL) is added slowly for 10 min to keep the reaction temperature low. The reaction medium is stirred for 30 min. Then, a mixture of isophdialic acid (0.41 g, 2.5 mmol) and terephdialic acid (0.41 g, 2.5 mmol) in pyridine (10 mL) is added slowly for 10-20 min to control the reaction temperature. The cooling badi is then removed and the reaction mixture is stirred at room temperature for 20 min. 2,2-Bis(4-hydroxyphenyl)propane (bisphenol-A, 1.14 g, 5 mmol) in pyridine (10 mL) is added all at once to the mixture, and the whole solution is heated to 80°C (bath temperature) for 4 h. The resulting viscous solution is diluted with pyridine and poured into methanol to precipitate the polymer, which is washed in boiling methanol and dried. The inherent viscosity of polymer is 2.2 dL/g (determined in 60/40 phenol-1.1.2.2-tetrachloroethane at 30°C)... 

In another study, P n.m.r. was used to follow the progress of the reaction between ammonium chloride and phosphorus pentachloride in yA/j-tetrachloroethane, and the mechanism of the reaction considered in some detail. The rate of hydrogen chloride evolution and changes in the... 

The traditional and most extensively used method of synthesis of chlorocyclophosphazenes [NPCl2] involves the reaction of finely ground ammonium chloride with phosphorus pentachloride in a high boiling solvent such as sym-tetrachloroethane. This reaction affords a mixture of cyclic and linear products from which the individual products have to be separated, usually by fractional distillation in high vacuum (1, 5,17,18,35-39), (Eq. 1) ... 

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]. 

Dihaloelimination has also been observed under partially aerobic conditions [274]. With cytochrome P-450CAM as a primary catalyst, dichloroelimination from hexa-, penta-, and 1,1,1,2-tetrachloroethane were catalyzed, and the products were PCE, TCE, and 1,1-DCE, respectively no reaction was observed with TeCA. Significant rates were observed for these reactions at 5% oxygen concentration. 

The metabolism of 1,1,1,2-tetrachloroethane (11.26), a representative aliphatic chlorohydrocarbon, provides an example of mechanistic ambiguity. When administered to mice, ca. 40-45% of the dose was excreted unchanged in the expired air, whereas ca. 30% and 4% of the dose was excreted in urine and feces as 2,2,2-trichloroethanol and 2,2,2-trichloroacetic acid, respectively [59]. Both Pathways a and b in Fig. 11.3, together with the redox reactions shown in Fig. 11.3, c, can explain these results. 

More general cases are encountered in the metabolism of a variety of ha-log enated hydrocarbon solvents and insecticides [58]. Examples include the dehydrochlorination of 1,1,2,2-tetrachloroethane to trichloroethylene in the mouse, and of DDT (l,l,l-trichloro-2,2-bis(4-chlorophenyl)ethane) to DDE (l,l-dichloro-2,2-bis(4-chlorophenyl)ethene) [58][77]. Glutathione transferases may be involved in some of these reactions. 

Thus hydrochloric acid is a derivative of chlorine. About 93% of it is made by various reactions including the cracking of ethylene dichloride and tetrachloroethane, the chlorination of toluene, fluorocarbons, and methane, and the production of linear alkylbenzenes. It is also a by-product of the reaction of phosgene and amines to form isocyanates. 

Azidoformic esters such as 342 react with Cgg in a [2-tl] addition (Scheme 4.70), if the temperature is high enough to induce the loss of nitrogen prior to addition, otherwise a [3-1-2] addition can be observed (Section 4.3.2) [172, 395, 397]. Typical conditions include heating of the mixture in solvents such as tetrachloroethane [395, 397, 398], chloronaphfhalene [397] or toluene [396] at 110-160 °C. These conditions also afford multiple addition products [172]. To avoid potential hazard during purification of the azido formiates, they were also generated in situ in one pot by the reaction of chloro-formic ester with sodium azide [396]. 

Flectrophilic addition of polychloroalkanes such as, e.g., chloroform or 1,1,2,2-tetrachloroethane to Cjq with AICI3 in a 100-fold excess gives the monoadduct with a 1,4-addition pattern (Scheme 8.12) [93, 94], The reaction proceeds via a CjqR cation (19, Scheme 8.12) that is stabilized by the coordination of a chlorine atom to the cationic center. The cation is trapped by Cl to give the product 20. The chloroalkyl fullerenes can be readily hydrolyzed to form the corresponding fullerenol 21. This fullerenol can be utilized as a proper precursor for the cation, which is easily obtained by adding triflic acid. The stability of CjqR is similar to tertiary alkyl cations such as the tert-butyl-cation [95],... 

Radical-chain processes that are usually operative in the auto-oxidation of free cod [73] can produce olefin oxygenation in some instances. This is the case of the reaction of [Ir(ri -CpO(cod)] (Cp = 3,5-(Me3Si)2Cp) [74] with dioxygen in tetrachloroethane (TCE) under reflux, where a free-radical chlorine-photosensitized oxidation gave two isomeric ketones (Eq. 18). 

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