Carbon tetrachloride, purification

Chlorinated by-products of ethylene oxychlorination typically include 1,1,2-trichloroethane chloral [75-87-6] (trichloroacetaldehyde) trichloroethylene [7901-6]-, 1,1-dichloroethane cis- and /n j -l,2-dichloroethylenes [156-59-2 and 156-60-5]-, 1,1-dichloroethylene [75-35-4] (vinyhdene chloride) 2-chloroethanol [107-07-3]-, ethyl chloride vinyl chloride mono-, di-, tri-, and tetrachloromethanes (methyl chloride [74-87-3], methylene chloride [75-09-2], chloroform, and carbon tetrachloride [56-23-5])-, and higher boiling compounds. The production of these compounds should be minimized to lower raw material costs, lessen the task of EDC purification, prevent fouling in the pyrolysis reactor, and minimize by-product handling and disposal. Of particular concern is chloral, because it polymerizes in the presence of strong acids. Chloral must be removed to prevent the formation of soflds which can foul and clog operating lines and controls (78). 

By-products from EDC pyrolysis typically include acetjiene, ethylene, methyl chloride, ethyl chloride, 1,3-butadiene, vinylacetylene, benzene, chloroprene, vinyUdene chloride, 1,1-dichloroethane, chloroform, carbon tetrachloride, 1,1,1-trichloroethane [71-55-6] and other chlorinated hydrocarbons (78). Most of these impurities remain with the unconverted EDC, and are subsequendy removed in EDC purification as light and heavy ends. The lightest compounds, ethylene and acetylene, are taken off with the HCl and end up in the oxychlorination reactor feed. The acetylene can be selectively hydrogenated to ethylene. The compounds that have boiling points near that of vinyl chloride, ie, methyl chloride and 1,3-butadiene, will codistiU with the vinyl chloride product. Chlorine or carbon tetrachloride addition to the pyrolysis reactor feed has been used to suppress methyl chloride formation, whereas 1,3-butadiene, which interferes with PVC polymerization, can be removed by treatment with chlorine or HCl, or by selective hydrogenation. 

Other options for the purification of CA include dissolution in hot water, aqueous ammonia, aqueous formaldehyde, or hot dimethylformamide followed by filtration to remove most of the impurities. The CA is recoverable by cooling the aqueous solution (84), acidifying the ammonium hydroxide solution (85), or cooling the dimethylform amide solution with further precipitation of CA by addition of carbon tetrachloride (86). Sodium hydroxide addition precipitates monosodium cyanurate from the formaldehyde solution (87). 

D. 3,3-Diahlarothietane 1,1-dioxide. Thietane 1,1-dioxide (5.0 g, 0.047 mol) Is placed In a 500-mL, three-necked, round-bottomed flask equipped with a reflux condenser, magnetic stirrer, and chlorine gas bubbler. Carbon tetrachloride (350 mL) Is added and the solution Is irradiated with a 250-watt sunlamp (Note 5) while chlorine Is bubbled through the stirred mixture for 1 hr (Note 9). Irradiation and chlorine addition are stopped and the reaction mixture is allowed to cool to room temperature. The product Is collected by filtration as a white solid (4.0-4.4 g, 49-53%), mp 156-158°C (Note 10). The product can be used without further purification or It can be recrystallized from chloroform. 

The present method offers several advantages over earlier methods. The use of carbon tetrachloride instead of diethyl ether as solvent avoids the intrusion of certain radical-chain reactions with solvent which are observed with bromine and to a lesser degree with chlorine. In addition, the potassium bromide has a reduced solubility in carbon tetrachloride compared to diethyl ether, thus providing additional driving force for the reaction and ease of purification of product. The selection of bro-... 

In a modified procedure the free carboxylic acid is treated with a mixture of mercuric oxide and bromine in carbon tetrachloride the otherwise necessary purification of the silver salt is thereby avoided. This procedure has been used in the first synthesis of [1.1.1 ]propellane 10. Bicyclo[l.l.l]pentane-l,3-dicarboxylic acid 8 has been converted to the dibromide 9 by the modified Hunsdiecker reaction. Treatment of 9 with t-butyllithium then resulted in a debromination and formation of the central carbon-carbon bond thus generating the propellane 10." ... 

Finally, the number of steps in the strigol synthesis could be reduced by the direct conversion of Xa to Xlla. To this end, Xa was treated with 1.2 equivalents of NBS in refluxing carbon tetrachloride under the irradiation of a 150-watt lamp. Purification of the crude product mixture by thin layer chromatography afforded two products Ila (27%) and the unanticipated bromoketone XV (31%). The reaction... 

Ethyl propiolate was used as received from Aldrich Chemical Company, Inc. (pure by 400 MHz 1H NMR analysis). Carbon tetrachloride was spectrophotometric grade and was used without purification. 

Rainbow trout (100-250 g) were purchased from Roaring River fish hatchery, Scio, Oregon and held under conditions previously described (11). Chlorobenzene (MCB) and carbon tetrachloride (CCI4) were obtained from commercial sources and used without further purification. Chlorobenzene was dissolved in an equal volume of com oil and administered as a single intra-peritoneal (i.p.) injection (either 0.5 or 1.0 ml/kg). Control animals received a similar volume of corn oil. Carbon tetrachloride was given undiluted by i.p. injection (0.2, 1.0, or 2.0 ml/kg) and control animals received a similar volume of physiological saline. 

Careful purification of a system has little effect for small and large drops and bubbles. Hence F reaches a maximum for a particular value of the abscissa and decreases to zero at large and small values of the abscissa. An envelope has been drawn to provide an estimate of the maximum increase in terminal velocity for bubbles and drops in pure systems over that for contaminated systems. This envelope, together with Eq. (7-10) and the correlation of the previous section, have been used to obtain the upper curve in Fig. 7.5 for carbon tetrachloride drops in water. The curve gives a good representation of the higher velocities observed for carefully purified systems. 

MnCl(CO)s begins to precipitate. After complete addition, the reaction mixture is allowed to warm to room temperature and is then stirred for 4 hours. The yellow precipitate is filtered in air and washed several times with carbon tetrachloride. The yield of crude product is 4.04 g (86%). The compound is contaminated with only small amounts of [MnCl(C0)4] 2 and white insoluble material. These impurities are negligible and usually no further purification is undertaken. If pure MnCl(CO)s is required, it is easily obtained by sublimation (40°/0.1 torr, yield 65%) [based on Mn2(CO)io]. Anal. Calcd. for MnCl(CO)s C, 26.06 Cl, 15.39. Found C, 26.08 Cl, 15.44. 

Carbon dioxide, 184, 358, 359 solid see Dry Ice Carbon disulphide, 767 purification of, 175 Carbon monoxide, 185, 1003, 1004 Carbon, decolourising, 127, 128 Carbon tetrachloride, 733, 815 drying of, 734 purification of, 176 Carbonyl chloride, 185 Carborundum chips, 4 Carboxylic acids, equivalent weights of, 1071 ... 

Ammonium tetrathiotungstate, octadecyltrimethylammonium bromide, anhydrous methanol and carbon tetrachloride were purchased from Aldrich Chemical, Co. and used without further purification. 

The checkers used tank chlorine obtained from the Ohio Chemical and Surgical Equipment Company, Detroit, Michigan. The gas was dried with concentrated sulfuric acid and used with no further purification. The rate of chlorine addition was regulated so that no chlorine escaped from the carbon tetrachloride solution. After 1.5-2.0 hours, 27-33 g. of chlorine was absorbed. The submitters generated chlorine by the action of concentrated hydrochloric acid on potassium permanganate. 

The crude 1,2,3-tribromopropane which remains after complete removal of the carbon tetrachloride weighs 418-420 g. It is almost pure and can be used for a number of reactions without further purification. 

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