Chloroform, purification

An alternative method of purification consists in dissolving the crude sulphonyl chloride in the minimum volume of boiling chloroform, transferring rapidly to a warm separatory funnel, and separating the lower chloroform layer upon cooling the chloroform solution, the crystalline sulphonyl chloride separates, and is collected by filtration with suction. A further quantity is obtained by concentrating the mother liquor. 

Syntheses of a,)3-dihalogenoethers can be achieved in various ways the classical method (37), wherein a current of dry gaseous hydrochloric acid, is made to react in an equimolar mixture of ethanol and aldehyde at 20°C first to form the monochloroether (50% yield) and then by the action of bromine, the dibromoether (80 to 90% yield) can be used. The second and simpler method is the direct bromination of ethylvinylether in a chloroformic or dioxane solution if the product is used directly without purification,... 

Purification of drinking water by adding CI2 to kill bacteria is a source of electrophilic chlorine and contributes a nonenzymatic pathway for a chlorina tion and subsequent chloroform formation Al though some of the odor associated with tap water may be due to chloroform more of it probably results from chlorination of algae produced organic com pounds... 

Fractional extraction has been used in many processes for the purification and isolation of antibiotics from antibiotic complexes or isomers. A 2-propanol—chloroform mixture and an aqueous disodium phosphate buffet solution are the solvents (243). A reciprocating-plate column is employed for the extraction process (154). 

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. 

MisceUaneous uses include extraction and purification of penicillin, alkaloids, vitamins, and flavors, and as an intermediate in the preparation of dyes and pesticides. Chloroform has also been used as a fumigant and insecticide, in the formulation of cough symps, toothpastes, liniments, and toothache preparations. These latter uses were banned by the FDA in 1976 (38). 

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. 

Cellulose for chromatography is purified by sequential washing with chloroform, ethanol, water, ethanol, chloroform and acetone. More extensive purification uses aqueous ammonia, water, hydrochloric acid, water, acetone and diethyl ether, followed by drying in a vacuum. Trace metals can be removed from filter paper by washing for several hours with O.IM oxalic or citric acid, followed by repeated washing with distilled water. 

Amides are stable compounds. The lower-melting members (such as acetamide) can be readily purified by fractional distillation. Most amides are solids which have low solubilities in water. They can be recrystallised from large quantities of water, ethanol, ethanol/ether, aqueous ethanol, chloroform/toluene, chloroform or acetic acid. The likely impurities are the parent acids or the alkyl esters from which they have been made. The former can be removed by thorough washing with aqueous ammonia followed by recrystallisation, whereas elimination of the latter is by trituration or recrystallisation from an organic solvent. Amides can be freed from solvent or water by drying below their melting points. These purifications can also be used for sulfonamides and acid hydrazides. 

Bis(3,4-diethyl-2-pyrrolylmethyl)-3,4-dietliyl-l//-pyrrole (2), prepared in situ from the di-t-butylester of the 5,5 -dicarboxylic acid (/), reacts with 4//-1,2,4-triazole-3,5-dialdehyde (3) in di-chloromethane in the presence of trifluoroacetic acid and 2,3-dichloro-5,6-dicyano-/)-benzoquino-ne as an oxidation reagent. Dark blue crystals are obtained after chromatographic purification. The dark violet chloroform solution fluoresces purple at 360 nm and gives the NMR experiments 39. Which compound and which tautomer of it has been formed ... 

Some samples were obtained with melting points ranging from 77° to 93°, but on dissolving the samples in chloroform and evaporating the solvent the values rose to 100-102°. This is not believed to be a process of purification. 

A solution of the acylated thiocyanatohydrin in a minimal amount of 5% potassium hydroxide in diglyme (other solvents such as methanol, ethanol or tetrahydrofuran have also been used) is stirred for 2 days at room temperature. Water is added to the reaction mixture to precipitate the product which is filtered or extracted with ether (or chloroform). The ether extract is washed several times with water, dried (Na2S04), and concentrated under vacuum. The thiirane usually can be crystallized from an appropriate solvent pair. Chromatography over alumina has been used for the purification of episulfides. 

This Fmoc analog is prepared from the chloroformate, O-succinimide, or p-nitrophenyl carbonate and is cleaved with 10% piperidine in 1 1 6M guanidine/IPA. It was designed to interact strongly on a column of porous graphitized carbon so as to aid in the purification of peptides after cleavage from the resin. 

Ciamician and Dennstedt reacted the potassium salt of pyrrole with chloroform in ether and isolated, after much purification, 3-chloropyridine, which was confirmed by crystallization with platinum. While the pyrrole salt can be used as the base, the chloroform carbene is typically formed with an alkali alcohol. Forty years later, Robinson and co-workers made 3-chloroquinolines from indoles using the Ciamician-Dennstedt reaction. ... 

The final purification consists of chromatographic separation of thyroxine and triiodo thyronine on a kieselguhr column using 20% chloroform in n-butanol equilibrated with... 

C. Isolation and purification of XK-62-2 100 g of the white powder obtained in the above step B are placed to form a thin, uniform layer on the upper part of a 5 cm0X 150 cm column packed with about 3 kg of silica gel advancely suspended in a solvent of chloroform, isopropanol and 17% aqueous ammonia (2 1 1 by volume). Thereafter, elution is carried out with the same solvent at a flow rate of about 250 ml/hour. The eluate is separated in 100 ml portions. The active fraction is subjected to paper chromatography to examine the components eluted. XK-62-2 is eluted in fraction Nos. 53-75 and gentamicin Cja is eluted in fraction Nos. 85-120. The fraction Nos. 53-75 are combined and concentrated under reduced pressure to sufficiently remove the solvent. The concentrate Is then dissolved in a small amount of water. After freeze-drying the solution, about 38 g of a purified preparate of XK-62-2 (free base) is obtained. The preparate has an activity of 950 units/mg. Likewise, fraction Nos. 85-120 are combined and concentrated under reduced pressure to sufficiently remove the solvent. The concentrate is then dissolved in a small amount of water. After freeze-drying the solution, about 50 g of a purified preparate of gentamicin Cja (free base) is obtained. 

Purification of the activation products (PMs). The methylamine activation product dissolved in methanol is purified by chromatography, first on a column of silica gel using a mixed solvent of chloroform/ethanol, followed by reversed-phase HPLC on a column of divinylbenzene resin (such as Jordi Reversed-Phase and Hamilton PRP-1) using various solvent systems suitable for the target substance (for example, acetonitrile/water containing 0.15% acetic acid). 

The dinitrophenylhydrazones were separated from the reaction mixture by thin-layer chromatography (silica gel G developed with benzene) and further purified by thin-layer chromatography on aluminum oxide G (petroleum ether-diethyl ether (96 to 4), silica gel G (chloroform), and silica gel G (diethyl ether)). In all cases, the specific activities of the dinitrophenylhydrazones remained constant over the course of the last two purifications. 

Stirring is continued for 2 hours at room temperature, and then methanol is added until a clear solution is obtained (ca. 10 ml. of methanol is required, and some heat is generated). When the solution has cooled, it is washed successively with 200 ml. of aqueous 2N potassium carbonate and 200 ml. of water. The aqueous phases are combined, washed with three 100-ml. portions of chloroform, and discarded. The organic phases are then combined, dried over sodium sulfate, and decolorized with activated carbon. Concentration of the chloroform solution thus obtained provides three crops of pale yellow crystals, which are washed with 30% hexane in chloroform and dried for 2 hours at 80°/0.1 mm. The total yield of 3-(2-phenyl-l,3-dithian-2-yl)indole is 22.3-25.4 g. (72-81%), m.p. 167-169° (Note 7). This material requires no further purification for use in Parts D or E. 

Dimethylphenylsilyl lithium (1 mmol, above THF solution) was added to copper(i) iodide (0.5 mmol) at — 23 °C, and the mixture was stirred at this temperature for 4h. The enone (0.75-0.5mmol) was then added, and stirring was continued at —23 °C for 0.5 h. The mixture was then poured on to ice(25 g)/HCl(5 ml), and extracted with chloroform (3 x 25 ml). The combined extracts were filtered, washed with HCI (25ml, 3m), water (25 ml), saturated sodium hydrogen carbonate solution (25 ml) and water (25 ml), and dried. Concentration and purification by preparative t.l.c. (eluting solvent 3 7 ether petrol) gave the /J-silylketone (40-99%). 

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