Chloroform water, concentrated

To a stirred solution of 2,3-dimethyl indole (6, 1.45 g, 10 mmol, 1.0 equiv) and tetra-n-butylammonium sulfate (3.40g, 10 mmol, 1.0 equiv) in chloroform (150 mL) was added potassium hydroxide (50% aqueous solution, 20 mL) over 30 minutes. The stirring was continued for six hours, at which time the mixture was extracted with chloroform, the chloroform-water mixture was washed with water, and the organic layer concentrated. Silica gel chromatography provided 2,4-dimethyl-3-chloroquinoline (7, 1.52 g, 79% yield). 

McKone (1993) demonstrated that chloroform in shower water had an average effective dermal permeability between 0.16 and 0.42 cm/hour for a 10-minute shower. The model predicted that the ratio of chloroform dermally absorbed in the shower (relative to chloroform-contaminated water concentration) ranged between 0.25 and 0.66 mg per mg/L. In addition, the McKone model demonstrated that chloroform metabolism by the liver was not linear across all dermal/inhalation exposure concentrations and became nonlinear at higher (60-100 mg/L) dose concentrations. 

The model was also used to assess the relationship of dermal and inhalation exposure to metabolized dose in the liver, as well as to determine the tap-water concentrations at which hepatic metabolism of dermal and inhalation doses of chloroform become nonlinear. This information is especially useful for risk assessment on persons exposed to a wide range of chloroform concentrations. Experimentally measured ratios of chloroform concentrations in air and breath to tap water concentration (Jo et al. 1990a) were compared with the model predictions. 

With respect to the reduced water concentration (1), it seems as if all but one of the hydrolysis reactions following the mechanism shown in Scheme 10 are retarded in micellar solutions (the exception being the hydrolysis of 4-nitrophenyl chloroformate la in cationic micelles ) and the lower water concentration in the micellar Stern region (estimated to be 45 mol dm for and 33 mol dm for SDS ) will... 

Tao et al. [765] describe a unique method combining gas chromatography and inductively coupled plasma emission spectrometry. Beryllium is extracted from a non saline water sample with acetylacetone into chloroform and concentrated by evaporation. 

At ambient temperature 3,3-dibromo-l,3-dihydro-2H-pyrrolo[2,3-b]pyridin-2-one (13.4 mmol) was dissolved in 100 ml apiece t-butyl alcohol and water followed by the dropwise addition of bromine (34.3 mmol) over 20 minutes. Thereafter 15 ml NaHC03 was added over 30 minutes to raise the pH to 6.5. A yellow solid formed and was removed. The filtrate was reduced to 100 ml, extracted twice with 50 ml chloroform, dried, concentrated, and the product isolated in 98% yield. H-NMR data supplied. 

The isolation procedures for the picrotoxanes have been mostly quite conventional. Plant material has been extracted with alcohols, and in few cases with chloroform. On concentration, water was added in many cases with subsequent... 

FIGURE 43.3 Simulated exhaled breath concentrations resnlting from a 30 min dermal-only exposure to chloroform (ISO g/L water concentration), as estimated by two different model formulations for the skin compartment. 

The mother liquors are concentrated under nitrogen atmosphere, reduced pressure to a small volume. The residue is adjusted to 20 cc with water, made alkaline at pH 9.5 with ammonium hydroxide and extracted with chloroform. The chloroform extract concentrated in vacuo at 30° C to small volume is passed through a column of400 g of silica gel in chloroform. By eluting with chloroform, a fraction is obtained containing ergocryptine which is evaporated to dryness. The residue is... 

Karl Fischer Titration -ASTM D6304 The Karl Fischer titration, KFT, method determines water concentration by titrating a measured amount of sample and Karl Fischer reagent. The reagent reacts with the OH molecules present in the moisture, and present in other compounds, and depolarizes an electrode. The corresponding potentiometric change is used to determine the titration end point and calculates the concentration value for water. KFT reagents include iodine, methanol and chloroform and thus require a separate waste stream due to the chloroform. 

Methylene dichloride is prepared by chlorination of methane and thus contains chloroform and carbon tetrachloride as impurities. Water can be removed by drying over sodium sulfate, calcium chloride, potassium carbonate, or phosphoric oxide. Further purification can be achieved by prior washing with, successively, water, concentrated sulfuric acid, water, sodium hydroxide solution, and again water. 

A vessel 1.0 m in diameter is to be used for stripping chloroform from water by sparging with air at 298 K. The water will flow continuously downward at the rate of 10.0 kg/s at 298 K. The water contains 240 pg/L of chloroform. It is desired to remove 90% of the chloroform in the water using an airflow that is 50% higher than the minimum required. At these low concentrations, chloroform-water solutions follow Henry s law (yj = mx) with m = 220. The sparger is in the form of a ring located at the bottom of the vessel, 50 cm in diameter, containing 90 orifices, each 3 mm in diameter. Estimate the depth of the water column required to achieve the specified 90% removal efficiency. Estimate the power required to operate the air compressor, if the mechanical efficiency of the system is 60%. 

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