Extraction organic mixtures

An improved solvent extraction process, PUREX, utilizes an organic mixture of tributyl phosphate solvent dissolved in a hydrocarbon diluent, typically dodecane. This was used at Savannah River, Georgia, ca 1955 and Hanford, Washington, ca 1956. Waste volumes were reduced by using recoverable nitric acid as the salting agent. A hybrid REDOX/PUREX process was developed in Idaho Falls, Idaho, ca 1956 to reprocess high bum-up, fuUy enriched (97% u) uranium fuel from naval reactors. Other separations processes have been developed. The desirable features are compared in Table 1. 

The open-column technique is commonly applied in the case of crude oils (being the least complex geochemical organic mixtures). MPLC, high-pressure liquid chromatography (HPLC), and PTLC are more often applied to more complex samples, especially those dominated by more polar compounds, such as hydrothermal bitumens or samples showing terrestrial organic matter input, such as extracts or pyroly-sates of coals of various ranks. 

Subsequently, it was shown that if the gorgonian is handled with extreme care (frozen with liquid N2 at the time of collection and then extracted with organic solvents) only the bis-ester of PGA2 (36) is isolable [64], If the coral is allowed to stand in water or methanol at room temperatures before extraction, a mixture of methyl 15R-acetoxy-PGA2 (36), methyl 15K-PGA2 (37), and 15/ -PGA2 (34) is obtained. These findings help to explain the wide array of acetate (35) and methyl esters that have been isolated in the many studies of Plexaura chemistry. 

Tandem mass spectrometry (i.e., MS-MS) is another technique that has recently become popular for the direct analysis of individual molecular markers in complex organic mixtures [87,505,509,578 - 583]. This technique provides a rapid method for the direct analysis of specific classes of molecular markers in whole sample extracts. In this approach the system is set up to monitor the parent ions responsible for a specific daughter ion as described above and the distribution of parent ions obtained under these conditions should provide the same information as previously obtained by GC-MS [505, 582]. Even greater specificity can be achieved by a combination of GC-MS-MS [516,584]. In view of the complexity of COM samples and the need to detect the presence of individual organic compounds or classes of compounds, it would seem that MS-MS, especially coupled with GC, would be extremely valuable in future environmental organic geochemistry studies. 

The separation of organic mixtures into groups of components of similar chemical type was one of the earliest applications of solvent extraction. In this chapter the term solvent is used to define the extractant phase that may contain either an extractant in a diluent or an organic compound that can itself act as an extractant. Using this technique, a solvent that preferentially dissolves aromatic compounds can be used to remove aromatics from kerosene to produce a better quality fuel. In the same way, solvent extraction can be used to produce high-purity aromatic extracts from catalytic reformates, aromatics that are essentially raw materials in the production of products such as polystyrene, nylon, and Terylene. These features have made solvent extraction a standard technique in the oil-refining and petrochemical industries. The extraction of organic compounds, however, is not confined to these industries. Other examples in this chapter include the production of pharmaceuticals and environmental processes. 

The Extra Pure process uses an unspecified solvent to extract organic contaminants from various wastes. The organics are separated from the solvent by distillation. The technology can be used for liquids, sludges, solids, or any mixture with a wide range of organics. 

The multicomponent organic mixture is dissolved in a suitable solvent this should be diethyl ether if at all possible for the reasons stated above, but any low boiling, water-immiscible solvent (light petroleum, dichloromethane, etc.) may be used. This solution is now shaken in a separatory funnel (see above) with several successive portions of dilute hydrochloric acid (1m) or dilute sulphuric acid (1m (1)). Basic components are thus extracted into the aqueous acidic... 

Extraction is based upon solubility due to similar polarities. Like dissolves like. We start with an organic mixture on top of an aqueous layer. They have different polarities and don t mix. There are three steps ... 

Solvent selection depends largely on the nature of the analytes and the matrix. Although the discussions in Chapter 2 can be used as a guideline to account for the solvent-analyte interactions, the matrix effects are often unpredictable. There is no single solvent that works universally for all analytes and all matrices. Sometimes, a mixture of water-miscible solvents (such as acetone) with nonmiscible ones (such as hexane or methylene chloride) are used. The water-miscible solvents can penetrate the layer of moisture on the surface of the solid particles, facilitating the extraction of hydrophilic organics. The hydrophobic solvents then extract organic compounds of like polarity. For instance, hexane is efficient in the extraction of nonpolar analytes, and methylene chloride extracts the polar ones. 

A suspension of simvastatin phenylboronate (30.0 g) and 1,3-propanediol (450 mL) was heated at 105-107°C at 0.2 mm Hg. After 1 hour, 182 mL of distillate was collected and the reaction was cooled to 20-25°C. Deionized water (270 mL) was added and toluene (3 times 75 mL) was used to extract the mixture. The combined toluene layers were washed with water (60 mL). The organic solution was heated at reflux for 1 hour and water was azeotropically removed. The solution was concentrated to a final volume of 24 mL under vacuum at 48-50°C. To the concentrated solution was added hexanes (215 mL) over 10 min. The resulting slurry was cooled to 0-5°C and filtered. The crude Simvastatin was washed at 0-5°C with hexanes and dried under vacuum to yield 21.0 g (88%) of Simvastatin. 

Extract the mixture with dichloromethane (3 x 10 mL). Dry the combined organic phase with magnesium sulfate, filter the solution, and evaporate the solvent on a rotary evaporator. 

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