Extractive distillation agents

Uses Solvent for cellulose ethers and paints azeotropic distillation agent motor fuel extractions of fats and wax shoe industry organic synthesis. 

Uses Extractive solvent azeotropic distillation agent organic synthesis. 

Usually collection of about 200-300 ml. of distillate is sufficient. The distillate is extracted with two 100-ml. portions of ether, and the extracts are combined with the dimethylfurazan obtained by direct distillation (Note 4). The ether solution is dried for a short time over anhydrous magnesium sulfate. The drying agent is removed by filtration, and the ether is evaporated on a steam bath. The residue is distilled at atmospheric pressure through a short column, and after a fore-run, consisting chiefly of biacetyl, the dimethylfurazan distils at 154-159° as a colorless liquid, 1.4234-1.4243, m.p. —7.2 to —6.6°. The yield is 59-63 g. (60-64%). 

Terpenes are found primarily in higher plants, less commonly in animals. They are often isolated by steam distillation or extraction. The major commercial applications of terpenes are as fragrance and flavoring agents. Terpenes often serve in organic chemistry as versatile carriers of chiral information. For example, (-)-a-pinene (2) is commonly used as a ligand for chiral induction. 

If one has three alternative simple separation methods (e.g. distillation, extractive distillation with extractive agent Si, and crystallation) to separate a 10 component mixture, the Thompson... 

Radiochemical purification of the induced activity in the presence of carrier involves chemical operations such as precipitation, distillation, solvent extraction, chromatography, and ion exchange. While the chemistry performed on the carrier and sample should be designed to isolate the material in a pure state, a useful operation frequently carried out is scavenging. Strongly adsorptive precipitates such as ferric hydroxide, lanthanum fluoride, and antimony sulfide may be formed in the solution. These precipitates, by coprecipitation, occlusion, and surface adsorption can be used to remove unwanted traces of activity. A scavenging agent should be chosen that wdll not carry down appreciable amounts of the carrier from solution. An alternative method is to add hold-back carriers for the unwanted traces of activity and precipitate the required element in their presence. 

If distillation is rejected, we might consider extractive distillation. The K-values of acetone and methanol at infinite-dilution (38.5 and 7.8, respectively) in water indicate that water could be used as an extractive distillation agent for the separation of these species. However, adding water would almost certainly introduce a second phase with the pentane. 

Use Organic synthesis, extractive solvent, azeotropic distillation agent. 

Blood, liver, kidney, brain Sample with added sulfamic acid and antifoaming agent, subjected to simultaneous distillation and extraction, extract concentrated. GC-TEA <1 ppb 93-97% at 2.3-4.2 ppb Pylypiw et al. 1985 Pylypiw 1987... 

The terms entrainer and solvent are commonly used interchangeably to refer to the separating agent used to enhance the separation of close boilers or azeotropes by azeotropic or extractive distillation. For consistency, the term entrainer will be used to designate the azeotropic distillation agent and solvent, the extractive distillation agent. 

The diazonium solution is added to the hot cuprous chloride solution while the latter is shaken by hand but is not cooled. After the solutions are thoroughly mixed, 840 cc. of concentrated hydrochloric acid is added, and the mixture is allowed to stand overnight. The reaction mixture is steam-distilled to separate the w-chlorobenzaldehyde, which is collected practically completely in the first 1500 cc. of distillate. The w-chlorobenzalde-hyde is removed from the aqueous distillate by extraction with two 150-cc. portions of ether, and the ethereal solution is dried with 10-15 g. of anhydrous calcium chloride. After being decanted from the drying agent, the ether is distilled, and the residual liquid is distilled under diminished pressure. The m-chlorobenzaldehyde boils at 84-86°/8 mm., io7-i09°/26 mm. (Note 5). The yield is 70-74 g. (75-79 per cent of the theoretical amormt) (Note 6). 

In general, when either distillation or extraction is feasible to achieve a separation, distillation is the method of choice. In distillation there is no mass-separating agent to be recovered. In extraction, on the other hand, the solvent is recovered continuously for reuse, usually by distillation. The addition of a new species to any system requires a separation process for its recovery. Thus, extraction separations must include two separation steps, while distillation separations require only one. 

In extractive distillation, an extractive agent is added to the mixture to be distilled for the purpose of modifying the relative volatility of the key components without forming an azeotrope. Extractive distillation is usually employed to improve the separability between close-boiling components for which ordinary distillation would not be economically feasible. 

When mass separating agents are used (i.e., extractive distillation, or extraction), perform die recovery steps for the mass separating agent and/Or dissolved products in the immediately following step. 

Separation operations are interphase mass transfer processes because they involve the creation, by the addition of heat as in distillation or of a mass separation agent as in absorption or extraction, of a second phase, and the subsequent selective separation of chemical components in what was originally a one-phase mixture by mass transfer to the newly created phase. The thermodynamic basis for the design of equilibrium staged equipment such as distillation and extraction columns are introduced in this chapter. Various flow arrangements for multiphase, staged contactors are considered. 

C. consist mainly of monoterpene hydrocarbons, above all limonene (see p-menthadienes) (exception bergamot oil, that only contains ca. 40%). Since the important odor and taste components are thus only present in relatively low concentrations, so-called concentrates of C. are produced, especially for use as aromatizing agents, by removing a large portion of the unwanted non-polar terpene hydrocarbons, thereby the content of the polar components is increased. This can be achieved technically by distillation, distribution, extraction, or adsorption processes. 

Uses Solvent for cellulose acetate, fat and oil extraction hydrocarbon propellant motor fuel azeotropic distillation agent org. synthesis laboratory reagent... 

Uses Extraction solvent for essential oils org. synthesis azeotropic distillation agent Manuf./Distrib. Aldrich http //www.sigma-aldrich.com, Fluka http //www.sigma-aldrich.com... 

In any given case there are usually a number of compounds that are effective as azeotropic- or extractive-distillation agents, and the choice depends on a number of factors ... 

Fig. 4.46 Experimental installation of extractive distillation (7 extractive distillation column, 2 packing, 3 feed tank, 4 product tank, 5 condenser, 6 partial condenser, 7 vent, 8 pump, 9 extractive agent tank, 10 extractive agent recovery column, and 11 recovered extractive agent tank) (reprinted from Ref. [16], Copyright 2011, with permission from CIESC)...

The second class of distillation operation using an extraneous mass-separating agent is extractive distillation. Here, the extraneous mass-separating agent is relatively involatile and is known as a solvent. This operation is quite different from azeotropic distillation in that the solvent is withdrawn from the column bottoms and does not form an azeotrope with any of the components. A typical extractive distillation process is shown in Fig. 3.11. ... 

As with azeotropic distillation, the separation is possible in extractive distillation because the extraneous mass-separating agent interacts more strongly with one of the components than the other. This in turn alters in a favorable way the relative volatility between the key components. 

In principle, extractive distillation is more useful than azeotropic distillation because the process does not depend on the accident of azeotrope formation, and thus a greater choice of mass-separating agent is, in principle, possible. In general, the solvent should have a chemical structure similar to that of the less volatile of the two components. It will then tend to form a near-ideal mixture with the less volatile component and a nonideal mixture with the more volatile component. This has the effect of increasing the volatility of the more volatile component. 

The ethereal extracts are then united, dried with a suitable drying agent and filtered. The filtrate is then cautiously distilled, the ether being first distilled and finally the organic compound if volatile if the compound is solid, the crude residue is purified by recrystallisation. Very great care must be taken on all occasions when ether is distilled because of the risk of fire or of an explosion full experimental details for this operation are given, both on p. 8o (Preparation of Ether) and on p. 164 (Pre-... 

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