Successive solution fractionation

The fraction of solute present in the organic phase is, therefore, 0.600. Extraction efficiency is the percentage of solute successfully transferred from its initial phase to the extracting phase. The extraction efficiency is, therefore, 60.0%. 

New Solution Fractionation Method Successive Solution Fractionation... 

Fig. 13. Schematic representation of successive precipitation fractionation (SPF) and successive solution fractionation (SSF)38)...

Almost molecularly monodisperse CD samples can be prepared using the successive solution fractionation method. 

A total gain of energy for the whole system by itself, however, does not guarantee a solution to the problem. The released energy produced by the reaction between magnesium and bromine could not be used directly to initiate the reaction between methane and carbon dioxide. The essence of the successful solution shown above lies in the fact that in the sequence of reactions (l)-(4) the energy of the exothermic counterpart of the process, reaction (6), is rendered into smaller fractions and consumed during key steps of the overall conversion... 

Beef liver (or lung) was minced and then autolyzed for twenty-four hours before extraction with an alkaline solution saturated with ammonium sulfate. Protein was precipitated by warming the extract, and the heparin-protein complex was precipitated from the supernatant liquor on acidification. Extraction of the complex with ethanol removed fatty material, and tryptic digestion removed most of the protein. The heparin was precipitated with ethanol, redissolved in warm alkaline solution to destroy trypsin, and reprecipitated with acetone. This material, crude heparin, was isolated in a yield of 15-50 g. per 100 lb. of animal tissue. In a later paper," the purification of crude heparin by fractionation successively with Lloyd s reagent, cadmium chloride, and acetone, was described. The purified heparin w-as 100 times as active as the crude material. Scott and Charles" reported the presence of nitrogen... 

First, the processing of inhibited plastics into products is accompanied by the liberation of harmful and toxic matter into the environment. In particular, these are volatile fractions of VCI, other engineering additives and thermal destruction products of the plastics. Second, the majority of inhibited plastic goods are expendable and their disposal and recovery pose a serious technological and organizational problem. The expediency and efficiency of using inhibited plastics as a rustproof method relies on a successful solution of this problem. 

Tref can also be combined with other fractionation techniques, such as size-exclusion chromatography (SEC) or successive solution fractionation (SSF). These cross-fractionation techniques can provide a great wealth of information on chain microstructme. The applications of cross-fractionation techniques using Tref will be summarized later in this review. 

If an organic solution or mixture of solvents is known to contain components of different volatility, partial evaporation or selective distillation can provide preferential enrichment of one or more components. The collection of spectra at different stages of the evaporation process can provide an insight into the nature of the key components. Careful use of spectral subtraction can help in the numerical extraction of chemical components from the different fractions. Successive subtractions may be used, with moderate success, in multicomponent situations. The main obstacle in this case is spectral variations due to mutual interaction of components in solution. Obviously, if nonvolatile components are present, this approach provides a practical separation of some of the main components—by complete evaporation. 

Another type of fractionation is called the Successive Solution Fractionation (SSF). In the SSF after phase separation the polymer-lean phase is removed and forms fraction 1. The polymer-rich phase is diluted by addition of solvent up to the initial volume of the feed phase and forms now the feed phase for separation step 2 etc. Continuous thermodynamics has also been applied to Baker-Williams fractionation where the polymer is fractionated in a column using a solvent and a non-solvent. The superposition of a solvent and nonsolvent gradient and a temperature gradient leads to a very high separation efficiency. 

In P-TREF, larger sample sizes and fi actionation columns are used and the temperature is increased in steps. All polymer material eluting at a particular temperature interval is collected for further analysis by other techniques, e.g., size exclusimi chromatography (SEC) or successive solution fractionation (SSF), FTIR or NMR. 

Figure 3 presents the schemes for successive precipitation fractionation (SPF) and successive solution fractionation (SSF). In both cases, by lowering the temperature (or adding nonsolvent) a homogeneous polymer solution (called feed phase F) splits into two coexisting phases, a polymer-lean sol phase I and a polymer-rich gel phase II, which are then separated. In SPF (Fig. 3a), the polymer is isolated from phase II as fraction FI. Phase I directly forms the feed phase for the next fractionation step, etc. 

Fractionation of polyethylene has been accomplished by a wide variety of techniques other than size elution chromatography and temperature rising elution fractionation, with a multitude of variations thereon. The most notable of these less widely employed techniques include crystallization analysis fractionation [13], solvent gradient elution [14], successive solution fractionation (SSF) [15], continuous countercurrent extraction [16], high temperature thermal field-fiow fractionation [17], supercritical fluid fractionation (SCF) [18,19], and high pressure Soxhlet extraction [20]. 

Commercial diethyl carbonate may be purified by the following process. Wash 100 ml. of diethyl carbonate successively with 20 ml. of 10 per cent, sodium carbonate solution, 20 ml. of saturated calcium chloride solution, and 25 ml. of water. Allow to stand for one hour over anhydrous calcium chloride with occasional shaking, filter into a dry fiask containing 5 g. of the same desiccant, and allow to stand for a further hour. Distil and collect the fraction boiling at 125-126°. Diethyl carbonate combines with anhydrous calcium chloride slowly and prolonged contact should therefore be avoided. Anhydrous calcium sulphate may also be used. 

Reflux a mixture of 68 g. of anhydrous zinc chloride (e.g., sticks), 40 ml. (47 -5 g.) of concentrated hydrochloric acid and 18-5 g. (23 ml.) of sec.-butyl alcohol (b.p. 99-100°) in the apparatus of Fig. 777, 25, 1 for 2 hours. Distil oflF the crude chloride untU the temperature rises to 100°. Separate the upper layer of the distillate, wash it successively with water, 5 per cent, sodium hydroxide solution and water dry with anhydrous calcium chloride. Distil through a short column or from a Claisen flask with fractionating side arm, and collect the fraction of b.p. 67-70° some high boiling point material remains in the flask. Redistil and collect the pure cc. butyl chloride at 67-69°. The yield is 15 g. 

In a 1500 ml. round-bottomed flask, carrying a reflux condenser, place 100 g. of pure cydohexanol, 250 ml. of concentrated hydrochloric acid and 80 g. of anhydrous calcium chloride heat the mixture on a boiling water bath for 10 hours with occasional shaking (1). Some hydrogen chloride is evolved, consequently the preparation should be conducted in the fume cupboard. Separate the upper layer from the cold reaction product, wash it successively with saturated salt solution, saturated sodium bicarbonate solution, saturated salt solution, and dry the crude cycZohexyl chloride with excess of anhydrous calcium chloride for at least 24 hours. Distil from a 150 ml. Claisen flask with fractionating side arm, and collect the pure product at 141-5-142-5°. The yield is 90 g. 

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