Extraction without reflux

FIG. 15-7 Dual-solvent fractional extraction without reflux. 

FIGURE 7-3-4 Triangular diagram for extraction without reflux. 

FIGURE 7.3-5 Distribution diagram for extraction without reflux, as le Fig. 7.3-1. showing both the operating and equilibrium curves. 

The formal integrations just discussed will be more successful if that for NtQR is used in the case of countercurrent extraction without reflux. If reflux is used, NtQj should be calculated for the stripping section, for the enriching section. 

Fig. 3.1.2 The apparatus used in 1956 for the methanol extraction of Cypridina luciferin. The dried Cypridina (500 g) is extracted at a temperature lower than 40°C with refluxing methanol under reduced pressure for two days. The atmosphere inside the apparatus is completely replaced with hydrogen gas that was purified by its passing through a quartz tube containing red-heated copper fragments. The temperature of the mantle heater is adjusted, the system evacuated, and then all stopcocks are closed. The extraction with refluxing methanol continues for many hours without any further adjustment. From the author s 1957 notebook.

So a compromise was reached (Fig. 856). Since you ll probably do more extractions than additions, with or without reflux, the pressure-equalizing tube went out, but the ground glass joint stayed on. Extractions no problem. The nature of the stem is unimportant. But during additions, you ll have to take the responsibility to see that nasty vacuum buildup doesn t occur. You can remove the stopper every so often or put a drying tube and inlet adapter in place of the stopper. The latter keeps moisture out and prevents vacuum buildup inside the funnel. 

To a solution of specified quantities (see above table) of ethane-1,2-dithiol (12-50 mmol) and KOH (0-20 mmol) in F.iOH/HjO (I 3, 25 mL) was added gradually the acid 20 (10 mmol), and the mixture was stirred at rt or reflux temperature for 0.5 48 h (see above table). The mixture was weakly acidified with dil HCI and then extracted with Et. O (3 x 50 ml.). With reactions performed in the absence of KOH. the mixture was subjected to extraction without acidification. The combined extracts were dried (Na2S04). 

Separate the Cj cut first use distillation without reflux and without the temperatures that might cause CO2 freezing. Do not use a solvent in the first column. This allows more CO2 to go overhead and the latter is lost by scrubbing the methane to free it from the CO2. The bottoms is sent to an extractive distillation column. Figure 23a shows the variation. This option is sho Miin Fig. P-23a. 

Most papers dealing with phenolic acid HPLC analysis in herbs describe only simple liquid extraction without the hydrolysis step. Acetone, methanol, or alcoholic-water or acetone-water mixtures are applied. Very rarely, pure water is used as the extraction solvent. " It was found that the extraction recoveries for water extracts are often lower in comparison to alcoholic-water mixtures, especially when the simultaneous separation of polar and less polar phenolic acids has been performed. Sometimes, the control of pH can improve the recovery. If necessary, n-hexane, chloroform, diethyl ether, benzene-acetone, petroleum ether, or other less polar solvents are recommended for removing interfering compounds. The extraction is usually performed by refluxing the samples for a specific time in a Soxhlet apparatus, with simple mechanical or magnetic stirring of the sample with the extraction solvent, or by plant sample maceration. The application of an ultrasonic bath for the liquid extraction has also become popular in recent years. The hydrolysis steps have also been recommended for medicinal species preparation, especially when other phenolic compounds are also analyzed simultaneously with phenolic acids in herbs. 

The second type of fractional extraction operation involves the use of stripping and washing sections without reflux (Fig. 15-7) to separate a mixture of feed solutes with close K values. In this case, the solute separation factor is low to moderate. Normally, must be greater than about 4 for a commercially viable process. Scheibel [Chem. Ene. Prog., 44(9), pp. 681-690 (1948) and 44(10), pp. 771-782 (1948)] gives several... 

Since in the acid mesophase product the surfactant cationic charge is exactly balanced by a chloride anion, the ion-pair surfactants are removable by extraction without providing an exchangeable cation as required for the anionic framework of MCM-41. It was found that most of the surfactant could be removed from the as-synthesized material by stirring it in pure ethanol at room temperature or by overnight reflux. Removal of the surfactant was also possible by calcination. Calcined SBA-3 has similar stability and absorption-desorption properties as has MCM-41. 

Minimum reflux corresponds to the overlap of an operating line and a tie-line (infinite stages at a pinch point). This concept is similar to minimum solvent flowrate for an extraction process without reflux. Total reflux corresponds to the minimum number of stages. Remember that total reflux means that no streams are going into or out of the column, so that F, B, and D are zero, and A = A. ... 

Analyze countercurrent extraction cascades without reflux. 

To a solution of 8 g of lithiim alanate in 250 ml of diethyl ether was added in 15 min 24 g (0.3 mol) of 2-penten-4-yn-l-ol (III, Exp. 57). The diethyl ether began to reflux and a rubber-like greyish precipitate was formed. After heating for 1 h under reflux the flask was placed in an ice + ice-water bath and water (150 ml) was added dropwise with vigorous stirring. After this hydrolysis procedure the ethereal solution was decanted and the aqueous jelly layer was extracted ten times with diethyl ether. The ethereal extracts were dried (without washing) over magnesium sulfate and subsequently concentrated in a water-pump vacuum. 

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