Drying Organic Solutions

Amorphous Films. An amorphous film is generally prepared by solvent evaporation of a dry organic solution of Chi on a solid substrate surface. The vacuum sublimation technique, which is widely employed for most synthetic dyes, is not applicable to Chi due to possible thermal degradation of the pigment. 

A mixture of 1 equiv. of the appropriate amine (10 mmol) with 2 equiv. (20 mmol) of compounds la-c is introduced into a Pyrex tube, which was then placed in a microwave reactor and irradiated by microwave (60 W) in the absence of solvent for 20 min. The nitrogen containing derivatives 2a-c, 3a and 4a were extracted with dichloromethane and washed with water to eliminate the residual amine. The solvent of the dried organic solution was eliminated under reduced pressure. The white solids 2a-c were washed with diethylether and dried. The yellow oils 3a-4a were analyzed as such. 

Silylation the final CH2C12 solution of the thioacidolysis sample is again carefully dried over Na2S04, 5-10/d of this dried organic solution is trimethylsilylated (TMS) at room temperature with 50/i of N,0 bis (trimethylsilyl) trifluoroacetamide (BSTFA) and 5 1 of GC-grade pyridine in a 200-/d reaction vial fitted with a Teflon-lined screwcap For soluble lignin samples, the silylation is complete within a few minutes, for lignocellulose residues, silylation is complete within 2 to 4h In both cases and with well-dried samples, silylations performed in the aforementioned vials are stable for several days (at least 48 h)... 

If water has to be avoided, dry organic solutions of the polymer and acid are mixed under an argon atmosphere and the solvent is then evaporated. Convenient solvents for H2SO4 and HjP04 are acetonitrile and tetrahydrofuran respectively ". ... 

Decant the dried organic solution into a fared 125-mL round-bottom flask. Equip the flask for simple distillation and evaporate the solvent using simple distillation. Alternatively, one of the techniques in Section 2.29 as directed by your instructor may be used to concentrate the solution. After the ether is completely removed, the pot residue is crude citral. 

Why is it necessary to separate a dried organic solution from the drying agent prior to distilling the solution ... 

With a filter-tip pipet, transfer the dried organic solution into a clean 5.0-mL conical vial, rinse the sodium sulfate with about 0.2 mL of diethyl ether, and add this rinse to the vial. Equip the vial for simple distillation. Remove the solvent by simple distillation withdraw the distillate from the Hickman stillhead as needed. Alternatively, use rotary evaporation or other techniques to concentrate the solution. The final traces of solvents may be removed by attaching the vial to a vacuum source. After the crude solid residue has dried, determine its melting range, which may be wide. ... 

Isolation and Purification Filter or carefully decant the dried organic solution into a round-bottom flask equipped for simple distillation, and concentrate to a volume of approximately 5 mL. Alternatively, use rotary evaporation or other techniques to concentrate the solution. Allow the solution to cool to room temperature. Transfer this solution to a 50-mL Erlenmeyer flask. Rinse the round-bottom flask with 0.5-1 mL of diethyl ether and transfer this rinse to the Erlenmeyer flask. Add approximately 15 mL of hexanes to the flask and place the flask in an ice-water bath. If crystals do not form within 5-10 min, use one of the methods described in Chapter 3 to induce crystallization. Isolate the crystals by vacuum filtration and air-dry them. Recrystallize the product from diethyl ether/hexanes (2 1). 

In the experiments using larger amounts of tetrabutylammonium bromide (0.5 to 1.0 equivalents), the reactions were done on 0.1 to 0.2 times the scale of the previous work (i.e., 4.535g of BPA). At the end of the reaction, the mixture was diluted with methylene chloride and the solution was extracted with water and the organic phase was dried over magnesium sulfate. The dried organic solution was added to methanol to give the polymer which was collected, dried, and analyzed. No further reprecipitation was required. 

By the reaction between a solution of an acyl halide in a dry organic solvent, such as toluene, with a cold solution of sodium peroxide, for example ... 

The combined organic solutions were washed five times with saturated sodium chloride solution and subsequently dried Over magnesium sulfate. After concentration of the extract in a water-pump vacuum the residue was distilled through... 

A solution of 0.10 mol of lithiated methoxyallene in about 70 ml of hexane and 50 ml of THF (see Chapter II, Exp. 15) was cooled to -40°C. Ory, pure acetone (0.12 mol) was added dropwise during 10 min, while keeping the temperature at about -30°. Five minutes after the addition 100 ml of saturated NHi,Cl solution, to which 5 ml of aqueous ammonia had been added (note 1), were run in with vigorous stirring. The product was extracted three times with diethyl ether. The combined organic solutions were dried over potassium carbonate and subsequently... 

R = tert.-CijHg). The combined organic solutions were dried over magnesium sulfate... 

The mixture was then poured into a solution of 10 g of KCN or NaCN and 40 g of NHi,Cl in 400 ml of water. After vigorous shaking the layers were separated and the aqueous phase was extracted four times with diethyl ether. The combined organic solutions were dried over MgSOi, and concentrated in a water-pump vacuum. 

To a mixture of 100 ml of THF and 0.10 mol of the epoxide (note 1) was added 0.5 g Of copper(I) bromide. A solution of phenylmagnesium bromide (prepared from 0.18 mol of bromobenzene, see Chapter II, Exp. 5) in 130 ml of THF was added drop-wise in 20 min at 20-30°C. After an additional 30 min the black reaction mixture was hydrolysed with a solution of 2 g of NaCN or KCN and 20 g of ammonium chloride in 150 ml of water. The aqueous layer was extracted three times with diethyl ether. The combined organic solutions were washed with water and dried over magnesium sulfate. The residue obtained after concentration of the solution in a water-pump vacuum was distilled through a short column, giving the allenic alcohol, b.p. 100°C/0.2 mmHg, n. 1.5705, in 75% yield. 

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