Extraction drying agents

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-... 

Purification. A three-phase distillation for producing high purity PO has been reported (82). PO can be purified in the laboratory by refluxing with a drying agent, such as calcium hydride, then fractionally distilling (83). Texaco has reported that PO can be purified by extractive distillation (84—89). 

In this step the recovered ether is collected in a dry atmosphere, and about 100 ml. of this ether is used in two portions to extract the sodium sulfate residue in order to transfer into the flask any small quantities of the aldehyde that may have been trapped by the drying agent. 

C. (E)- -Iodo-4 -phenyl-2-butene. In a 20-ml., round-bottomed flask are placed 2.0 g. (0.008 mole) of 2-(4/-phenyl-l -buten-3 -yl)thio-2-thiazoline, 5 ml. of methyl iodide [Methane, iodo-], and 2 ml. of di-methylformamidc. The resulting solution is heated at 75-80° for 2.5 hours under a nitrogen atmosphere (Note 13), cooled, and poured into 10 ml. of water. Extraction with three 12-ml. portions of ether separates the product from water-soluble by-products. The extracts are combined, washed with 8 ml. of 1% aqueous sodium thiosulfate and two 8-ml. portions of water, dried over anhydrous magnesium sulfate, and filtered to remove the drying agent. Removal of ether by distillation at 30° (100 mm.) leaves 1.5-1.7g. (74-82%) of ( )-l-iodo-4-phenyl-2-butene (Notes 14 and 15). 

The two-phase mixture is placed in a separatory funnel, and the heavy red-brown oil is separated. The aqueous phase is extracted with 100 ml. of ether. The oil and the ether extract are combined, washed with 50 ml. of saturated sodium chloride, and dried over potassium carbonate. The drying agent is removed by filtration, and the filtrate is distilled. Colorless 2-bromoallyl-amine is collected at 65-68°/100 mm. weight 49-59 g. (59-72%) 1.5075-1.5085 (Note 6). 

The residue is dissolved in 300 ml. of water. The solution is poured onto 200 g. of ice and acidified to a pH of about 4 by addition of 75 ml. of 10% hydrochloric acid. The resulting mixture is extracted with four 100-ml. portions of peroxide-free ether, and the combined extracts are washed with 50 ml. of a saturated aqueous solution of sodium chloride and dried over 2 g. of anhydrous magnesium sulfate (Note 2). The ether solution is separated from the drying agent and concentrated at room temperature under reduced pressure. The residual oil is distilled from a 25-ml. 

A 500-ml. three-necked flask is fitted with a reflux condenser and a thermometer, the bulb of which reaches far enough into the flask to be covered by the liquid. A solution of 46.0 g. (0.205 mole) of a-phenylcinnamic acid (p. 70) (Note 1) in 280 ml. (307 g., 2.38 moles) of quinoline (Note 2) is added to the flask along with 4.0 g. of copper chromite.2 The reaction flask is heated by means of a mantle or an oil bath until the temperature of the reaction mixture reaches 210-220°. The mixture is kept within this temperature range for 1.25 hours. The solution is then cooled immediately and added to 960 ml. of 10% hydrochloric acid in order to dissolve the quinoline (Note 3). The product is extracted from this mixture with two 200-ml. portions of ether followed by a 100-ml. portion. The combined ether extracts are filtered to remove particles of catalyst, washed with 200 ml. of 10% sodium carbonate, and dried over anhydrous sodium sulfate. The dry solution is removed from the drying agent by filtration and heated on a steam bath to distil the ether. The residue is dissolved in a hexane fraction, b.p. 60-72° (Skellysolve B) the solution is cooled to 0° and filtered to remove /raws-stilbene, if any. The hydrocarbon solvent is removed by distillation, and the czs-stilbene is distilled. The yield is 23-24 g. (62-65%), b.p. 133-136°/10 nun., 95-97°/l mm. tig 1.6183-1.6193, 1.6212-... 

Although it is not common, sometimes a drying agent is added to soil before extraction. In these cases, the same drying agents are used and are added and mixed with soil before starting the extraction process. 

Dimethyl-2-oxazoline is commercially available from Columbia Organic Chemicals, 912 Drake Street, Columbia, South Carolina, or may be prepared as follows. In a 250-ml., three-necked flask is placed 89.14 g. (1.0 mole) of 2-amino-2-methyl-l-propanol, and the flask is cooled in an ice bath. The amine is carefully neutralized with 52.3 g. (1.0 mole) of 90.6% formic acid over a 1-hour period. A magnetic stirring bar is added, the flask is fitted with a short path distillation head, and the reaction mixture is placed in a silicon oil bath which is rapidly heated to 220-250°. The azeotropic mixture of water and oxazoline distills over a period of 2-4 hours and is collected in an ioe-cooled flask containing ether. The aqueous layer is separated, saturated with sodium chloride, and extracted with three 50-ml. portions of ether. The combined ethereal extracts are dried over potassium carbonate, filtered to remove the drying agent, and the ether is removed at 35-40° at atmospheric pressure. The 4,4-dimethyl-2-oxazoline is collected as the temperature rises above 85°. The yield is 56.7-62.7 g. (57—63%) of a colorless mobile liquid, b.p. 99-100° (758 mm. Hg). 

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