Rotary drying, theory

In a 250 ml Erlenmeyer flask covered with aluminum foil, 14.3 g (0.0381 mole) of 17a-acetoxy-3j5-hydroxypregn-5-en-20-one is mixed with 50 ml of tetra-hydrofuran, 7 ml ca. 0.076 mole) of dihydropyran, and 0.15 g of p-toluene-sulfonic acid monohydrate. The mixture is warmed to 40 + 5° where upon the steroid dissolves rapidly. The mixture is kept for 45 min and 1 ml of tetra-methylguanidine is added to neutralize the catalyst. Water (100 ml) is added and the organic solvent is removed using a rotary vacuum evaporator. The solid is taken up in ether, the solution is washed with water and saturated salt solution, dried over sodium sulfate, and then treated with Darco and filtered. Removal of the solvent followed by drying at 0.2 mm for 1 hr affords 18.4 g (theory is 17.5 g) of solid having an odor of dihydropyran. The infrared spectrum contains no hydroxyl bands and the crude material is not further purified. This compound has not been described in the literature. 

Vinvlbenzvl Iodide—Vinylbenzyl chloride (20 g 0.131 mol) was added dropwise to dry sodium iodide (29.5 g 0.198 mol) in 130 mL dry acetone. The mixture was stirred at 50°C for 40 min, cooled to room temperature, and filtered. The acetone was removed by rotary evaporation, and 100 mL water and 150 mL ether were added to the solid residue. The aqueous layer was washed with ether. The combined ether layers were washed with water containing 2% sodium thiosulfate and dried over magnesium sulfate. The ether was removed by rotary evaporation and the yellow residue was dissolved in 50 mL hexane and cooled to -20°C. Within 1.5 hr, yellow crystals formed. Fast filtering with chilled glassware provided 17.1 g (53.5% of theory) of vinylbenzyl iodide. 

The reaction mixture is cooled in a water-ice bath, and a saturated aqueous ammonium chloride solution is added at such a rate as to maintain the temperature below 35°C. Ammonium chloride solution is added in portions until addition produces no further exothermic reaction (Note 3). The supernatant solution is decanted through glass wool onto 400 g of ice in a 4-L separatory funnel. The residual solids are washed with three portions of hexane, approximately 1000 nt total, and the washes are decanted into the separatory funnel. After the phases are separated, the aqueous phase is washed with an additional 500-mL portion of hexane. The combined organic extracts are washed with 500 nl of saturated ammonium chloride, and then with 500 nl. of brine. The organic layer is dried over anhydrous magnesium sulfate and filtered. Most of the solvent is removed by a rotary evaporator and the residual oil is distilled at reduced pressure using an ice water-cooled fraction cutting head. After a small forerun, approximately 390-392 g (94% of theory) is collected as a colorless oil, bp 116°C/1.6 nm (lit. 155°C/17 rim). ... 

Section V deals with the drying of porous solids in continuous operations. The study of drying in rotary and tunnel dryers is presented based on the relationships derived from basic theory. The effect of the operating variables on drier performance is discussed. A suitable procedure is developed for sizing rotary and tunnel driers. 

The study of drying in rotary driers is based upon the following relationships derived from basic theory ... 

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