Magnesium chloride pressure/vacuum

After reduction is complete, most of the magnesium chloride is mechanically separated from the reduced mass the remaining fraction is removed along with the excess magnesium reductant by vacuum distillation at about 900 °C under a pressure of 10 3 to 10-1 torr. A schematic diagram of the reactor used for vacuum distillation is shown in Figure 4.23. 

Calcium and Magnesium Chloride (Mother liquors from salt works).— Weak liquor 29°B6., heavy liquor 45°B6. The concentration is done in horizontal-tube and vertical-tube single effects at a capacity of 1 gal. per square foot, with a steam pressure of 10 lb. and a vacuum of 26 in. Sodium chloride will separate. Final concentration to 59°Be. is done in open pans with high-pressure steam. All parts must be of cast iron or wrought iron, as copper will discolor the product. 

The yellow solution was poured into 150 ml of water. After addition of 20 g of ammonium chloride and vigorous shaking, the layers were separated. The aqueous layer was extracted twice with diethyl ether. The combined solutions were dried over magnesium sulfate and concentrated in a water-pump vacuum. The residue was distilled at low pressure giving the desired carbinol, (b.p. 40°C/0.1 mmHg), n 1.5505 in 66-702 yield. A small viscous residue remained in the distillation flask. 

To a solution of 0.25 mol of the trimethylsilyl ether in 120 ml of dry diethyl ether was added in 20 min at -35°C 0.50 mol of ethyllithium in about 400 ml of diethyl ether (see Chapter II, Exp. 1). After an additional 30 min at -30°C the reaction mixture was poured into a solution of 40 g of ammonium chloride in 300 ml of water. After shaking, the upper layer was separated off and dried over magnesium sulfate and the aqueous layer was extracted twice with diethyl ether. The ethereal solution of the cumulenic ether was concentrated in a water-pump vacuum and the residue carefully distilled through a 30-cm Vigreux column at 1 mmHg. The product passed over at about 55°C, had 1.5118, and was obtained in a yield of 874. Distillation at water-pump pressure (b.p. 72°C/I5 mmHg) gave some losses due to polymerization. 

The solution is stirred and cooled to —75° with a dry ice-acetone bath, and 2.90 g. (0.05 mole) of propionaldehyde (Note 18) is added through a dropping funnel. The solution is stirred at —75° for 5 minutes. The dry ice-acetone bath is replaced by a water bath, and the solution is stirred at 20° for 30 minutes. The solution is diluted with 250 ml. of ether and washed with two 100-ml. portions of 5M aqueous ammonium chloride, two 100-ml. portions of water, and 100 ml. of saturated aqueous sodium chloride. Each of the aqueous washes is extracted with the same 250-ml. portion of ether. The combined ethereal solution is dried over anhydrous magnesium sulfate (Note 4), filtered, and evaporated at 40° under a pressure of 25 mm. The residual liquid is distilled under reduced pressure through a 10 x 0.7 cm., unpacked, vacuum-jacketed column, and the material boiling at 93-98° (2 mm.) furnishes 7.90-7.99 g. (82-83%) of l,3-bis(methylthio)-l-hexen-4-ol (Notes 19, 20). 

A suspension of l-[7,8-dimethoxy-l,3-dihydro-2H-3-benzazepin-2-on-3-yl]-3-(N-benzylmethylamino)propane and 10% palladium-on-charcoal in glacial acetic acid was hydrogenated at 50°C and at a hydrogen pressure of 5 bar. After the catalyst had been filtered off, the solvent was evaporated in vacuum, and the residue was taken up in methylene chloride. After the solution had been extracted with an aqueous sodium bicarbonate solution and washed with water, it was dried over magnesium sulfate, evaporated and purified over silica gel with methylene chloride and then with increasing amounts of methanol (up to 10%). The N-[3-(7,8-dimethoxy-l,3,4,5-tetrahydro-2H-3-benzazepin-2-one-3-yl)propyl]methylamine hydrochloride. Yield 87% of theory. Melting point 110°C (dec.). 

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