Steam distillation yield calculation

Di-n-amyl ether. Use 50 g. (61 5 ml.) of n-amyl alcohol (b.p. 136-137°) and 7 g. (4 ml.) of concentrated sulphuric acid. The calculated volume of water (5 ml.) is collected when the temperature inside the flask rises to 157° (after 90 minutes). Steam distil the reaction mixture, separate the upper layer of the distillate and dry it with anhydrous potassium carbonate. Distil from a 50 ml. Claisen flask and collect the fractions of boiling point (i) 145-175° (13 g.), (ii) 175-185° (8 g.) and (iii) 185-190° (largely 185-185-5°) (13 g.). Combine fractions (i) and (u), reflux for 1 hour in a small flask with 3 g. of sodium, and distil from the sodium amyloxide and excess of sodium this yields 9 5 g. of fairly pure n-amyl ether (iv). The total yield is therefore 22 - 5 g. A perfectly pure product, b.p. 184 185°, is obtained by further distillation from a Little sodium. 

The trees cultivated for oil production must be at least 30 years old to make oil production profitable. The oil yield, calculated on the amount of wood used for steam distillation, is 4-6.5%. The production in India and Indonesia amounts to ca. lOOt/yr. 

A mixture of 231 g. of the above barium salt and 300 ml. of sulfuric acid (sp. gr. 1.67) is distilled with superheated steam (inlet steam temperature at 200-220° and exit steam at 150-160°). The oily layer of the distillate is separated, washed with water, dried, and distilled twice through a 1-m. packed fractionating column to give 40 g. of o-xylene and 149 g. of l-bromo-2,3-dimethylbenzene, b.p. 210.5-212.5°. This is a 42% yield calculated on the barium salt. 

With 10-mm. glass tubing for the steam inlet and outlet and an efiicient condenser the maximum rate of steam distillation is 3 1. per hour. The 20 1. of distillate collected contains 95% of the calculated yield of acetic acid. The removal of the acetic acid is slow because the rate of hydrolysis in the final stages appears to be slow and the rate of acetic acid distillation is slow. The remainder of the acid is collected so slowly that it is not considered worth while to distil further, although the yield of product can be slightly increased. 

Acetone phenyl-hydrazoue is first prepared by mixing phenyl-hydrazine (30 gms.) with acetone (18 gms.). The mixture becomes warm and water separates it is then heated on the water-bath for half an hour, and at the end of this time heated in a dish on the water-batli, to drive off acetone and steam. The hydrazone is then mixed with five times its weight of anhydrous zinc chloride, and heated under a reflnx condenser in an oil-bath at 180°. A vigorous reaction takes place, and when completed, the dark-coloured mass is distilled with steam. The a-methyl-indole collects in the receiver and soon solidifies to a pale yellow mass. It may be purified by recrystallisiug from ligroin. M.p. 59°. Yield is over 60 per cent, of that calculated. 

Pyridine (200 ml) and anhydrous sodium carbonate (70 g) are placed in a flask fitted with a reflux condenser and are then heated in an oil-bath to about 90° and treated with potassium persulfate (150 g) that is added in 2-3 portions during 0.5 h. The mixture is heated for some hours, after which the pyridine solution is filtered from the salts, which are then washed with pyridine. The pyridine solutions are united and distilled in a vacuum. After recovery of unchanged pyridine there remains a dark oil (about 40 g) containing bi- and ter-pyndines. The 2,2 -bipyridine can be isolated from this mixture by distillation in steam or, particularly from large batches, by distillation in a vacuum (air-condenser), the 2,2 -isomer passing over at 150-165°/12 mm. This product solidifies in a refrigerator to large, colorless crystals, which, when collected, washed with cold water, dissolved in ca. 20% acetic acid and reprecipitated by ammonia, are pure and melt at 71°. The yield is 20% calculated on unrecovered pyridine. 

---