For fractional distillation

Moreover, certain commercial products should meet specifications including those for fractions distilled at certain temperatures. 

Fractional distillation. Fig. II, 60, 2 illustrates a set-up for fractional distillation wdth a Hempel-type column and cold finger, the latter to give manual control of the reflux ratio. Any other fractionating colunm, e.g., an all-glass Dufton or a Widmer column may, of course, be used. 

Fig. A3.13. Setups for atmospheric pressure distillation (a) for simple distillation (b) Vigreux column for fractional distillation.

Claude (2) A process for fractionally distilling liquid air, based on the original Linde process but using two stages. Developed by G. Claude. 

Remove the catalyst by filtration at the pump, distil the solvent using a receiver for fractional distillation and collect the adipic aldehyde by distillation in a vacuum from a small flask fitted with a column. Yield 12-14 g. Pure adipic aldehyde boils at 92°-94°/12 mm., solidifies in an ice-salt freezing mixture and then melts at -8° to - 7°. Keep it in a sealed tube under nitrogen or C02 in order to protect it from auto-oxidation. 

This partial condenser, which is a modificatioh of one described by Hahn,1 is very effective in reducing the time required for fractional distillation of many mixtures. It is best constructed of Pyrex. The dimensions given are approximate and may be varied to suit individual needs. The inside container is a 30 by 140 mm. Pyrex test tube sealed at the top to standard Pyrex tubing. It is very effective in the purification of cyclohexene (Org. Syn. Coll. Vol. 1, 177).2 The crude hydrocarbon mixture is first put into the flask with ethyl alcohol in the partial condenser, and the whole heated as long as a distillate is obtained. The alcohol is then replaced by ethylene chloride and the cyclohexene collected. 

Set up a distillation rig for fractional distillation at high temperature. The flask is placed in an oil bath containing a high temperature silicone oil. 

The checkers used a 18-cm. Vigreux column to remove low-boiling material, and then transferred the residue to a 250-ml. round-bottomed flask for fractional distillation under reduced pressure. 

Preparation of Hydrazine. Assemble an apparatus as shown in Fig. 85b. Put an amount of potassium hydroxide into a two-neck flask provided with a reflux condenser such that there is a 2-3-mm layer of hydrazine hydrate over it. Cool the flask in a bath with ice and transfer the previously prepared hydrazine hydrate into it wear eye protection ). Pass a stream of dry nitrogen through the reaction mixture. Carefully heat the flask until the alkali dissolves completely, then cool the flask to room temperature, and, without stopping the nitrogen stream, replace the reflux condenser with a dephlegmator. Assemble an apparatus for fractional distillation (see Fig. 20) and distil off the anhydrous hydrazine in a nitrogen stream at 112-114 °C. 

When the reaction ends, rapidly transfer the product into an apparatus for fractional distillation at atmospheric pressure (see Fig. 20). Distil off the benzene at 80 °C, heating the flask on an electric stove with an enclosed coil. After distilling off the benzene, pour the water out of the cooler. Disconnect the receiver with the benzene and connect a new dry receiver. Perform further distillation and gather the fraction boiling at 172-174 °C. 

Pour the reaction mixture into the flask of an apparatus for fractional distillation under atmospheric pressure (see Fig. 20). Collect the fraction boiling at 125 °C. Pour the phosphorus thiochloride into a weighed drawn out test tube. Seal the ampoule wear eye protection ). Weigh the ampoule and the remaining parts of the test tube. Write the equation of the reaction. Calculate the yield in per cent. Test the reaction of phosphorus thiochloride with water. Write the equation of the reaction. What is the oxidation state of sulphur in this compound ... 

The resulting mixture is transferred to an apparatus for fractional distillation, and carefully fractionated, an oil bath being used for heating (Note 3). A low-boiling fraction, consisting of acetone containing some ketene, acetic acid, and a small quantity of acetic anhydride, is removed at atmospheric pressure. As the distillation progresses the temperature of the oil bath is raised to 220° over a period of about an hour and held there until three hours have elapsed from the time distillation started (Note 4). 

Costica Stratula, Vasile Marinoiu, and Gheorghe Sorescu, Methods and Computation Programs for Fractional Distillation and Absorption Processes, Editura Tehnica, Bucharest, 1976. 

One metric ton of crude tall oil yields about 350 kg of rosin, 300 kg of fatty acids, and 300 kg of head and pitch fractions. For each metric ton of pulp produced, northern pines yield about 50 kg of tall oil, and the southern pines yield about 125 kg. The U.S. capacity for fractional distillation of tall oil is nearly one million metric tons per year. 

On completion of the triethyl phosphite addition and cessation of ethyl iodide evolution (less than 30 min after completion of the addition, up to 3.8 mL, 7.6 g, 99% is evolved, along with some triethyl phosphite) cool the reaction mixture and set up for fractional distillation. Distil the product at vacuum-pump pressure, discarding any low boiling fore-run, and collect pure diethyl phenylphosphonate, 16 (b.p. 94-101°C, 0.1 mmHg, 9.45 g, 90 %), as a liquid. 

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