The apparatus² consists of a 3-l. three-necked round-bottomed creased flask, with standard ball joints and an indented cone-shaped bottom (Note 1), which is heated by means of an electric mantle and is equipped with a high-speed stirrer of stainless steel driven by a 10,000 r.p.m. motor (Note 2). One side neck is fitted with a bulb-type air-cooled condenser (Note 3), on top of which fits a 1-l. pressure-equalizing Hershberg dropping funnel (Note 4). The top of the dropping funnel is connected in turn to a U-tube containing a 1-cm. head of mercury. The entire apparatus is securely fastened to a sturdy support.

In the flask is placed 900 ml. of xylene (Note 5), and a slow stream of purified nitrogen (Note 6) is passed through the system from which the dropping funnel has been temporarily removed. The stirrer is run at slow speed, and the solvent is brought to a gentle reflux. The air stream cooling the condenser is shut off, the mercury valve is disconnected from the condenser, and a few milliliters of solvent is allowed to distil out the top of the condenser (Note 7). The dropping funnel (Note 8), containing a solution of 115 g. (0.50 mole) of dimethyl sebacate (Note 9) and 500 ml. of xylene (Note 5) is then inserted between the top of the condenser and the mercury valve. The air to the condenser is then turned on, and the electric mantle is turned off. The solvent is allowed to cool below its boiling point, and the stirrer is gradually brought to a stop. Throughout these operations the nitrogen flow is adjusted to keep air out of the system. Through a side neck is then added 50.6 g. (2.20 g. atoms) of crust-free sodium metal cut into lumps of convenient size. The side neck is closed, and the stirrer and the heater are turned on. The sodium is dispersed by stirring at about 6000–8000 r.p.m. for 10 minutes, and, with continued heating and stirring at a rate somewhat slower (to give suitable mixing), the dropwise addition of the ester solution is begun at such a rate as to be complete in about 24 hours (Note 10) and (Note 11).

Heating and stirring are continued for 1 hour after the addition is completed. The stirrer is then slowed, heating is stopped, the heater is removed, and the reaction flask is allowed to cool for about 15 minutes (Note 12). The reaction flask is then cooled in a water bath, and is finally thoroughly cooled in an ice bath. A solution of 140 ml. of glacial acetic acid in an equal volume of xylene is then added dropwise during about 30 minutes with continued cooling and stirring (Note 13). After addition of 450 ml. of water, stirring is stopped, the nitrogen is turned off, and the flask is disconnected from the apparatus. The two-phase mixture is filtered through a large Büchner funnel with suction to remove a small amount of gum, and the filtrate is then poured into a 3-l. separatory funnel. The aqueous phase is drawn off, extracted with 100 ml. of xylene, and is discarded. The xylene phases are washed in series with 100 ml. of water, and are combined and dried with 10 g. of anhydrous magnesium sulfate. The solution is filtered into a 3-l. round-bottomed flask, and the bulk of the xylene is distilled with the aid of an aspirator (Note 14) and (Note 15). The residue is transferred to a smaller flask and is distilled through a 2-ft. Vigreux column, the fraction boiling at 134–138°/14 mm. or 124–128°/9 mm. being collected as a yellowish liquid weighing 57–63 g. (67–74%). This material solidifies on standing and is sufficiently pure for most purposes (Note 16) and (Note 18). For further purification it may be crystallized from 150 ml. of pentane by cooling to −10° in an ice-salt bath for several hours. The mixture is filtered, and the crystals are washed with 50 ml. of pentane which has been cooled to −80°. The pure product thus obtained is a white granular crystalline solid, m.p. 38–39°, weighing 53–56 g. (63–66%) (Note 17) and (Note 18).