In a 5-l. round-bottomed flask, fitted with an 80-cm. reflux condenser, are placed 3 l. of absolute alcohol (Note 1) and 490 g. (327 cc., 4.1 moles) of chloroform (Note 2). The flask is arranged for outside cooling by running water. To the solution, 207 g. (9 atoms) of clean sodium cut into pieces which will conveniently drop through the condenser is added during the course of about two hours. In order to add the sodium at this rate, the flask must be cooled during the addition. When the sodium has entirely reacted and the mixture has been cooled to room temperature, the sodium chloride which has separated is removed by suction filtration with the use of thoroughly dry apparatus (Note 3). The salt is washed on the filter with 200 cc. of absolute alcohol, and the washings are allowed to run into the main filtrate.

The solution is placed in a 3-l. flask fitted with an 80-cm. fractionating column (Note 4), and the excess chloroform and most of the alcohol are distilled off on a steam or water bath. The distillate is caught in a 2-l. suction flask protected from moisture by a drying tube. This distillation requires five or six hours. A mixture of chloroform and alcohol, weighing about 2000 g., is recovered and saved for the next run (Note 3). The liquid remaining in the flask is decanted from the small amount of salt which has separated, into a Claisen flask with a 30-cm. fractionating column (Note 5). The mixture is distilled at atmospheric pressure. The fraction boiling below 85° is mainly alcohol and is discarded. An intermediate fraction of about 100 g., boiling at 85–140°, contains about one-fourth of the total yield. This may be fractionated but is best added to a subsequent run. The orthoformic ester is collected at 140–146° and weighs 120–140 g. (27–31 per cent of the theoretical amount). There is practically no higher-boiling material. Another distillation gives almost all the material boiling over a 2° range.

After the first run, 400 g. of chloroform and enough absolute alcohol (800–1000 cc.) are added to the recovered chloroform-alcohol mixture to give a total volume of 3 l. The sodium is then added as before. After the excess of chloroform and alcohol has been distilled through the fractionating column, the intermediate fraction from the previous run is added before fractionating. The yield from such a run is about 200 g. (45 per cent of the theoretical amount) (Note 6) and (Note 7).