The synthetic process of Ketene diethylacetal (CAS NO. ) contains one step. The synthetic route is as follows:

In a 2-l. round-bottomed flask, preferably fitted with an interchangeable ground-glass joint, are placed 650 g. (820 ml.) of absolute tert-butyl alcohol and 39.1 g. (1 gram atom) of potassium. A reflux condenser is attached to the flask and the mixture is refluxed until all the potassium is dissolved (about 8 hours). The solution is allowed to cool slightly, and 198 g. (1 mole) of bromoacetal, together with some boiling chips is quickly added. A cream-colored precipitate of potassium bromide begins to deposit immediately. The flask is attached at once to a closely indented 46-cm. Vigreux column, equipped with a glass insulating jacket and a total-reflux partial take-off still head1, and the tert-butyl alcohol is distilled from an oil bath (about 120–130°) at the rate of 25 drops per minute with a reflux ratio at the still head of about 6:1. This operation requires 16–18 hours, and at the end of this time the temperature of the oil bath is raised to 160° and maintained there until no more alcohol comes over. The bath is then lowered and allowed to cool while the pressure within the fractionating system is very gradually reduced to 200 mm. and held there by a barostat.

A small amount of the alcohol comes over at 51–52° /200 mm., and then, after the heating bath is replaced, 4–6 ml. of an intermediate fraction distils. This is followed by a fraction which boils at 83–86°/200 mm. and which is collected as pure ketene acetal. A total of 78–87 g. is obtained (67–75%). The major portion is collected while the temperature of the bath is 120–140°, and the remainder is obtained by raising the bath temperature to 170–180°. Ketene acetal is best stored in a bottle made of alkaline glass which is preferably new and dusted with sodium tert-butoxide. The glass stopper should be very well greased. Even with these precautions a small amount of a voluminous precipitate of the white polymer will develop.