A solution of 218 g. (5.5 moles) of sodium hydroxide in 1960 g. of water and 1000 g. (1225 cc.) of 95 per cent alcohol are introduced into a 5.5-l. bottle which is loosely covered with a perforated disk of cardboard, supplied with an effective stirrer, and supported in a larger vessel so as to permit cooling with cracked ice. Into the alkaline solution, 520 g. (4.3 moles) of pure acetophenone (Note 1) is poured, the bottle is rapidly surrounded with cracked ice, and the stirrer started; 460 g. (4.3 moles) of u. s. p. benzaldehyde (Note 2) is then added at once. The temperature of the mixture should not be below 15° and it should not be allowed to rise above 30° during the reaction (Note 3). If it tends to do so, the stirring is not sufficiently vigorous.

It is advantageous, though not essential, to inoculate the mixture with a little powdered benzalacetophenone after stirring for one-half hour. After two to three hours, the mixture becomes so thick that the stirring is no longer effective. The stirrer is then removed and the mixture left to itself in an ice box for about ten hours. The mixture now is a thick paste composed of small shot-like grains suspended in an almost colorless liquid. It is cooled in a freezing mixture and then either centrifuged or filtered on a large Büchner funnel, washed with water until the washings are neutral to litmus, and finally washed with 200 cc. of 95 per cent alcohol, which has previously been cooled to 0°. After thorough drying in the air, the crude product weighs about 880 g. (97 per cent of the theoretical amount) and melts at 50–54°. It is sufficiently pure for most purposes but tenaciously holds traces of water. It is most readily purified by recrystallization from four to four and one-half times its weight of 95 per cent alcohol (Note 4). Eight hundred and eighty grams of crude product give 770 g. (85 per cent of the theoretical amount) of light yellow material (m. p. 55–57°) and 40–50 g. that require recrystallization.