In recrystallizing benzalacetophenone, the alcohol should be saturated at 50'0. If the solution is saturated above this temperature, the benzalacetophenone tends to separate as an oil. The solution should be allowed to cool gradually, and should finally be chilled in a freezing mixture. 3. Other Methods of Preparation
The methods for producing benzalacetophenone are: the action of acids on a mixture of benzaldehyde and acetophenone or on a solution of these substances in glacial acetic acid;[1] the condensation of benzaldehyde and acetophenone with a 30 per cent solution of sodium methylate at low temperatures;[2] the action of sodium hydroxide on an alcoholic solution of benzaldehyde and acetophenone.[3]
The methods based on the use of acids as condensing agents were not considered, because Claisen, who devised them, abandoned them after he found that alkaline condensing agents gave better results. The preliminary experiments showed that condensation with sodium methylate takes a long time and gives a product which it is difficult to handle in large quantities. The method devised by Kostanecki and Rossbach[3] has therefore been developed.
[1] Ber. 14, 2463 (1881).
[2] Ber. 20, 657 (1887).
[3] Ber. 29, 1492 (1896).
II
BENZYL BENZOATE
2 C6H5CHO + C6H5CH2ONa—> C6H5CO2CH2C6H5 + C6H5CH2ONa
Prepared by O. KAMM and W. F. KAMM. Checked by ROGER ADAMS and R. L. JENKINS.