Benzalacetone dibromide

It is not necessary to purify the crude primary amine by redistillation if it is to be used immediately for the preparation of /3-alanine. However, the moist nitrile is not stable in storage, pressure being developed in a container stored at room temperature. 

Yields of 60-80% of the primary amine 1 have been obtained by introducing the acrylonitrile below the surface of the aqueous ammonia preheated to 110° in a steel reactor suitable for pressure reactions. 

Submitted by Norman H. Cromwell and Richard Benson. Checked by R. L. Shriner and William O. Foye. 

In a 1-1. three-necked round-bottomed flask fitted with an efficient mechanical stirrer, a thermometer, and a 125-ml. dropping funnel are placed 100 g. (0.68 mole) of pure, redistilled benzal- 

After all the bromine has been added, stirring is continued for 4 to 5 minutes longer and the dibromide is collected by filtration on an 11-cm. Buchner funnel, using suction. The product is washed with 100 ml. of warm 75% ethanol (Note 3). The crude product is purified by dissolving in the minimum amount of boiling methanol (800-1000 ml.) and cooling the solution in an ice bath for 4 hours. The product is collected by filtration and dried in a vacuum desiccator in the absence of light for 24 hours. The yield amounts to 110-120 g. (52-57%) of white needles which melt at 124 125° (Note 4). 

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Benzalacetone dibromide has been prepared by the addition of bromine to a solution of benzalacetone in chloroform,2 in carbon disulfide,3 and in carbon tetrachloride.4... 

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