The preparation of pure sodium ricinoleate.

Abstract

The sodium ricinoleate used by Larson in his work on toxin neutralization has been prepared from commercial castor oil.

Castor oil is a triglyceride of ricinoleic acid. It contains small amounts of stearic, hydroxystearic, and oleic acids. The object of the purification process is to remove practically all traces of these impurities.

In saponifying the castor oil to obtain the crude ricinoleic acid any standard method may be used. The fatty acid obtained is a brownish, viscous liquid that forms considerable sediment upon standing. After about two weeks' standing the semi-clear oil is decanted from the sediment. This is converted into the sodium soap in an aqueous solution. This solution is made up to about 20 per cent, and to it is added a 10 per cent solution of barium chloride until no more precipitate is formed. The barium ricinoleate is removed by filtration, and dissolved in 95 per cent alcohol. The barium soap recovered from 50 grams of fatty acid will require about one liter of alcohol. The barium ricinoleate is soluble in hot alcohol, whereas the barium stearates, hydroxystearates, and oleates are much less soluble. The solution is cooled to about 50° C. and filtered. Activated charcoal is added to the resulting filtrate, and after heating for about ten minutes it is again filtered. The portion that does not dissolve in the alcohol should be discarded, When this alcoholic solution is cooled to 5° C., the barium ricinoleate crystallizes out almost quantitatively. The solution should be kept at that temperature for a day to allow the crystallization to come to completion. The soap is separated from the alcohol by filtration. The process should be repeated, using 800 cc. of 95 per cent alcohol, redissolving, treating with more charcoal, filtering and allowing to recrystallize.