I'Jll.] PUBLIC DOCUMENT — No. 31. 131 



PURIFICATION OF INSOLUBLE FATTY ACIDS. 



I3Y E. B. HOLLAND. 



Workers in oils and fats experience the same difficulty in 

 obtaining chemically pure products as investigators in other 

 lines of organic chemistry. The best insoluble fatty acids on the 

 market — judging from our experience — are unsatisfactory in 

 both physical characteristics and neutralization number. In 

 general appearance the acids that are offered resemble granu- 

 lated curd, though varying in color from white to yellow, and 

 contain considerable dust and dirt. The molecular weight, as 

 measured by titration in an alcoholic solution, may deviate from 

 the theoretical by 10 to 15 points. These statements apply to 

 chemicals marked " C. P." and bearing the name of a reputable 

 manufacturer or dealer. 



The writer required stearic, palmitic, myristic, lauric and oleic 

 acids for certain tests, and, finding it impossible to purchase 

 them of the desired quality, was forced to undertake a study of 

 various methods for their purification. As the character of the 

 unsaturated acids is so unlike that of the saturated, only treat- 

 ment of the latter will be considered at this time. The methods 

 that seemed the best adapted for the purpose were (a) distilla- 

 tion of the fatty acids in vacuo, (6) crystallization from alcohol, 

 and (c) distillation of the ethyl esters in vacuo, and all were 

 given extended trial. 



A. Distillation of the Fatty Acids in Vacuo. 

 Direct distillation under reduced pressure was successfully 

 employed a few years ago by Partheil and Ferie,^ starting with 

 Kahlbaum's best acids. Upon careful test the writer found that 

 the method possessed certain objectionable features which render 

 it rather impracticable for ordinary use. If it was merely a 



» Arch. Pharm., 241, 545 (1903). 



