94 



Scientific Proceedings (8i). 



been possible to judge of the purity of a cerebroside by the com- 

 position of the fatty acid fraction obtained on hydrolysis. This 

 standard has been employed by us in testing the purity of the 

 substance designated as phrenosin and kerasin. 



By methods employed in different laboratories, it has been 

 possible to obtain phrenosin in a fair degree of purity. Upon 

 hydrolysis of phrenosin of the highest dextrorotation one obtains 

 cerebronic acid. With the progress of purification the dextro- 

 rotation of phrenosin increases. On the other hand, the kerasin 

 fraction acquires an increasing levorotation. Hence one can also 

 be guided in purifying the kerasin by the magnitude of its levorota- 

 tion. This method has been employed in our laboratory and also 

 by Rosenheim; Rosenheim used in addition to this the selenite 

 plate test. Guided by these tests, Rosenheim obtained substances 

 which showed levorotation of — 2 to — 3.5 0 , and claimed them 

 to be pure kerasin. On hydrolysis of these fractions he obtained 

 only lignoceric acid. 



Several years ago in our laboratory, hydrolyses were made on 

 substances with the same and even higher rotatory power than 

 those employed by Rosenheim. Using methods of hydrolyses 

 different from the conventional method introduced by Thudichum, 

 and used by all other workers, it was found that these fractions 

 contained not only lignoceric acid but also cerebronic acid. From 

 this it was concluded that kerasin had not, as yet, been prepared 

 in a pure state. These results were not published because at- 

 tempts to isolate kerasin in larger amounts by the methods then 

 used, were not successful, and it was desired to obtain a more 

 satisfactory method for preparation of the cerebroside. 



It was thought that by the fractionation, not of the cerebroside 

 mixture itself, but of an acyl derivative, one might obtain more 

 satisfactory results. With this object in view the acyl derivatives 

 of phrenosin and fractions corresponding to kerasin were prepared, 

 as follows: 





M. 



r i J 0 



c. 



H. 





41-43° 



-II.08 



65-31 



9.27 





54-56° 



— 16.46 



67.00 



9-95 



Tri-benzoyl phrenosin 



65-66 0 



+ 21.20 



73-45 



8.83 





69-70° 



+ 21.72 



73.22 



9-45 



Tri-/>-nitrobenzoyl phrenosin 



94-96° 



+ I2.I8 



63.61 



7-99 



