HYDROLYSIS PRODUCTS OF CEREBROSIDES 493 



diethyl ether at room temperature, but dissolves more readily on warm- 

 ing. When it is crystallized from acetone, the crystals are spherolithic, 

 with a structure consisting of radiating fibers and with a glistening appear- 

 ance. The crystals melt at 83-84°C. and have an iodine number of 38.8 

 (theoretical 38.1). The compound forms tri-r/i-nitrobenzojdcerebronyKV- 

 sphingosine when treated with m-nitrobenzoyl chloride. This derivative 

 melts at 96-97°C. and is easily soluble in diethyl ether and acetone; it can 

 be purified by separation from absolute alcohol, in the form of needle-like 

 crystals. 



On hydrolysis, cerebronyl-iV-sphingosine splits to yield one molecule 

 each of cerebronic acid and sphingosine: 



C42H83NO4 + H2O > C.4H48O3 + CsHsyNO, 



Cerebrouyl-.V- Cerebronic Sphingosine, 



sphingosine acid, 57.7% 45% 



(3) Sphingosine 



The chemistry of sphingosine has been considered earlier in the discus- 

 sion on sphingomyelin (see page 461). 



(4) Fatty Acids 



a. Cerebronic Acid, (a) Structure. Cerebronic acid is a-hydroxylig- 

 noceric acid. The piesence of the hydroxyl group was established by 

 Thierfelder,^!^ who prepared the acetyl derivative. Up to recently it was 

 believed that cerebronic acid had 25 carbon atoms. This suggestion was 

 especially unique, since all the natural fatt}' acids which have been pre- 

 pared have an even number of carbon atoms. However, the recent work of 

 Klenk has furnished proof that cerebronic acid belongs to the C24 series. 



Le\ene and Jacobs*^'' based their opinion that cerebronic acid was a C25 

 acid on the fact that, on o.xidation with potassium permanganate, lignoceric 

 acid (C24H48O2) was obtained. However, by means of a similar reaction, 

 Klenk"^ isolated an acid which he believed was tricosanic acid (C23H46O2) 

 in a yield of 74% of the theory for the crude acid and 43% for the purified 

 product. Klenk's product melted at 78.5°C.; Levene and Taylor^^^ state 

 that it should melt at 80-81°C., although 76.5-77.5°C. was later given 

 as the correct figure.^'" 



Klenk^^* obtained further data to prove his contention by determuiing 

 the products of ozonization of a-hydroxynervonic acid, CH3(CH2)7CH: 

 CH(CH2)i2CHOHCOOH. This acid was known to be closely related to 

 cerebronic acid since, on careful reduction, it was converted to the latter. 

 When .split at the double bond under conditions of oxidation, pelargonic 



*" P. A. Leveiie and F. A. Tavlor, J. Biol. Chem., 59, 905-921 (1924). 

 *5o F. A. Taylor and P. A. Levene, ./. Biol. Chem., 80, 609-G13 (1928). 



