238 



VITAMINS 



H 



^C, II 

 HC^ ^C—C—OU 



II I 



Nicotinic acid, C6H5NO2 

 (Niacin) 



H O 



II 



HC^ ^C— C— NHj 

 II I 



Nicotinamide, CeHjONj 

 (Niacinamide) 



As its name implies, the compound is closely related to nicotine, from 

 which it can be easily formed by oxidation in the laboratory. This 

 vitamin is soluble in dilute alcohol and in water; it is very stable to 

 heat, light, acids, alkalies, and oxidizing agents. In fact, it is more 

 resistant to chemical attack than any of the other vitamins. Nicotin- 

 amide is preferred for therapeutic use since it is less likely to cause 

 a burning sensation of the face that is often noted after doses of nicotinic 

 acid. 



Occurrence 



Nicotinic acid is a substance that was known to organic chemists for 

 many years before its usefulness as a vitamin was discovered. It is now 

 prepared synthetically on a rather large scale and is among the most 

 easily obtainable and cheapest of the vitamins. An amount sufficient 

 to cure a pellagrin costs only about ten cents. The synthetic material is 

 now being used in the enrichment of white flour. The term "niacin" has 



-Z^r^ 



?,.j»f. 



I; .*i 



'^- 



Courtesy of Merck & Co., Inc. 

 Fig. 9-10. Nicotinic acid. 



