II. CHEMISTRY 



311 



and the side chain produces acetaldehyde, formaldehyde, and an acid, 

 probably formic acid.''- 



The alkaline hydrolysis of riboflavine gives urea and l,2-dihydro-G,7- 

 dimethyl-2-keto-l-D-ribityl-3-(iuinoxaline-carboxylic acid (III). (This acid 

 has recently been shown to have a depressant action on cardiac and visceral 

 muscles when injected intravenously in the dog."*^) In the case of lumiflavin, 

 l,2-dihydro-2-keto-l,6,7-trimethyl-3-quinoxaUnecarboxyUc acid (IV) is 

 obtained along with urea.^^''' ^^' ^* 



R 



H3C 



N 



\ 



oir 



NH 



CO 



/\/\ C— COOH 



+ NH2CONH2 



^ 



H3C 



H3C N 



III, R = D-ribityl; IV, R = CH3 



The oxocarbonic acid (IV) can be decarboxylated by sublimation with 

 formation of the lactam (V). This, when heated with NaOH, gives 1,2-di- 

 methyl-4-amino-5-methylaminobenzene (VI) . 



H3C 



H3C 



H3C 



H3C 



NHCH3 



NHo 



VI 



On reduction, riboflavin readily takes up two hydrogen atoms with for- 



« M. Halwer, J. Am. Chem. Soc. 73, 4870 (1951). 



" A. R. Surrey and F. C. Nachod, J. Am. Chem. Soc. 73, 2336 (1951). 



" R. Kuhn and T. Wagner-Jauregg, Ber. 66, 1577 (1933); R. Kuhn and 11. Rudy, 



Bcr. 67, 892, (1934); R. Kuhn, K. Reinemund, and F. Wovgand, Ber. 67, 1460 



(1934). 



