840 



X. THE VITAMIN K GROUP 



theoretical yields can be obtained by these syntheses. 2-Methylnaph- 

 thalene is available as a by-product of the coal-tar industry. ^^ 



A simple synthesis has been proposed by Sah et at}''' and by Sah alone,^^ 

 starting with naphthalene. On sulfonation, naphthalene-/3-sulfonic acid is 

 formed, which is changed to the nitrile upon treatment with potassium fer- 

 rocyanide. The nitrile is readily converted to ^S-naphthoic acid on hy- 

 drolysis, and this is reduced to the corresponding aldehyde by distillation 



500 



400 



»*o300 



100 



240 



260 280 300 



WAVE LENGTH, mjx 



340 



Fig. 1. Absorption curves of vitamin Ki (I), and vitamin Ko (II) in hexane-^^^ 



with barium formate in a G0% yield. 2-Methylnaphthalene results when a 

 Clemmensen reduction is applied to the aldehyde. The 2-methylnaphtha- 

 lene is readily converted to the corresponding 1,4-naphthoquinone by the 

 oxidation methods described above. 



A total synthesis of menadione from benzene has been accomplished by 

 Sah and Briill.^'' These workers condensed benzene with the anhydride of 

 methylsuccinic acid, using aluminum chloride as the catalyst. The result- 

 ing product, a-methyl-iS-benzoylpropionic acid, is first reduced to a- 

 methyl-7-phenylbutyric acid by the use of the Clemmensen reaction; 



64 E. A. Coulson, J. Soc. Chem. Ind., 60, 123-126T (1941). 



65 D. T. Ewing, J. M. Vanderbelt, and O. Kamm, /. Biol. Chem., 131, 345-356 (1939). 



66 P. P. T. Sah and W. Briill, Bet., 73, 1430-1432 (1940). 



