596 PANTOTHENIC ACID 



the chick antidermatitis vitamin with pantothenic acid came with the 

 synthesis of pantothenic acid.^"- *"• ^^- ^^ 



Williams and Major" announced the synthesis of pantothenic acid 

 which was made possible by the isolation from pantothenic acid concen- 

 trates of the lactone moiety in pure form. They named this compound 

 pantoic lactone. The lactone and /3-alanine were coupled to form pure 

 pantothenic acid. Pure pantothenic acid thus was first prepared as a syn- 

 thetic compound. Its preparation clarified its relation to the "filtrate fac- 

 tor" of the English workers^^- -^ who were also well along toward its isola- 

 tion. They suggested that their factor and pantothenic acid were identical.-' 

 Pantothenic acid also seemed to be identical with factor 2 of Lepkovsky 

 et a/.3o 



B. CHEMICAL AND PHYSICAL PROPERTIES 



Pantothenic acid is a pale-yellow viscous oil with a molecular weight of 

 219. It has weak basic properties. It has never been prepared in crystalline 

 form, but its sodium, potassium, and calcium salts crystallize readily. It is 

 generally distributed commercially as its calcium salt. It is readily soluble 

 in water, ethyl alcohol, dioxane, and glacial acetic acid.^^ It is somewhat 

 soluble in ether acetone and amyl alcohol and practically insoluble in 

 benzene, chloroform, and the hydrocarbon solvents. It is hydrophilic and 

 is adsorbed on charcoal but not on fuller's earth. ^^ It is readily esterified. 

 Its methyl or ethyl esters are active for animals but have little activity for 

 microorganisms. The vitamin activity of pantothenic acid is lost when the 

 OH groups in the pantoic acid part of the molecule are esterified. The 

 activity is regenerated by careful saponification.^^ Its acetyl derivative can 

 be distilled at approximately 10~^ mm. Hg.^" 



Panthothenic acid is quite stable in neutral solution, but its activity is 

 destroyed by hot acid or alkaline solutions. Under these conditions, it 

 decomposes largely into pantoic acid or its lactone and j8-alanine. 



The vitamin is optically active, owing to an asymmetric carbon atom in 

 pantoic lactone. Free pantothenic acid has a rotatory power [a]^ + 37.5. 



" E. T. Stiller, J. C. Keresztesy, and J. Finkelstein, /. Am. Chem. Soc. 62, 1779 



(1940). 

 2^ E. T. Stiller, S. A. Harris, J. Finkelstein, J. C. Keresztesy, and K. Folkers, /. Am. 



Chem. Soc. 62, 1785 (1940). 

 " R. J. Williams and R. T. Major, Science 91, 246 (1940). 



28 T. F. Macrae, A. R. Todd, B. Lythgoe, C. E. Work, H. G. Hind, and M. M. El 

 Sadr, Biochem. J. 33, 1681 (1939). 



29 B. Lythgoe, T. F. Macrae, R. H. Stanley, A. R. Todd, and C. E. Work, Biochem. 

 J. 34, 1335 (1940). 



3° S. Lepkovsky, T. H. Jukes, and M. E. Krause, J. Biol. Chem. 115, 557 (1936). 

 '^ H. R. Rosenberg, Chemistry and Physiology of the Vitamins. Interscience Pub- 

 lishers, New York, 1945. 



