34 II. CHEMISTRY OF FATTY ACIDS AND GLYCEROL 



isolated later by Anderson and Roberts^^^ from bovine tubercle wax as well 

 as from the leprosy bacilli. ^*^ 



Spielman^^^ assigned to it the structure of 10-methylstearic acid, CH3- 

 (CH2)7CH(CH3)(CH..)8COOH. Although later evidence seemed to dis- 

 prove this structure, Velick^^^ has recently concluded, largely on the basis 

 of its x-ray diffraction patterns, that this structure is the correct one. The 

 final proof has apparently been furnished by the brilliant studies of Prout, 

 Cason, and IngersoU.^*"-^''^ These workers compared natural tuber- 

 culostearic acid with d- and /-10-methylstearic acid, synthetically prepared. 

 It was found, on the basis of meliing points and mixed melting points of 

 the natural and synthetic acids as well as of the amides and tribrom- 

 anilides derived from them, that tuberculostearic acid is /-10-methyloctade- 

 canoic acid. 



c. Phthioic Acid. Another branched-chain acid, isolated by Spielman 

 and Anderson ^^'' and also by Ginger and Anderson ^'*^ from tubercle bacilli, 

 was named phthioic acid. It is a polymethylated compound with an 

 empirical fornmla of C26H5i02. Stenhagen and Stallberg''*'' suggested that 

 phthioic acid was ethyldecyldodecylacetic acid, but Polgar and Robinson^^^ 

 showed that this was probably incorrect. The first structure proposed 

 by the latter workers could be either 10,13,19- or 3,13,19-trimethyltri- 

 cosanoic acid.^^** On the basis of the high rotation, and especially in view 

 of the identity of the synthetic 3,13,19-trimethyltricosanoic acid with 

 phthioic acid, the latter structure was indicated. •'*'' However, Cason and 

 Prout^^^ disagreed with the postulated structure, since they believed that 

 such a compound should not have as high a specific rotation as that de- 

 termined for phthioic acid. 



CH3 CH3 CH3 



I I I 



CH3(CH2)3CH(CH2)5CH{CH2)9CHCH2C00H 

 Phthioic acid (Polgar and Robinson'''*) 



d. Mycolic Acid. Mycolic acid is an acid with a high molecular weight, 

 containing hydroxyl or hydroxymethoxy groups. According to Stodola, 



'36 R. J. Anderson and E. G. Roberts, J. Biol. Chem., 89, 599-610 (1930). 

 1" R. J. Anderson and N. Uyei, J. Biol. Chem., 97, 617-637 (1932). 



138 M. A. Spielman, J. Biol. Chem., 106, 87-96 (1934). 



139 S. F. Velick, /. Biol. Chem., 154, 497-502 (1944). 



i« F. S. Prout, J. Cason, and A. W. Ingersoll, /. Am. Chem. Soc, 69, 1233 (1947). 



"i F. S. Prout, J. Cason, and A. W. Ingersoll, J. Am. Chem. Soc, 70, 298-305 (1948). 



"2 M. A. Spielman and R. J. Anderson, ./. Biol. Chem.., 112, 759-767 (1936). 



1" L. G. Ginger and R. J. Anderson, ./. Biol. Chem., 156, 443-451 (1944). 



1" E. Stenhagen and S. Staill)erg, ./. Biol. Chem., 139, 345-364 (1941). 



i« N. Polgar and R. Rohins.m, J. Chem. Soc, 1943, 615-619. 



i« N. Polgar and R. Robinson, ./. Chem. Soc, 1945, 389-395. 



i« J. Cason and F. S. Prout, J. Am. Chem. Soc, 70, 879-880 (1948). 



