8 BULLETIN 1057, U. S. DEPARTMENT OF AGEICULTUEE. 



The acid present in the largest proportion possesses the formula 

 C 18 H 32 2 , and has been designated chaulmoogric acid, with reference 

 to the vernacular name of the oil. It is accompanied by a lower homo- 

 logue, 16 H 28 O 2 , which has been termed " hydnocarpic acid," on ac- 

 count of having first been isolated from a Hydnocarpus oil. Both of 

 these acids are beautifully crystalline substances, from which a num- 

 ber of derivatives have been prepared, and their constitution has also 

 been definitely established. They constitute what is now known as the 

 chaulmoogric acid series. 



Chaulmoogric acid, C 18 H 32 2 , melts at 68.5° C. and is dextrorota- 

 tory, having [<x]d + 62.1°. Although isomeric with linolic acid, it 

 is capable of combining directly with only two atomic proportions of 

 bromin or iodin. It must, therefore, possess only one ethylenic 

 linking and contain in its structure a closed carbon ring, which has 

 been shown to be the case. The methyl ester (methyl chaulmoograte) 

 distils at 227° C. under a pressure of 20 mm. as a colorless oil, which 

 on cooling forms a solid mass of needles, melting at 22° C. The 

 ethyl ester (ethyl chaulmoograte) is a colorless oil, which boils at 

 230° C. under a pressure of 20 mm. 



Hydnocarpic acid, C 16 H 28 2 , melts at 60° C. and like chaul- 

 moogric acid is optically active, having [a]D -j- 68°. Its methyl 

 ester is a colorless oil, which boils at 200° to 203° C. under a pres- 

 sure of 19 mm. When cooled it solidifies to a mass of colorless crys- 

 tals, which melt at 8° C. The ethyl ester is a colorless oil, which 

 boils at 211° C. under 19 mm. pressure. 



Besides the above-mentioned acids, chaulmoogra oil contains a 

 small amount of palmitic acid, together with an acid or acids hav- 

 ing a higher iodin value than either chaulmoogric or hydnocarpic 

 acid. As was noted several years ago, this observation, in connec- 

 tion with other characters of the acids, indicated the presence in the 

 oil of an acid or acids of the series C n H 2 „_ 4 2 , but with two ethylenic 

 linkings. Inasmuch as linolic acid, C 18 H 32 2 , possesses two ethylenic 

 linkings and an iodin value of 181.2, it is probable that a considerable 

 proportion of this acid is contained in both chaulmoogra and hydno- 

 carpus oils. Linolenic acid, C 18 H 30 O 2 , which contains three ethylenic 

 linkings and has an iodin value of 273.7, may also be present. 



An interesting occurrence of chaulmoogric acid has been recorded 

 by Goulding and Akers (8, 10) . They obtained it from the fatty oil of 

 so-called " Gorli " seed from Sierra Leone and found it to be present 

 to the extent of 84.5 per cent in the mixed acids, the remainder con- 

 sisting of liquid acids having a higher iodin value and therefore 

 more unsaturated. The botanical source of these seeds is Oncoba 

 echinata Oliver, which belongs to the same family as the chaulmoogra 

 tree. 



