336 INOSITOLS 



pinitol.^^ According to the nomenclature of Fletcher et al} it would conse- 



OCH3 



quently be designated as 5-methyl-D-inositol. 



The levorotatory quebrachitol is a monomethyl ether of Z-inositol (struc- 

 ture IX). It was discovered by Tanret^^ in the bark of the quebracho tree. 

 In addition to several other plants,^ • ^ it occurs in the latex of Hevea brasi- 

 liensis,^^ which appears to be the best source. The natural occurrence of 

 racemic inositol also has been reported. ^^ 



4. Other Cyclohexitols 



None of the other isomers of ?neso-inositol appears as yet to have been 

 found in nature. It is, however, perhaps suggestive that the 7 isomer of 

 hexachlorocyclohexane ("gammexane"), widely used as an insecticide, has 

 been shown to have the configuration of muco-inositol (structure VI). ^^ In 

 this connection, a brief mention of the structures of the other hexachloro- 

 cyclohexanes may be of interest: the a isomer corresponds to (/,Z-inositol 

 (structures VIII and IX), the /3 isomer to scyllitol (structure VII), the 

 8 isomer to meso-inositol (structure V), and the e isomer to the unknown 

 cyclohexitol IV.-^ 



E. PROPERTIES 



The cyclohexitols are white crystalline, non-reducing substances, soluble 

 in water, the most sparingly soluble being scyllitol (VII). They are usually 

 recrystallized from aqueous ethanol. For additional characterization the 

 hexaacetates are often employed; and the distillation in vacuum of similar 

 hexa derivatives has been suggested as a procedure for final purification.^^ 



Some of the characteristics of the various isomers are as follows: epi- 

 inositol (II), m.p. 285° (with decomposition); hexaacetate, m.p. 188°; 

 aZZo-inositol (III), m.p. 270-275°; mm-inositol (V), m.p. 225-227°; hexa- 

 acetate, m.p. 216-217°; mwco-inositol (VI), m.p. 285-290° (with decomposi- 

 tion); scyllitol (VII), m.p. 352° (with decomposition); hexaacetate, m.p. 



" A. B. Anderson, D. L. MacDonald, and H. O. L. Fischer, /. Am. Chem. Soc. 74, 



1479 (1952). 

 6s C. Tanret, Compt. rend. 109, 908 (1889). 

 66 A. W. K. De Jong, Rev. trav. chim. 25, 48 (1906). 

 " C. Tanret, Compt. rend. 145, 1196 (1907). 

 68 G. W. van Vloten, C. A. Kruissink, B. Strijk, and J. M. Bijvoet, Nature 162, 



771 (1948). 



