II. CHEMISTRY 331 



structures of II,* VII/ and IX^ were elucidated by Posternak, those of 

 III and VI by Dangschat and Fischer.'"- '^ Table I also indicates the num- 

 bering devices and trivial names suggested by Fletcher et al.^ 



C. SPATIAL CONSTELLATIONS 



Most textbooks and even review articles represent meso-inositol and 

 its isomers in the form of planar structures. This is, however, far from 

 acceptable, since it could lead to the assumption that the various hydroxyls 

 situated in what would be considered as the same plane are chemically 

 equivalent. Actually, it has been shown by Magasanik and Chargaff^' '^'^^ 

 that the several hydroxyl groups in cis position are treated differently in 

 a biological system, according to their position in space. These findings on 

 the selective oxidation of the inositol isomers by resting cells of Acetohacter 

 suboxydans, to yield mono- or dicarbonyl derivatives, were later extended 

 to cell-free enzyme preparations.'^- '^ 



It is, of course, evident that the structural formulas I-IX in Table I, 

 representing the series of inositol isomers, do not describe the actual posi- 

 tions in space of the various atoms, but merely represent planar projections 

 based on the conventions introduced into stereochemistry by Emil Fischer.'^ 

 If the biological function and fate of meso-inositol and its isomers are to be 

 understood, the element of rigidity, i.e., the lack of free rotation around 

 carbon-to-carbon bonds, prevailing in these derivatives of cyclohexane, 

 cannot be ignored. 



The well-known Sachse-Mohr concept postulates the existence of puck- 

 ered rings in cyclohexane; two strain-free forms are possible, the chair 

 configuration and the boat configuration. Recent work based on electron 

 diffraction studies'* and spectroscopic'^ and thermodynamic'" properties 

 has led to the conclusion that at room temperature cyclohexane exists pre- 

 dominantly in the chair form. Similar considerations haVe been brought to 

 bear upon the structures of the mono- and dimethyl derivatives of cyclo- 



» T. Posternak, Helv. Chim. Acta 29, 1991 (1946). 

 "T. Posternak, Helv. Chim. Acta 19, 1007 (1936). 

 1" G. Dangschat and H. O. L. Fischer, Naturwissenschaften 27, 756 (1939). 



11 H. O. L. Fischer, Harvey Lectures 40, 156 (1945). 



12 E. Chargaff and B. Magasanik, J. Biol. Chem. 165, 379 (1946). 

 " B. Magasanik and E. Chargaff, /. Biol. Chem. 175, 929 (1948). 

 " B. Magasanik and E. Chargaff, /. Biol Chem. 175, 939 (1948). 

 16 R. E. Franzl and E. Chargaff, Federation Proc. 9, 173 (1950). 



i« R. E. Franzl and E. Chargaff, Nature 168, 955 (1951). 



" K. Freudenberg, Stereochemie, p. 662, Deuticke, Leipzig and Vienna, 1933. 



1* O. Hassel, Tidsskr. Kjemi, Bergvesen Met. 3, 32 (1943); Quart. Revs. (London) 



7, 221 (1953). 

 i» R. S. Rasmussen, /. Chem. Phys. 11, 249 (1943). 

 2" C. W. Beckett, K. S. Pitzer, and R. Spitzer, /. Am. Chem. Soc. 69, 2488 (1947). 



