250 



I. 



atom to which the group COOH is linked, is a pseudo-asymmetric 

 one, while both the neighbouring carbon-atoms are really asymmetric. 



The third isomeride (/// mpt: 50C) is a cis-trans-iorm. ; it must 

 represent a racemic compound, because its configuration is wholly 

 asymmetrical (group A), and under favorable circumstances it 

 must therefore be possible to resolve it into two enantiomorphously 

 related components. Up till now this fission has however not yet 

 been performed. 



In this connection the investigations of Von Baeyer 1 ) and 

 Perk in 2 ) on the hexa-hydro-phtalic- , -isophtalic-, and -terephtalic- 

 acids may be mentioned here. While both (cis-, and trans-}-hexa- 

 hydro-terephtalic acids have the symmetry S, and thus are not 

 resolvable into optically active antipodes, while the same is the case 

 with the cis-isomerides of the corresponding phtalic-, and- isophtalic- 

 acids, the trans-hexa-hydro-phtalic- , and the corresponding hexa- 

 hydro-isophtalic acids have however the axial symmetry of the 

 group C 2 . In accordance with this, Werner and Conrad 3 ) succeeded 

 in resolving the trans-hexa-hydro-phtalic acid by means of its quinine- 

 salt, and measured the optical rotation of both antipodes. 



Here the fission of trimethylene-dicarboxylic acid by Buchner 

 and Von der Heide 4 ), and that of the corresponding tricarboxylic 

 acid, may again be mentioned, as being also in full accordance with 

 the theoretical predictions. 



24. Again another remarkable case is found in the inosites 5 ) 

 which have the composition: C 6 H 6 (OH) 6 , and which must be con- 

 sidered to be hexa-hydroxy-hexa-hydro-benzenes. Besides a racemic 



1) A. Von Baeyer, Ann. der Chemie 245. 103. (1888); 251. 258. (1889); 258. 

 1, 145. (1890). 



2) W. H. Perkin Jr., Journ. Chem. Soc. London 59. 798. (1891). 



3) A. Werner and H. E. Conrad, Ber. d.d. Chem. Ges. 32. 3046. (1899). 



4) E. Buchner and.R. Von der Heide, Ber. d.d. Chem. Ges. 38. 3112. (1905). 



5) L. Maquenne, Ann. de Chim. et Phys. (6). 29. 271. (1893); G. Tanret, 

 Compt. rend, de 1'Acad. des Sc. Paris, 109. 908 (1899). 



