126 Report of Department of Animal Industry of the 



It is impossible at the present time to decide definitely between 

 any of the above constitutional formulas, as the substance has not 

 yet been synthesized in the laboratory. 



As represented by the empirical formula, C6H24O27P6, phytic acid 

 corresponds to a hexa-phosphoric acid ester of inosite plus 3 H2O. 



C6H606[PO(OH)2]6 + 3H20. 



At present it is impossible to say whether the compound represents 

 a pyrophosphate or if the water is linked in some other way. That 

 the acid contains 12 acid (OH) groups as expressed in the formula 

 of Starkenstein, which would also be the case if it were a hexa- 

 phosphoric acid ester of inosite, and not 18 (OH) groups as in the 

 formula of Neuberg, seems certain, for in no case have we been 

 able to prepare any salt in which more than 12 H-valences were 

 replaced by bases. 



As observed by Starkenstein only one half of the 12(0H) groups 

 are particularly reactive. This finds expression in the fact that 

 the barium salt obtained from acid solutions contains only 3 Ba 

 to 6 P. As suggested by the above author, it is probable that these 

 reactive hydroxyls are adjacent but linked to different phosphoric- 

 acid residues. The salts with binary bases would then be represented 

 by the following: 



— OH 



— P = 



\m 



-0/ 



— P = 



— OH 



A further confirmation of this is found in the fact that the tri-barium 

 phytate as well as other similar salts of phytic acid with binary 

 bases are strongly acid in reaction. 



The presence of only 8 acid (OH) groups, however, can be shown 

 by titrating an aqueous solution of the acid with deci-normal sodium 

 hydroxide using phenolphthalein as indicator. Patten and Hart 

 (loc. cit.) who titrated with deci-normal barium hydroxide using 

 phenolphthalein as indicator obtained results agreeing with a hexa- 

 barium salt. 



Of special interest in connection with the constitution of phytin 

 are the phosphoric acid esters of inosite. 



Neuberg and Kretschner^ report obtaining a poly-phosphoric 

 acid ester of inosite by their method of preparing phosphoric acid 

 esters of the carbohydrates and glycerine, that is, by the action of 

 phosphorus oxychloride. The product could, however, not be 

 obtained pure as it was found impossible to separate it from the 

 inorganic phosphates. 



* Biochem. Ztschr. 36: 5. 



