New York Agricultural Experiment Station. 127 



Contardi^ claims to have prepared the hexa-phosphoric acid 

 ester of inosite by heating inosite with an excess of phosphoric 

 acid in a stream of carbon dioxide to 160°-165° C. The product 

 was purified as the barium salt and after decomposing the latter 

 with sulphuric acid the free ester was obtained, which he describes 

 as identical with phytic acid. The same author claims to have 

 prepared poly-phosphoric acid esters of mannite, quercite and 

 glucose by the same method. 



Carre,' however, repeating these experiments, found that the 

 products described by Contardi were merely mixtures of free phos- 

 phoric acid and the polyhydric alcohols in question together 

 with their decomposition products mixed with some monobarium 

 phosphate. 



Many fruitless efforts have been made in this laboratory to 

 synthesize phytic acid and the hexa-phosphoric acid ester of inosite. 

 All experiments in this direction lead only to the tetra-phosphoric 

 acid ester of inosite, C6H6(OH)2 O4 [PO(OH)2]4. 



The method of Contardi was modified to the extent that inosite, 

 either dry or with water of crystallization, was heated with phos- 

 phoric acid, previously dried at 100° to constant weight, in vacuum 

 to a temperature of 140°-160° C. for about two hours. 



The same product, viz., the tetraphosphoric ester was obtained 

 whether the phosphoric acid was present in large or small excess 

 above six molecules of H3PO4 to one molecule of inosite. When it 

 was present in less quantity than this, however, for instance 1 

 molecule of inosite to 3 molecules of H3PO4, then a mixture of 

 esters was formed. It was found impossible to separate these 

 products completely owing to the fact that they possess about 

 the same solubility. 



The tetraphosphoric ester is most conveniently isolated by means 

 of its barium salt. The separation of the ester from the excess of 

 the phosphoric acid or barium phosphate succeeded because its 

 barium salt is much less soluble in dilute alcohol acidified with 

 hydrochloric acid than is barium phosphate. 



The new ester is a well characterized compound, very similar in 

 appearance and reactions to phytic acid. By heating with acids, 

 inosite and phosphoric acid are regenerated. It gives a white 

 precipitate with the ordinary molybdate solution, and with excess 

 of silver nitrate a white precipitate is also produced. These re- 

 actions are identical with those of phytic acid. 



The inosite used in these experiments was prepared from the 

 crude magnesium compound previously mentioned and carefully 

 purified by recrystallization. 



The reason why phytic acid could not be obtained by the action 

 of phosphoric acid on inosite is no doubt to be found in that it is 

 not a simple ester but a complex compound as suggested by Starken- 



^ Atti R. Accad. dei. Ldncei, Roma (5) 19, I: 23. 



2 Atti R. Accad. dei. Ldncei, Roma (5) 19, I: 823. 



3 Bull. Soc. Chim. France (4) 9: 195. 



