TRICARBALLYLIC ACID ACONITIC ACID. 179 



D. TRIBASIC, TRIATOMIC ACIDS, C n H 2n - 4 6 . 



Tricarballylic Acid. 



CH 2 .CO.OH 



C 6 H 8 6 = CH.CO.OH. 



CH 2 .CO.OH. 



Formation. By heating tricyanhydrine with caustic 

 potassa and by the action of nascent hydrogen (sodium- 

 amalgam and water) on aconitic acid. 



Properties. Colorless, transparent, rhombic prisms. 

 Fusing point, 157-158. Easily soluble in water, alco- 

 hol, and ether. 



The calcium salt, (C 6 H 5 6 ) 2 Ca 3 + 4H 2 0, is a white, 

 amorphous powder, difficultly soluble in water. 



Ethyl tricarballylate, C 3 H 5 (CO.O.C 2 H 5 ) 3 . Color- 

 less liquid, but slightly soluble in water, boiling at 

 about 300. 



E. TRIBASIC, TRIATOMIC ACIDS, C n H 2w ~ 6 6 . 



Aconitic Acid. 

 C 6 H 6 6 = C 3 H 3 (CO.OH) 3 . 



Occurrence. As calcium salt in Aconitum napellus, 

 in Delphinium consolida, and Equisetumfluviatile. 



Formation. By rapidly heating citric acid until 

 oily streaks appear in the neck of the retort. It is 

 extracted from the residue with ether. 



Properties. Colorless laminse or verrucose crystal- 

 line mass, easily soluble in water, alcohol, and ether. 

 Fusing point, 140. It is resolved at a high tempera- 

 ture into carbonic anhydride, water, itaconic acid, and 

 citraconic anhydride. It combines with hydrogen, 

 forming tricarballylic acid. 



The calcium salt, (C 6 H 3 6 ) 2 Ca 3 + 6H 2 0, forms 

 colorless, difficultly soluble prisms. 



or THB 



