ITACONIC ACID.* 167 



liquid, boiling at 250-260, is formed by the action of 

 phosphorus chloride on ethyl tartrate. 



Brommaleic and Isobrommaleic acids, C 2 HBr 



(CO.OH) 2 . The acid barium salts of these acids are 

 formed by boiling barium dibrom- and isodibromsuc- 

 cinates with water. Both acids crystallize in easily 

 soluble prisms, and are converted into succinic acid by 

 nascent hydrogen. Brommaleic acid fuses at 126, 

 isobrommaleic acid at 160. 



2. Itaconic Acid. 



CO.OH 



^ CO.OH. 



Formation. Together with citraconic anhydride, by 

 the distillation of citric and itamalic acids ; by heating 

 citric acid to 160. Can be most readily obtained in a 

 pure condition by heating a concentrated solution of 

 citraconic acid (or the distillate from citric acid) to 

 120-130. 



Properties, Colorless rhombic octahedrons, soluble in 

 15 parts of water of ordinary temperature, more easily 

 in hot water. Is resolved, by heating, into water and 

 citraconic anhydride. Combines with nascent hydro 

 gen, forming pyrotartaric acid ; with chlorine, bromine, 

 and hydrogen acids, forming substitution-products of 

 citraconic acid. 



The following acids are isomeric with itaconic acid. 



Citraconic acid, C 5 H 6 4 == C 3 H 4 (CO.OH) 2 . When 

 citric and itaconic acids are distilled, an oily substance, 

 citraconic anhydride, C 5 H 4 3 , passes over, which is con 

 verted into this acid by water, and when left in contact 

 with moist air. Four-sided deliquescent prisms. Fuses 

 at 80. Is converted into itaconic acid slowly at 100, 

 completely when heated in aqueous solution to 120- 

 130. Conducts itself towards hydrogen, chlorine, etc., 

 like itaconic acid. 



Mesaconic acid, C 5 H 6 4 = C 3 H 4 (CO.OH) 2 , is pro- 

 duced by boiling a dilute solution of citraconic acid 



