HILL AND CORXELISON. — CROTOXOLACTONES. 29 



evaporation a viscous residue. After long standing in desiccator a 

 few microscopic rhombic plates appeared, which were doubtless muco- 

 bromic acid. On repeating this experiment later, when the mean 

 temperature of the room was much higher, the reaction was com- 

 pleted in about half the time, the product gave a decided blue color 

 in alcoholic solution with sodic carbonate, showing the formation of 

 mucobromylbromide, but on long standing crystals of dibromcrotono- 

 lactone were also formed. On heating with two molecules of bromine 

 for several hours at 100°, mucobromylbromide is formed in quantity. 

 The product gradually solidified on standing, gave an intense blue 

 color with sodic carbonate, and after recrystallization from alcohol 

 melted at 56-57°. 



Action of Oxidizing Agents. 



Concentrated nitric acid oxidizes the a-bromcrotonolactone without 

 much difficulty at 100°. Carbonic dioxide is freely evolved, and a 

 small quantity of a volatile oil is formed, which has a suffocating, 

 sharp odor, and contains both nitrogen and bromine. We were un- 

 able to isolate other characteristic products of the reaction. With 

 bromine in aqueous solution we had somewhat better success. The 

 reaction progressed slowly, but after boiling for several hours with an 

 excess of bromine a small amount of an oily product had been formed 

 which was not further examined. The aqueous solution upon evapo- 

 ration gave characteristic crystals of mucobromic acid, which, after re- 

 recrystallization from water, melted at 120-121°. The weight of 

 mucobromic acid thus obtained was, however, barely 20 per cent of 

 the theoretical amount, and carbonic dioxide was also formed in the 

 reaction. Hill and Sanger had found that the body which they de- 

 scribed as having the composition of a bromcrotonolactone and melt- 

 ing at 77° was converted by bromine and water into an amorphous 

 substance insoluble or sparingly soluble in all common solvents. Two 

 experiments which we tried with small quantities of their old prepa- 

 ration failed to confirm their statements. It gave precisely the same 

 results which we had already obtained with the a-bromcrotonolactone. 

 The yield of mucobromic acid given by the reaction is so small, and 

 the quantity of the old material at our disposal was so limited, that 

 we were unable to purify our product sufficiently for a sharp deter- 

 mination of the melting point. Its appearance and behavior left no 

 doubt as to its identity. 



