20 PROCEEDINGS OF THE AMERICAN ACADEMY. 



the microscope. In appearance they closely resembled mucobromic 

 acid, but they were insufficient in quantity even for a melting point 

 determination. Since the dibromcrotonolactone reduced an ammoni- 

 acal solution of argentic nitrate on heating, we made one attempt to 

 effect its oxidation with argentic oxide. On boiling an aqueous solu- 

 tion of the lactone with a large excess of well washed argentic oxide, 

 metallic silver was formed, but at the same time argentic bromide in 

 large quantity. An approximate quantitative determination showed 

 that 87.0 per cent of the total bromine contained in the lactone had 

 been converted into argentic bromide. After a careful search we 

 failed to find any products of the oxidation except an amount of 

 dibrommaleic acid, which was just sufficient for its complete identifi- 

 cation through the microscopic appearance of its barium salt and the 

 melting point of its anhydride, 114-115°. 



Action of Bromine. 



Dibromcrotonolactone is not attacked by bromine at ordinary tem- 

 peratures, but at 100° substitution is quite rapidly effected. If equal 

 molecules of bromine and the lactone are taken, a colorless oil is ob- 

 tained after several hours' heating, which on standing gradually solidi- 

 fies, and the crystalline solid may be purified by recrystallization from 

 small quantities of alcohol. The substance which was thus obtained 

 melted at 56-57°, and gave with alkalies in alcoholic solution the 

 characteristic blue color described by Hill and O. R. Jackson.* 

 Mucobromylbromide had therefore bt j en formed from the dibrom- 

 crotonolactone according to the equation 



C 4 H 2 Br 2 2 + Br 2 = C 4 HBr 3 2 + HBr. 



When heated with an excess of bromine further substitution is 

 effected and a product is obtained in which both the hydrogen atoms of 

 the dibromcrotonolactone are replaced. For the preparation of this 

 body we heated equal molecules of mucobromylbromide and bromine in 

 sealed tube at 125-130°. At this temperature the reaction proceeds 

 rapidly, but it is also completed at 100° on longer heating. The col- 

 orless oil which we obtained gave no blue color in alcoholic solution 

 with sodic carbonate, and on standing gradually solidified. The 

 carefully pressed solid proved to be extremely soluble in alcohol, 

 ether, chloroform, benzol, or carbonic disulphide, but it was somewhat 

 more sparingly soluble in ligroin and could be purified by recrystalli- 



* These Proceedings, XVI. 175. 



