HILL AND CORNELISON. — CROTONOLACTONES. 47 



Calculated for Found. 



C 4 HBr,N0 2 . I. II. HI. IV. V. 



Br 62.75 63.00 63.07 63.08 



N 5.49 5.65 5.45 



Mucobromoxirae anhydride dissolves quite readily in alcohol, chloro- 

 form, or benzol ; with somewhat more difficulty in ether or carbonic 

 disulphide; and is almost insoluble in ligroin. It crystallizes in den- 

 dritic needles, which melt at about 117-118°, but this melting point 

 varies with the conditions under which it is taken. If the melted sub- 

 stance be heated to a higher temperature, it solidifies again below 

 140° and melts then for a second time at 218°. This behavior is due 

 to the conversion of the anhydride into the isomeric dibrommalein- 

 imide, which melts, according to Ciamician and Silber,* at 225°. If 

 this isomerization is brought about by plunging the tube containing a 

 considerable quantity of the substance into a bath heated to 115°, 

 the reaction is violent, but also attended with decomposition. The 

 anhydride is sparingly soluble in cold water, although more readily in 

 hot. If the hot solution is quickly cooled the anhydride separates, but 

 on prolonged heating it is completely converted into the acid ammo- 

 nium salt of dibrommaleic acid. This acid was identified through its 

 characteristic barium salt and the melting point (114°) of its anhydride. 



Methyl Ester of Mucobromoxime, C 4 H 2 Br 2 N0 3 CH3. — Although 

 hydroxylamine hydrochlorate reacts at ordinary temperatures upon 

 mucobromic acid when dissolved in strong methyl alcohol, and forms 

 the mucobromoxime anhydride, if the reaction takes place at the boil- 

 ing point of the methyl alcohol the methyl ester of the oxime results. 

 The same body is also formed when the anhydride is boiled for a 

 short time with methyl alcohol. For its preparation we found it ad- 

 vantageous to dissolve mucobromic acid in rather less than twice its 

 weight of methyl alcohol, to add a little more than one molecule of 

 hydroxylamine hydrochlorate dissolved in the smallest possible quan- 

 tity of water, and to boil with reverse cooler for twenty minutes. On 

 cooling, the methyl ester then separated in abundance. 



L 0.4336 grm. substance gave 0.3370 grm. CO., and 0.0915 grm. H 2 0. 

 II. 0.2946 grm. substance gave 0.3899 grm. AgBr. 



Pound. 



II 



56.31 



* Berichte d. deutsch. cliem. Gesellsch., XVII. 556. 



