16 PROCEEDINGS OP THE AMERICAN ACADEMY. 



a^ent we found to be stannous chloride with hydrochloric acid, since 

 this gives at once an essentially pure product in satisfactory quantity. 

 Mucobromylbromide is added to an equal weight of stannous chlo- 

 ride dissolved in the same amount of concentrated hydrochloric acid. 

 The reduction proceeds rapidly with the evolution of heat, although 

 in working with small quantities the reaction is greatly facilitated by 

 warming gently at first. "When the melting point of the mucobro- 

 mylbromide is reached, the flask must be well shaken until the oil has 

 completely disappeared. As the solution cools the dibromcrotonolac- 

 tone crystallizes out, and still more separates on dilution. The yield 

 which may be obtained in this way amounts to from 75 to 80 per cent 

 of the weight calculated from the mucobromylbromide taken, or about 

 70 per cent of that theoretically required by the mucobromic acid 

 employed. A single recrystallization from alcohol is sufficient for its 

 complete purification. 



Dibromcrotonolactone is very sparingly soluble in cold water, and 

 dissolves in from 30 to 40 times its weight of boiling water. As the 

 hot aqueous solution cools, the lactone crystallizes in small six-sided 

 plates, or in pointed prisms crossing at an angle of 60°. From 

 alcohol, in which it is somewhat sparingly soluble at ordinary tem- 

 peratures, although very readily soluble on heating, it crystallizes in 

 bundles of long friable prisms. From concentrated nitric acid it crys- 

 tallizes in large, clear, brilliant oblique prisms. In boiling ligroin it 

 dissolves somewhat sparingly on boiling, and as the solution cools the 

 greater part of it separates in finely felted needles. It is readily 

 soluble in chloroform or benzol, more sparingly soluble in ether or 

 carbonic bisulphide. It melts at 90-91°, and boils under a pressure 

 of 18 mm. at 145°. With steam it volatilizes rapidly. Although it 

 is remarkably stable in acid solutions, it is easily attacked by alkalies. 

 The alkaline hydrates dissolve it, forming deep yellow solutions, and 

 at the same time alkaline bromides are formed. In studying the 

 action of decinormal potassic hydrate in the cold, we have found that 

 approximately two molecules of potassic hydrate are neutralized by 

 each molecule of the lactone taken, while but one molecule of potassic 

 bromide is formed, but have been able to isolate no definite products 

 of the reaction. The lactone was not attacked by hydroxylamine ; 

 with aniline it yielded, with the elimination of bromine, the well 

 crystallized aniline derivative, which will be described later. Phenyl- 

 hydrazine also removed bromine, but gave no well characterized 

 product. 



