HILL AND CORNELISON. — CROTONOLACTONES. 27 



partially solidified with the separation of the original substance. The 

 solid portion melted at 54-55°, while the brommaleyl bromide, accord- 

 ing to Hill and Sanger, melts at 55-56°. The liquid portion was 

 much more readily attacked by cold water than the original substance, 

 and gradually dissolved, leaving about one third its weight of the 

 crystalline solid, which had been held in solution. In the aqueous 

 solution was found monobrommaleic acid melting at 130°, and by 

 evaporation monobromfiimaric acid melting at 178° was obtained. 

 These facts seem to us sufficient to show that we had in our hands 

 two different bodies, each of which showed the properties of a brom- 

 maleylbromide. The relation between these bodies will be more fully 

 investigated. For the preparation of the a-bromcrotouolactone we 

 found that no purification of the crude product was necessary. 



The brommaleylbromide is readily reduced by a solution of stannous 

 chloride in strong hydrochloric acid, but the isolation of the lactone 

 which is formed is difficult. Although it is volatile with steam, it dis- 

 tils slowly, remains dissolved in the distillate, and must be extracted 

 from the dilute solution by ether. We have found it more convenient 

 to use zinc and acetic acid for the reduction. The brommaleylbromide 

 is suspended in one and a half times its weight of 80 per cent acetic 

 acid, and somewhat more than the calculated amount of zinc dust 

 added with careful cooling. The reaction is at first attended with 

 great evolution of heat, and the zinc dust must be slowly added. 

 After the completion of the reaction the addition of water to the 

 filtered solution precipitates but a small part of the lactone, and the 

 solution must be thoroughly extracted with ether. The ethereal solu- 

 tion, when washed with a dilute solution of sodic carbonate and dried 

 with calcic chloride, leaves upon distillation the beautifully crystalline 

 a-bromcrotonolactone contaminated with but small amounts of oily 

 impurities. The thoroughly pressed substance may most readily be 

 purified by recrystallization from ether. This same a-bromcrotono- 

 lactone is also formed by the action of bromine in aqueous solution 

 upon /3-brompyromucic acid. As is the case with the analogous 

 reaction by which n/3-dibromcrotonolactone is formed from /3y-dibrom- 

 pyromucic acid, the yield is small, and we have as yet merely satis- 

 fied ourselves of the identity of the product through its physical 

 properties. 



0.2000 grm. substance gave 0.2304 grm. AgBr. 



Calculated for C 4 H 3 Br0 2 . Found. 



Br 49.08 49.01 



