HILL AND CORNELISON. — CROTONOLACTONES. 17 



Dibromfumaric Aldehyde of Toennies. 



The melting point and other properties of the clibromcrotonolactone 

 recalled a body of like composition which was obtained in 1879 by 

 Toennies,* through the action of bromine water upon 0-y-dibrornpyro- 

 mucic acid. He gives no analytical data to support his formula, and 

 apparently had but small quantities of material at his disposal. From 

 its behavior he considered the body to be the aldehyde of mucobromic 

 acid, or the double aldehyde of dibromfumaric acid. In 1866 Hill and 

 Sangerf again prepared this body from /3y-dibrompyromucic acid, but 

 were unable to obtain it in satisfactory quantities, and hoped to return 

 to it at some future time. A further study of the reaction has shown 

 us that it is by no means simple in its nature. While we have been 

 unable to obtain a satisfactory yield of the desired product, we have 

 succeeded in preparing an amount amply sufficient for its identifica- 

 tion, and at the same time we have isolated a second product of the 

 reaction. 



Preliminary experiments showed us that it was most advantageous 

 to add about 20 per cent more than one molecule of bromine to the 

 finely divided dibrompyromucic acid suspended in 20 times its weight 

 of cold water. We therefore boiled 5 grm. of pure /3y-dibrompyro- 

 mucic acid with 100 c.c. of water, and quickly cooled the solution 

 in order to obtain the acid in a finely divided condition. "When the 

 temperature reached 16°, 1.2 c.c. of bromine were added, and the 

 whole well shaken. The color of the bromine gradually faded, but 

 when it had completely disappeared a considerable amount of a well 

 crystallized body remained undissolved. Instead of allowing the solu- 

 tion to stand over night, as Hill and Sanger had done, we filtered out 

 the insoluble substance at the end of three hours, and extracted the 

 colorless aqueous solution thoroughly with ether. The ethereal ex- 

 tract left on distillation a syrupy residue, which partially solidified on 

 standing over night in vacuo over sulphuric acid. The crystals when 

 thoroughly drained upon the pump and pressed weighed 0.85 grm. 

 Two crystallizations from small quantities of hot alcohol yielded 

 0.65 grm. of substance, which melted at 90-91°, and showed the 

 characteristic behavior of the dibromcrotonolactone. In order to 

 identify it with- precision, we converted it into the a-iod-/3-bromcroto- 

 nolactone, which is fully described later, by heating it with hydriodic 



* Berichte d. deutsch. cliem. Gesellsch., XII. 1202. 

 t These Proceedings, XXI. 172. 

 vol. xxix. (n. s. xxi.) 2 



