OF ARTS AND SCIENCES. 133 



III. On the Relation between Dibromacrylic Acid and 

 Tuir.KOMPuorioNic Acids. 



By Henry B. Hill and Clement W. Andrews. 



Nearly two years ago Michael and Norton * published a description 

 of the tribrompropiouic acid melting at 92° which was first mentioned 

 by Linnemann and Penl,t and which they obtained by the addition 

 of bromine to the so-called ^ monobromacrylic acid of ToUens and 

 Wagner. In this paper they remarked that potassic hydrate attacked 

 the acid readily in alcoholic solution, but they attempted no isolation 

 of the dibromacrylic acid which was thus formed. They soon after- 

 wards offered to 'relinquish the farther study of this acid, in case we 

 felt interested to undertake its preparation and comparison with the 

 dibromacrylic acid which one of us had already described. This kind 

 offer was accepted, and we began the investigation at once. Although 

 we had no difficulty in the isolation of a dibromacrylic acid which 

 closely resembled that which had been made from mucobromic acid, 

 still it was impossible to establish the identity of the two until the 

 latter had been somewhat more carefully studied. In the mean time 

 Mauthner and Suida, t in an article upon substituted acrylic and pro- 

 pionic acids, described again the preparation of the tribrompropiouic 

 acid melting at 92°, without having seen more than a brief notice of 

 Michael and Norton's work. In this article they further showed that 

 it might be converted by the action of potassic hydrate into a dibrom- 

 acrylic acid, which, as they asserted, was identical with that which 

 O. R. Jackson and one of us had obtained from mucobromic acid.§ 

 The only facts which they brought forward in support of this assertion 

 were, the melting-point, 85°, the ready formation of malonic acid by 

 the action of baric hydrate, and the anhydrous form of the lead salt. 

 Since neither the melting-point nor the action of baric hydrate will 

 discriminate between the two isomeric forms of dibromacrylic acid 

 already known, and moreover since the lead salt of one of these two 

 acids has never been described and of the other is not anhydrous, as 

 one of us has recently shown, it is evident that these facts were wholly 

 insufficient to characterize the acid in question. Our investigation of 



* Amer. Chem. Journ. ii. 18. 



t Berichte der deutsch. chem. Gesellsch., viii. 1008. 



t Sitzungsberichte der kk. Akademie, Wien, Ixxxiii. 273. 



§ These Proceedings, Vol. XVI. (n. s. viii.) p. 192. 



