OF ARTS AND SCIENCES. 185 



BrC = C - COOH 

 \ 



o 



/ 

 HC = CII 



By oxidation with nitric acid it gives, as it should, monobromfuoiaric 

 acid. 



Since all the fiirfuran hydrogens are replaced by bromine in tribrom- 

 pyromucic acid, but one form of the acid is possible, and that is 



BrC = C - COOH 



\ 

 C 



/ 

 BrC = CBr 



Of the substituted pyromucic acids which we have studied, those 

 which contain a bromine atom in the S-posidou give, by oxidation 

 with bromine water, dibasic acids, while those in which the 8-hydrogen 

 is not thus replaced yield ultimately the aldehyde acid, mucobromic 

 acid. Although we are unable to follow at present the successive steps 

 by which this oxidation proceeds, it may fairly be inferred that the 

 a-carbon atom is in any case completely oxidized, while the 8-carbon 

 atom appears in the aldehyde group whenever this is formed. 



The strong analogies between the derivatives of furfuran and of 

 benzol have frequently been pointed out during the past few years. 

 It is interesting to note that by the action of bromine upon pyromucic 

 acid the S and /3 hydrogen atoms are successively replaced. If the 

 group CH=CH be substituted for the oxygen of furfuran, these become 

 respectively the para and ortho positions of the aromatic series. While 

 benzoic acid itself is converted into metabrombeuzoic acid by the 

 action of bromine, the formation of para and ortho derivatives under 

 these conditions is more frequently observed in the aromatic series. 



While we, unfortunately, have been able as yet to obtain no direct 

 evidence as to the constitution of the substituted furfnrans which we 

 have described, there can be little doubt as to their structure. The 

 trihromfurfuran obtained in the preparation of tribrompyromucic acid 

 must certainly have the formula 



BrC=CII 

 \ 



o 



/ 

 BrC = CBr 



