202 PROCEEDINGS OF THE AMERICAN ACADEMY 



afterward by Decker.* It crystallized in small yellow prisms, 

 which melted at 156-157°, and dissolved in concentrated sulphuric 

 acid with a red color. Analysis showed that it had the formula 

 C 11 H 12 N 2 2 . 



I. 0.2240 grin, substance gave 0.5299 grin. C0 2 and 0.1190 grin. 

 H 2 0. 

 II. 0.2173 grm. substance gave 26.6 c.c. of moist nitrogen at 23° 

 and under a pressure of 752 mm. 



Calculated for Found. 



C n H 12 N 2 2 . I. n. 



C 64.71 64.52 



H 5.88 5.90 



N 13.73 13.64 



Bromine in aqueous solution, therefore, converts methylpyro- 

 mucic acid into acetacrylic acid according to the equation 



C 6 H 6 3 + 2 Br 2 + 2 H 2 = C 5 H 6 3 + C0 2 + 4 HBr. 



The formation of this ketone acid from methylpyromucic acid, 

 while pyromucic acid under the same conditions yields an aldehyde 

 acid, shows conclusively that the methyl group of the methylpyro- 

 mucic acid stands in the 8 place. 



Action of Concentrated Sulphuric Acid. 



We have thought that it might be possible to bring additional 

 evidence as to the structure of the methylpyromucic acid through 

 an investigation of the sulphonic acid derived from it. A study of 

 the sulphonic acids derived from pyromucic acid had already shown 

 that 5-sulphonic acids were always formed by the action of fuming 

 sulphuric acid, whenever the b hydrogen had not already been other- 

 wise replaced; when the 8 hydrogen had been thus replaced, /3-sul- 

 phonic acids were formed. Moreover it was very easy to distinguish 

 between the two isomers in that bromine in aqueous solution in- 

 stantly formed sulphuric acid from the 8-sulphonic acids, while the 

 /3-sulnhonic acids were oxidized to products which retained the sul- 

 pho group. Methylpyromucic acid was added with careful cooling 

 to three times its weight of fuming sulphuric acid, the whole 

 allowed to stand for twenty-four hours, and the diluted solution 

 then neutralized with baric carbonate as usual. The barium salt 

 which was obtained by evaporating the filtered solution crystallized 



* Berichte der deutsch. chem. Gesellsch., XXI. 2937. 



