512 CHEMISTRY OF THE PROTEIDS CHAP. 



CH 3 C = C CH 2 . CH 2 . COOH 



O.C C.O 

 O 



Partial anhydride of tribasic hsematinic acid. 



Kiister has based this last formula on the fact that this compound 

 by further oxidisation is changed into succinic acid. The anhydride 

 of tribasic hsematinic acid becomes dibasic by splitting off carbonic 

 acid (Kolle) l according to the equation : 



CH 3 C ==* C CH 2 . CH 2 . COOH CH 3 C C CH 2 . CH 3 

 O.C C.O > O.C C.O + C0 2 



X o o 



Anhydride of tribasic hsematinic acid. Anhydride of dibasic hsematinic acid. 



This dibasic anhydride, according to Galler, 2 is identical with ethyl- 

 methyl-maleic acid anhydride : C 7 H 8 3 . 



On dissolving one gramme of hsematin in 60 volumes of hot glacial 

 acetic acid, and oxidising as quickly as possible with 12*5 grammes of 

 Cr0 3 , corresponding to 2 1 atoms of oxygen for each hsematin mole- 

 cule, and at once distilling off the glacial acetic acid, Kiister 3 showed 

 in his third paper that the hsematinic acids were obtained in such 

 amounts that at least three molecules of C 8 H 9 4 N 15 if not, indeed, 

 four molecules, could be obtained from one molecule of hsematin. 

 For this reason he considers the hsematinic acids to be the most im- 

 portant dissociation -products of hsematin. Kiister succeeded in 

 synthetising the ester of tribasic hsematinic acid : 



H 3 C 



BO-CO C COOR 



I II 

 H 2 C C COOR 



H 2 . 



This compound must be able to undergo intramolecular condensation 

 between the methyl and the neighbouring carboxethyll group. With 

 sodium ethylate a substance is obtained which gives a colour reaction 

 with ferric chloride. This same ester, when heated with alcoholic 



1 M. Kolle, Dis. Tiib. 1898 ; W. Kiister, Ber. d. deuts. chem. Ges. 35. 2948 (1902). 

 2 Galler, ibid. 35. 2948 (1902). 3 W. Kiister, Zeit.f.phys. CJiem. 44. 391 (1905). 



