180 REPORT — 1903. 



anhydride (figs. 14, 15, and 17). The relationship between these com- 

 pounds is shown by the following formulse : — 



a.-Aminoethylpiperonyl- Corydaldine. 

 carboxylic anhydriae. 



o o 



H2 H2 



Hydrastinine. Oxyhydrastinine, 



CHO 



. /\/ NH-CH3 o/\/'^NCH 



<^H.<ol J^^Jh, ^H2<-! 



H 



H2 



Though Dobbie and Lauder have found that cotarnine and hydras- 

 tinine in alcoholic solution do not possess the constitution commonly 

 assigned to them, this in no way affects the argument, since there is an 

 important constitutional difference between oxycotarnine and oxyhydras- 

 tinine on the one hand, and cotarnine and hydrastinine on the other, what- 

 ever formulse be accepted for the two latter. 



Again, when the pyridine ring of cotarnine and hydrastinine is closed 

 by the conversion of these substances into their salts or by their reduction 

 to hydro-derivatives, the changes of structure are reproduced in a striking 

 manner in the spectra. 



Belationships established between differences in Constitution and Absorption 

 SiJectra, which may be ajyplied to the study of Alkaloids of unknown 

 Constitution. 



It is now known that many alkaloids which possess the same formula 

 are stereoisomerides. Alkaloids v^hich are related in this way give, like 

 other stereoisomerides, identical spectra.' Illustrations of this are 

 afforded by c?-corydaline and i-corydaline (fig. 16), narcotine and gnos- 

 copine (fig. 15), tetrahydroberberine and canadine (fig. 17). Quinidine 

 (conquinine) and cinchonidine also give absorption spectra identical with 

 those of quinine and cinchonine respectively, of which substances they 

 are probably stereoisomeric forms (figs. 18 and 19). This relationship 

 might sometimes be used to assist the investigation of cases of suspected 

 stereoisomerism. Where, for example, two compounds of the same 

 formula are known, one active and the other inactive, it may be inferred 

 that they are not optical isomerides if they have different absorption 

 spectra. 



A case in point is afforded by canadine and papaverine, which 

 possess the same molecular formulae but give widely different absorption 

 spectra. Even if it were not known otherwise that these two substances 



• Hartley and Dobbie, Chem. Soc. Trans., 1900, 77, 498 and 509. 



