I 



ON ABSORPTION SPECTRA AND CHEMICAL CONSTITUTION. 129 



region of such low refrangibility as \ 3000 when 1 mm. of liquid is 

 examined containing only T^/^oth of substance, so that no band is visible. 

 The remarks on narceine are also applicable to papaverine in every 

 particular.' ' 



Dobbie and Lauder ^ have shown that corydaline and berberine give 

 rise to parallel series of derivatives. The absorption spectra of the 

 corresponding derivatives are related to one another in the same way as 

 the spectra of the parent substances. When corydaline is acted on with 

 mild oxidising agents, four atoms of hydrogen are removed, and a yellow 

 substance is obtained, which stands in the same relation to corydaline as 

 berberine to tetrahydroberberine.^ 



Oxidation with dilute nitric acid converts corydaline and berberine 

 respectively into the dibasic corydic and berberidic acids : 



C, 3He(CH3)(OCH3)2-N(C02H)2, 



Corydic acid. 



Berberidic acid. 



whilst oxidation with permanganate gives rise, amongst other pro- 

 ducts, to corydaldine in the former case, and to co-aminoethylpiperonyl- 

 carboxylic anhydride in the latter. The corresponding derivatives differ 

 structurally from one another in the same way as corydaline and tetra- 

 hydroberberine, excepting that, in the case of corydaldine and w-amino- 

 ethylpiperonylcarboxylic anhydride, ring II having disappeared, the 

 difference between the two compounds is confined to the replacement 

 of the two methoxyl groups of the former by dioxymethylene in the 

 latter. The spectra of the corresponding derivatives (figs. 10 and 11 

 and 14 and 15), exhibit the same close relationship as those of the alka- 

 loids themselves. The general absorption of the berberine derivatives 

 is, however, always slightly greater than that of the corresponding 

 corydaline derivatives. This is probably due to the influence of the dioxy- 

 methylene group, and the correctness of this inference is supported by 

 the fact that piperonylic acid, C6H3(CH202)-COaH, shows slightly 

 greater general absorption than veratric acid, CfiH,(OCH,),-COoH 

 (figs. 12 and 13). 



Whilst the spectra of corydaldine and w-aminoethylpiperonylcar- 

 boxylic anhydride approach one another closely, they differ widely from 

 those of cotarnine and hydrastinine (figs. 14, 15, and 16), the correspond- 

 ing oxidation products of narcotine and hydrastine respectively. The 

 difference finds a sufficient explanation in the fact that whilst all four 

 substances are nearly related, the chain containing the nitrogen atom, 

 which is closed in the two former, is open in the two latter. When' 

 however, hydrastinine is oxidised by means of an aqueous solution of 

 potassium hydroxide, the open chain is closed, and oxyhydrastinine 

 results, the absorption spectra of which substance are almost identi- 

 cal with those of corydaldine and w-aminoethylpiperonylcarboxylic 



' Phil. Tram., 1885. " CAem. Soc. Trans., 1902, 81, 145. 



» Ibid., 1902, 81, 145. 

 1903. K 



