128 REPORT— 1903. 



On comparing this formula with that of papaverine, the differences 

 will be seen to consist in the partial reduction of the isoquinoline nucleus 

 and in the presence of carbon atom (5), which, with its associated methyl 

 group, is linked on the one hand to carbon atom (4), and on the other to 

 the nitrogen atom, thus forming a fourth closed chain in the molecule. 

 Here, again, the difference between the absorption spectra and those of 

 papaverine is very marked. The amount of general absorption is less, and 

 there is only one absorption band, which is, however, better defined and 

 more persistent than the papaverine bands (tigs. 2 and 6). 



In discussing the relations between corydaline and berberine, it is to 

 be remembered that corydaline corresponds to tetrahydroberberine, and 

 berberine to dehydrocorydaline. The constitutional connection between 

 corydaline and tetrahydi'oberberine is undoubtedly very close, ^ as a com- 

 parison of the above formulse will show, and between the spectra of 

 the two substances there is also a very close relation (figs. 6 and 7), 

 the only difference being that the general absorption of tetrahydro- 

 berberine is slightly greater than that of corydaline. 



When papaverine is reduced to tetrahydropapaverine, it is brought 

 structurally very near to corydaline. A comparison of the formulae of 

 the two substances shows that the former substance differs from the latter 

 in the absence of carbon atom (5) of ring II with its associated hydrogen 

 atom and methyl group. The spectra of the two compounds are almost 

 identical (figs. 3 and 6). Viewing corydaline as derived from tetra- 

 hydropapaverine by the addition of CHg forming a fourth closed chain in 

 the molecule, it might have been anticipated that the difference between 

 the absorption spectra of the two substances would be greater than is 

 found to be the case. It should be noted, however, that ring II in cory- 

 daline is a reduced ring, and would not therefore exert the same in- 

 fluence on the absorption spectra as the formation of a pyridine ring. 

 It might be expected to produce an effect comparable with that produced 

 by the substitution of a dioxymethylene for two methoxyl groups, 

 which, we shall show later, is slight in compounds of high molecular 

 weight.'-^ 



Narceine is the extreme member of this group. It has two benzene 

 nuclei, but no pyridine ring, and in other particulars differs considerably 

 in constitution from papaverine. The absence of any absorption band 

 diSerentiates the spectra widely from those of the other members of the 

 group (fig. 22). 



Note. — This was accounted for by Hartley in the following explana- 

 tion : ' Carbonyl, carboxyl, hydroxyl, and methoxyl on side-chains, or as 

 forming a portion of the substituted benzene nuclei, exhibit great absorp- 

 tive power, and the occurrence of several oxidised radicals may cause the 

 following variations in spectra : (a) the absorption band becomes so 

 widened as to extend into the region of rays affected by naphthalene, 

 quinoline, and their derivatives ; (6) or the absorption is so powerful 

 that it extends to rays less refrangible than those in which the band 

 is situated, and continues so far down the curve that the selective 

 absorption is not made manifest. Narceine appears to be a good ex- 

 ample of this ; its absorptive power is very great, extending into the 



> Chem. Soc. Trans., 1902, 81, 145. 



- Hartley, Chem. Soc. Trans., 1885, 47, 691 ; Hartley and Dobbie, Chem. Soc. 

 Trans. 1900, 77, 846. 



