BILADIENES-(a,b) AND RELATED SUBSTANCES 



133 



Mesobilipurpurin II differs from mesohiliviolin also in its double-banded 

 spectrum (344. .501 m/x) in neutral chloroform solution which is of orange-red 

 color. As compared with mesoi)ilipurpurin I the al)sorption band of the zinc 

 complex lies more toward the ultraviolet ((JIJ) m/n as compared with (i'23 mju). 



680 



550 



650 600 



WAVELENGTH, m/x 

 Fig. 21. Absorption curve of mesobilipurpuriii-zinc in methanol. 



The mesobilipurpurin "G'-2'2" of Siedel and Frowis {2o-'j-j) appears to resem- 

 ble our mesobilipurpurin II, while compounds corresponding to our meso- 

 bilipurpurin I may have been obtained by bromine or quinone oxidation of 

 mesobiliverdin {870,2556). The present data however, allow no clear con- 

 clusions. 



5.4.3. Bilichrysins. Mesnbilichrysin has been obtained in pure crystal- 

 line form. Its analysis indicated tlie formula C.UH3SO7X4. Sodium amalgam 

 gave mcsobilane, while oxidation with ferric chloride or autoxidation in 

 ammoniacal solution in the presence of zinc salt yielded mesobilipurpurin II. 

 The yellow needles have a melting point of '■240° C. The absorption curve 

 in alcohol with 0.02% ammonia shows an absorption band at 41C m/x 

 (cniM = 40. .5) and a weaker band at 311 m^ (e,„M = 23) (1324). 



Bilickri/.sin was also prepared in cry.stalline form. It has no definite 

 melting point. 



The yellow color of the chrysins indicates interruption of the conjugated 

 system in the center (ef. Section 2.3.), which is in agreement with the formula 

 suggested in Figure 20. 



5.4.4. Bilierythrinoid Oxidation Products of Bilatrienes. Bilierythri- 

 noid pigments may also occur among the oxidation products of bilatrienes. 



