118 



SPECTROSCOPIC INVESTIGATIONS 



unpublished). On the other hand, the tricycHc hydroquinones show 

 a type of absorption spectrum, quite different from those of the 

 naphthohydroquinones. 



240 



320 



400 tny 



240 



320 



400 



4 80 mu 



Fig. 12. The effect of substituents upon the absorption spectra of naphthyl-2- 



methylketones. Left: l-hydroxynaphthyl-2-methylketone, 1,5- 



dihydroxynaphthyl-2-methyIketone. Right: l,4-dihydroxynaphthyl-2- 



methylketone, - - - - l,5,8-trihydroxynaphthyl-2-methylketone, 



l,3,4-trihydroxynaphthyl-2-methylketone. 



In how far are the absorption spectra determined by the properties 

 of the aromatic ring system? To answer this question one should like 

 to have a means of continuously altering these properties. Obviously 

 this is impossible, and the next best one can do is to compare a 

 series of analogous quinones containing different heterocycHc ring 

 systems, instead of the naphthalene nucleus. If the hetero atoms show 

 different electron affinities, we have more or less what we want. 



