108 



rEpoM— 1902. 



and then form a judgment from what has been observed as to the effect of 

 substitution in the benzene ring in a large number of instances, we can 

 conceive of the change in their combined spectra resulting in a curve 

 not dissimilar from that of quinone, the benzene residue C^H^ being 

 united to O.^, as in the preceding formula. 



The following alternative formulpe have been proposed for ^j-nitroso- 

 phenol, quinone, and the related substances quinone chlorimide, quinone 

 dichloriraide, and quinone dioxime. The chemical arguments by which 

 these alternate formulEc are supported are sufficiently well known ; they 

 are generally regarded as inconclusive. 



If the formulae II. are accepted, the substances have the benzenoid 

 structure ; whereas, if the formulae III. are accepted, they all contain 

 partially I'educed benzene nuclei. So far all the substances containing 

 partially or completely reduced nuclei ' which have been examined differ 

 from those containing unreduced nuclei in giving absorption spectra which 

 show no bands ; i.e., they behave like open chain compounds. If this rule 

 is of general application, and if we assume that nitroso-phenol, quinone, &c., 

 are correctly represented by formulae III., they should show only general 

 absorption. But as a matter of fact the spectra of all the bodies show 

 well-marked absorption bands. Their spectroscopic examination, therefore, 

 favours the peroxide rather than the ketonic theory of their constitu- 

 tion. 



On comparing the curves of the various substances with one another, 

 it will be seen that there is a considerable amount of agreement between 

 the curves of quinone dichlorimide and quinone dioxime, and between 

 those of quinone chloi'imide and quinone dichlorimide, the differences 

 between them being such as were to be anticipated from the differences 

 in their composition. 



The spectra of quinone, on the other hand, differ widely from the 

 others, and it is impossible in the present state of our knowledge of the 

 subject to say whether this difference is due to the difference in composi- 

 tion or to some structural difference. We had hoped, from a comparison 

 of the spectra of quinone chlorimide and p-nitroso-phenol, to be able to 



' Hartlej% Chem. Sue. Tra>is., 1885, 47, 685; Hartley and Dobbie, ibid., 1900, 

 77, 846. 



