NEW DERIVATIVES OF DIPHENOOUINONE, AND A 

 NEW VARIETY OF STEREOISOMERISM. 



By James Moir. M.A., D.Sc. F.C.S. 



Diphenoquinone, Q. 



was discovered in 1905 by Willstaetter and Kalb ( Bcrichtc, 1905,. 

 1232), who remarked at the time on its considerable differences'^ 

 from coerulignone (which is supposed to be its tetramethoxy- 

 derivative), but satisfied themselves that it really is the parent- 

 substance of the latter, despite its unique properties. Not having 

 been quite satisfied on this important point, the author has for 

 some years been investigating the coerulignone family, and in par- 

 ticular the methyl-derivatives of diphenoquinone, which he finds 

 to be obtainable in good yields by simpler methods than those 

 necessary in the case of diphenoquinone. The starting material 

 is 0-0-dicresol (3-3' dimethyl diphenol-4-4') for the oxygenated 

 bodies, and tolidine {2i~2) dimethylbenzidine ) for the imino- 

 derivatives of the quinone. The present paper deals only with 

 these new derivatives, and the coerulignone question will be dis- 

 cussed when the full evidence has accumulated. 



A. Dicrcsoquinonc (3-3' dimethyl-diphenoquinone ) has 

 been obtained in two apparently stereoisomeric forms, correspond- 

 ing respectively to the following structures.* 



Three methods of preparation have been successful. The 

 first is Willstaetter's general method, namely, boiling dicresol 

 with ten times its weight of lead peroxide in benzene for ten 

 minutes, filtering and cooling. The product is the trans-forrn, 

 a network of very fine deep-yellow needles devoid of metallic 

 lustre (c/. coerulignone V It melts at 163° with decomposition, 

 and "verpufft" if faifly rapidly heated. In all other respects, 

 including solubilities, it resembles Willstaetter's yellow modifica- 

 tion of diphenoquinone. Acetone, ethyl-acetate and benzene are 

 the only solvents which dissolve it appreciably. Stannous 

 chloride in hydrochloric acid reduces it almost instanta neously 



* The author has a recollection that this type of isomerism was predicted 

 by H. E. Armstrong in 1901, but it does not seem to have been published. 



;0 and 0'. 



3-3' or Cis-Porm (red), m.p 148°. 3-5' or Trans-Form (Yellow), m.p. 163^ 



The dotted bonds between the rings indicate that they lie n a plane perpen- 

 dicular to the paper, on which fact the isomerism dep nds. 



