JACKSON AND KOCH. — DERIVATIVES OP ORTHOBENZOQUINONE. 199 



are united, two theories seem especially worthy of attention : first, the two 

 rings may be joined directly, so that the compound is a substituted di- 

 phenyl, (I.) 02(HO)H2C6-CoH3(OH)2 ; or second, they may be united by 

 two atoms of oxygen forming a substituted pyrocatechine ether according 

 tothisform.da: (II.) (HO) H3C6=02=C6H2(OII)o* The first (diphenyl) 

 formula is rendered much more probable than the second by the anal- 

 ogy between our orthoquinone and the orthonaphthoquinone, whicli 

 is converted by dilute sulphuric acid into dinaphthyldiquiuhydrone,t 

 02H5Cio"CioH5(OFI)2. a black powder like our alteration product; this 

 has been proved by Korn t to be a dinaphthyl body by conversion into 

 a-a dinaphthyl and diphthalylic acid, (COCO)(CeH4COOH)2. The 

 support of the diphenyl formula by this analogy is so strong that we 

 should feel it was hardly worth while to consider the second (ether) 

 formula, if it were not for the fact that we have observed an oxygen 

 attachment similar to that in Formula II. in a derivative of tetrabrom- 

 orthoquinone, described later in this paper. To decide between Formula 

 I. and Formula II. we studied the action of reducing agents on the black 

 substance, as, if it were an ether (Formula II.), it should be reduced to 

 a mixture of pyrocatechine and a trioxybenzol ; whereas a diphenyl com- 

 pound (Formula I.) would only take up two atoms of hydrogen without 

 decomposition. § We selected as the reducing agent sodium amalgam 

 and water, because this had proved effective in breaking up the pyrocate- 

 chine ether containing bromine already alluded to; but, even after long 

 continued action on our black alteration product, not a trace of pyrocate- 

 chine could be detected ; the only reduction product was a black substance 

 evidently as complex as the original body. This I'esult, therefore, de- 

 clares decisively in favor of the diphenyl structiwe (Formula I.). 



The action of beuzoylchloride on the black substance in presence of so- 

 dic hydrate converted it into a tribenzoyl derivative, Ci2lIi;0203(COCoH5)s, 

 thus proving the existence of three hydroxyl groups in the substance ; 

 and this benzoyl derivative, and also the original black compound, gave 

 new substances with phenylhydrazine, which contained nitrogen, as was 

 shown by the analyses. Unfortunately the percentage of nitrogen found 

 in both cases was far below that required by the probable, formulas, which 



* In both these formulas the third hydroxyl group may be attached to the other 

 benzol ring. 



t Steriliouse and Groves, Ann. Chem. (Liebig), CXCIV. 205. 



t Ber. d. chem. Ges., XVII. 3020. 



§ Korn dill not succeed in splitting dinaphthyldiquinliydrone into simpler bodies 

 by reduction. — Ber. d. chem. Ges., XVII. G02i. 



