JACKSON AND KOCH. — DERIVATIVES OP ORTHOBENZOQUINONE, 201 



the action of hydrochloric acid on parabenzoquinone consists in the 

 formation of hydroquinone and chlorine, which subsequently react to- 

 gether, and in this corresponding case part of the pyrocatechine formed 

 could well have escaped the substituting action of the chlorine. Re- 

 ducing agents like ammonic sulphide or sulphurous dioxide produced 

 pyrocatechine from this chloroform solution. Bromine formed with it 

 tetrabrompyrocatechine, the reduction of the orthoquinone being achieved 

 in this case by the hydrobromic acid formed in making the substituted 

 quinone. 



When the chloroform solution was added drop by drop to a solution 

 of benzolsulphinic acid also in chloroform, an orthodioxydiphenylsul- 

 phone, CeHaSOaCc 1^3(013)2, melting at 153° was formed, which should 

 be identical with that obtained by Hinsberg and Himmelschein * by 

 oxidizing pyrocatechine in presence of benzolsulphinic acid, but the 

 properties of the two substances show they are different. Hinsberg 

 and Himmelscheiu's substance contained water of crystallization, and 

 melted at 117°, if this were not driven off; at 143° to 145° after heat- 

 ing in the steam-bath; and at 164° if completely dried by previous 

 fusion; our compound contained no water, and melted at 153°, whether 

 dried at ordinary temperatures or by previous melting. We have not 

 succeeded in finding the conditions under which Hinsbers: and Him- 

 melschein's compound is formed, so that we were unable to compare the 

 two substances, and must consider with our present knowledge that they 

 are isomeric. 



With aniline the chloroform solution gave a dianilidoquinoneanil, 

 C6Ho(C6H5NH)20(CcH5N), which melted at 203°, and by this and 

 a careful comparison of its other physical properties was proved to 

 be identical with the body prepared by Zincke and von Ilagen f from 

 paraquinone by the action of aniline and acetic acid. As this sub- 

 stance has previously been made only from paraquinone, it has always 

 been supposed that it contains the oxygen and anil group in the para 

 position to each other, but after our preparation of it from ortho- 

 quinone it is also possible that it is a derivative of orthoquinone ; and 

 some weight is given to this view by the fact that it is formed easily 

 from the orthoquinone by aniline alone, whereas it can be prepared 

 from the paraquinone only with difficulty, and by the combined action 

 of aniline and acetic acid. On the other hand, it seems hanlly prob- 



* Ber. d. chem. Ges., XXIX. 2025. 

 t Ber. (1. chem. Ges., XVIII. 785 



