JACKSON AND KOCH. — DERIVATIVES OF ORTHOBENZOQUINONE. 215 



Action of Sulphurous Dioxide. — Dry sulphurous dioxide was passed 

 through the chloroform solution of orthoquiuone until it was saturated ; 

 the principal product was a black unmanageable precipitate, probably a 

 compound of orthoquinone and pyrocatechiue corresponding to chiuhy- 

 drone ; but the filtrate from this left on evaporation crystals, which were 

 recognized as pyrocatechiue by their properties and the formation of the 

 lead salt. 



Action of Bromine on the Solution of Orthobenzoquinone. 



An excess of bromine was added to the solution of orthoquinone in 

 chloroform, the chloroform allowed to evaporate spontaneously, and the 

 crystalline residue, after being heated gently to drive off the excess of 

 bromine, was spread on unglazed porcelain to remove oily impurities. 

 After recrystallization from benzol it showed the constant melting point 

 191°, which is near enough to 192°-193°, that given by Zincke* for 

 tetrabrompyrocatechine to leave no doubt as to the nature of the sub- 

 stance. For greater certainty the substance was analyzed with the fol- 

 lowing results : — 



'& 



I. 0.1835 gram of the substance gave by the method of Carius 0.3210 

 gram of argentic bromide. 

 II. 0.1509 gram of the substance gave 0.2637 gram of argentic bromide. 



Calculated for Found. 



C 6 Br 4 (OH) 2 . I. II. 



Bromine 75.11 74.44 74.39 



These numbers are sufficiently near to show that the product of the 

 action of bromine on the orthobenzoquinone is tetrabrompyrocatechine. 



Behavior of the Solution of Orthobenzoquinone with Benzolsulphinic Acid. 



The chloroform solution of orthoquinone was added drop by drop to a 

 solution of benzolsulphinic acid, f also in chloroform, until the color began 

 to disappear less rapidly, and the solution of the sulphinic acid had as- 

 sumed a decided reddish tint. After standing over night, the liquid was 

 filtered, the filtrate evaporated to dryness, and the residue allowed to 

 solidify. The solid residue was next treated with hot benzol, which 



* Ber. d. chem. Ges., XX. 1777. 



t If ttie conditions were reversed, and the solution of benzolsulphinic acid was 

 added to the solution of orthoquinone, none of the desired sulphone was obtained; 

 we ascribe this difference in behavior to the oxidation of the sulphinic acid by the 

 excess of orthoquinone. 



