JACKSON AND KOCH. — DERIVATIVES OF ORTHOBENZOQUINONE. 205 



phenol hydroxyl groups it contains, according to its most probable for- 

 mula. We should explain this anomaly in the same way as before, 

 althouorh this substance is much more soluble than the reduction 

 compound. 



With glacial acetic acid the tetrabromortlioquinone C6Br402 formed a 

 white compound, to which we have given much attention, but of which 

 we can only give a very imperfect account. Zincke * in his paper on 

 tetrabromorthoquinone noticed that it was attacked by glacial acetic acid, 

 but did not isolate the product ; on the other hand he obtained a white 

 body by crystallizing tetrabromorthoquinone from ether and ligroin, which 

 we have not succeeded in encountering. When tetrabromorthoquinone is 

 evaporated to dryness with glacial acetic acid, a small amount of the red 

 hexabromorthoquinopyrocatechine ether is formed, but the greater part 

 of the quinone is converted into a white crystalline body melting at 230°, 

 the analysis of which led to one of the two following formulas, CiiHgBrgOs 

 or Ci^BrgOs. The first would be formed by the union of two molecules 

 of the tetrabromorthoquinone with one of acetic acid, one molecule of 

 water being eliminated, thus : — 



2C6Br402+C2H402= CnHsBrsOs+HsO. 



The second would be formed from the first by removing two atoms of 

 hydrogen, which could be done by the oxidizing action of another portion 

 of the tetrabromorthoquinone, and the tetrabrompyrocatechiiie thus 

 formed would then give rise to the red body, which always accompanied 

 the white product ; but the amount of this red compound always fell far 

 below that which should be formed, if it had taken such an important 

 part in the reaction (10 grams of tetrabromorthoquinone should give 5 

 grams of the red product, whereas the usual yield was only 0.8 gram), 

 and, as the amount of hydrogen found in the white compound was dis- 

 tinctly larger than should have been given by a body free from that 

 element, we have decided to adopt provisionally the formula CHlLiBrgOj. 

 We had hoped to settle this question by studying the decomposition prod- 

 ucts of this substance, but so far it has either been unaffected or com- 

 pletely decomposed by all the reagents we have tried. We hope that in 

 the coming year the study of this body will be completed and the work 

 carried on in various other directions in this Laboratory. 



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



