152 PROCEEDINGS OF THE AMERICAN ACADEMY 



(OH), ^(OH) 2 (OH), 

 CH 3 C CO3-CH, or CH 3 -C- C CH 3 . 



The above observations also suffice to clear up the hitherto enig- 

 matic behavior of quinone toward hydrogen haloids and water. 

 Hesse * and Ciamicianf have shown that water converts quinone 

 into hydroquinone, while Levy and Schultz, j as well as Sarauw,§ 

 have converted quinone by means of hydrobromic and hydrochloric 

 acid into chlor- and bromhydroquinone respectively. 



I supposed formerly || that these reactions were to be explained 

 by an addition of water and halogen hydride respectively to the 

 two pairs of double bonds present in quinone. 



That this, however, is not the case, will be soon shown in detail 

 by Mr. Clark. It seems to me, therefore, very probable that the 

 peculiar behavior of quinone towards water and hydrogen haloids 

 is due to the presence of the two carbonyl groups in this compound. 

 Two molecules of water or of hydrochloric acid add themselves to 

 quinone, forming 



CI 

 I. II. 



which then lose H 2 2 and Cl 2 respectively, forming hydroquinone : 

 the chlorine set free then reacts further, giving chlorhydroquinone 

 and hydrochloric acid. That the intermediate products I. and II. 

 should lose H 2 2 or Cl 2 so readily, and go over into benzene deriva- 

 tives, is not surprising when one considers how easily A 2,5 dihy- 

 droterephthalic acid goes over into terephthalic acid.1T 



The fact that a carbonyl group reacts with phenylhydrazine, 

 forming an addition product, as well as the behavior of this group 

 towards water and alkalies, suffices to throw an entirely new light 



* Ann. Chem. (Liebig), CCXX. 367. 

 t Gazzetta Chim., XVI. 111. 

 t Ann. Chem. (Liebig), CCX. 133. 

 § Ibid., CCIX. 93. 

 || Amer. Chem. Journal, XIII. 427. 

 1 v. Baeyer, Ann. Chem. (Liebig), CCLI. 293. 



