52 Journal of the Mitchell Society [^Octoher 



HALOGENATION OF HYDEOXYNAPHTHOQUINONES. 



The next investigation undertaken here was the behavior of jug- 

 lone with the halogens, chlorine and bromine. This work was done 

 with the assistance of J. W. Scott, candidate for the degree of Doctor 

 of Philosophy. Very little work indeed has been published on the be- 

 havior of naphthoquinones with halogens. Dielil and Merz^ dis- 

 covered 3-bromo-2-hydroxy-naphthoquinone. Kehrmann and Mas- 

 cioni^^ prejDared the analogous iodo compound. Zincke and 

 Schmidt^ ^ made naphthazarine dichloride and 2-chloronaphthazarine. 

 That is a very short story. In 1917 I published with V. C. Edwards^ ^ 

 our study of the bromination of naphthazarine and of 1, 4,5,6 -tetra- 

 hydroxynaphthalene, reporting eight new derivatives of the first 

 compound and nine of the second. If we add to this the new work 

 on the halogenation of juglone, we see that this very small field has 

 been very greatly extended, and the end is not yet. 



HALOGENATION OF JUGLONE. 



The accompanying chart (pi. 18) shows clearly in outline the work 

 on the halogenation of juglone. Chlorine and bromine were used, the 

 juglone being dissolved in all cases in glacial acetic acid. The action 

 of the halogens is very different in a hot acid solution from that in 

 a cold solution, ' If the halogen is added to a cold solution, the addi- 

 tion products, B and Gr, are obtained. These are called juglone di- 

 chloride and juglone dibromide-. Each of these loses one molecule 

 of halogen acid by the action of warm alcohol, yielding the mono- 

 halogen substitution products, C and H. The proof that these still 

 contain the hydroxyl group is shown by the ready formation by acetic 

 anhydride of the acetyl derivatives, D and I. If, however, the halo- 

 gens are added to hot solutions of juglone, then substitution products 

 are obtained which are far more stable than the addition compounds. 

 We find here, however, a difference in the action of the halogens for, 

 strange to say, juglone takes up only two chlorine atoms, E, as against 

 three bromine atoms, J. These compounds behave in the same way 



9Ber.d.d.Chem.Ges., 11: 1066. 1878. 

 loBer.d.d.Chem.Ges., 28: 345. 1895. 

 iiAnnalen der Chemie, 286: 41. 1895. 

 i2Jr.Amer.Chem.Soc., 39: 2460. 1917. 



