1919li JUGLONE 53 



with acetic anhydride, giving the acetyl derivatives, F and K. Much 

 more attention has been paid to tribromojugione than to dichloro- 

 juglone. Tribromojugione, on being heated with an alcoholic solu- 

 tion of hydrochloric acid loses one bromine atom which is replaced 

 by a chlorine atom, M. Again, on being heated with an alcoholic 

 solution of caustic soda, one bromine atom is replaced by the hydroxyl 

 group, ]Sr. These two reactions indicate that one bromine atom is 

 unlike the other two, that is, its environment must be different. This 

 fact is expressed in the formula given, in which one bromine atom is 

 placed in position 8. This gives a unique position to one bromine 

 atom, placing it in the phenol ring where it ought to be more reactive. 

 On the other hand, the other two bromine atoms being alike are there- 

 fore placed symmetrically in the quinone ring. Finally tribromo- 

 jugione forms a sodium salt, L. 



NEW DYES. 



Dichlorojuglone consists of golden brown needles and tribromo- 

 jugione of brilliant rich red needles. Being highly colored and con- 

 taining at the same, time a reactive hydroxyl group these compounds 

 should be typical dyes, and my experiments have shovsni that they 

 ai-e in reality very beautiful dyes. So far more attention has been 

 paid to tribromojugione. If this compound is dissolved in ether and 

 the solution is shaken with an aqueous solution of sodium carbonate, 

 an indigo blue salt separates out. This readily dissolves in water. 

 If a piece of silk or wool is placed in the solution and the solution is 

 boiled, the purple color of the solution quickly changes to a yellow, 

 showing a reaction between the textile and the sodium salt. Silk is 

 thus dyed a very beautiful champagne and wool a medium shade of 

 tan. No mordant is necessary to fasten the color on the goods. How- 

 ever, if mordants are used the shades are changed in a number of 

 instances, especially with wool. In only one instance was a change 

 noticed with silk, a tin mordant producing a greenish bronze tint. 

 Cotton is not affected by the dye unless it is mordanted. If the cot- 

 ton is first impregnated with tannic acid, an<l then with tlio dyo, it 

 assumes an ecru color. 



The dichlorojuglone is also a dye and imparts to silk a rich reddish 

 bronze color. Other compounds such as C, H, M and N are un- 



