Algae, Fogakty, & Ryan — Dichromone and Dibenzyldichromone. 317 



Thus Hey wang and von Kostanecki (Ber. Dtsch. Chem. Ges., xxxv, 1902, 

 p. 2887) obtained chronione by the action of hydriodic acid on the dilcetone 

 formed by the condensation of diethyl oxalate with o-hydroxy-acetophe- 

 none : — 



OH 



CO. CH .CO. COOC^H^ 



CH 



CH 



CO 



CO 



When diacetoresorcinol was employed instead of o-hydroxyacetophenone 

 in this reaction, no indication of the formation of a diketone was, however, 

 obtained. Diketones were, on the other hand, formed by the condensation 

 of diacetoresorcinol-dimethylether with the esters of acetic, oxalic, and 

 phenylaeetic acids ; but the yields of these were so small that it was not 

 practicable, at the time, to convert the diketones into the corresponding 

 dichromones. 



We have again prepared diketones of this type, but, as before, in very 

 small yields, and it was only with considerable difficulty that we were able 

 to obtain sufficient amounts of the substances for our purpose. 



When the diketones formed by the condensation of diacetoresoreinol- 

 dimethylether with dimethyl and diethyl oxalates were treated with the 

 usual demethylating agents, hydriodic acid or aluminium chloride, red- 

 coloured products were obtained, from which no pure substances could be 

 isolated. But by prolonged boiling with concentrated hydrobromic acid, 

 each of these diketones was converted into dichromone, and the synthesis of 

 the parent member of the group was effected. 



The yield of dichromone was small, the body being accompanied by a 

 green substance, together with resinous products. It consists of light 

 straw-yellow needles, which melt at 176-177° 0. Its solution in concentrated 

 sulphuric acid has a light yellow colour and a bright emerald-green 

 fluorescence. The solution of ohromone in sulphuric acid is colourless, and 

 has a violet-blue fluorescence. 



A second synthesis of dichromone was effected by means of ethyl formate 

 and diacetoresorcinol-dimethylether. In the presence of metallic sodium 

 these substances condensed, giving diformylaceto-resorcinol-dimethylether : — 



CHO-f-^^^OCH. 



OHCCH.CO-'\ ^CO. CH-CHO 



And when the latter body was heated with concentrated hydrobromic acid, 



it formed dichromone. 



[2L2] 



