316 



Proceedings of the Royal Irish Academy. 



the chief tinctorial constituents of the anthocyan pigments, may be referred 

 to a dihydrochromone : — 



HO 



C.OH 



|CH, 



HO 



C.C^HjCOH)^ 



C.OH 



OH 



CH 



OH OH 



BuAziLiK. Cyanidin Chloridk. 



Attempts to prepare substances related to these colouring matters were 

 made by H. Eyan and P. O'Neill (Proc. Koy. Ir. Acad., xxxii. B, pp. 48, 167). 

 By condensing diacetoresorcinol-dimethylether with ethyl benzoate they 

 obtained dibenzoylaceto-resorcinol-diinethylether, which was converted by 

 hydriodic acid into diflavone : — 



o o 



CH^O- 



C,H-COCH CO 

 6 5 z 



OCH, 



CH-C 

 6 S 



HC 



^C.C,H. 

 '^ 6 5 



CH 



CO CO 



Dn^LAVONE. 



Diflavone was also obtained by the action of alcoholic potash on the 

 tetrabromide of dibenzylidene-diacetoresorcinol-diacetate : — 



o o 



Ac 0^y^\ OAc 



■CH..CHBr. CHBr. CO 



CO. CHBr. CHBr. C^H^ 



o 5 



^e"5^ 



HC 



■C S^5 



CH 



CO CO 



Although none of the four condensation products which they obtained 

 from diacetoresorcinol and benzaldehyde appeared to be diflavanone, deriva- 

 tives of the latter substance were formed by the action of aldehydes on the 

 ketone in the presence of hydrochloric acid. Thus from benzaldehyde and 

 diacetoresorcinol they obtained dibenzylidene-diflavanone : — 



o o 



C = CH. CH 



C^K CH = C 



CO CO 



In 1916 one of us (J. Algar, Proc. Royal Irish Acad., x.Kxiii, B, p. 8) 

 attempted to prepare dichroinone by methods similar to those which had 

 been already employed by von Kostanecki and his co-workers for the 

 preparation of chromones. 



