Ryan and O'Neill — Studies in the Diflavone Group. 173 



then passed through a dry filter paper. A solution of 0-45 gramme of 

 bromine in chloroform was added, and the mixture was let stand over-night 

 in a stoppered flask. The chloroform was evaporated, and the residue, which 

 was oily, could not be obtained in a crystalline form. On warming it with 

 alcoholic potash, potassium bromide separated. The oily reaction-product was 

 soluble in alkali, and gave a brownish-red colour with concentrated sulphuric 

 acid without any blue fluorescence. Since, after addition of a very small 

 amount of diflavone to the brownish-red sulphuric acid solution, a blue 

 fluorescence was easily observed, it is evident that the action of potash on 

 the bromine derivative of ■y-dibenzylidene-diacetoresorcinol does not form 

 diflavone. 



2. Action of Alcoholic Alkali on Diacetoresorcinol and Benzaldehyde. 



We experienced at first some difficulty in preparing the dibenzylidene- 

 diacetoresorcinol, which Eijkman, Bergenia, and Henrard (loc. cit.) obtained 

 by the condensation of diacetoresorcinol with benzaldehyde in the presence of 

 alcoholic sodium hydroxide, and which they said consisted of reddish-yellow 

 needles melting at 202° C. 



"We found ultimately that the substance is best got by slowly adding 

 some concentrated sodium hydroxide to a solution of diacetoresorcinol and 

 benzaldehyde in boiling alcohol. 



About 25 ccs. of 50 per cent, sodium hydroxide were added, drop by drop, 

 to a solution of 9'7 grammes of diacetoresorcinol and 20 ccs. of benzaldehyde 

 in 300 ccs. of boiling alcohol. During the heating, which was maintained for 

 a quarter of an hour, a reddish-orange solid separated, and this, after filtration, 

 was washed with alcohol. On further washing with dilute hydrochloric acid, 

 its colour changed to orange-yellow. The solid was dried, and recrystallized 

 from boiling benzene. It melted at 204° C. 



a-Dibenzylidene-diacetoresorcinol crystallizes in elongated rhombic prisms, 

 the angles of the prismatic face being approximately 144° and 36°. The 

 prisms had pyramidal ends and straight extinction in the direction of the 

 elongation. 



The crystals are coloured dark-red by concentrated sulphuric acid, in 

 which they dissolve, giving an orange-red solution. On adding water to the 

 sulphuric acid solution, a yellowish-white precipitate was obtained. 



Ferric chloride gives a brownish-red coloration with a saturated solution 

 of the substance in boiling alcohol. 



The compound is probably identical with that previously described by 

 Eijkman, Bergema, and Henrard (loc. cit.). 



