Algau, Fogarty, & Ryan — Dichromonc and Dibensyldichromone. 319 



impurity. An alcoliolic solution of dichronione .drives no colouration with 

 ferric chloride, whereas the original diketoue gives a brownish-red colouration 

 with that reagent. 



II. Ethyl dimethoxyisophthaloyl-dipyruvate when heated for several 

 hours with concentrated hydrobromie acid also foinied dichrbmone, which 

 was isolated and purified by the method described in the last experiment. 



The dipyruvic esters required for these experiments were prepared by 

 the method already described by one of us (J. Algar, Proc. Eoyal Irish 

 Acad., 1916, xxxiii, B, pp. 89-90). 



III. (a) Diformylaceto-resorcinohliinethyUthcr. 



OHC . CHgCO-\^CO. CHgCHO 



A mixture of 6 g. of diacetoresorcinol-dimethylether and 70 c.c. of ethyl 

 formate was heated to 50° C. and 4'8 g. of sodium wire was added. A 

 vigorous reaction ensued, and when this had ' subsided the mixture was 

 heated to 85-90° C. for half an hour. A small quantity of ether was added 

 and the mixture allowed to remain for twelve hours. It was then mixed 

 with a further quantity of ether, and water was added until a clear dark red 

 aqueous layer was obtained. On passing a current of carbon dioxide through 

 the aqueous alkaline solution a light yellow solid was precipitated. This 

 solid was filtered, washed with water, dried and crystallised first from a 

 mi.xture of acetone and alcohol, afterwards from carbon tetrachloride. It 

 melted at 98° C. and gave on analysis the following results : — 

 . 0-30.S3 substance gave 0-6826 CO, and 0-1387 H^O, 



corresponding to C 60'38, H 5-0. 



CuHuOe requires C 60-43, H 5-0. 

 - Diformylaceto-resorcinol-dimethylether crystallises in light yellow 

 prismatic plates,, melting at 98° 0. It is sparingly soluble in ether, 

 petroleum ether, ligroin or cold alcohol, and readily soluble in hot alcohol, 

 chloroform, acetone, or carbon tetrachloride. In alcoholic solution it gives a 

 deep red colour with ferric chloride. Concentrated sulphuric acid colours 

 the crystals orange red, and they dissolve therein to a deep red solution. 



(h) Dichrotnone. 

 o o 



CO CO 



Two grammes of diformylaceto-resorcinol-dimethylefcher were heated 



