JACKSON AND SOCH. — TRINITROPHENYLMALONIC ESTER. 405 



It is worthy of remark that, whereas Dittrich from the action of 

 picrylchloride on sodium acetacetic ester obtained a considerable 

 quantity of dipicrylacetacetic ester, our principal product was the 

 monopicrylmalonic ester, and only on one occasion have we observed 

 a trace of a substance with a much higher melting point, which we 

 took to be the dipicryl compound. We should add that, in applying 

 the same method to the action of sodium acetacetic ester on picryl- 

 chloride, we obtained almost exclusively monopicrylacetacetic ester. 



Properties of Picrylmalonic Ester. — It crystallizes from alcohol in 

 white, long, rather slender rectangular plates, which develop into rather 

 thick prisms with blunt ends often as much as two centimeters long. 

 It melts at 59°, and is very soluble in chloroform, ether, benzol, or 

 glacial acetic acid ; somewhat less soluble in carbonic disulphide ; 

 soluble in cold alcohol, freely in hot ; rather more soluble in methyl 

 than in ethyl alcohol ; insoluble m ligroine or cold water, slightly 

 soluble in hot water. All the solutions of this substance except that 

 in glacial acetic acid have a pink color, which is the more marked the 

 stronger the solution, and the alcoholic solution imparts to the fingers 

 a crimson color not unlike rosaniline, although less purple. This 

 coloration of the fingers is much deeper than the color of the solu- 

 tion, and IS tolerably fast. The formation of these pink or crimson 

 colors from the white crystals is striking, and will be more carefully 

 studied. 



Cold strong sulphuric acid dissolves it ; if this solution is warmed 

 it turns red, and gives off bubbles of gas ; dilution of the red solution 

 after it had cooled precipitated a yellow solid. Sti'ong nitric acid acted 

 in the same way, except that the picrylmalonic ester dissolves more 

 slowly in cold nitric acid than in sulphuric acid. Strong hydrochloric 

 acid did not dissolve it in the cold, but on warming the substance 

 melted, and then went into solution very slowly. The picrylmalonic 

 ester has well marked acid properties forming the red sodium salt 

 when treated with an aqueous solution of sodic hydrate. As is often 

 the case with substances of this class, the sodium salt is nearly in- 

 soluble in a strong solution of sodic hydrate. The sodium salt is 

 also formed by the action of a solution of sodic carbonate on the free 

 ester. 



Trinitrophenylbrommalonic Ester {Plcrylhrommalonic Ester), 

 C6H2(N0o),,CBr(C00dH5)2. 



This substance was made by dissolving some of the trinitrophenyl- 

 malonic ester described in the preceding section in a small quantity 



