JACKSON AND PHINNEY. — PICRYLMALONIC ESTER. 113 



by two planes, and apparently belonging to the monoclinic system. It 

 melts at 125°, and is easily soluble in ethyl or methyl alcohol, benzol, 

 chloroform, or acetone ; somewhat soluble in ether, less so in carbonic 

 disulphide ; soluble in glacial acetic acid ; insoluble in ligroine ; insoluble 

 in cold water, slightly soluble in hot, forming a pink solution. Strong 

 hydrochloric acid does not dissolve it. Nitric acid when hot dissolves it 

 apparently without decomposition. Sulphuric acid dissolves it, and de- 

 composes it, when heated. Alkalies have no effect on it in ths cold, but, 

 if heated with it, form the red salts of its decomposition product. 



The benzoyl derivative of trinitrophenyltartronic ester was also made, 

 but the close of the academic year prevented us from getting a satisfac- 

 tory analysis of it. It was made by heating the tartronic ester with 

 benzoylchloride in a sealed tube to 110° for four or five hours. On 

 evaporating off the excess of benzoylchloride, it was obtained in white 

 crystals, which were purified by recrystallization from alcohol until they 

 showed the constant melting point 152°. 



Saponification of Trinitrophenylmalonic Ester. 



In all these experiments the modification melting at 64"^ was used. 

 The method of saponification adopted was that which had given such 

 excellent results with the other substituted malonic esters studied in this 

 laboratory, that is, the action of sulphuric acid diluted to a specific grav- 

 ity of 1.44. Five grams of trinitrophenylmalonic ester were mixed with 

 100 c.c. of this acid, and the mixture boiled in a flask with a return con- 

 denser. The ester melted almost immediately to a straw-colored oily 

 liquid, which gradually decomposed with evolution of gas, and finally 

 was completely dissolved. This usually took place in from one and a 

 half to two and a half hours, and showed that the reaction had come to 

 an end. During the earlier part of the boiling the liquid appearing in 

 the condenser had a pinkish color, but this disappeared later in the pro- 

 cess. As soon as all the ester had dissolved, the liquid was allowed to 

 cool, when it deposited a bulky precipitate made up of yellowish white 

 needles. This substance consisted of the trinitrophenylacetic acid, and 

 was purified in the way described in the following paragraph. 



Trinitrophenylacetic Acid, C6H2(N02)3CH2COOH. — The purification 

 of this substance cannot be effected by crystallization from alcohol or 

 water, as either of these solvents converts it into the corresponding sub- 

 stituted toluol C6ll2(N02)3CIl3. We tried at first as a solvent water 

 containing a small amount of sulphuric acid, since this had given excellent 

 VOL. xxxiv. — 8 



