JACKSON AND GAZZOLO, — NITRO COMPOUNDS. 265 



since certain substituted toluols give less stable colored derivatives than 

 the corresponding benzoic acids.* Picramide, the first substance selected 

 for this work, gave colored compounds with sodic methylate or sodic 

 malonic ester, but too unstable to analyze, whereas trinitranisol or tri- 

 uitrobenzol, in which the negative character of the nitro groups is not 

 weakened by the presence of a positive radical like NHo, gave stable 

 well marked colors. Dinitroxylol ((CH3)., 1. 3. (NOo)^ 4. 6.) also gave a 

 slight and evanescent coloration with sodic methylate, and no reaction 

 with sodic malonic ester, whereas trinitroxylol ((CIi3)2l.3. (N02)3 2. 4. 6.) 

 gave colored compounds with both these reagents, which, although much 

 more stable, could not be prepared for analysis. These results, there- 

 fore, as far as they go, show that an increase in the negative nature of the 

 aromatic constituent increases the tendency to form colored compounds. 



The next subject considered by us was the effect of the presence of 

 methyl groups attached to the benzol ring on the formation of colors. 

 Dinitrotoluol ((^03)2 2. 4.) gave colored compounds with sodic methy- 

 late or sodic malonic ester ; dinitroxylol ((€113)2 1. 3. (NO-2)2 4. 6.) gave 

 only a passing coloration f with sodic methylate, none at all with sodic 

 malonic ester ; and dinitromesitylene gave no color with either reagent. 

 Trinitroxylol gave strong color reactions with both reagents, trinitrome- 

 sitylene none whatever. It is evident, therefore, that the presence of 

 methyl groups on the benzol ring diminishes the tendency to form these 

 colored compounds. Whether this effect is due to a specific action t of 

 the methyl group, or to the fact that these groups stand in the ortho 

 position to the nitro groups, or to both these causes, cannot be deter- 

 mined from the facts at present at our disposal. 



In consideration of the complete absence of a color reaction with 

 trinitromesitylene and sodic methylate, it is interesting to note that M. 

 Konowalow § obtained red salts from nitromesitylenes in which one of 

 the nitro groups stands in the side chain. We cannot find that he ana- 

 lyzed these salts to determine whether they were true salts or addition 

 products with sodic hydrate. If the latter, they would have a strong 

 bearing on the discussion given above. 



Another series of experiments was tried with aromatic bodies rich in 



* Am. Chem. Journ. (Remsen), XIX. 201. 



t This may have been due to a small quantity of a thiophene compound. As a 

 rule we have not considered that a colored product belonged to the class we are 

 studying unless we could obtain a copious precipitate of it with benzol. 



I Lobry de Bruyn, Rec. Trav. Chim. Pays-Bas, XIV. 95. 



§ Ber. d. chem. Ges., 1896, 2204. 



