244 PROCEEDINGS OP THE AMERICAN ACADEMY 



This conversion of the metabromdinitrophenylacetic acid into the 

 corresponding toluol by boiling with alcohol, when it is so stable in 

 presence of boiling dilute sulphuric acid, seemed to us so interesting 

 that we have examined it more carefully. Having in the first place 

 determined that the alcohol was neutral to test jiapers, to prove that 

 the reaction could not be due to a trace of alkali, or acid in it, a 

 quantity of the substance melting at 177° was boiled in a flask under 

 a return condenser with a little alcohol for three hours, and pure air 

 occasionally drawn through the apparatus to sweep out its contents 

 into a set of absorption bulbs filled with lime-water ; in this way a 

 heavy precipitate was obtained, which consisted in great part of 

 calcic hydrate precipitated by the alcohol vapor, but also contained 

 calcic carbonate, as was shown by effervescence when it was dissolved 

 in an acid, thus proving that carbonic dioxide had been given off. 

 The alcoholic solution, after it had been boiled for an hour and a half 

 longer, gave crystals, melting at 103° to 104°. It seems evident, 

 therefore, that the reaction runs as follows, 



CJI,P>r(N02)2CH,COOH = C6H,Br(NO,)2CH3+COo, 



and the alcohol seems to take no part in it. Methyl alcohol, in which 

 the substance is more soluble than in ethyl alcohol, brings about a 

 similar decomposition, but more slowly. In boiling water the meta- 

 bromdinitrophenylacetic acid is tolerably soluble, but nearly insoluble 

 in cold water. The decomposition produced by alcohol also takes 

 place when the aqueous solution is boiled, but very slowly, so that 

 long boiling is necessary to convert the substance completely into the 

 substituted toluol ; nevertheless, after distilling with steam for several 

 hours, the whole of the substance had passed over into the receiver 

 as metabromdinitrotoluol, since none of the substituted acetic acid, 

 which does not distil with steam, was left in the flask. The presence 

 of a very small amount of sulphuric acid (two or three drops of the 

 dilute acid to 100 c.c. of water) is sufficient to prevent this decomposi- 

 tion entirely, as a specimen of the substituted acetic acid showed no 

 signs of decomposition, even after having been distilled with steam for 

 three hours with only the amount of dilute sulphuric acid which 

 remained adhering to it after the excess of acid used in its preparation 

 had been removed by filtration. The best solvent for the bromdini- 

 trophenylacetic acid therefore is boiling water containing a few drops 

 of sulphuric acid. If the substance has become contaminated with 

 the substituted toluol, it can be purified conveniently by distilla- 

 tion with steam in presence of a few drops of sulphuric acid, when 



