( 286 ) 



On perusing the literature we have found that this regularity 

 does not exist in this series of dinitrobenzoic acids ouly, but is observed 

 in a comparatively large number of cases. The strongest acids 

 are the most slowly esterified. This might lead us to the conclusion 

 that in the esterification by alcoholic hydrochloric acid it is not the 

 ionised but the unsplit molecules of the acids which take part in 

 the reaction. 



A more detailed account of this investigation will appear in the 

 Recueil. 



Amsterdam | 



Groningen ' 



Sept. 1906, Laboratory of the University. 



Chemistry. — Prof. Holleman presents a communication from 

 himself and Dr. J. Huisinga. ''On the nitration of phthalic 

 acid and iso phthalic acid" . 



(Communicated in the meeting of September 29, 1906). 



Of phthalic acid, two isomeric monoderivatives are possible, both 

 of which are known particularly by a research of Miller (A. 208, 

 233). Isophthalic acid can yield three isomeric mononitro-acids. Of 

 these, the symmetric acid, which is yielded in the largest quantity 

 during the nitration, is well known. As to the mononitrated by- 

 products formed, the literature contains a difference of opinion ; in 

 any case, there is only made mention of one second mononitro-acid 

 whose structure has remained doubtful. 



The investigation of the nitration of phthalic and isophthalic acid 

 was taken up by us in order to determine the relative amount of 

 the isomers simultaneously formed, as in the case of the mononitro- 



