( 280 ) 



in tlie same manner, tetranitroresorcinol ^) yields trinltroplilorogliicinol ; 

 tetranitrochloro- and bromophenol also yield trinitrophloroglucinol on 

 boiling with water or, more readily, with Na, CO, solution. By the 

 action of NHg or NH, Cj Hj etc. in alcoholic solution various other 

 products are obtained, such as those substances included in (he scheme 

 which have been obtained previously from pentanitrophenol ^). We 

 also see that water or alcohol cannot serve as a solvent for the 

 purpose of recrystallising these compounds but that chloroform or 

 carbon tetrachloride may be used. 



If, in the above cited 3-5-substituted phenols the OH-group is sub- 

 stituted by OCH3 it is not possible to introduce three nitro-groups. 

 For instance the dimethylether of 5-nitroresorcinol yields two iso- 

 meric trinitroresorcinoldimethylethers (principally those with the 

 melting point 195°, just as in the nitration of 5-nitro-m-xylene) ') ; 

 similarly, the methylether of 5-nitro-m-cresol (m.p. 70°) yields the 

 methylethers of three isomeric trinitro-m-cresols, principally the 

 compound with m.p. 139°. The constitution of these substances is 

 not yet determined. 



Amsterdam, September 1906. 



Chemistry. — Prof. Holleman presents a communication from him- 

 self and Dr. H. A. Sirks: ''The six isomeric dinitrohenzoic acids." 



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



Complete sets of isomeric benzene derivatives Cg ^,^,-6 have been 

 studied but little up to the present ; yet, for a closer understanding 

 of those derivatives, it must be deemed of great importance to subject 

 the six possible isomers of which such sets consist, to a comparative 

 investigation. A contribution hereto is the investigation of the six 

 isomeric dinitrohenzoic acids which Dr. Sirks has executed under 

 my directions. 



The considerations which guided me in the choice of this series 



') According to Henriques (Ann. Ghem. 215, 335), tetranitroresorcinol (m.p. 166°) 

 is formed by the nitration of 2-5-dinitropheno]. In Beilstein's manual (vol. II, 926) 

 a reasonable doubt is thrown on the correctness of this observation. The sub- 

 stance obtained has probably been an impure trinitroresorcinol formed by the 

 action of water on the primary formed tetranitrophenol. (Rec. 21, 258). 



2) Rec. 21, 264. 



3) Rec. 25, 165. 



