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CH, 



NOj. 



NII2 



4-chloro(bromo)6-iiitro-m. xylene yields, however, on subseqnent 

 nitration 4-cliloro(bronio)2-6-(linitro-in. xylene ^). This made two cases 

 in which an iodine atom was replaced by a NOj-group whilst it 

 was shown at the same time that Br and CI were not displaced by 

 the NOjgroup under the same circumstances *). 



If we compare the melting points of the three trinitro-m-xylenes 

 CIIs cii, oil. 



NO2/ \N02 NOo/ \ NO2X \N02 



|t82°l \Vlb^ I I 90° I 



. NO2 NO2 



we notice that these are situated the higher the more symmetrical 

 the position of the nitro-groups in the core is ; this consequently 

 agrees with the rule that the melting point of isomeric substances 

 is generally the more elevated the more symmetrically constructed 

 the molecule is. 



It was also found that the higher the melting point of the three 

 isomers is situated the less their solubility in alcohol becomes '). 



Dr. Jaeger was kind enough to examine the crystals of the three 

 trinitro-compounds and communicated to me his results. 



2-5-Q-7)'mitro-l-S-xi/lene ^ =: 90° crystallised from alcohol. 



Triclino pinacoidal.' a : b : c=2.8359 : 1:0,8510 with .4 = 1I7°.2V;. 

 5 = 114°.38' C=120\22'; «=100^54' p'=106°.59' y= il7°.51V;. 



Forms: a=\100\, è=:|010|, ;>=|ll0| all very lustrous; c=i001|, 

 striped parallel (c : a) ; r = jlOlj, 6- = ISOlj, t = |20T| ; tinally 

 o=:|lllj very narrow and dull. 



4:-5-Q-Trinitro-l-S-xi/Ie7ie ^ = 125° crystallised from alcohol. 



Monoklino prismatic, a : 6 : cr^O.5950: 1 :0.2706 with ^=88=^.11'. 

 Large long- prismatic crystals. Forms b ^ \010\ broad; m = \110\ 

 also; a = jlOOj narrow; c = |001| large; ?' = |101| well developed 

 = |110| very narrow. Cleaves well towards ?'. 



2A-Q-Trinitro-l-^-xylene. ^ = 182° crystallised from benzene -}- 

 alcohol. Large thick prismatic very lustrous crystals; well built. 



Rhorabic-bipyramidal. a:b:c:= 0.6587 : J : 0.5045. Forms a= {lOOj, 



1) Ber. 24. 2012. 



2) Many cases where GOOH, SO;jH, I etc. is replaced by Br and this in turn by 

 Gl or NO3 have been described or referred to previously. Rec 21, 283, 336. 23, 207. 



^) Gompare Garnelley and Thomson, Journ. Gliem. Soc. 53, 782. Lobry de Bruyn, 

 Rec. 13. 116. 



