( 249 ) 



o- and p-nitrotoluene are formed by adding catalyzers (generally 



consisting of metallic salts) to the mixture of' nitric and sulphuric 

 acid used in the nitration. The amount of o-nitrotoluene present in 

 the product of nitration only varied however from 57.16. to 60.85° . 

 In these experiments the temperature was kept between 5 and 10°. 

 When nitrated at 0° with nitric acid (sp. gr. 1.52) 52.7" „ of nitro-toluene 

 was obtained; on addition of different sails (the proportions are not 

 stated) to this acid the quantity of o-compound diminished and when 

 nickel sulphate was added it even got as low as 45.5" . 



Friswell, (C. 1)1. 1908 1 , 2092) nitrated toluene under many various 

 conditions in order to increase the yield of p-nitro toluene. He obtained 

 however, always 60 — 65% of ortho- and 40 — 35% of para-com pound. 



None of these chemists make any statement as to the method used 

 in these determinations, although Holdermann expresses his results 

 even in two decimals. As will be noticed from the above quotations 

 the figures differ widely. Moreover, Nölting (B. 12, 443 ; 18,1337) 

 has shown that the nitration product of toluene contains 7?i-nitrotoluene 

 the amount of which he estimates at 1 — 2%. It is, therefore, obvious 

 that there is, as yet, no question of a fairly accurate knowledge as 

 to the composition of the product of nitration of toluene, and, for 

 this reason, I instructed Mr. van den Arend to determine the com- 

 position, with the aid of the more accurate methods, which for that 

 purpose have been worked out in my laboratory. In this particular 

 case the method of the solidifying points was the most practical one. 



In order to apply the same, it is necessary to procure, first of 

 all, the three mtwonitrotoluenes in an absolutely pure condition. 

 A preparation of o-nitrotoluene of great purity has been obtainable 

 for the last few years from Meister, Lucius and Brüning. A specimen 

 received previously from that firm still contained 0.4" of p-nitrotoluene 

 (These Proc. VII, p. 395). At my request they were kind enough to 

 once more purify a sample of this almost pure o-nitrotoluene by 

 freezing, and to place two kilos of the purified preparation at my 

 disposal, for. which I express to that firm my sincere thanks. This 

 was found to contain only 0.13% of p-nitrotoluene and was used 

 by Mr. van DEN Arend in his experiments without any further puri- 

 fication, except a single distillation in order to remove the dissolved 

 water; a correction was then applied for the /^-compound content. 



It was shown that the methods proposed by Reverdin and LA Harpe 

 (Heilsteins Handbuch II, 91) and by Loesner, (J. pr Chem. (2) 50, 567) 

 to i'vee o-nitrotoluene from any p-nitrotoluene present are quite 

 useless. 0-Nitrotoluene is dimorphous; the melting points of tin 1 two 

 modifications were determined by van den Arend bv means of his 



