( 266 ) 



Let us now include all the figures obtained in the subjoined tables. 



I. Nitration of //z-chlorobenzoic acid; % of byeproduct in the nitration mixture. 

 de Leeuw Polak Holleman, 7?.20,206 



o Imol. weight 



Temp. 0°. 

 Temp. -30° 



Temp. (P. 

 Temp.— 30' 



7.6 7.2 

 6 5 7.2 



11.7 

 11.4 



203.2 

 200.4 



o/ mol. weight' 



8.0 7. 'J 

 6.7 6 3 



202.9 

 203.8 



mol. weight mol. weight 



8.7 

 8.3 



II. Nitration of 7/7-bromobenzoic acid. 

 243.7 13.0 12.9 245.7 



243.4 



202.5 

 201.5 



245 

 243.2 



calculated 

 201 5 



mol. weight 



calculated 



246 



10.7 10.8 245.2 || 1!.8 



My own figures were deduced from solidifying point determinations. 



As regards 1 1 io titration figures of Messrs. de Leeuw and Polak it 

 must be observed thai t he end reaction was obtained within one 

 drop of )i 10 alkali so that there can be only a doubt as to one 

 drop more or less. This represents ' ,,,„ millimol. or about 0.3% 

 of the quantity taken for analysis. If we consider further thai 

 the above figures are deduced from the tables communicated above, 

 the figures of which present inaccuracies of the same order, the 

 difference between the above percentages may be about 0.6 without 

 exceeding the errors inherent to the process. 



From this point of view Mr. Polak's figures may be pronounced 

 excellent ones. It appears from the table that when the molecular 

 weights found approach more closely to the calculated ones, the 

 percentage of the byeproducts is higher. This is easy of explanation. 

 Kor the nitration product may be considered all the purer when 

 there exists a closer agreement between the calculated molecular 

 weight and that actually found. As. however, the impurities are 

 dissolved on shaking with water, and count as main product in the 

 titration, the figures of this become loo high and those of the bye- 

 products consequently too low. 



For this reason the following percentages, showing the composition 

 ol' the nitration products, must be considered as being nearest to 

 the truth. 



I. Nitration of m-chlorobenzoic acid 

 byeprod. mean prod 



Temp. 0°. 

 Temp— 30°. 



92 

 93 



II. Nitration of m-bromobenzoic acid 

 byeprod. main prod. 



13 87 



n 



Temp. 0°. 

 Temp.— 30 '. 



89 



The uncertainty, of the figures obtained from the solidifying point 

 determinations is a little greater, owing to the circumstance that the 

 mass darkens during the fusion, which causes the solidifying points 

 (which are rather high) to be determined with loss sharpness than is 

 usually the case. 



August 1908. Amsterdam, Org. chem lab. University. 



