( 290 ) 



determination of the total amount of byproduct showed that this 

 had formed to the extent of 3.1 7o only. The qualitative investigation 

 had shown already that this contains the asymmetric acid, and that 

 it consists of this solely was proved in the following manner. If the 

 3.1 7o found were indeed simply asymmetric acid, a solution, 

 obtained by shaking 100 grams of water with excess of symmetric 

 and vicinal acid -\- 1 gram of nitration product (containing 0.031 

 gram of asymmetric acid), ought to have the same titre as a solution 

 obtained by shaking 100 grams of water with excess of both acids 

 -|- 0.031 gram of asymmetric acid. If on the other hand the nitration 

 product also contained vicinal acid, therefore less than 0.031 gram 

 of asymmetric acid, the titre ought to have been found less. This 

 however, was not the case, which shows that the asymmetric acid 

 is the sole byproduct. The result, therefore, is that in the nitration 

 of isophthalic acid with absolute nitric acid at 30° there is formed : 



96.9 7o of symmetric and 3.1 °/o of asymmetric nitroisophtalic acid. 



If we compare the above results with that of the nitration of 

 benzoic acid where (at 30°) is formed 22.3 7o ortho-, 76,5 7o meta- 

 and 1.27o paranitrobenzoic acid the following is noticed. 



COJI 



/iXcOjH 

 As in phthalic acid IJ ^1 the positions 3 and 6 are meta in 



regard to the one carboxyl and ortho in regard to the other and 

 the positions 4 and 5 are also meta in regard to the one carboxyl 

 but para in regard to the other it might be expected from my 

 theories that the «-acid (the vicinal) is the main product and 

 the /3-acid the byproduct, because in the latter the nitro-group 

 must be directed by one of the carboxyles towards para and 

 because ^9-nitrobenzoic acid is formed only in very small quantity 

 in the nitration of benzoic acid. As regards the isophthalic acid 



COaH 



''i\ it might be expected that the chief product will be sym- 



\l l\ metric acid but that there will also be byproducts. (1, 3, 2) 

 \V^ ^ and (1, 3, 4) the first in the largest quantity, although it 

 should be remembered that a nitro-group seems to meet with great 

 resistance if it must take a position between two other groups. 



As regards the nitration of isophthalic acid the result of the above 

 investigation is fairly satisfactory, although the total absence of the 

 vicinal nitroisophthalie acid is somewhat remarkable. In the case of 

 phthalic acid this is true in a less degree as about equal quantities 

 are formed of the two possible isomers. 



In his dissertation. Dr. Huisinga has now endeavoured to calculate, 



