995 
already quantitatively studied in my laboratory by VAN DEN AREND, 
who had found that 58°/, of the isomer 1,4,2 and 42 °/, of the 
other one (1,4,3) are formed. 
As we supposed that the nitration of ortho-chlorotoluene would 
yield all the four possible mono-nitroderivatives, the first thing to do 
was to prove this. The nitration product presents itself as a yellow oil 
which commences to congeal only at about +1°; on the other hand, the 
eutectic temperature of the binary mixtures of the isomers CH,,Cl, 
NO, = 1,2,341,2,4 was found at 8°.2; of 1,2,3+1,2,5at+1.1; 
1,2,441,2,6 at 17° .2; 1,2,5-+-1,2,6 at 7°.2. It was therefore evident, that 
‘the nitration product could not be a mixture of only two isomers, 
but must contain still a third and perhaps also a fourth. Of 
course, this conclusion only holds good, when the nitration product 
contains only the mononitrocompounds. This was proved to be so by 
fractional distillation and the determination of the refraction of the 
first passing drops and of the residue, which showed both the same 
refraction as the principal portion of the distillate. 
As it proved to be impossible to separate the isomer nitro-o-chloro- 
luenes themselves, we reduced them; the chlorotoluidine CH,,Cl,NH, 
= 1,2,5, melting at 81°, separates easily in large quantities. The 
oily mixture which remains then was acetylated, because we stated 
that the acetyleompounds of ‘the two vicinal chlorotoluidines CH,, 
Cl, NH, —1, 2,3 and 1, 2,6 are sparingly soluble in cold benzene. 
Indeed, by treating the mixture of acetyleompounds with this solvent, 
these two isomers were easily isolated and identified; the presence 
of the isomers CH,, Cl, NO, —=1,2,3 and 1,2,6 in the nitration 
product was thus proved. 
It was far more difficult, to prove also the presence of the 
fourth isomer 1,2,4. After about six months of strenuous labour, 
in which a great many methods were tried, we succeeded at last 
in the following way: about 100 grams of the nitration product 
was reduced. After separation of the isomer 1,2,5, the residue was 
acetylated and the vicinal isomers isolated by treatment with ben- 
zene. The products that remained in the benzenic solution were 
saponified ; from the mixture of chlorotoluidines so obtained. a 
great deal of the isomer 1,2,5 separated again on cooling. The liquid 
residue, again converted into acetylcompounds, yielded again on treat- 
ment with benzene a considerable pertion of the vicinal compounds. 
After all these operations, there remained about 9 grs. of a mixture 
of acetamino-2-chlorotoluenes, in which the compound 1,2,4 must be 
accumulated. By dissolving this mixture in a little quantity of ben- 
zene and by fractional precipitation of this solution with petroleum 
39% 
