598 
hand and of toluene on the other hand. It must only be taken into 
consideration that one of the ortho-places both of methyl and of 
chlorine is occupied and so the remaining o-places will be substituted 
in the same ratio as if both o-places towards CH, and Cl were free. 
One should therefore expect a ratio of the isomers as follows: 
1°92 3 ed Se ee ee 
30-+2: 38: 70+2: 58 
because the nitration of toluene gives 58°/, 0-, 38°/, p- and 4°/, 
meta-compound and the nitration of chlorobenzene gives 30 °/, o- 
and 70°/, p-chloronitrobenzene. Of course the 4°/, of meta-compound 
formed in the nitration of toluene, must be divided equally between 
the places 3 and 5. 
I deduced however that chlorine causes a larger velocity of sub- 
stitution than methyl. If we call the ratio of these velocities x, we 
find for the proportion in which the isomers must be formed: 
13,24 2/4. dao 43; 6 
307 +2 : 38: 70x42 : 58 
With the same reasoning we find for the proportion in which the 
isomer nitro-p-chlorotoluenes must be formed: 
1,4,2 1,4,3 
58: 4 +304 
CH; for also in this case methyl and chlorine act independently 
of each other. 
aay .  Equalling these figures with those found by experiment, 
‘we get the equations: 
Or a 2:38: 70z a 2:58 = 19:2 : 17.0: 43.3 : 20.5 and 
58 : 3027 +4— 58: 42 
from which « may be calculated. As mean value of 2 we find in 
this way: 
go=4 A901 
expressing that chlorine causes a velocity of substitution 1.491 times 
as fast as methyl. 
Calculating now with this value of z the proportion in which the 
isomers are formed, we get: 
CH, CH, CH, CH, 
93.3 6 CI 20.5 (_N CI ie 554 AN 58 
d 
49.7) | Gelrrwamiesh a kek 
ark }187 438\ 19 EG 
133 170 Cf Cf 
caleulated found calculated found 
