1027 
Chemistry. — “The replacement of substituents in benzene deriva- 
tives.” By Prof. Honteman. 
(Communicated in the meeting of December 30, 1914). 
In close connexion with the problem of the introduction of sub- 
stituents in aromatic compounds exists another: that of the replace- 
ment of substituents already present, for after all the introduction 
is really also a substitution, namely of hydrogen. It, therefore, 
appeared to me desirable to also take in hand the study of the 
replacement, in addition to my researches on the introduction of 
substituents. 
Some generalities on this subject are to be found in every text- 
book on organie chemistry. We know that the substituent in mono- 
substituted benzene derivatives is very difficult of substitution ; that 
in the disubstituted derivatives it is the combination of halogen and 
the mitro-group in which halogen is replaceable if the groups are o 
or p in regard to each other; that in compounds C,H,ABC replace- 
ment also occurs if the substituents consist of halogen, nitro, car- 
boxyl, cyanogen or the sulpho-group (with this understanding, how- 
ever, that except in a very few cases, there is no such thing as 
A=bB=O); finally that also in the higher substituted benzene deri- 
vatives instances of replacement occur. As interacting substances 
have been employed almost exclusively alcoholates, ammonia and 
amines. In order to obtain a better insight in this problem the com- 
pounds C,H,X could be passed over; on the other hand the literature 
on the compounds C,H,AB and C,H,ABC had to be studied more 
closely. 
Statistically, this yielded the following results: If we consider the 
compounds C,H,AB and C,H,ABC, in which also A, B, and C may 
be equal, and if for these substituents we take the following 14: 
F, Cl, Br, J, NO,, SO,H, Alkyl (Aryl), CO,H, NH, (amine), OH (O Alk), 
. - eet m(n+1) 1415 
CN, NO, CHO, COR, we can derive from C,H,AB- Ae —~—105 
repeated combinations all of which can form three isomerides ; hence 
a total of 315 cases (included A = 5). 
Of C,H,A, are possible > 14 combinations; 3 isomerides of each 
= 42 cases. 
Of C,H,A,B are possible n(n—1) = 14X18 = 182 combinations ; 
each can occur in 6 isomerides, thus representing 1092 cases. 
NL / 2, 
Of C,H,ABC are possible se ee coms 
binations ; 10 isomerides of each = 3640 cases. 
68* 
