686 REPORT—1899., 
ordinary sulphuric acid at about 180°, or by chlorosulphonic acid; but when 
carefully sulphonated by fuming acid it yields a large proportion of meta- acid. 
Doubtless, in this latter case, the conditions correspond to those pictured in the 
case of benzanilid undergoing nitration. That the formation of meta~ acid is a 
consequence of the sulphate undergoing sulphonation, and is not merely due to the 
use of the more powerful agent 5O,, clearly follows from the fact that so powerful 
an agent as SO,HCl converts dimethylaniline only into para- acid. 
The behaviour of acetanilid and benzanilid towards fuming sulphuric acid is 
precisely similar to their behaviour towards nitric acid—the former gives only o- 
and p-acid ; the latter a considerable proportion of meta- acid. Probably both are 
initially converted into sulphamic acid, but the acid formed from the latter being 
less prone to undergo isomeric change it becomes in part meta-sulphonated. 
12. In the case of compounds other than amines which afford meta- derivatives, 
it may be supposed that the radicle is both unattractive and ‘ ortho-para inhibitive,’ 
and that consequently opportunity is given for the attack to become concentrated 
upon the benzenoid portion of the molecule in the meta- position. 
As in such cases some proportion of o- and p- compound is usually obtained, it 
is necessary to assume—if the radicle be regarded as altogether unattractive—that 
the benzenoid portion of the molecule is open to attack at several points—indeed, 
this may be more or less true of all compounds. Thus it may be supposed that 
when nitrobenzene is brominated two compounds are initially formed, thus: 
NO, Be NO, Br 
VA 
) (\ (\* 
Ke ag \F 
Br 
The 1:2 compound being a very minor product, but little ortho- compound is 
eventually obtained, and owing to the unattractive and inhibitive influence exer- 
cised by the NO, group, bromine is chiefly separated from the para- position of the 
8:4 compound; consequently but little para- derivative is formed. 
13. The phenols in many ways closely resemble the amines in their behaviour 
towards substituting agents. The hydrogen in association with the oxygen clearly 
plays an important part; in fact, the extreme activity of phenols is probably, in 
large measure, due to the presence of hydrogen in the extra-benzenoid radicle, as in 
the case of the amines, but the part which the hydrogen plays cannot at present 
be at all clearly made out. 
By displacing the hydroxylic hydrogen by allcyls, effects are produced very 
similar to those observed in the case of amines. Thus phenol-parasulphonic acid, 
like sulphanilic acid, at once exchanges two atoms of hydrogen for bromine, and 
then quite readily exchanges the SO,H group for bromine. But the acids obtained 
by introducing methyl, ethyl, or benzyl in place of the hydroxylic hydrogen yield 
only monobrominated acids, which on further treatment exchange the SO,H group 
for bromine; and this action takes place only partially, as a large proportion of the 
acia directly exchanges the SO,H group for bromine,a monobrominated compound 
being formed, just as in the case of acetyl- and benzoyl-sulphanilic acid. 
Benzoyl appears to exercise a very remarkable inhibitive effect, as preliminary 
experiments show that benzoylated phenolparasulphonic acid remains unattacked 
by bromine under conditions which involve the conversion of the unbenzoylated 
acid into tribromo-phenol. 
It may therefore be supposed that oxygen in phenols, being possessed of residual 
affinity, exercises an influence on substitution similar to that which nitrogen 
exercises in amines ; and as it has no basic qualities, it is difficult, if not impossible, 
to deprive it of its activity, and consequently of its para-ortho-orienting power: 
hence it is that phenols do not yield meta- derivatives. Should conditions be dis- 
covered which will make it possible to hold the activity of oxygen in check, it will 
probably be found possible to direct!y prepare meta-phenolic derivatives. 
14, Sulphur, whilst resembling oxygen, apparently has a still stronger inhibitive 
