The manner in which the rate of removal of halogen from halogenated benzenoid derivatives is governed by atoms or groups of atoms which repress reactivity
1. Investigations have been carried out with
a view to discovering to what extent the influence
of the oxygen atom in p-cresol is neutralised by
(a) a (>C=0) group, (b) a (NO₂) group, (c) a
Br atom, when the two latter are situated at some
distance from this oxygen atom.2. Advantage has been taken of the fact that
there is a close connection between the ease of
removal of halogen from compounds containing a
CH .Hal.group and direct substitution in the
benzene nucleus to which this .group is attached.3. The alkaline hydrolysis of the nitrobenzylbromides
gives an abnormal result because of the
production of a secondary reaction. This was
not observed in the case of the w-bromotoluicacids.4. It has been shown that the conversion of the
nitrogen atom in an amino group to one which has
a positive charge in a substituted amino group
prevents the removal of an iodine atom from any
position in the nucleus to which the nitrogen is
attached.5. It has been shown that a (>C=0) group
directly attached to a benzylchloride molecule
represses the ease of removal of the halogen atom
very markedly.6. An attempt has been made to explain all the
phenomena observed from the standpoint of the
recent theories on reactivity in an organic
molecule
