series of syn- and anti-diazo-cyanides and -sulphonates (_Ber._, 1895,
28, p. 666; 1900, 33, p. 2161; 1901, 34, p. 4166). By diazotizing
para-chloraniline and adding a cold solution of potassium cyanide, a
salt (melting at 29 deg. C.) is obtained, which readily loses
nitrogen, and forms para-chlorbenzonitrile on the addition of copper
powder. By dissolving this diazocyanide in alcohol and reprecipitating
it by water, it is converted into the isomeric diazocyanide (melting
at 105-106 deg. C.), which does not yield para-chlorbenzonitrile when
treated with copper powder. Similar results have been obtained by
using diazotized para-anisidine, a syn- and an anti- compound being
formed, as well as a third isomeric cyanide, obtained by evaporating
para-methoxy-benzenediazonium hydroxide in the presence of an excess
of hydrocyanic acid at ordinary temperatures. This salt is a
colourless crystalline substance of composition
CH3O.C6H4.N2.CN.HCN.2H2O, and has the properties of a metallic salt;
it is very soluble in water and its solution is an electrolyte,
whereas the solutions of the syn-and anti- compounds are not
electrolytes. The isolation of these compounds is a powerful argument
in favour of the Hantzsch hypothesis which requires the existence of
these three different types, whilst the Bamberger-Blomstrand view only
accounts for the formation of two isomeric cyanides, namely, one of
the normal diazonium type and one of the iso-diazocyanide type.

Benzene diazonium hydroxide, although a strong base, reacts with the
alkaline hydroxides to form salts with the evolution of heat, and
generally behaves as a weak acid. On mixing dilute solutions of the
diazonium hydroxide and the alkali together, it is found that the
molecular conductivity of the mixture is much less than the sum of the
two electrical conductivities of the solutions separately, from which
it follows that a portion of the ions present have changed to the
non-ionized condition. This behaviour is explained by considering the
non-ionized part of the diazonium hydroxide to exist in solution in a
hydrated form, the equation of equilibrium being:

C6H5.N. --> C6H5.N.OH
H2O + ... + OH' |
N <-- HO.N.H

On adding the alkaline hydroxide to the solution, this hydrate is
supposed to lose water, yielding the syn-diazo hydroxide, which then
gives rise t