Improvements in the Preparation of Cyanogen Compounds.
Year: 1893

page_text: Date of Application, 8th Nov., 1893
Complete Specification Left, 6th Sept., 1894-Accepted, 6th Oct., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Preparation of Cyanogen Compounds.
JOHN JAMES HOOD of 21 Shepherds Bush Road in the County of Middlesex
Chemist, and ALFRED GORDON SALAMON of 1 Fenchurch Avenue in the City
of London Chemist do hereby declare the nature of this invention to be as
follows:-
Our improvements relate to the preparation of compounds of cyanogen, and more
particularly to cyanides, oxy-cyanides or cyanates of the alkalies and alkaline
earths or other bases.
It is well known that under suitable conditions ammonia and carbon-bisulphide
may be caused to react according to the following equation :-
CS, NH, H₂S + HCNS.
=
:―
It is further known that in the presence of suitable bases such as lime, manganese,
or ammonia, sulphide and sulpho-cyanide of the bases are formed.
The existence of many chemical analogies between carbon bisulphide (CS₂) and
carbonic acid (CO2) would suggest the possibility that under suitable conditions
carbonic acid (CO2) would react with ammonia (NH,) and that such reaction
would be expressed by the equation CO2 + NH, H₂O + HCNO in which it
will be seen that oxygen takes the place of sulphur in the equation first stated
above, and as a result gives rise to the formation of water and cyanic acid. We have
practically proved the correctness of this assumption, and we have further found
that under suitable conditions, and in the presence of suitable base or bases, the
oxy-cyanide of the base may be formed instead of the sulpho-cyanide which results
when carbon bisulphide is employed. It is know that the alkali sulpho-cyanides
e.g. sodium sulpho-cyanide may be caused to part with the contained sulphur when
heated with a reducing body such as zinc or lead, in which case the sulpho-cyanide
is converted into cyanide according to the following equation:-Na CNS+ Zo
NaCN + ZnS. By following the analogy above quoted, it might be expected
that the oxy-cyanide when similarly heated, would undergo the following
decomposition: :-
NONO Z Z0; NCN
We have proved this to be true under proper and variable conditions, and hence
we have proved the possibility of producing from ammonia and carbonic acid in
conjunction with a suitable base and reducing agent, the cyanide of the base.
We now proceed to further describe how the above mentioned reactions may be
We have proved this to be true under proper and variable conditions, and hence
we have proved the possibility of producing from ammonia and carbonic acid in
conjunction with a suitable base and reducing agent, the cyanide of the base.
We now proceed to further describe how the above mentioned reactions may be
rendered applicable to the commercial production of cyanogen compounds.
To prepare the cyanide of any particular base the reagents ammonia and
carbonic acid may be employed separately, the one as a liquid which may be
volatilised as required, and the other carbonic acid as a gas. Or the two may be
employed together as a solid carbonate of ammonia, and volatilised as required.
As above shown these three reagents only tend to form an oxy-cyanide, and a
reducing agent is further required to take the oxygen from the oxy-cyanide and
form cyanide, and for this purpose we employ one or other of the ordinary reducing
materials, such as carbon metallic lead or zinc, by preference the latter. Or we
may employ the equivalent of a metallic reducing agent ris., the oxide or carbonate
with the addition of solid carbon or other suitable solid or liquid carbonaceous
material. It is not absolutely necessary, in order to bring about the reaction, that
D
031

page_text: carbonic acid be employed per se, for the base itself that it is desired to employ
may be in the form of carbonate, thus simplifying the requirements for the reaction,
to ammonia, a carbonated base and a reducing agent. Or it may be better to
employ two carbonated bases so as to supply the carbonic acid from one base to
form the cyanide of the other base. Thus, to form cyanide of sodium ordinary
carbonate or bi-carbonate of soda in suitable proportion is incorporated with a
reducing material such as metallic zinc. Heat the mixture at a suitable tempera-
ture and pressure, with the vapour of ammonia, and there will result oxide of zinc
and cyanide of soda, the latter being washed out from the oxide of zinc and the
solution dealt with for purposes of commerce. The above reaction may be thus
theoretically expressed :-
From this it will be seen that only half the base goes to form cyanide, but in the
presence of bi-carbonate of soda, or, if chalk or other suitable carbonate in proper
proportion be added, sufficient carbonic acid may be supplied by such added
materials to yield a substantially complete reaction.
It might be found better in practice to employ zinc in conjunction with carbon,
so that the former would reduce the oxy-cyanide to cyanide and the latter in turn,
reduce the oxide of zinc formed to the metallic state. In such case the zinc would
be again ready for further action, thus making only a small amount of zinc
necessary in the presence of the equivalent of carbon.
Dated this Eighth day of November 1893.
ERNEST
SALAMAN,
Pinner's Hall, Great Winchester Street, E.C., Agent for Applicants.

page_text: the oxy-cyanide of the base may be formed instead of the sulphocyanide which results
when carbon bisulphide is employed. It is known that the alkali sulphocyanides
e.g. sodium-sulphocyanide may be caused to part with the contained sulphur when
heated with a reducing body such as zinc or lead in which case the sulphocyanide
is converted into cyanide according to the following equation :-
We have proved this to be true under proper and variable conditions, and
hence we have proved the possibility of producing from ammonia and carbonic
acid in conjunction with a suitable base and reducing agent, the cyanide of the
base.
We now proceed to further describe how the above mentioned reactions may be
rendered applicable to the commercial production of cyanogen compounds.
In preparing the cyanide of any particular base the reagents ammonia and
carbonic acid may be employed separately, the one as a liquid which may be
volatilized as required, and the other carbonic acid as a gas. Or the two may
be employed together as a solid carbonate of ammonia and volatilized as required.
As above shewn these reagents only tend to form an oxy-cyanide, and a reducing
agent is further required to take the oxygen from the oxy-cyanide and form cyanide
and for this purpose we employ one or other of the ordinary reducing materials,
Or we may
such as metallic zinc, manganese or lead, by preference the former.
employ the equivalent of these metallic reducing agents viz. the oxide or carbonate
with the addition of solid carbon or other suitable solid or liquid carbonaceous
material.
It is not absolutely necessary in order to bring about the reaction that carbonic
acid be employed per se, for the base itself that it is desired to employ may be in
the form of carbonate, thus simplifying the requirements for the reaction to
ammonia, a carbonated base and a metallic reducing agent, or the equivalent of
such. Or it may be better to employ two carbonated bases so as to supply the
Thus to form
carbonic acid from one base to form the cyanide of the other base.
cyanide of sodium, ordinary carbonate or bicarbonate of soda in suitable proportion
is incorporated with a metallic reducing material such as metallic zinc. Heat the
mixture to dull redness with the vapour of ammonia, and there will result oxide of
zinc and cyanide of soda, the latter being washed out from the oxide of zinc, and
the solution dealt with for purposes of commerce, being purified from contaminated
zinc by crystallization or other suitable means. The above reaction may be thus
theoretically expressed :-
-
NH.Na.CO. + Zn = NaCN+NaHO + ZnO + H₂O.
From this it will be seen that only half the base goes to form cyanide. To
complete the reaction, sufficient carbonic acid may be supplied by passing this gas
over the heated mass simultaneously with the ammonia.
It is sometimes found better in practice to employ zinc in conjunction with
carbon so that the former would reduce the oxy-cyanide to cyanide, and the latter
in turn reduce the oxide of zinc formed to the metallic state, thereby avoiding the
action that takes place to a greater or less extent between the sodic or potassic
hydrates and the zinc oxide. In such case the zinc would be again ready for further
action, thus making only a small amount of zinc necessary in the presence of the
equivalent of carbon. Instead of employing sodic or potassic carbonates or the
bicarbonates alone, we may employ mixtures of these so as to produce a more or less
mixed cyanide material consisting of potassium and sodium cyanides.

page_text: .
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what
we claim is⭑
(1.) The preparation of sodium or potassium cyanides or mixtures of such
cyanides, by passing gaseous ammonia over a heated mixture of sodium or potassium
carbonate or mixtures of these carbonates with a metallic reducing body substantially
as described.
(2.) The preparation of sodium or potassium cyanides or mixture of such cyanides
by passing ammonia over a heated mixture of sodium or potassium bicarbonates or
mixtures of such bicarbonates with a metallic reducing body substantially as
described.
(3.) The employment of metallic zinc or its equivalent viz. oxide or carbonate
with the addition of a reducing agent for the direct preparation of cyanides.
(4.) The employment of metallic manganese or its equivalent viz. oxide or
carbonate with the addition of a suitable reducing agent for the direct production
of cyanides.
(5.) The employment of metallic lead or its equivalent viz. oxide or carbonate
with the addition of a suitable reducing agent for the direct production of
cyanides.
Dated this Sixth day of September 1894
ERNEST SALAMAN,
Pinner's Hall, Great Winchester Street, London, E.C.,
Agent for the Applicants.