Year: 1887

page_text: Date of Application, 26th Feb., 1887
Complete Left, 11th Nov., 1887
Complete Accepted, 13th Dec., 1887
I Dr. FRITZ RASCHIG of 78 Friedrich Strasse, Berlin, in the Empire of Germany,
Chemist, do hereby declare the nature of this invention to be as follows:-
The object of the present invention is to produce hydroxylamin by the decomposi-
tion of hydroxylamindisulphonatic salts of alkali, and to obtain the latter by the union
of alkali nitrites and alkali bi-sulphites, or by treating with sulphurous acid a mixture
which contains to every 2 molecules of alkali nitrite, 1 molecule of alkali carbonate,
or 2 molecules of caustic alkali.
In carrying out the invention, if to solid nitrate of soda, or to nitrate of soda
dissolved in the smallest possible quantity of water, be added exactly the quantity
of a solution of acid sulphate of soda which will correspond with the following
furmula :-
Na NO, +2 H. So, Na=H.O (So, Na) 2+Na OH, (preferably while the temperature
of the solution is kept at zero [0° C.], by the addition of ice), there will be produced
as the above formula expresses, hydroxylamindisulphonate of soda and free soda, both
in solution. If there now be added such a quantity of easily soluble potash salt, say
acetate of potash or chloride of potassium in watery solution, as will be sufficient to
convert the said hydroxylamindisulphonate of soda into the corresponding potash
salt, the hydroxylamindisulphonate of potash-HON (So, K) 2 + 2 H, O-will be
separated in compact, crystals, easily separable from the mother liquor.
This salt is capable of being divided up, according to the following formula :-
2 H.O.N (SO,K) 2+4H,O=(NH, OH), SO, +2 K, SO, + H.SO,-into hydroxylamin
sulphate, sulphate of potash, and sulphuric acid, either by boiling a watery solution
thereof for some hours, or, quicker, by heating this solution up to a high temperature,
say about 130° C. As the sulphate of potash is much less soluble in water than
the hydroxylamin sulphate, these salts are easily separable by "fractional" crystalli-
zation.
The hydroxylamindisulphonate of potash can also be produced direct by the
admission of a solution of bisulphite of potash into a solution of nitrite of soda, or
nitrite of potash, under suitable stirring, not allowing the temperature to rise
beyond 40°, and it then sepárates as minute crystals (crystal meal).

page_text: The production of the bisulphite of potash, and the union of the same with nitrite
of potash, may also be effected under one operation by allowing sulphurous acid to
flow into a solution of nitrite of potash, to which has been added such a quantity of
carbonate of potash or caustic potash as will correspond with the following formula
-
or
K N O₂ + K O H + 2 SO₂ = HON (SO, K) 2.
The hydroxylamindisulphonate of potash may also be obtained by passing
sulphurous acid over a wet mixture of nitrite of potash with carbonate of potash
or caustic potash, the union of which will correspond with these formula.
Dh oth 1
1007

page_text: I Dr. FRITZ RASCHIG of 78 Friedrich Strasse Berlin in the Empire of Germany,
Chemist do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
The object of the present invention is the production of hydroxylamin by the
decomposition of the hydroxylamin-disulphonates of potassium or sodium. I obtain
the said derivatives of hydroxylamin either by the mutual reaction, hereaftor to be
described, of the nitrites and bisulphites of the said alkaline metals, or by treating
with sulphurous acid a mixture containing, for every two molecules of the nitrite
employed, either one molecule of the carbonates, or two molecules of the hydroxides
of potassium or sodium.
My new process for the production of hydroxylamin contains, therefore, two
consecutive steps, viz
:-
1. The preparation of the hydroxylamin-disulphonates.
2. The decomposition of the said hydroxylamin derivatives.
I now proceed to describe the manner in which my invention may be carried into
effect.
1. The preparation of the hydroxylamin-disulphonates.
The preparation of the hydroxylamin-disulphonates of potassium or sodium is based
upon the following observations :-
=
If to solid nitrite of sodium, or to a solution thereof in the smallest requisite
quantity of water, a solution of acid sulphite of sodium be added, the proportion of
which is in strict accordance with the equation: Na NO2 + 2 HSO³ Na HON
[SO³ Na] Na OH [particularly whilst the temperature of the mixture is kept.
at zero (0° Centigrade-)], then there will be produced a solution containing
hydroxylamin-disulphonate of sodium and free caustic soda, as is expressed by the
above equation. If there now be added an aqueous solution of an easily soluble
potassium salt, say, for instance, of the acetate or chloride of potassium, in sufficient
quantity to convert the hydroxylamin-disulphonate of sodium into the corresponding
potassium salt, then the latter salt will be observed to separate out in compact
crystals, the composition of which corresponds to the formula:
HON [SOK] + 2 H² 0.
As an example, I proceed as follows:-
:-
1 take a ouantity of commercial nitrite of sodium containing about ten ports he

page_text: parts of water, is gradually added, taking care, that the temperature of the mixture
does not rise considerably above zero. I then add to the solution thus obtained,
about twenty-two parts by weight of chloride of potassium dissolved in about seventy-
five parts of water, when, within the course of twenty four hours, the nearly insoluble
hydroxylamin-disulphonate of potassium thus produced will become deposited in
crystalline crusts, from which the mother liquor may then be separated by decantation
or otherwise.
The above described process may be varied by employing bisulphite or nitrite of
potassium in lieu of the corresponding sodium compounds hereinbefore mentioned.
By operating in such a manner, hydroxylamin-disulphonate of potassium will be the
direct result of the reaction between the bisulphite and nitrite, no further addition of
chloride of potassium being required to furnish the requisito potassium-base.
As an example, I proceed as follows:-
About ten parts by weight of pure nitrite of potassium [or a corresponding quantity
of the commercial nitrite], either in its dry state or in the state of a concentrated
aqueous solution, are mixed with about sixty parts by weight of ice, and then, under
constant stirring, a solution containing about twenty-eight and three-tenths parts by
weight of bisulphite of potassium, in about forty parts of water, is added by degrees,
care being taken not to allow the temporature of the mixture to rise considerably
above zero. During the operation, hydroxylamin-disulphonate of potassium separates
out in the state of a crystalline powder, and after about twenty-four hours standing, the
crystals thus obtained may be freed from their mother-liquor by filtration or
otherwise.
In the before described example, nitrite of potassium may be replaced by its
equivalent amount of nitrite of sodium, and in such case, the reaction will proceed

page_text: Composture
une nydroxy
surpronates.
The sulpho groups of the hydroxylamin-disulphonates of potassium or sodium may
be completely eliminated by the action of water at an elevated temperature. The
reaction thus taking place is represented by the following equation:—
2 HON [SO³K]' + 4 H² O
-
[NH³ OH] SO' + 2 K2SO4 + H2SO*.
The result of this reaction is therefore a strongly acid solution, containing sulphate
of hydroxylamin in admixture with sulphuric acid, the latter being partly neutralized
by the base of the hydroxylamin-disulphonate employed.
The said elimination of the sulpho groups is effected either by boiling an aqueous
solution of the hydroxylamin-disulphonate for some hours, or, quicker, by heating
such solution up to a more elevated temperature, say, to about one hundred and thirty
degrees Centigrade, in a closed digester.
The presence of free caustic or carbonated alkalies interferes with the described
reaction. If it should therefore be desired to produce hydroxylamin from the strongly
alkaline solution of hydroxylamin-disulphonate of sodium, such as results from the
mutual reaction of nitrite and bisulphite of sodium, as hereinbefore described, it will
be necessary, first, to neutralize the free caustic soda contained therein by means of
dilute sulphuric or hydrochloric acid, and then to apply heat.
The result of the reaction likewise depends upon the absence of substances which,
say, for instance, nitrites or sulphites, would be able partly to destroy the hydroxyl-
amin as soon as it forms. On that account I prefer to employ the hydroxylamin-
disulphonate of potassium for the production of hydroxylamin, because the said salt
can, in consequence of its small degree of solubility and high power of crystallization,
be readily obtained in an almost perfect state of purity, whilst the hydroxylamin-
disulphonate of sodium cannot be conveniently separated from its solution, and is thus
more liable to be contaminated with the above named objectionable nitrites or sulphites.
For many purposes, the crude solutions of sulphate of hydroxylamin, such as they
result from the before described reaction, may be employed without any further
purification or separation of their above-named constituents.
But in order to produce hydroxylamin in the mercantile state of a solid saline
compound, it becomes necessary to effect a separation, as complete as possible, of the
sulphate of hydroxylamin from the other products formed by the decomposition of
the hydroxylamin-disulphonates, and which, as I have hereinbefore stated, principally
consist of the sulphates of potassium or sodium in admixture with free sulphuric
acid. Such separation of the sulphate of hydroxylamin may be effected by suitable
concentration of the acid solution resulting from heating the aqueous solution of the
hydroxylamin-disulphonate, as above described, and by fractional crystallization of
the saline compounds contained therein. Sulphate of hydroxylamin, being more
soluble than the sulphates of potassium or sodium, can thus be obtained in a more or
less pure condition, and may afterwards, if thought convenient, be converted into the
hydrochlorate or other salt of hydroxylamin, or into a solution of free hydroxylamin
by the application of known methods.
In practice I have found that the best results, as far as regards yield and purity of
the sulphate of hydroxylamin thus produced, may be obtained by the employment
of the hydroxylamin-disulphonate of potassium, not only for the reasons already above
stated, but likewise on account of the greater facility with which the almost insoluble
sulphate of potassium may be separated from the sulphate of hydroxylamin, and on
account of the absence of other saline compounds in the solution.
As an example of the manner in which I prefer to produce hydroxylamin by the
decomposition of its sulphonated derivatives, I proceed as follows:-
About ten parts by weight of the above described crystallized hydroxylamin-
disulphonate of potassium are added, in small portions at a time, to about two parts
of boiling water, and the solution thus produced is kept at a boiling heat during about
two hours. The result of the operation is then evaporated upon the water-bath until
crystals begin to form, and it is then set aside to cool. The first crystallization thus
obtained principally consists of sulphate of potassium. The mother liquor is then

page_text: further concentrated and allowed to cool, when another crop of crystals will be obtained,
consisting chiefly of neutral and acid sulphates of potassium, which is then drained
from the mother liquor and slightly washed with ice cold water. The liquor is then
again evaporated and strongly cooled, until, by such repeated crystallizations, an
almost complete separation of the potassium salts has been effected, and the crystals
at last obtained principally consist of sulphate of hydroxylamin, practically free from
sulphate of potassium. The mother liquor then remaining is too strongly charged
with sulphuric acid to allow the sulphate of hydroxylamin contained therein to be
recovered by further concentration. Alcohol is then added, in order to precipitate
the saline compounds contained in the said acid mother liquor, and the mixture of
sulphate of hydroxylamin with the remainder of sulphate of potassium thus obtained,
is afterwards dissolved in water and separated by successive crystallizations in the
manner before described.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what 1
claim is
The production of hydroxylamin by the hereinbefore described process, consisting
of two consecutive steps, the first of which is the preparation of the hydroxylamin-
disulphonates of potassium or sodium either by the mutual reaction of the nitrites
and bisulphites of the said alkaline metals employed in the molecular proportions
hereinbefore indicated, or by treating with sulphurous acid a mixture containing, for
every two molecules of the nitrite employed, either one molecule of the carbonates,
or two molecules of the hydroxides of potassium or sodium. The said first step of
my process also includes the conversion of the easily soluble hydroxylamin-disulphonate
of sodium into the difficulty soluble and crystallized hydroxylamin-disulphonate
of potassium by the employment of easily soluble potassium-salts.
The second step of my process consists in the decomposition of the above named
hydroxylamin-disulphonates [and by preference of the hydroxylamin disulphonate
of potassium] by the action of water at an elevated temperature: All substantially
as hereinbefore described.
Datel this 11th day of November 1887