Process for the Preparation of Easily Soluble Compounds of Formic Aldehyde for Preserving, Disinfecting, and Therapeutic Purposes.
Year: 1897

page_text: Date of Application, 5th Aug., 1897-Accepted, 18th Sept., 1897
Process for the Preparation of Easily Soluble Compounds of Formic
Aldehyde for Preserving, Disinfecting, and Therapeutic Purposes.
I, HEINRICH OPPERMANN of Markgrafen Strasse No. 22, Berlin, Kingdom of
Prussia, German Empire, Doctor of Philosophy, 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 present invention relates to the utilisation of the formic aldehyde for pre-
serving, disinfecting, and therapeutic purposes and it has for its object to enable
said substance to be made use of in a greater extent than hitherto possible, and
especially in combination with such substances as are capable of exerting specific
actions. For this purpose the present invention consists in a process by which the
formic aldehyde is caused to combine with other substances to form solid com-
pounds which are easily soluble in water and allow to be readily decomposed with
reformation of their components, but which are sufficiently stable under ordinary
circumstances.
As already known the aldehydes are capable of combining with bi-sulphite of
ammonium to crystalline compounds which are easily soluble in water and which
are decomposable with liberation of the aldehydes etc. This property of the
aldehydes has been employed for separating the aldehydes from mixtures or for
purifying the same.
Now applicant has found that by the agency of ammonium it is possible
to couple the formic aldehyde with any substance provided the latter be capable
of combining with, or dissolving in ammonia, and that such coupling results in
solid compounds which behave in a like manner as the above mentioned bi-sulphite
compound. Thus ammonia affords a very valuable means of combining the formic
aldehyde with substances having disinfecting preserving or specifically therapeutic
properties, and of thereby forming compounds, by means of which the action of
the formic aldehyde can be made use of together with the specific action of the
substance combing therewith. All these combinations are sufficiently stable
under ordinary conditions, they are easily soluble in water, easily decomposable into
their components, and easily applicable. They are powerful reagents. Thus, for
instance, experiment has proved that the combination of formic aldehyde and
boracic acid far exceeds in efficacy the effect of mercury combined with chlorine.
In the case of the combination of formic aldehyde and carbolic acid, the evaporation
of a small portion thereof suffices to perfectly disinfect a large space. The inven-
tion consists, therefore, in the preparation of quick powerful, and specifically
acting reagents for preserving, disinfecting, and therapeutic purposes by the com-
bination of formic aldehyde with other antiseptic, disinfecting or therapeutically
acting substances by means of ammonia, whereby these new reagents are obtained
in the form of solid, easily soluble and, in ordinary circumstances, stable chemical
compounds capable of being changed back into the component substances.
For the preparation of these compounds it suffices to mix together the substances
to be brought into reaction in the form of solutions, and to remove the heat
resulting from the reaction by means of a suitable cooling arrangement. If the

page_text: :
compound does not crystallise out of itself, the separation will be obtained by
evaporating the liquor at a low temperature in vacuo. The mixing. together of
the substances can be affected in various ways, as, for instance, in the following
descriptions given by way of example of the preparation of several of the most
important compounds.
1. COMBINATION OF FORMIC ALDEHYDE AND BITARTRATE OF POTASSIUM.
Bitartrate of Potassium is dissolved in the requisite quantity of ammonia and
there is poured into solution slowly, with constant stirring, and effective cooling,
as much formaline (that is, a solution of formic aldehyde in water, which forms
an article of commerce) as is necessary' for saturating the ammonio-potassic
tartrate formed. For the preparation of the dry substance, the solution is
evaporated in vacuo at a temperature below 60° Centigrade.
By way of example 400 grammes of potassic bitartrate are dissolved in about
two litres of an aqueous solution of ammonia having 30 per cent, and the solution
neutralized with 2½ litres of formaline containing 40 per cent of formic aldehyde.
2. COMBINATION OF FORMIC ALDEHYDE AND BORACIC ACID.
Boracic acid is dissolved in formaline and there is then added with constant
stirring and cooling as much ammonia as is necessary. for neutralisation. The
liquor is evaporated in vacuo at a low temperature.
By the way of example two kilogrammes of boracic acid are dissolved in 5 kilo-
grammes of formaline having 40 per cent of formic aldehyde. The solution is
then treated with time as much ammonia as there is boracic acid, in the solution.
3. COMBINATION OF FORMIC ALDEHYDE AND SALICYLIC ACID.
Ammonia is added to salicylic acid and there is then added with constant stirring
and cooling as much formaline as is necessary for neutralisation.
By way of example 2 kilogrammes of salicylic acid have poured over them
2. kilogrammes of aqueous ammonia of 30 per cent strength, and to this is added
5 kilogrammes of formaline containing 40 per cent. of formic aldehyde.
4. COMBINATION OF FORMIC ALDEHYDE AND CARBOLIC ACID.
Fluid carbolic acid and formaline are mixed together and neutralised with
ammonia with constant stirring and cooling; after allowing them to react for a
short time the combination separates out in the form of a crystalline cake.
By way of example equal weights of carbolic acid and formic aldehyde in the
form of formaline are mixed together and the solution treated with half its.weight
of ammonia in the form of an aqueous solution.
The best method is to take, for instance, 40 grammes of carbolic acid, having
100 per cent, 100 grammes of formaline containing 40 per cent of formic aldehyde,
and an aqueous solution of ammonia of 30 per cent strength.
There may also be two or more substances combined with the formic aldehyde.
Thus, for instance, tannin and boracic acid, or menthol and carbolic acid, as
hereinafter set forth by way of example.
5. COMBINATION OF FORMIC ALDEHYDE, BORACIC ACID AND TANNIN.
Boracic acid and tannin are dissolved by slowly heating them with an aqueous
solution of formic aldehyde; the solution is cooled, and there is then added thereto
the necessary quantity of ammonia for neutralisation, with effective cooling. The
compound separates out as an amorphous mass; this mass is easily soluble in
water, whereas the already known combination of formic aldehyde with tannin is
only soluble in a potash lye.
By way of example, 20 parts of boracic acid and 10 parts of tannin are heated
with 30 parts of formaline of 40 % and after cooling there are added 15, parts of
ammonia which is most conveniently added in the form of an aqueous solution
containing 30 per cent.
1.

page_text: The proportion of tannin must not exceed 25 per cent, as the employment of a
greater quantity of same results in the production of an insoluble compound.
G. COMBINATION OF FORMIC ALDEHYDE, CARBOLIC ACID AND MENTHOL.
Formaldehyde and carbolic acid are mixed as indicated above in Example 4.
Menthol is first added thereto, and finally ammonia, with effective cooling, the
compound crystallizing out of itself.
By way of Example: Equal parts of carbolic acid and formic aldehyde in the
form of 40% formaline are mixed together; then two to five per cent. of menthol
is added, and finally half the weight of ammonia preferably in the form of an
aqueous solution having 30 per cent strength.
Finally it has been found that the compound obtained by the combination of
formic aldehyde and bi-tartrate of potassium as described in the first example has
the property of combining with acids. As very valuable products I cite the com-
binations of the said compound with salicylic acid and citric acid.
7. COMBINATION OF FORMIC ALDEHYDE, BITARTRATE OF POTASSIUM AND CITRIC
ACID OR SALICYLIC ACID.
Formic aldehyde and potassic bitartrate are combined according to the method
described in the first example, and then to the solution thus obtained of said
compound is added citric acid or salicylic acid, in such proportion as not to exceed
20 per cent of the former compound. The liquor thus obtained is evaporated at a
low temperature in vacuo.
Having now particularly described and ascertained the nature. of this invention
and in what manner the same is to be performed, I would observe that the com-
bining of aldehydes and bisulphite of ammonia for the purpose of separating the
former from other substances is already known, and I do not claim such as my
invention, but what I claim is:-
1. The process of combining formic aldehyde with substances of preserving,
disinfecting or therapeutic properties into easily soluble compounds by means of
ammonia, substantially as described.
2. The preserving, disinfecting and therapeutic compounds formed by combining
formic aldehyde with tartrates, boracic acid, salicylic acid, carbolic acid, carbolic
acid and menthol, boracic acid and tannin, tartrates and citric acid, tartrates and
salicylic acid, and the like, as hereinbefore described.
1007
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.