Patented Dec. 7, 1943
'
2,336,131‘
UNITED STATES PATENTV'OFFICE
2,336,131
PROCESS OF PREPARING SILVER
ALLANTOINATE
Charles F. Scha?’er, Philadelphia, Pa.
No Drawing. Application November 25, 1940,
Serial No. 367,052
2 Claims. (01. 260-299)
This invention has to do with the provision
of the invention reference may be had to the
of a novel compound intended for medicinal pur
following description, in which certain quantities
poses, and is also concerned with the process of
of the several ingredients and materials employed
preparing the same.
are set forth to indicate the proportions which
Silver nitrate is well recognized for its germi
are desirable in preparing silver allantoinate for
cidal properties. However, when directly applied
medicinal use.
_ to the human body it has marked erosive and
Thus, about 100 grams of allantoin (C4H5N4O3)
irritating effects. Because of this well recog
are placed in suspension in 4000 cubic centi
nized condition it is generally accepted as unde
meters of water, This suspension is a necessary
sirable to treat the membranes of the eyes, ears 10 condition, as only about .6 of 1% of the allan
‘and throat, as well as those of the genitourinary
toin will ordinarily go into solution. However,
system, with any preparations containing silver
a true solution is established by the addition of
nitrate. In view of the bene?ts which may be
250 cubic centimeters of an aqueous solution of
obtained by the germicidal qualities of silver
sodium hydroxide (NaOH) in which the sodium
compounds, there have been provided such silver
hydroxide is present as 20% of the solution. To
compounds as silver-proteinate for treatment of
this solution of allantoin, water and sodium hy
the above-listed parts of the human body.
However, such silver-proteinate preparations
have not proven to be entirely satisfactory, be
droxide is added a solution of 117 grams of silver
nitrate ,(AgNOs) in 150 cubic centimeters of wa
ter, together with 25 cubic centimeters of dilute
cause if for any reason there should be traces 20 nitric acid (HNOa). This dilute nitric acid is
of the silver nitrate present in the preparation
made up of one part of concentrated acid to
there is a decided irritating effect on the mem
two parts of water.
branes, and the damage which may be caused is
A vigorous stirring is now carried out for a
greatly enhanced if there should be any lesions
short period of time. As a result of the chemi
in the membranes. As a practical matter the
cal reaction between the various ingredients of
silver-proteinate preparations which are now sold
the mixture, silver allantoinate is formed, this
to the public very often carry such traces of
compound being represented by the formula
silver nitrate, which condition may be largely
C4H5N403AgOH. The silver allanto-inate is then
due to faulty preparation of the compound.
‘ ?ltered, washed and dried, and the resulting
In view of the foregoing conditions this in 30 product is in solid form, which by analysis con
vention has in View, as its foremost objective,
tains substantially 38.19% silver and 61.76% al
the provision of a silver compound which is in
lantoin.
tended for medicinal use on the membranes of
The silver allantoinate provided by the above
the eye, ear, throat and genitourinary system,
noted process is entirely free from any traces
and which compound also includes, as an essen
of silver nitrate, and presents all the germicidal
tial element, allantoin. Allantoin is a carbon
effects of the silver ion. At the same time the
compound which is recognized as having decided
compound embodies the well-known healing
healing qualities on lesions of the membranes.
healing properties for lesions of the allantoin
Another important objectof the invention is
itself.
the provision of a process of preparing silver 40
While a preferred speci?c embodiment of the
allantoinate, and which process provides the ?n
invention is hereinbefore set forth it is to be
ished product without any traces of silver ni
clearly understood that the invention is not to
trate present. Thus not only are the irritating
be limited to the proportions of the ingredients
and erosive effects of the silver nitrate avoided,
and materials speci?ed, because various modi?
but a compound is provided which affords, at 45 cations of these details may be provided in put
the same time, the germicidal properties of the
ting the invention into practice Within the pur
silver and the healing qualities of allantoin.
view of the appended claims.
Various other more detailed objects and ad
I claim:
vantages of the invention will in part become
1. The process of preparing silver allantoinate
apparent, and in part be hereinafter stated, as 50 in which ingredients are employed in proportions
the description of the invention proceeds.
represented by the quantities set forth in carry
The invention, therefore, comprises the novel
ing out the following steps: 100 grams of allan
compound of silver allantoinate, and the process
toin (C4H5N4O3) are suspended in 4000 cubic
of preparing the same.
centimeters of water (H2O), a true solution 010- '
For a full and more complete understanding 55 tained by the addition of 250 cubic centimeters
2,336,131
‘
centimeters of water (H2O), a true solution ob
of an aqueous solution of sodium hydroxide
tained by the addition of 250 cubic centimeters
(NaOH) in which the sodium hydroxide is pres
of an aqueous solution of sodium hydroxide
ent in the amount of 20%, a solution of 117 grams
(NaOH) in whichjthe sodium hydroxide is pres
of silver nitrate (AgNOa) and 150 cubic centi
meters of water, plus 25 cubic centimeters of 5 ent in the amount of 20%, a solution of 117
grams of silver nitrate (AgNOa) and 150 cubic
dilute nitric acid, (one part of concentrated acid
centimeters of water, plus 25 cubic centimeters
(HNOa), two parts of water) is added, and vig
orous stirring carried out for a short period of"
time.
of dilute nitric acid, (one part of‘ concentrated
acid (HNOs), two parts of water) is added, and
2. The process of preparing silver allantoinate 10 vigorous stirring carried out for a short period
in which ingredients are employed in proportions , , ofh time‘after which the steps of ?ltering, wash
ing and drying are carried out.
represented by the quantities set forth in carry
ing
toin out
(C4H5N4Os)
the following
are steps:
suspended
100 grams
in 4000
of allan'cubic"
'
CHARLES F. SCI-IAFFER.