Improvements in the Extraction and Purification of Tannin.
Year: 1893

page_text: Date of Application, 16th Dec., 1893
Complete Specification Left, 16th Oct., 1894-Accepted, 2nd Feb.,
1895
PROVISIONAL SPECIFICATION.
Improvements in the Extraction and Purification of Tannin.
I, OTTO CHRISTIAN HAGEMANN, of 15 Wall Street, in the City of New York,
United States of America, Chemical Engineer, do hereby declare the nature of this
invention to be as follows:
In the extraction of tannin from raw materials the difficulty is experienced that
the solvents used for taking up the tannin also dissolve the impurities. Now I have
found that amylic alcohol (fusil oil) dissolves pure tannin in very large quantities
but refuses to take up other bodies contained in the raw materials such as ellago-
tannin acid, ellagic acid, quercotannic acid, also certain colouring matters and
salts, elc.
I find that from solution in amylic alcohol, tannin can be separated in a state of
great purity by mixing the extract with certain solvents of amylic alcohol. I prefer
to proceed as follows:-I disintegrate and dry the raw materials or impure tannin
and subject the same to extraction with amylic alcohol, or I may first prepare a
solution say with water or glycerine from the raw materials or impure tannin and
extract the tannin from this solution by means of amylic alcohol. Amylic alcohol
may be separated from the extract by distillation or freezing but by preference
I precipitate the tannin by mixing the extract with hydrocarbons such as benzole, or
with bi-sulphide of carbon or other suitable solvent of amylic alcohol which does
not dissolve tannin. The tannin after the removal of the amylic alcohol or after
precipitation may be further washed with the solvents or hydrocarbons before
mentioned.
-
...
December 1893.
COMPLETE SPECIFICATION.
Improvements in the Extraction and Purification of Tannin.
I, OTTO CHRISTIAN HAGEMANN, of 15 Wall Street, in the City of New York,
United States of America, Chemical Engineer, 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 :—
According to the present processes of extracting tannin from raw materials the
solvents employed cause a final separation with the tannin of many impurities, such
as coloring matters, ellagogenic, and similar acids, gallic acid, chlorophyll, sugars,
fatty and waxlike substances, etc., derived from the raw material. It has either been
impossible to remove such impurities or the further purification of the tannin has
been very difficult.
•
1 have discovered that amyl alcohol (fusil oil) will dissolve from the raw materials
or impure tannin large quantities of tannin, but that other bodies, such as coloring
matters and the heterogeneous tannins, remain undissolved; thus amyl alcoholic

page_text: extractions from nut-galls containing even as high as thirty or forty per cent. of
tannin are of remarkably light color. From other materials, such as sumach, divi-
divi, and myrobolans, the amyl alcohol takes up only the light colored tannin.
From low grade technical tannins.as, made by the present methods, pure tannin can
by this method be readily extracted. From the darkest tannin liquid (tannin
extract) a light colored and quite pure tannin is obtained; in fact, amyl alcohol acts
as a specific separator of the tannin from a certain class of impurities.
But it is likewise true that amyl alcohol will dissolve chlorophyll and certain fatty
or waxlike bodies as, also, some gallic acid; but I have discovered that these bodies
are very easily removable from amyl alcohol solution. From a highly-concentrated
amyl alcohol solution of tannin, water will extract the tannin in a state of great
parity leaving the other impurities behind.
I have further discovered that tannin can be easily precipitated from this amyl
alcohol solution by an addition of benzine, or similar hydro-carbon or solvent that.
will mix with amyl alcohol, but in which tannin is insoluble. Upon the above facts
my improved process of separating tannin is based.
In carrying out my process practically, I proceed as follows:
I macerate or digest finely disintegrated nut-galls, sumach or other raw materials
containing tannin thoroughly with amyl alcohol. I prefer to keep the temperature
of the solvent at about 60° or 70° C., at which temperature rapid progress is made
in the extraction and the product remains of a good color; I may, however, proceed
at a higher temperature if desired, going even to 120° C. and above, at which
temperature the tannin seems to remain unchanged. but becomes somewhat darker.
On the other hand, the extraction may be carried out at an ordinary temperature,
Fay 15° C. if the amyl alcohol used contains a small and sufficient percentage of
water. In this case 1 prefer to use amyl alcohol containing about one half the.
proportion of water soluble in same. Also at higher temperatures the extraction
may advantageously be carried out with the amyl alcohol in a slightly watered
condition. Having obtained my tannin solution, I may filter the solution thus
obtained and concentrate the same in a vacuum, and simultaneously recover the amyl
alcohol which may be repeatedly used.
If, however, I desire to still further purify my tannin, I separate the same from
its amyl alcohol solution by dissolving it in water, which will leave certain of the
impurities in the amyl alcohol together with a small percentage of tannin. In this
case, I treat the concentrated and amyl alcohol solution of tannin with several times
(say three times) its volume of water when a rapid separation of tannin occurs, the
tannin going into the solution of water and leaving the amyl alcohol. In this case
the amyl alcohol liquid rises to the surface of the water, and gathers there as a well
defined upper layer. The fact is, that under these conditions the small amount of
amyl alcohol in the original concentrated extract can retain but little tannin in the
presence of water. I separate, of course, the supernatant amyl alcohol solution from
the water and may return the amyl alcohol for subsequent separations with other
bodies of water, or may still further concentrate this withdrawn solution and effect
further water separations.
I take my water solution of tannin, concentrate the same in a vacuum and finally
dry the tannin if I desire it in that condition.
Instead of using the raw materials directly and subjecting them to the amyl
alcohol I may use a concentrated watery solution of impure tannin (tannin extract);
in this case I mix intimately with the aqueous tannin solution about an equal amount
of amyl alcohol, which latter takes up a large amount of tannin from the aqueous
solution or tannin extract, which should previously have been concentrated to the
consistency of a syrup. The method of obtaining the tannin from this amyl alcohol
solution may be as above described.
When it is desired to obtain the tannin from the amyl alcohol solution directly
by precipitation, I proceed as follows:-
1
I take said solution of moderate strength, containing say not more than twenty-
five per cent. of tannin; I add thereto, under agitation, say from-one to two volumes

page_text: of benzine, or any such hydrocarbon or solvent, which, while readily mixable with
amyl alcohol, will not dissolve tannin. I prefer such solvents the boiling point of
which is rather remote from that of amyl alcohol, thereby more readily separating
the solvents after use. The tannin thus precipitated is collected and treated again
with other solvents, such as benzine, for the removal of amyl alcohol, and finally
dried. It will be understood that in this case such bodies as chlorophyll, fats and
wax remain in the mixed solution, while the tannin and some of the gallic acid
present precipitates.
If it is desired to be rid of the gallic acid in the precipitated tannin, that may be
separated, as before described, either, for instance, by the addition of water to the
mixed solution of benzene and amyl alcohol whereby practically only the tannic
acid is dissolved, or by taking the dried tannin and dissolving it in several times its
weight of water, the gallic acid remaining practically undissolved, and separating
the tannin solution by filtration.
It is to be understood, of course, that when I speak of amyl alcohol, I do not
necessarily use this in a pure condition, but other bodies not injurious to the process
may be mixed with it. I prefer, of course, to use the amyl alcohol in a reasonably
pure condition.
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 I
claim is :-
1. The process herein described of separating tannin from materials containing
the same, which consists in dissolving it in amyl alcohol (fusil oil), substantially
as described.
2. The process herein described of separating tannin from other bodies, which
consists in dissolving the same in amyl alcohol, and subsequently separating the
tannin, substantially as described.
3. The process herein described of separating tannin from other bodies, which
consists in dissolving the same in amyl alcohol, and subsequently separating the
tannin by adding benzine or an equivalent body, substantially as described.
4. The process of separating tannin from other bodies which consists in making
a solution of tannin in amyl alcohol, separating the amyl alcohol from the tannin, and
finally recovering the tannin, substantially as described.
Dated this 15th day of October 1894.