Improvements in the Manufacture of Products of Condensation from Formaldehyde and Tannin.
Year: 1897

page_text: Date of Application, 15th Mar., 1897
Complete Specification Left, 13th Dec., 1897-Accepted, 5th Mar., 1898
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Products of Condensation
from Formaldehyde and Tannin.
I, Dr. ERNST HEINRICH CARL DURKOPF, of 52, Rossdorferstrasse, Darmstadt, in the
Empire of Germany, Chemist, do hereby declare the nature of this invention to be
as follows:-
This invention relates to the manufacture of a new class of products of condensation
from tannins and formaldehyde which are not identical with the methyleneditannio
acids of the Patent No. 816 dated the 11th January 1896.
As proposed by the inventor, methyleneditannic acid may be obtained as a product
of condensation of tannin and formaldehyde, the composition of which may be
considered analogous or corresponding to the formula
by heating molecular quantities of the respective tannin and formaldehyde. Further
experiments have shown that when use is made of an excess of formaldehyde an
entirely new class of compounds will be produced, which form the subject of the
present invention and which differ from the tannin employed, as regards the quantity
of carbon they contain, by an additional atom of carbon.
When I heat for example 5 parts of tannin with 1 part of paraformaldehyde or the
equivalent quantity of the aqueous 40% solution of formaldehyde in a vessel for
several hours to 950, the product of reaction forms a yellowish crumbly mass which
is freed from any initial material which may have remained unchanged, by washing
with water; the yield is almost quantitative.
The properties of this product of condensation, which must of course approximate
methyleneditannic acid (tannoform) are best shown by a comparison with the
lotter

page_text: Very different, however, is the behaviour of the two products of condensation
towards concentrated sulphuric acid. The colour' reactions always relate to equal
units of time.
A.
ITH COLD CONCENTRATED ULPI
ID.
The percentage of the composition of the new product of condensation,
average from three analyses,
on an

page_text: For a compound. which would be produced according to the equation
But with this formula the ascertained quantity of water contained therein agrees
very badly; if however it is taken into consideration that this product of condensa-
tion is obtained only by the use of an excess of formaldehyde, it may be found that
the reaction has proceeded according to the following equation :
С„HО + 2 HCOH
10
H
CsHgO + HCOOH
BOHO
15
The condensation would then have taken place with departure of 1 atom of oxygen
which transformed a second molecule of formaldehyde into formic acid; for this
formula the following values C-53-6, H=3.6% are computed, which agree
sufficiently with the values ascertained.
The product of condensation of quercitannic acid and formaldehyde is obtained
exactly in the same manner as the corresponding tannin derivative. In the washing
of the product of reaction with water a distinct smell of alcohol was perceived,
which can only be produced by reduction of formaldehyde. This fact accounts for
the following equation:
B
59.90 and H 4.54 %.
The product of condensation from quebrachotannic acid and formaldehyde resembles
in its properties the corresponding tannoform. Assuming that in this case the con-
densation has taken place as with the derivative of quercitannic acid, the following
equation may be put:
13
CH₂O10+2 HCOH СНО+CH₂OH,
for which formula the following values are computed:
1
221.00 11
1.50

page_text: Improvements in the Manufacture of Products of Condensation
from Formaldehyde and Tannin.
I, Dr. ERNST HEINRICH CARL DURKOPF, of 52, Rossdorferstrasse, Darmstadt, 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 ascer-
tained in and by the following statement :-
This invention relates to the manufacture of a new class of products of condensation
for tannins and formaldehyde, which are not identical with the methyleneditannic
acids of former Patent No. 816 dated the 11th January 1896.
As proposed by the inventor, methyleneditannic acid may be obtained as a product
of condensation of tannin and formaldehyde, the composition of which may be
considered analogous or corresponding to the formula
C₁HO,
CH
\C₁H₂O
by heating molecular quantities of the respective tannin and formaldehyde. Further
experiments have shown that when use is made of an excess of formaldehyde an
entirely new class of compounds will be produced, which form the subject of the
present invention and which differ from the tannin employed, as regards the quantity
of carbon they contain, by an additional atom of carbon.
When I heat for example 5 parts of tannin with 1 part of paraformaldehyde or
the equivalent quantity of the aqueous 40% solution of formaldehyde in a vessel for
several hours to 95° C. the product of reaction forms a yellowish crumbly mass which
is freed from any initial material which may have remained unchanged, by washing
with water; the yield is almost quantitative.
The properties of this product of condensation, which must of course approximate
methyleneditannic acid (tannoform) are best shown by a comparison with the
latter.

page_text: If tannoform (old product) is dissolved in sulphuric acid without heating, it
dissolves at once with yellow colour: this colour passes within a few minutes into.
green, which green colour becomes gradually darker.
The new product dissolves in sulphuric acid without heating also with yellow
colour, but the solution does not become green, the same becomes-contrary to
tannoform-gradually reddish yellow and then brownish red.
If alcohol is added to the said sulphuric acid-solution, the tannoform-solution
becomes firstly violet and then rapidly blue: by the addition of alcohol the solution
of the new product does not change its colour essentially otherwise than without
such addition of alcohol.
If an excess of soda-lye is added to the said sulphuric tannoform-solution the
latter becomes green whilst the corresponding solution of the new product becomes
brownish red.
Table A. Behaviour of methyleneditannic acid (tannoform) and of the new product
of condensation, if each has been dissolved in concentrated sulphuric acid without
RELATING
If tannoform has been dissolved in concentrated sulphuric acid under heating, the
same dissolves with a yellow colour, which changes rapidly into dark blue, whilst the
new product dissolves also with a yellow colour, which changes rapidly into reddish
yellow and brownish yellow (moss-coloured).
If alcohol is added to the said sulphuric solutions, the tannoform solution becomes
at once blue, whilst the solution of the new product remains reddish yellow.
On the addition of an excess of soda lye, the said sulphuric solution of tannoform
becomes green, whilst the corresponding solution of the new product remains reddish
to brownish vellow.
:

page_text: Table B. Behaviour of methyleneditannic-acid (tannoform) and of the new product
of condensation, if each has been dissolved in concentrated sulphuric acid on
heating.
The
sulphate yellow dark blue deep dark
reddish
maderia
moss
solution;
blue
yellow
colored
colored
with addition of rapidly blue
blue
reddish
alcohol
to
yellow
of soda lye
green
green
light light brownish
yellow
brownish
yellow
The percentage of the composition of the new products of condensation on an
average from three analyses
(C= 53.64, 53.85, 54·17 H= 3.83, 3.64, 3.85%)
But with this formula the ascertained quantity of water contained therein agrees
very badly; if however it is taken into consideration that this product of condensation
is obtained only by the use of an excess of formaldehyde, it may be found that the
reaction has proceeded according to the following equation:
CHO, + 2 HCOH
=
CHO, + HCOOH
The condensation would then have taken place with departure of 1 atom of
oxygen which transformed a second molecule of formaldehyde into formic acid; for
this formula the following values C 53.6, H 3.6% are computed, which agree
sufficiently with the values ascertained.
-
The product of condensation of quercitannic acid and formaldehyde is obtained
exactly in the same manner as the corresponding tannin derivative. In the washing
of the product of reaction with water a distinct smell of alcohol was perceived, which
can only be produced by reduction of formaldehyde. This fact accounts for the
following, equation:

page_text: ====
For quercitannoform, which it otherwise resembles completely, were ascertained
C = 59.90 and H 4.54%. The product of condensation from quebracho tannic
acid and formaldehyde resembles in its properties the corresponding tannoform.
Assuming that in this case the condensation has taken place as with the derivative
of quercitannic acid, the following equation may be put:
CHO10+2 HCOH
=
1
1
C97 H21011
CH,OH for which formula the following
61.8, H4-6, found C
=
62.00, H4.7%, whilst for
values are computed: C
the known quebrachotannoform C 64.50, H4.9 were ascertained.
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 :-
:-
First. A method of manufacturing a new class of products of condensation from
formaldehyde and tannins, which differ from the latter as regards the quantity of
carbon they contain by an additional atom of carbon, by the action of an excess of
paraformaldehyde or solution of formaldehyde upon tannins.
Second. As new chemical products the products of condensation of tannin with an
excess of formaldehyde, obtained by the method described in the first claim,
substantially as set forth.
Dated this 11th day of December 1897.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.