Improvements in the Manufacture of Laevulose.
Year: 1893

page_text: Date of Application, 19th Dec., 1893
Complete Specification Left. 19th Sept., 1894-Accepted, 24th Nov., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Laevulose.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, (a communi-
cation to me from abroad by The Chemische Fabrik auf Actien vorm. E. Schering,
of 170 Müllerstrasse, Berlin,) do hereby declare the nature of this invention to be
as follows:-
Pure laevulose, free from dextrose, is an excellent food material for diabetic
persons, as, unlike dextrose, it is completely used up in the organism. It has not
however up to the present found employment for dietetic purposes, because no
method was available by which laevulose could be prepared free from dextrose on
a manufacturing scale.
On the basis of the Dubrumfaut lime process for the separation of dextrose from
laevulose, I have now discovered a technical process of manufacture which permits
the preparation of laevulose in large quantities, either as a colourless syrup or as a
solid of absolute purity, effected at comparatively such a small cost and with such
a good yield, that the general employment of laevulose as a food material is
rendered possible.
Dubrumfaut utilised the comparative insolubility of the laevulose lime compound
to separate dextrose and laevuluse from a mixture of both. Dextrose forms a
soluble lime salt. The lime laevulosate precipitated on addition of milk of lime
was decomposed according to former authors by oxalic acid, sulphuric acid or
carbonic acid, and the laevulose liquors obtained after removal of the lime
evaporated in vacuum to the consistence of a syrup.
For the preparation of laevulose I have modified two important operations and
rendered the method applicable as a manufacturing process and thus of technical
utility.
I. DECOMPOSITION OF LIME LAEVULOSATE WITH CARBONIC ACID.
The decomposition of lime laevulosate is ordinarily effected by treatment of the
lime compound made into a thin paste with water, with oxalic acid, sulphuric acid
or carbonic acid. For definite reasons oxalic acid is most frequently employed.
I have found that the decomposition can be effected with very great advantage
in the following way:-The lime lacvulosate in solid or semi-solid condition as it
comes from the filter, is treated with carbonic acid under high pressure in
mechanical stirrers kept cool with ice. After short exposure to the action of the
carbonic acid under high pressure the mass commences to liquefy, for I find that
the small quantity of laevulose set free by the brief action of the carbonic acid is
able to dissolve or liquefy the time laevulosate still unaltered. After the
decomposition is completed a thick pasty miss is obtained, which, after removal of
the calcium carbonate by expression or centrifugation, yields a liquid containing
30 per cent. or more laevulose without concentration.
The advantage gained by carrying out the decomposition under high pressure
consists in the ability to perform the operation with extraordinary rapidity without
any deleterious rise in temperature, and consequently the absence. of any decom-
position of the laevulose and accompanying discolouration which is to be feared
from the prolonged treatment with carbonic acid under ordinary atmospheric
pressure. A further and greater advantage which is gained by the decomposition
with carbonic acid under high pressure is that by employment of the lime
laevulosate direct as it comes from the filter, laevulose solutions of a high degree of
[D037

page_text: concentration can be produced. Consequently there is a great economy of fuel,
and what is most important-the decomposition and consequent discolouration of
the laevulose which takes place from prolonged evaporation of more dilute solutions
even under the precautions set forth Sub. II, is avoided.
The decomposition with carbonic acid under high pressure is effected, for
instance, in the following way: The lime precipitate, well washed with ice-cold
water and sucked as dry as possible, is introduced into a tinned mechanical stirrer
surrounded with ice-cold water. The mechanical stirrer is in communication
with a reservoir which contains compressed carbonic acid, or from which
carbonic acid gas is pumped under compression. The introduction of the carbonic
acid into the mechanical stirrer is regulated by cock and manometer. During
the whole decomposition the temperature in the mechanical stirrer ought not
to rise above 5° C. At the commencement the carbonic acid is only absorbed
slowly and it is therefore advantageous to employ as high a pressure as possible.
After a short time it is observed that the stirrer works more easily and the carbonic
acid is absorbed more quickly. The pressure is then somewhat reduced. As soon
as a test quantity removed by means of a test-cock is no longer coloured by the
addition of phenolphtalein solution, the cock controlling the admittance of carbonic
acid is closed and the thick pasty mass brought upon a filter or into a centrifugal
machine. The liquid that runs out is water-white and contains 30 per cent. or more
laevulose.
The decomposition can also be carried out although not with the same
advantages, by first liquefying the lime laevulosate, dried as far as possible on the
filter, by the addition of a highly concentrated solution of laevulose and then
admitting carbonic acid with or without pressure.
11. THE PREPARATION FROM THE LAEVULOSE SOLUTION OBTAINED BY
DECOMPOSITION OF LIME LAEVULOSATE, OF A COLOURLESS SYRUP OR
OF LAEVULOSE IN SOLID FORM BY EVAPORATION IN VACUUM OF THE
LAEVULOSE SOLUTION AS FAR AS POSSIBLE FREED FROM LIME, AND
WITH SMALL QUANTITIES OF ACID OR ACID SALTS ADDED.
The preparation of a colourless syrup or of laevulose in solid form from the
laevulose solution obtained by decomposition of the lime laevulosate with oxalic
acid, sulphuric acid or carbonic acid, has hitherto been accompanied with con-
siderable difficulties. Ou evaporation of the solution in vacuum a yellow or even
brown colouration always developes in consequence of a partial decomposition.
I have found that this is occasioned by the extraordinary instability of laevulose
in contact with the slightest traces of carbonate, such as barium or calcium
carbonate etc. Especially in very concentrated solutions the slightest trace of
such substances causes a yellow discolouration and the development of a carainel
odour. It has been moreover determined that the slightest trace of free acid or of
an acid salt hinders this. Furthermore I have discovered that it does not suffice
only to acidify the laevulose solution before evaporation, but that a certain degree
of acidity is necessary, which theoretically is to be measured principally by the
percentage of saccharinic acid in the solution, in order to ensure that the laevulose
when evaporated to a highly concentrated syrup is still acid in reaction.
According to the above discovery a laevulose solution obtained from the
decomposition of lime laevulosate, most practically by means of carbonic acid, and
still coutaining calcium bicarbonate, is next to be freed from lime, so that only
very small traces remain in the solution. This is effected by the addition of
quantities of lime or of lime laevulosate equivalent to that of the calcium carbonate,
or by means of oxalic acid or of phosphoric acid. After the removal of the
precipitate from the liquid so much acid or acid salt is added that, on evaporating
or boiling a test-sample of the solution and adding phenolphtalein, no red coloration
is developed. The most suitable acids for this purpose are phosphoric acid and
organic acids, as formic acid, acetic acid, lactic acid, tartaric acid, citric acid, malic

page_text: acid, malonic acid. Instead of the free acids their calcium salts can of course be
employed, from which the free acids are liberated by means of oxalic acid. Instead
of phosphoric acid or the organic acids, boric acid, hydrochloric acid or sulphuric
acid can also be employed, but the latter two are however least suitable, as if
the quantity of acid required is not determined with great accuracy, even a
comparatively slight excess of acid causes a reversion of laevulose into laevulosan
like bodies.
If phosphoric acid alone is used, the following method may be adopted.
-
The quantity of phosphoric acid to be added depends upon the amount of
dissolved lime, which is determined by analysis. The calculated quantity of
phosphoric acid is then added, and subsequently further quantities until a sample
taken out and boiled in a test-tube to about one third of its volume no longer
reddens phenolphtalein. A slight excess of phosphoric acid above the quantity
calculated for the formation of normal calcium phosphate has then been added,
which as acid phosphate both prevents the yellow discoloration of the syrup on
evaporation and causes the complete deposition of the lime. The effect produced
by this slight excess of phosphoric acid is surprising. It may be added that the
phosphoric acid added in the technical process can be either employed as such or
in a half combined form, that is to say, as acid phosphate.
When employing phosphoric acid together with, for instance, lactic acid it is
most practical to proceed thus: The quantity of phosphoric acid calculated to form
the neutral phosphate is first added, the solution warmed in vacuum and then
separated from the precipitated calcium phosphate and then further evaporated
after addition of lactic acid.
Dated this 19th day of December 1893
•
COMPLETE SPECIFICATION.
"
Improvements in the Manufacture of Laevulose.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, (a communi-
cation to me from abroad by The Chemische Fabrik auf Actien vorm. E. Schering,
of 170 Müllerstrasse, Berlin,) 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 :-
Pure laevulose, free from dextrose, is an excellent food material for diabetic
persons, as unlike dextrose, it is completely used up in the organism. It has not
however up to the present found employment for dietetic purposes, because no
method was available by which laevulose could be prepared free from dextrose on
a manufacturing scale.
On the basis of the Dubrumfaut lime process for the separation of dextrose
from laevulose, a technical process of manufacture has now been discovered which
permits the preparation of laevuluse in large quantities, either as a colourless syrup,
or as a solid of absolute purity, effected at comparatively such a small cost and
with such a good yield, that the general employment of laevulose as a food material
is rendered possible.
Dubrumfaut utilised the comparative insolubility of the laevulose lime compound
to separate dextrose and laevulose from a mixture of both. Dextrose forms a
soluble lime salt. The lime laevulosate precipitated on addition of milk of lime
was decomposed according to former authors by oxalic acid, sulphuric acid or
carbonic acid, and the laevulose liquors obtained after removal of the lime
evaporated in vacuum to the consistence of a syrup.
For the preparation of laevulose according to this invention two important
operations have been modified and the method rendered applicable as a manu-
facturing process of technical utility.

page_text: 1. DECOMPOSITION OF LIME LAEVULOSATE WITH CARBONIC ACID.
The decomposition of lime laevulosate is ordinarily effected by treatment of the
lime compound made into a thin paste with water, with oxalic acid, sulphuric acid
or carbonic acid. For definite reasons oxalic acid is most frequently employed.
Now the decomposition can be effected with very great advantage in the
following way: The lime laevulosate in solid or semi-solid condition as it comes
from the filter, is treated with carbonic acid under high pressure in mechanical
stirrers kept cool with ice. After short exposure to the action of the carbonic
acid under high pressure the mass commences to liquefy, for the small quantity of
laevulose set free (by the brief action of the carbonic acid is able to dissolve or
liquefy the lime laevulosate still unaltered. After the decomposition is completed
a thick pasty mass is obtained, which, after removal of the calcium carbonate by
expression or centrifugation, yields a liquid containing 30 per cent. or more
laevulose without concentration.
The advantage gained by carrying out the decomposition under high pressure
consists in the ability to perform the operation with extraordinary rapidity without
any deleterious rise in temperature, and consequently the absence of any decom-
position of the laevulose and accompanying discolouration which is to be feared
from the prolonged treatment with carbonic acid under ordinary atmospheric
pressure. A further and greater advantage which is gained by the decomposition
with carbonic acid under high pressure is that by employment of the lime lacvulosate
direct as it comes from the filter, laevulose solutions of a high degree of concen-
tration can be produced. Consequently there is a great economy of fuel, and,
what is most important, the decomposition and consequent discolouration of the
laevulose which takes place from prolonged evaporation of more dilute solutions
even under the precautions set forth Sub. II, is avoided.
The decomposition with carbonic acid under high pressure is effected, for instance,
in the following way: The lime precipitate, well washed with ice-cold water and
sucked as dry as possible, is introduced into a tinned mechanical stirrer surrounded
with ice-cold water. The mechanical stirrer is in communication with a reservoir
which contains compressed carbonic acid, or from which carbonic acid gas is
pumped under compression. The introduction of the carbonic acid into the
mechanical stirrer is regulated by cock and manometer. During the whole
decomposition the temperature in the mechanical stirrer ought not to rise
above 5° C. At the con:mencement the carbonic acid is only absorbed slowly and
it is therefore advantageous to employ as high a pressure as possible. After a short
time it is observed that the stirrer works more easily and the carbonic acid is
absorbed more quickly. The pressure is then somewhat reduced. As soon as a
test quantity removed by means of a test-cock is no longer coloured by the addition
of phenolphtalein solution the cock controlling the admittance of carbonic acid is
closed and the thick pasty mass brought upon a filter or into a centrifugal machine.
The liquid that runs out is water-white and contains 30 per cent. or more
laevulose.
The decomposition can also be carried out although not with the same advantages,
by first liquefying the lime laevulosate, dried as far as possible on the filter, by the
addition of a highly concentrated solution of laevulose and then admitting carbonic
acid with or without pressure.
II. THE PREPARATION FROM THE LAEVULOSE SOLUTION OBTAINED BY
DECOMPOSITION OF LINE LAEVULOSATE, OF A COLOURLESS SYRUP OR
OF LAEVULOSE IN SOLID FORM BY EVAPORATION IN VACUUM OF THE
LAEVULOSE SOLUTION AS FAR AS POSSIBLE FREED FROM LIME AND
WITH SMALL QUANTITIES OF ACID OR ACID BALTS ADDED.
The preparation of a colourless surun
נ
laevulove in solid form from the

page_text: laevulose solution obtained by decomposition of the lime laevulosate with oxalic
acid, sulphuric acid or carbonic acid, has hitherto been accompanied with con-
siderable difficulties. On evaporation of the solution in vacuum a yellow or.even
brown colouration always developes in consequence of a partial decomposition.
Now it has been found that this is occasioned by the extraordinary instability of
laevulose in contact with the slightest traces of carbonate, such as barium or
calcium carbonate etc. Especially in very concentrated solutions the slightest trace
of such substances causes a yellow discoloration and the development of a caramel
odour. It has been moreover determined that the slightest trace of free acid or of
an acid salt hinders this. Furthermore it has been discovered that it does not
suffice only to acidify the laevulose solution before evaporation, but that a certain
degree of acidity is necessary which theoretically is to be measured principally by
the percentage of saccharinic acid in the solution, in order to ensure that the
laevulose when evaporated to a highly concentrated syrup is still acid in reaction.
According to the above discovery a laevulose solution obtained from the decom-
position of lime laevulosate, most practically by means of carbonic acid, and still
containing calcium bicarbonate, is next to be freed from lime, so that only very
small traces remain in the solution. This is effected by the addition of quantities
of lime or of lime laevulosate equivalent to that of the calcium carbonate, or by
means of oxalic acid or of phosphoric acid. After the removal of the precipitate
from the liquid so much acid or acid salt is added that on evaporating or boiling a
test sample of the solution and adding phenolphtalein, no red coloration is developed..
The most suitable acids for this purpose are phosphoric acid and organic acids as
formic acid, acetic acid, lactic acid, tartaric acid, citric acid, malic acid, malonic
acid. Instead of the free acids their calcium salts can of course be employed from
which the free acids are liberated by means of oxalic acid. Instead of phosphoric
acid or the organic acids, boric acid, hydrochloric acid or sulphuric acid can also be
employed, but the latter two are however least suitable, as if the quantity of acid
required is not determined with great accuracy, even a comparatively slight excess
of acid causes a reversion of laevulose into laevulosan like bodies.
If phosphoric acid alone is used, the following method may be adopted.
The quantity of phosphoric acid to be added depends upon the amount of
dissolved lime, which is determined by analysis. The calculated quantity of
phosphoric acid is then added, and subsequently further quantities until a sample
taken out and boiled in a test tube to about one third of its volume no longer
reddens phenolphtalein. A slight excess of phosphoric acid above the quantity
calculated for the formation of normal calcium phosphate has then been added,
which as acid phosphate both prevents the yellow discoloration of the syrup on
evaporation and causes the complete deposition of the lime. The effect produced
by this light excess of phosphoric acid is surprising. It may be added that the
phosphoric acid added in the technical process can be either employed as such or in.
a half combined form, that is to say, as acid phosphate.
When employing phosphoric acid together with, for instance, lactic acid, it is
most practical to proceed thus: The quantity of phosphoric acid calculated to
form the neutral phosphate is first added, the solution warmed in vacuum and then.
separated from the precipitated calcium phosphate and then further evaporated
after addition of lactic acid.
The amount of acid to be added during the treatment of the laevulose solution.
cannot be given quantitatively as it depends entirely on the conditions of the
development in the process whether more or less acid is required to make the
solution reacting slightly acid, after evaporation. The essential part is that this
slightly acid reaction should be obtained.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In the manufacture of laevulose, the decomposition of lime laevulosate by the

page_text: action thereon of carbonic acid under high pressure and at a low temperature
substantially as described.
2. In the manufacture of laevulose, the treatment of line laevulosate by the
addition thereto of a highly concentrated solution of laevulose to form a liquid
mixture and by then admitting carbonic acid to react substantially as described.
3. In the manufacture of laevulose from its solutions, the addition to such
solutions prior to the evaporation thereof, of acids, especially organic acids or
phosphoric acid or boric acid, in such quantity and such manner that the evaporated
solution of laevulose will react acid.
Dated this 19th day of September 1894.
CARPMAEL & Co.,
Agents for the Applicant.