An Improved Process for the Preparation of Carbolic Acid in a Non-hygroscopic Form
Year: 1897

page_text: -PROVISIONAL SPECIFICATION.
"An Improved Process for the Preparation of Carbolic Acid in a
Non-hygroscopic Form."
I, Dr FRANZ LUTZE, of No. 34, Elisabeth Ufer, Berlin, S.O., in the Empire of
Germany, Manufacturer of Pharmaceutical preparations, do hereby declare the
nature of this invention to be as follows:-
This invention relates to a process for the preparation of carbolic acid in the form of
powder suitable for the manufacture of concrete tablets.
The attempts which have been made with the object of preparing pure carbolic
acid in a form enabling the dispensation of the fluid, highly caustic, carbolic acid, to
the public, to be discontinued, are many.
pure
According to one of these processes the carbolic acid is melted and then made to
crystalize, by being allowed to cool, and by stirring; the crystalline mass is next, as
far as practicable, freed from water, and mixed with one-tenth of its weight of
boracic acid; after which it is finely triturated. The product obtained by such means
is a loose flaked substance, not unlike snow in appearance, which may be pressed into
moulds.
According to another of these processes, carbolic acid vapours are conducted over
heated boracic acid, a snow-like distillate being formed by the sublimation of the
carbolic acid and boracic acid in suitable receivers.
These and other proposed methods have been exhaustively discussed by
H. Salzmann in No. 99 of the German "Apothecaries' Journal" (Apothekerzeitung) for
1896; that author at the same tiine making certain fresh suggestions of his own,
regarding the production of carbolic acid pastilles or lozenges. But the defectiveness
of even the method hitherto adopted by the Applicant himself-viz:-the addition
of boracic acid to the crystallized carbolic acid-is illustrated and accounted for by
the fact, that boracic acid, as used until now in the preparation of carbolic acid
pastilles, has not led to any satisfactory practical result. So also has the addition of
soap recommended in Mr. Salzmann's paper-proved inadequate in practice, especially
where large quantities had to be dealt with in all these cases it is the pre-eminently
hygroscopic nature of the carbolic acid that has proved an insuperable obstacle to
the production of carbolic acid in the concrete form of lozenges or the like. In view
of this I have endeavoured to discover a medium which, whilst being adapted to extract
water from the carbolic acid, is not liable, itself, to liquefy through the absorption of
water, and which, at the same time may be added to the carbolic acid in any proportion,
without affecting either the solubility of the acid, or its efficiency as an antiseptic
agent. The compounds, comparatively poor in water, which are evolved from boracic
acid, as it is heated, have a tendency to become re-converted in plain boracic acid,
through water-absorption, owing to which tendency they exercise a water-extracting
or dehydrating action, without becoming fluid themselves. Thus, when boracic acid
is heated to 100° Centigrade, it loses one molecule of water and becomes meta-
boracic acid, whence-as the heating and the separation of water continues-there
next forms pyro-boracic acid, and lastly anhydrous boracic acid. The acid in the

page_text: course of this operation, becomes converted into a colourless vitreous mass, which,
by being dissolved in, and by absorbing, water retransforms into ordinary boracic
acid.
When crystallized carbolic acid, synthetic carbolic acid or absolute phenol is added
to the boracic acid, thus melted, the acid added entirely dissolves as the mixture
is stirred, and upon the fluid mass being allowed to solidify in suitable drying
apparatus at an ordinary temperature, there is obtained a crystalline mass which
does not exhibit any of the hygroscopic properties of carbolic acid, and which may
be readily ground to powder and conveniently utilized in the manufacture of solid
tablets or lozenges. This result is equally attainable whether small or large
quantities of boracic acid be treated, so that carbolic acid containing almost
indefinitely varying proportions of boracic acid, may by this method be
prepared.
PILL
c
1005
"An Improved Process for the Preparation of Carbolic Acid in a
Non-hygroscopic Form."
I,, Dr.. FRANZ LUTZE, of No. 34 Elisabeth Ufer, Berlin, S.O., in the Empire of
Germany, Manufacturer of pharmaceutical preparations, 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 :-
This invention relates to a process for the preparation of carbolic acid in the form
of powder suitable for the manufacture of concrete tablets.
;
The attempts which have been made with the object of preparing pure carbolic
acid in a form enabling the dispensation of the fluid, highly caustic, carbolic acid, to
the public, to be discontinued, are many. According to one of these processes the
carbolic acid is melted and then made to crystallize, by being allowed to cool, and by
stirring the crystalline mass is next, as far as practicable, freed from water, and
mixed with one tenth of its weight of pure boracic acid; after which it is finely
triturated. The product obtained by such means is a loose flaked substance, not
unlike snow in appearance, which may be pressed into moulds. According to
another of these processes carbolic acid vapours are conducted over heated boracic
acid, a snowlike distillate being formed by the sublimation of the carbolic acid and
boracic acid in suitable receivers.
These and other proposed methods have been exhaustively discussed by
H. Salzinann in No. 99 of the German " Apothecaries Journal" (Apothekerzeitung)
for 1896; that author at the same time making certain fresh suggestions of his own,
regarding the production of carbolic acid pastilles or lozenges. But the defective-
ness of even the method hitherto adopted by the Applicant himself-viz : the
addition of boracic acid to the crystallized carbolic acid--is illustrated and
accounted for by the fact, that boracic acid, as used until now
in the pre-
paration of carbolic acid' pastilles, has not led to any satisfactory practical
result. So also has the addition of soap-recommended in Mr. Salzmann's
paper proved inadequate in practice, especially where large quantities had to be dealt
with in all these cases it is the pre-eminently hygroscopic nature of the carbolic
acid, that has proved an insuperable obstacle to the production of carbolic acid in the
concrete form of lozenges or the like. In view of this, I have endeavoured to discover

page_text: a medium which, whilst being adapted to extract water from the carbolic acid, is not
liable, itself to liquefy through the absorption of water, and which at the same time,
may be added to the carbolic acid in any proportion, without effecting either the
solubility of the acid, or its efficiency as an antiseptic agent. The compounds, com-
paratively poor in water, which are evolved from boracic acid, as it is heated, have a
tendency to become re-converted into plain boracic acid, through water absorption,
owing to which tendency they exercise a water extracting or dehydrating action,
without becoming fluid themselves. Thus, when boracic acid is heated to 100° Centi-
grade, its loses one molecule of water and becomes meta-boracic acid, whence-as the
heating and the separation of water continue-there next forms pyro-boracic acid, and
lastly anhydrous boracic acid.
The acid, in the course of this operation, becomes converted into a colourless
vitreous mass, which, by being dissolved in, and by absorbing water, re-transforins
into ordinary boracic acid.
When crystallized carbolic acid, synthetic carbolic acid or absolute phenol is added
to the boracic acid, thus melted, the acid added entirely dissolves as the mixture is
stirred; and upon the fluid mass being allowed to solidify in suitable drying
apparatus at an ordinary temperature, there is obtained a crystalline mass which does
not exhibit any of the hygroscopic properties of carbolic acid, and which may be
readily ground to powder and conveniently utilized in the manufacture of solid
tablets or lozenges. This result is equally attainable, whether small or large
quantities of boracic acid be treated, so that carbolic acid containing almost indefi-
nitely varying proportions of boracic acid, may by this method be prepared.
Similarly to anhydrous boracic acid, other water-binding agents, which therefore
do not chemically affect the carbolic acid itself, will, when intimately mixed with the
carbolic acid free the carbolic acid from its hygroscopic properties.
Such agents are, for example, other anhydrous acids, such as anhydrous arsenic
acid, also basic anhydrides, such as aluminium oxide, magnesium oxide, likewise
dehydrated salts such as calcined borax or alum, the dehydrated salts of phosphoric
acid, pyrophosphoric acid and meta-phosphoric acid.
All the above named substances combine chemically with carbolic acid to an
equally small extent as anhydrous boracic acid, but when mixed in suitable propor-
tions with this acid enable the production of carbolic acid in the form of powder and
having no hygroscopic properties.
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. A process for the preparation of carbolic acid in the form of powder having no
hygroscopic properties, characterised by the fact that carbolic acid is mixed with
water binding agents producing no chemical action, for example with anhydrous
acids such as anhydrous boracic acid, arsenic tri-oxide, or basic anhydrides such as
alumininum oxide, magnesium oxide, or dehydrated salts such as borax, the salts of
phosphoric acid, meta-phosphoric acid or burned alum, the resultant mixture
after undergoing a suitable drying operation being pulverised.
2. Carbolic acid in the form of powder prepared according to the process
described in claim 1.
1007
HASELTINE LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.