Improvements in the Manufacture of Ortho-halogen-phenol, and in the Production of Pyro-catechine therefrom.
Year: 1893

page_text: Date of Application, 1st July, 1893
Complete Specification Left, 14th Mar., 1894-Accepted, 14th Apr., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Ortho-halogen-phenol, and in
the Production of Pyro-catechine therefrom.
1, HEINRICH BAUM, of 28 Forsthausstrasse, Frankfort on the Main, 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 pyro-catechine, for the production of
which ortho-halogen-phenol (more especially ortho-bromo-phenol or ortho-chloro-
phenol) is employed; the object of the invention being at the same time to produce
ortho-halogen-phenol in a practical manner and in a sufficiently pure condition
to be eminently fitted for the production of pyro-catechine on strictly technical
lines.
The action of pyro-catechine is similar to that of pyrogallic acid in that it has a
powerful reducing effect which enables it, like that acid, to be made use of for the
purposes of photography.
It has hitherto generally been considered impossible to halogenize phenol (or to
brominate or chlorinate it, as the case may be) so as substantially to form ortho-
halogen-phenol, which is employed for the production of pyro-catechine. The
employment of phenol for the manufacture of pyro-catechine has therefore also
been necessarily regarded as a technical impossibility.
:
Experiment has shown, however, that ortho-halogen-phenol, especially ortho-
bromo-phenol and ortho-chloro-phenol, may be produced practically alone and in so
pure a condition, that, even without being further purified it will produce pyro-
catechine by being melted with an alkali, preferably soda.
The production of ortho-halogen-phenol from phenol, which is extremely valuable
both from a technical point of view and as a means of producing pyro-catechine, is
due, as experiments made according to this invention have demonstrated, and as will
be hereinafter more fully explained with reference to ortho-bromo-phenol and ortho-
chloro-phenol, to the action of the halogen upon phenol heated to a high temperature ;
and it has been found that the mixture of reagents is capable, whether purified or
not, of being converted into pyro-catechine.
The trials made have shown, moreover, that it is advantageous to obtain pyro-
catechine from ortho-halogen-phenol, not only when it is obtained in the manner
above stated (and purified or not as the case may be), but also when it is produced
by any of the ordinary methods; the ortho-halogen-phenol being for this purpose
melted along with liberal quantities of a suitable alkali (soda or potash), under
pressure and at a high temperature.
The following examples may serve to illustrate the manner in which ortho-
bromo-phenol and ortho-chloro-phenol are produced in accordance with the principle
of this invention.
Bromine and phenol have previously been jointly submitted to the action of cold,
with the result that a main product was formed crystallizing para-bromo-phenol (see
Hubner and Breuker's Report of the German Chemical Society VI p. 171). The
liquid ortho-bromo-phenol thus obtained was not pure. Pure ortho-bromo-phenol
was first obtained by the employment of ortho-bromo-aniline (see Fittig & Mager's
Reports of the German Chemical Society, VIII, p. 563). When this product was
melted with an addition of caustic potash, it formed with the latter a mixture
containing pyro-catechine but in which resorcine predominated.
The employment of ortho-chloro-phenol in the production of pyro-catechine has
also, up to the present time, proved rather unsuccessful than otherwise. It has been

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stated, indeed, that pyro-catechine has been obtained by melting ortho-chloro-phenol,
together with an alkali, in a silver crucible. But as the pyro-catechine is readily
oxydizable when exposed to air, especially where there is a large quantity of caustic
potash in excess, the process has not proved sufficiently profitable. In addition to
the fact that, although ortho-chloro-phenol was found to be obtainable by the
introduction of chlorine into the phenol, yet to obtain it in a pure condition, repeated
distillation had to be resorted to, so that the quantity eventually realized was
insignificant and could not be with certainty relied on. (See Faust & Müller,
Liebig's Annals of Chemistry 173, p. 303.)
These methods having proved unsatisfactory both as regards the quantity and the
purity of the products obtained (ortho-bromo-phenol, ortho-chloro-phenol and pyro-
catechine) especially from a technical or industrial point of view-attempts have
been made to remedy the deficiencies of these methods and thereby to secure more
favourable results. The first of these attempts was directed to the production of
halogen-phenols. The halogenizing of phenol by the cold process did not
prove sufficiently remunerative. The employment of heat was then tried,
and, the operation being carried out as hereinafter described, it led to a
satisfactory result.
According to these experiments abundant quantities of ortho-chloro or ortho-
bromo-phenol, are obtained by admitting bromine-vapour or chlorine-gas into phenol
heated to a high temperature, from 150° to 180° C., being generally sufficient.
Thus, in order to obtain ortho-bromo-phenol for practical purposes it will suffice
to introduce, say, 160 kilogrammes of bromine, in the condition of vapour,
into 94 kilogrammes of phenol heated to from 150° to 180° C., and continually
stirred. The escaping vapours, containing bromide of hydrogen are conducted
into a cooler, so that the condensable products flow back into the mixture of reagents,
while the bromide of hydrogen is collected separately.
The ortho-bromo-phenol thus obtained is practically pure and contains but small
quantities of bye-products.
It may be most satisfactorily and simply purified according to this invention by
partly combining non-purified ortho-bromo-phenol with bases, of which the most
suitable are the alkaline bases, soda and potash; for example by adding about
10 kilogrammes of caustic soda, in the condition of a soda lye, to the ortho-bromo-
phenol obtained by employing the agents named in the proportions stated; thereby
retaining only a part of the non-purified ortho-bromo-phenol, whereupon the pure
ortho-bromo-phenol is distilled, by steam being conducted through the mixture or
preferably by simply using a vacuum. The product of the distillation boils at
from 196 to 202° C., and when melted with caustic potash, yields pure pyro-
catechine.
To obtain ortho-chloro-phenol, the 160 kilogrammes of bromine vapour
are replaced by an equivalent quantity (i.e. 71 kilogrammes) of chlorine gas the
operation being the same. In this case there escapes hydrochloric acid instead of
hydro-bromic acid and the resulting product is distilled at less than 200º C.
This product is comparatively pure, containing but small quantities of impurities.
The purifying is then proceeded with in the same manner as in the case of
the ortho-bromo-phenol, by partly combining the product with bases, pre-
ferably soda or potash, for which purpose there is also preferably added to the
total quantity of the ortho-chloro-phenol, obtained under the circumstances above
stated, 10 kilogrammes of caustic potash in the condition of potash lye, whereupon
the operation is continued in the same way as before described. The product
thus purified, being melted with potash, yields almost the same quantity of pyro-
catechine.
To obtain pyro-catechine adapted for use in actual practice from ortho-halogen-
phenol which is itself produced in any suitable manner, but preferably by the
process above described the said ortho-halogen-phenol being preferably but not
necessarily purified, the process to be adopted according to this invention, nd
which enables the inconveniences above mentioned to be avoided, is as follows:
In a vessel capable of being closed, preferably provided with a stirring device,

page_text: ortho-halogen-phenol with caustic soda are heated to about 180° C., the closing
device such as a valve or cock being open. This cock or valve is then closed and
the vessel is further heated to about 250° C. When from 6 to 8 hours have elapsed
and the pressure has risen to 3 or 4 atmospheres, the operation is completed. It is
best to use liberal quantities of alkali, say to 1 molecule of ortho-halogen-phenol
from 3 to 4 molecules of caustic soda. Thus for every 16 kilogrammes of caustic
potash, employed in the condition of a potash lye (22 litres of a specific gravity
of 1.53) 17.3 kilogrammes of ortho-bromo-phenol or 12.85 kilogrammes of ortho-
chloro-phenol may, in this process, be advantageously used.
The molten
When ortho-chloro-phenol is employed it is preferable to carry the temperature
of the closed chamber, not to about 250° C., but only to about 50° C. more, which
will create a pressure of from 5 to 6 atmospheres or thereabouts.
product obtained with a view to the separation of pure pyro-catechine, may
advantageously be dissolved in a small quantity of water, for which purpose
sulphuric or muriatic acid are preferably used. No separation of resinous substances
will here be noticeable. From the acidulated, and if necessary, filtered solution
pyro-catechine will be obtained by shaking it, with an addition of ether, the latter
being thus caused to absorb it. This solution of pyro-catechine in ether is then
separated from the remaining liquid, whereupon the ether may be allowed to
evaporate, or be distilled off.
By this means pure pyro-catechine will be retained which will produce no
fluoresceine under the action of phthalic acid.
Dated this 1st day of July 1892
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Ortho-halogen-phenol, and in
the Production of Pyro-catechine therefrom.
I, HEINRICH BAUM, of 28 Forsthansstrasse, Frankfort on the Main, 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
ascertained in and by the following statement:-
This invention relates to the manufacture of pyro-catechine, for the production of
which ortho-halogen-phenol (more especially ortho-bromo-phenol or ortho-chloro-
phenol) is employed; the object of the invention being at the same time to produce
ortho-halogen-phenol in a practical manner and in a sufficiently pure condition to
be eminently fitted for the production of pyro-catechine on strictly technical lines.
The action of pyro-catechine is similar to that of pyrogallic acid in that it has a
powerful reducing effect which enables it, like that acid, to be made use of for the
purposes of photography.
It has hitherto generally been considered impossible to halogenize phenol (or to
brominate or chlorinate it as the case may be) so as substantially to form ortho-
halogen-phenol, which is employed for the production of pyro-catechine. The
employment of phenol for the manufacture of pyro-catechine has therefore also
been necessarily regarded as a technical impossibility.
Experiment has shown, however, that ortho-halogen-phenol especially ortho-
bromo-phenol and ortho-chloro-phenol may be produced practically alone and in
so pure a condition, that, even without being further purified it will produce pyro-
catechine by being melted with an alkali, preferably soda.
The production of ortho-halogen-phenol from phenol, which is extremely valuable
both from a technical point of view and as a means of producing pyro-catechine, is.
due-as experiments made according to this invention have demonstrated and as

page_text: will be hereinafter more fully explained with reference to ortho-bromo-phenol and
ortho-chloro-phenol-to the action of the halogen upon phenol heated to a high
temperature; and it has been found that the mixture of reagents is capable,
whether purified or not, of being converted into pyro-catechine.
The trials made have shown, moreover, that it is advantageous to obtain pyro-
catechine from ortho-halogen-phenol, not only when it is obtained in the manner
above stated (and purified or not as the case may be), but also when it is produced
by any of the ordinary methods; the ortho-halogen-phenol being for this purpose
melted along with liberal quantities of a suitable alkali (soda or potash) under
pressure and at a high temperature. Water may be present within this mixture.
The following examples may serve to illustrate the manner in which ortho-bromo-
phenol and ortho-chloro-phenol are produced in accordance with the principle of
this invention.
Bromine and phenol have previously been jointly submitted to the action of cold,
with the result that a main product was formed crystallizing para-bromo-phenol
(see Hübner and Brenker's Report of the German Chemical Society VI, page 171).
The liquid ortho-bromo-phenol thus obtained was not pure. Pure ortho-bromo-
phenol was first obtained by the employment of ortho-bromo aniline (see Fittig
and Mager's Reports of the German Chemical Society, VIII, p. 563). When this
product was melted with an addition of caustic potash, it formed with the latter a
mixture containing pyro-catechine but in which resorcine predominated.
The employment of ortho-chloro-phenol in the production of pyro-catechine has
also, up to the present time, proved rather unsuccessful than otherwise. It has
been stated indeed, that pyro-catechine has been obtained by melting ortho-chloro-
phenol, together with an alkali, in a silver crucible. But as the pyro-catechine is
readily oxydizable when exposed to air, especially where there is a large quantity
of caustic potash in excess, the process has not proved sufficiently profitable. In
addition to the fact that, although ortho-chloro-phenol was found to be obtainable
by the introduction of chlorine into the phenol, yet to obtain it in a pure condition,
repeated distillation had to be resorted to, so that the quantity eventually realized
was insignificant and could not be with certainty relied on (see Faust and Müller,
Liebig's Annals of Chemistry 173, p. 303).
These methods having proved unsatisfactory both as regards the quantity and
the purity of the products obtained (ortho-bromo-phenol, ortho-chloro-phenol and
pyro-catechine)-especially from a technical or industrial point of view-attempts
have been made to remedy the deficiencies of these methods and thereby to secure
more favourable results. The first of these attempts was directed to the production
of halogen phenols. The halogenizing of phenol by the cold process did not prove
sufficiently remunerative. The employment of heat was then tried, and, the
operation being carried out as hereinafter described, it led to a satisfactory result.
According to these experiments abundant quantities of ortho-chloro- or ortho-
bromo-phenol, are obtained by admitting bromine-vapour or chlorine-gas into
phenol heated to a high temperature from 150° to 180° C., being generally
sufficient.
Thus, in order to obtain ortho-bromo-phenol for practical purposes it will suffice
to introduce, say, 160 kilogrammes of bromine, in the condition of vapour, into
94 kilogrammes of phenol heated to from 150° to 180° C., and continually stirred.
The escaping vapours, containing bromide of hydrogen, are conducted into a cooler,
so that the condensable products flow back into the mixture of reagents, while the
bromide of hydrogen is collected separately.
The ortho-bromo-phenol thus obtained is practically pure and contains but small
quantities of bye-products.
It may be most satisfactorily and simply purified according to this invention by
partly combining non-purified ortho-bromo-phenol with bases, of which the most
suitable are the alkaline bases, soda and potash; for example by adding about
10 kilogrammes of caustic soda, in the condition of a soda lye, to the ortho-bromo-
phenol obtained by employing the agents named in the proportions stated; thereby

page_text: retaining only part of the non-purified ortho-bromo-phenol; whereupon the pure-
ortho-bromo-phenol is distilled, by steam being conducted through the mixture, or
preferably by simply using a vacuum. The product of the distillation boils at
from 1960 to 202° C. and, when melted with caustic potash, yields pure pyro-
catechine. To obtain ortho-chloro-phenol, the 160 kilogrammes of bromine vapour
are replaced by an equivalent quantity (ie. 71 kilogrammes) of chlorine gas, the
operation being the same. In this case there escapes hydro-chloric acid instead of
hydro-bromic acid and the resulting product is distilled at less than 200° C. This
product is comparatively pure, containing but small quantities of impurities. The
purifying is then proceeded with in the same manner as in the case of the ortho-.
bromo-phenol, by partly combining the product with bases, preferably soda or
potash, for which purpose there is also preferably added to the total quantity
of the ortho-chloro-phenol, obtained under the circumstauces above stated,.
10 kilogrammes of caustic potash in the condition of potash lye, whereupon the
operation is continued in the same way as before described. The product
thus purified, being melted with potash, yields almost the same quantity of pyro-
catechine.
To obtain pyro-catechine adapted for use in actual practice from ortho-halogen-
phenol, which is itself produced in any suitable manner, but preferably by the
process above described, the said ortho-halogen-phenol being preferably, but not.
necessarily, purified, the process to be adopted according to this invention, and
which enables the inconveniences above mentioned to be avoided, is as follows:
In a vessel capable of being closed, preferably provided with a stirring device,.
ortho-halogen-phenol with caustic soda are heated to about 180° C., the closing-
device such as a valve or cock, being open. This cock or valve is then closed and
the vessel is further heated to about 250° C. When from 6 to 8 hours have.
elapsed and the pressure has risen to 3 or 4 atmospheres, the operation is completed..
It is best to use liberal quantities of alkali, say to 1 molecule of ortho-halogen--
phenol from 3 to 4 molecules of caustic soda. Thus for every 16 kilogrammes of
caustic potash, employed in the condition of a potash lye (22 litres of a specific
gravity of 153) 17.3 kilogrammes of ortho-bromo-phenol or 12.85 kilogrammes of
ortho-chloro-phenol may, in this process, be advantageously used.
When ortho-chloro-phenol is employed it is preferable to carry the temperature
of the closed chamber, not to about 250° C., but only to about 50° C., more, which
will create a pressure of from 5 to 6 atmospheres or thereabouts. The molten,
product obtained with a view to the separation of pure pyro-catechine may
advantageously be dissolved in a small quantity of water, for which purpose
sulphuric or muriatic acid are preferably used. No separation of resinous
substances will here be noticeable. From the acidulated and, if necessary, filtered
solution, pyro-catechine will be obtained by shaking it, with an addition of ether,
the latter being thus caused to absorb it. This solution of pyro-catechine in ether
is then separated from the remaining liquid, whereupon the ether may be allowed
to evaporate, or be distilled off. By this means pure pyro-catechine will be
retained which will produce no fluoresceine under the action of phthalic acid.
Having now particularly described and ascertained the nature of my said inven-
tion and in what mauner the same is to be performed, I declare that what I
claim is :-
1. The hereindescribed process of manufacturing ortho-halogen-phenol,.
especially ortho-bromo- and ortho-chloro-phenol, by treating together, and bringing
about a reaction between, halogen, especially bromine and chlorine, and intensely
heated phenol.
2. The hereindescribed process of manufacturing halogen-phenol, which process.
consists in adding to the mixture of reagents, referred to in the 1st claim, a
sufficient quantity of basic substances (especially potash or soda) to fix or bind
only a portion of the product of reaction; whereupon the mixture is distilled, pure-
ortho-halogen-phenol being obtained in the product of distillation.

page_text: 3. The hereindescribed process of manufacturing pyro-catechine, which consists
in melting ortho-halogen-phenol, howsoever produced, but especially such as
obtained according to the first and second claims, together with liberal quantities
of an alkali, preferably soda or potash, under pressure and at a high temperature.
Dated this 13th day of March 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.