Improvements in the Manufacture of Pyrocatechin-sulphonic Acid and Intermediate Products.
Year: 1896

page_text: Date of Application, 6th July, 1896
Complete Specification Left, 6th Apr., 1897-Accepted, 19th June, 1897
IDIONA
Improvements in the Manufacture of Pyrocatechin-sulphonic Acid
and Intermediate Products.
A communication from abroad by LA SOCIÉTÉ CHIMIQUE DES USINES DU
RHONE ANCIENNEMENT GILLIARD P. MONNET ET CARTIER, of Lyons,
France, Manufacturers.
I, GEORGE BELOE ELLIS of the Firm of J. C. Mewburn and Ellis of
55 and 56 Chancery Lane in the County of London, Chartered Patent Agents, do
hereby declare the nature of this invention to be as follows:-
This invention relates to the manufacture of pyro-catechin-sulphonic acid and
intermediate products.
Recently the mono-sulphonic acid of pyro-catechin has attained considerable
importance in the chemical industry on account of its easy conversion into
pyrocatechin by simply heating the aqueous solution of the acid or of its salts
for some time under pressure.
This present invention consists of improvements in the manufacture of pyro-
catechin-mono-sulphonic acid from para-phenol-sulphonic acid by means of effecting
substitution in the benzene nucleus of the latter with a halogen, and ultimately
fusing the halogenated phenol-sulphonic acid together with caustic alkali, whereby
the halogen group is very readily replaced by hydroxyl, and pyrocatechin mono-
sulphonic acid is obtained.
Briefly the sense of the chemical changes involved in the invention may be
expressed by the following graphic formula.

page_text: The preparation of para-phenol-sulphonic acid halogenated in the meta position,
either by halogenation of the sulphonate or by sulphonation of halogenated phenols,
has hitherto been accomplished with very great difficulty, and small yields mixed
with large quantities of isomeric or analogous products obtained. It has now been
discovered by my foreign correspondents that by the introduction of a halogen such
as chlorine or bromine into an acid solution of para-phenol-sulphonic acid a very
much improved yield of meta-halogenated acid is obtained.
..
PREPARATION OF META-HALOGENATED PARA-PHENOL-SULPHONIC ACID.
Para-phenol-sulphonic acid is prepared in the ordinary manner by heating
together equal molecules of phenol and sulphuric acid of 66° for several days at
water bath temperature.
The cooled and congealed mass is then dissolved in a third of its weight of water
and 5 to 10 per cent. sulphuric acid added. A stream of chlorine gas or bromine is
then conducted into the solution at ordinary temperature, two molecules of chlorine
or bromine for each molecule of phenol-sulphonic acid in solution. Thus for 94 kilos.
phenol in the form of phenol-sulphonic acid 71 kilos. chlorine or 160. kilos.
bromine are used. During the process the temperature of the mixture rises
from 20° to about 60° C.
The product of the reaction is poured into water, neutralised with lime, and the
lime salt converted into the sodium salt by treatment with carbonate of soda in the
usual manner. The principal product of the action of the halogen is the meta-
mono-halogen derivative of phenol-sulphonic acid together with small quantities
of di-halogen derivatives of phenol-sulphonic acid. A small quantity of trichloro
or tri-bromo-phenol is also formed and can be recognized by its unpleasant
characteristic odour; this body is however precipitated in a flocculent mass when
the product of the reaction is poured into water prior to neutralisation, and can be
easily removed before the addition of the lime.
.
CONVERSION OF THE META-HALOGENATED PARA-PHENOL-SULPHONIC ACID
INTO PYROCATECHIN-MONO-SULPHONIC ACID.
To the sodium salt of the meta-halogenated para-phenol sulphonic acid obtained
as above is added half its weight or an equal weight of caustic soda in aqueous
solution. The whole is thoroughly mixed and then heated either in an open vessel
or under pressure for eight to ten hours at 250° C. By this treatment the
halogenated phenol-sulphonic acid is almost completely converted into pyro-
catechin-mono-sulphonic acid. The product is dissolved in water and neutralised
with a mineral acid, preferably with 30 per cent. sulphuric acid in slight excess.
The resulting solution is coloured violet and with ferric chloride gives a beautiful
green coloration which is characteristic of pyrocatechin-mono-sulphonic acid. By
addition of carbonate of soda this colour changes from green to blue, then violet
and finally red.
The aqueous solution is evaporated to a syrupy consistency, allowed to cool, and
the greater part of the sodium sulphate separated by crystallisation. The crystals
are filtered off and washed with cold water until free from color. The wash water
may serve for the solution of the next batch of the product, or it may be evaporated
and added to the original solution.
A concentrated aqueous solution of the sodium salt of pyro-catechin-mono-
sulphonic acid is thus obtained which without further purification, on heating in an
autoclave, yields very pure pyrocatechin.
Dated this 6th day of Jul 1806
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents.

page_text: Improvements in the Manufacture of Pyrocatechin-Sulphonic Acid
and Intermediate Products.
A communication from abroad by LA SOCIÉTÉ CHIMIQUE DES USINES DU
RHONE ANCIENNEMENT GILLIARD P. MONNET ET CARTIER, of Lyons,
France, Manufacturers.
I, GEORGE BELOE ELLIS of the Firm of J. C. Mewburn and Ellis of
55 and 56 Chancery Lane in the County of London, Chartered Patent Agents, 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-catechin-sulphonic acid and
intermediate products.
Recently the mono-sulphonic acid of pyro-catechin has attained considerable
importance in the chemical industry on account of its easy conversion into
pyrocatechin.
This present invention consists of improvements in the manufacture of pyro-
catechin-mono-sulphonic acid from para-phenol-sulphonic acid by means of effecting
substitution in the benzene nucleus of the latter with a halogen, and ultimately
fusing the salt of for instance the sodium salt of halogenated phenol-sulphonic acid
together with caustic alkali, whereby the halogen group is very readily replaced
by hydroxyl, and the salt of pyrocatechin mono-sulphonic acid is obtained.
Briefly the sense of the chemical changes involved in the invention may be
expressed by the following graphic formulæ :-
Sodium salt of meta-chlor-para-phenol-
sulphonic acid.
РУ
sulphonic acid.
The preparation of para-phenol-sulphonic acid halogenated in the meta position,
either by hologenation of the sulphonate or by sulphonation of halogenated phenols,
has hitherto been accomplished with very great difficulty, and small yields mixed

page_text: with large quantities of isomeric or analogous products obtained. It has now been
discovered by my foreign correspondents that by the introduction of a halogen such
as chlorine or bromine into an acid solution of para-phenol-sulphonic acid a very
much improved yield of meta-halogenated acid is obtained.
PREPARATION OF META-HALOGENATED PARA-PHENOL-SULPHONIC ACID.
Para-phenol-sulphonic acid may be prepared in the ordinary manner by heating
together equal molecules of phenol and sulphuric acid of 66° B. for several days at
water bath temperature.
The cooled and congealed mass is then dissolved in a third of its weight of water
and 5 to 10 per cent. of sulphuric acid added. A stream of chlorine gas or bro nine
is then conducted into the solution at ordinary temperature two atoms of chlorine
or bromine for each molecule of phenol-sulphonic acid in solution. Thus for 94 kil
phenol in the form of phenol-sulphonic acid 71 kilos. chlorine or 160 kilos. bromina
are used. During the process the temperature of the mixture rises from 20° to
about 60° C.
The product of the reaction is poured into water, neutralised with lime, and the
lime salt converted into the sodium salt by treatment with carbonate of soda in the
usual manner. The principal product of the action of the halogen is the meta-
mono-halogen derivative of phenol-sulphonic acid together with, small quantities of
-di-halogen derivatives of phenol-sulphonic acid. A small quantity of trichloro or
tri-bromo-phenol is also formed and can be recognised by its unpleasant
-characteristic odour: this body is however precipitated in a flocculent mass when
the product of the reaction is poured into water prior to neutralization, and can be
easily removed before the addition of the lime.
CONVERSION OF THE META-HALOGENATED PARA-PHENOL-SULPHONIC ACID
INTO PYROCATECHIN-MONO-SULPHONIC ACID.
To the sodium salt of the meta-halogenated para-phenol sulphonic acid obtained
as above is added half its weight or an equal weight of caustic soda in aqueous
solution. The whole is thoroughly mixed and then heated either in an open vessel
or under pressure for eight to ten hours at about 250° C. or above. By this
treatment the halogenated phenol-sulphonic acid is almost completely converted
into pyro-catechin-mono-sulphonic acid. The product is dissolved in water and
neutralised with a mineral acid, preferably with 30 per cent. sulphuric acid in slight
excess.
The resulting solution is coloured violet and with ferric chloride gives a beautiful
green coloration which is characteristic of pyro-catechin-mono-sulphonic acid. By
addition of carbonate of soda this colour changes from green to blue, then violet
and finally red.
The aqueous solution is evaporated to a syrupy consistency, allowed to cool, and
the greater part of the sodium sulphate separated by crystallisation. The crystals
are filtered off and washed with cold water until free from colour. The wash water
may serve for the solution of the next batch of the product, or it may be evaporated
and added to the original solution.
A concentrated aqueous solution of the sodium salt of pyro-catechin-mono-
sulphonic acid is thus obtained which without further purification, on heating in
an autoclave preferably with dilute sulphuric acid, yields very pure pyrocatechin.
Having now particularly described and ascertained the nature of the said inven-
tion as communicated to me and in what manner the same is to be performed I
declare that what I claim is :-
1. The preparation of meta-chlor and meta-bróm-para-phenol-sulphonic acids
by chlorination or bromination of paraphenol-sulphonic acid in an acid solution
substantially as described.
C.:

page_text: 2. The conversion of metachlor or meta-brom-phenol sulphonic acid into
pyrocatechin-mono-sulphonic acid by melting the sodium or potassium salt with
caustic soda or caustic potash in open vessels or under pressure at a temperature
about 250° C. or above substantially as described.
3. The preparation of pyrocatechin-mono-sulphonic acid from para-phenol-
sulphonic acid by halogenation in acid solution and melting the sodium or other
salt of the halogenated product with caustic alkali, at a temperature about 250° C.
or above, substantially as described.
Dated the 6th day of April 1897.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, W.C., Chartered Patent Agents.