A New or Improved Preparation of Orthochlorophenol.
Year: 1899

page_text: Date of Application, 12th Apr., 1899-Accepted, 24th June, 1899
COMPLETE SPECIFICATION.
A New or Improved Preparation of Orthochlorophenol.
I, JOHN OWDEN O'BRIEN, M.I.Mech. E., of the Firm of W. P. Thompson & Co.,
of 6, Bank Street, Manchester, Liverpool and London, in the Counties of Lancaster
and Middlesex respectively, Patent Agents (a communication from Maurice Hazard-
Flamand, of Boulogne-sur-Seine, in the Republic of France, Engineer,) do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following state-
ment-
The principle of this new preparation depends on the two following discoveries:-
1st. In the Annals, Kolb and Gauhe write that if a chlorinating mixture, com-
posed of hydrochloric acid and potassium chlorate be caused to act on the salts of
paraphenol sulphonic acid one never obtains anything but a bichloro-derivative.
Now, my correspondent has found that if this operation is carried on below 50° C.
by adding gradually the chlorate to the mixture of hydrochloric and sulphonic
acid, this latter acid being, before pouring in the hydrochloric acid, either free or
combined, one obtains only the monochloro substitute in opposition to the opinion
of Kolb and Gauhe.
2nd. My correspondent has also found, moreover, that the orthochloroparaphenol
sulphonic acid is unstable towards 180° or 200° C., and decomposes at this tem-
perature producing orthochlorophenol.
METHOD.
1st. The phenol is sulphonated so as to obtain phenol-parasulphonic acid. If
the process, being performed with the theoretical quantities of phenol and of
sulphuric acid at 66° Baumé, at the temperature of 100° to 110° C., be carried on
in a vacuum for 15 hours, the water formed distils along with about 5% of the
phenol used, all the rest entering into the reaction. The product (chemical) is
about 95% and commercially 100% of the phenol, since the portion which does not
enter into reaction is recovered, as explained.
2nd. This acid is chlorinated by means of a chlorinating mixture formed of
potassium chlorate and hydrochloric acid. If the chlorate is thrown into the
mixture a little at a time, along with cooling and stirring, so as to keep the
temperature below 50° C. there is formed the orthochloro derivative, and the mon o-
chloro derivative as opposed to what Kolb and Gauhe maintain, who, by pro-
ceeding differently have only been able to obtain the bichloro derivative.
3rd. Desulphonating of the orthochlorophenolparasulphonic acid. My corre-
spondent has discovered that this acid is unstable towards 180° to 200° C. If one
forms the monosodium salt, leaving at liberty a trace of free acid and after evaporat-
ing and drying the mass, the temperature be raised towards 200° C. the free acid
decomposes.

page_text: and H2O. This water passing to another molecule of SO3 forms H2SO4 which sets
free two molecules of chlorosulphonic acid which is then oxidized. The action goes
on continuously, the orthochlorophenol distils, and there remains in the retort
sodium sulphate and bisulphate, along with organic carbon. The yield is about 75%
by weight of the phenol used. It may be seen that the defect of this method is
the dehydrating action of SO3 and of the bisulphate on the organic compound.
This result may be avoided by performing the process in the presence of water.
For this purpose the chlorosulphonic acid is diluted with water so as to make 400
litres result from treating 100 kgs. of phenol.
The whole is kept in an enamelled digester for 15 hours. The chlorophenol
then appears separated from the liquid, in the form of an oily black mass, which it
then suffices to purify after decantation by dry distillation, or in a current of
steam.
The yield amounts by weight to 90% of the phenol used.
EXAMPLE.
110 kilograms of ordinary sulphuric acid are mixed with 100 kgs. of phenol.
The whole is brought to a temperature of 100° or 110° C. while stirring. At
the end of 6 or 7 hours, the heating and the stirring are continued, whilst a good
vacuum is kept up by a condenser. Water distils over and 5 kgs. of phenol.
This process being completed at the end of 15 hours, 100 kgs. of water and
105 kgs. of ordinary hydrochloric acid are added to the product say to each
kilogramme of phenol 900 c.cm. of acid at the density 1,180.
The mixture is stirred in an enamelled boiler cooled through a double bottom.
There is then added 41 kgs. of potassium chlorate, a little at a time, so as to
balance exactly the cooling effect of the double bottom, with the heat of the
reaction, and keep the temperature of the mixture constantly below 50° C. When
this operation is completed it is filtered if any insoluble chloranil has been formed,
and the volume is brought up to 400 litres by the addition of water.
This mixture is then treated in a digester as has been described.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me
from abroad by my foreign correspondent I declare that what is claimed is:-
1st Claim. A cycle of operations for obtaining the preparation of orthochlor-
phenol based on the following new scientific facts:-
1st. The preparation of a monochloro substitute or derivative by causing a
chlorinating mixture to act upon phenolparasulphonic acid at the temperature
of 50° C.
(This new fact is really in opposition to the opinion expressed by Kolb and
Gauhe a long time ago.)
2nd. Decomposition of the orthochlorophenolparasulphonic acid at about
200° C. into chlorophenol and sulphuric anhydride. (Until now desul-
phonating was regarded as a phenomenon of hydrolysis.)
2nd Claim. The employment of a vacuum in the sulphonating process.
3rd Claim. The process of preparing ortho-chloro-phenol substantially as
described.