Improvements in Purifying Anthracene and Anthraquinone...
Year: 1892

page_text: Date of Application, 21st Mar., 1892
Complete Specification Left, 20th Dec., 1892-Accepted, 4th Feb., 1893.
PROVISIONAL SPECIFICATION.
Improvements in Purifying Anthracene and Anthraquinone...
I, BENJAMIN WILLCOX of 47 Lincoln's Inn Fields, in the County of London,
Patent Agent do hereby declare the nature of this invention (which has been'
communicated to me from abroad by the Farbenfabriken vormals Friedrich
Bayer & Coy. of Elberfeld in the Empire of Germany) to be as follows:-
--
This invention relates to a new method of purifying raw anthracence and anthra-
quinone.
My foreign correspondents have found that in order to prepare pure anthracene
and anthraquinone from the raw products sulphurous anhydride can advantageously
be employed as the bye products of anthracene which are in the raw anthracene,
are for the most part readily soluble in liquid sulphur dioxide, whilst only very
slight traces of anthracene are dissolved by this solvent, and in employing the
latter for purifying raw anthraquinone the foreign associates of the pure anthra-
quinone and also the small traces of anthracene therein, are readily dissolved by
liquid sulphurous anhydride whilst the anthraquinone, as my foreign corre-
spondents have found, is almost insoluble in cold sulphur dioxide.
This new process can be carried out in general in the following manner
employing for example a raw anthracene containing about 30 per cent. of pure
anthracene. By mixing the raw product with an equal weight of liquid sulphur
dioxide and filtering almost half the quantity of the raw anthracene is dissolved.
The residual part, after removing the sulphurous anhydride adherent, has been
found by analytical research to contain about fifty per cent. of pure anthracene
whilst out of the filtrate obtained as above mentioned after the removal of the
sulphur dioxide a residue was obtained which contains only about 2 per cent. of
anthracene.
My foreign correspondents have found that by employing a greater quantity of
the said solvent the process yields much better results because in this case but little
more anthracene is dissolved whilst the percentage of the anthracene so purified is
very much increased for example to about from 70 to 80 per cent. if four times the
weight of liquid sulphur dioxide be employed.
In treating crude or raw anthraquinone with liquid sulphurous anhydride
(for example with four times its weight thereof) the foreign associates which are
detrimental to its subsequent use are dissolved with great ease whilst less than
one per cent. of anthraquinone is thereby dissolved.
If the process be carried out in closed vessels my foreign correspondents have
found the results to be still better.
The advantages of this process as compared with the other processes hitherto in
use, viz. the purification by means of hydrocarbons or other organic solvents, are
not only that a much purer product is obtained but also that a much cheaper
material is used and that low temperatures can be employed and the agent can be
recovered with great ease.
.
Dated this 21st day of March 1892.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in Purifying Anthracene and Anthraquinone.
I, BENJAMIN WILLCOX of 47 Lincoln's Inn Fields in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention (which
Tuning Rd

page_text: has been communicated to me from abroad by the Farbenfabriken vormals
Friedrich Bayer & Co. of Elberfeld in the Empire of Germany) 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 new method of purifying raw or technical anthracene
and anthraquinone.
My foreign correspondents have found that in order to prepare pure anthracene
from the raw or technical product sulphurous anhydride can be advantageously
employed, as the associated impurities in crude anthracene are for the most part
readily soluble in liquid sulphur dioxide whilst only small quantities of anthracene
are dissolved by this liquid and that in employing this solvent for purifying raw or
technical anthraquinone the associated foreign matters and also the traces of
anthracene therein, are comparatively readily dissolved by liquid sulphur dioxide
the anthraquinone as my foreign correspondents have found being almost insoluble
in cold sulphur dioxide.
This new process can be carried out in general in the following manner
employing, for example a crude anthracene containing about 30 per cent. of pure
anthracene. By mixing the raw product with an equal weight of liquid sulphur
dioxide and filtering, almost 60 per cent. of the raw anthracene employed is
dissolved. The residue after removing the adherent sulphur dioxide, has been
found by analysis to contain about 50 per cent. of pure anthracene whilst the
filtrate obtained as above mentioned yielded after the removal of the sulphur
dioxide a residue containing only about 2 per cent. of anthracene.
My foreign correspondents have found that by employing a greater quantity of
the said solvent the process yields much better results, as in this case but little
more anthracene is dissolved, whilst the percentage of anthracene in the material
so purified is very much increased, for example to from about 70 to 80 per cent. if
four times the weight of liquid sulphur dioxide be employed.
1
In treating technical anthraquinone with liquid sulphur dioxide (for example
with four times its weight thereof) the detrimental foreign matters are dissolved
with great ease, whilst the anthraquinone being almost insoluble remains on
the filter.
The process can be carried out in closed or open vessels; but as a matter of
course it is more advantageous to use closed vessels thereby preventing the loss of
sulphur dioxide.
The advantages of this process as compared with the processes hitherto in use,
viz., the purification by means of hydrocarbons or other organic solvents, are not
only that a much purer product is obtained but also that a much cheaper material
is used, that low temperatures can be employed, and that the agent can be
recovered with great ease.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is,
1) The employment of liquid sulphur dioxide for purifying anthracene or
anthraquinone.
2) The process for purifying anthracene or anthraquinone, which consists in
treating raw or technical anthracene or anthraquinone in open or closed vessels
with liquid sulphur dioxide and separating the undissolved purified anthracene
or anthraquinone from the associated foreign matters dissolved in the sulphur
dioxide.
Dated this 16th day of December 1892.