The Manufacture or Production of Hydroxyanthraquinones.
Year: 1894

page_text: Date of Application, 16th Jan., 1894
Complete Specification Left, 12th Oct., 1894-Accepted, 17th Nov., 1894
PROVISIONAL SPECIFICATION.
[Communicated from abroad by THE FARBENFABRIKEN, vormals FRIEDRICH
BAYER & Co., of Elberfeld, in the Empire of Germany.]
The Manufacture or Production of Hydroxyanthraquinones.
I HENRY EDWARD NEWTON of The Office for Patents, 6 Bream's Buildings,
Chancery Lane in the County of London, Patent Agent, do hereby declare the
nature of this invention to be as follows :-
My foreign correspondents have discovered some time ago a process for producing
hydroxyanthraquinone derivatives, which consists in treating anthraquinone with
nitric acid, and heating the resulting nitro products with concentrated or fuming
sulphuric acid in the presence of boric acid, and my foreign correspondents found
at the same time that the reaction, when effected without the presence of boric acid,
yields products of no value.
The researches of my foreign correspondents have now shown, that the nitric
acid used in the aforesaid process, can be replaced by nitrous acid, or substances
acting in the same or a similar manner.
This process is profitably carried out, for instance, either by introducing nitrous
acid into a heated solution prepared by dissolving anthraquinone and boric acid
in sulphuric acid, or by mixing first the necessary agents, riz., anthraquinone, boric
acid, sulphuric acid, and advantageously, in place of nitrous acid, salts of nitrous
acid, or such compounds which yield nitrous acid in the presence of sulphuric acid,
and subsequently heating the so-formed mixtures at elevated temperatures.
The presence of boric acid or, the like, is very advantageous also in the above
defined reactions, which proceed gently, by-products not being formed.
According to the researches of my foreign correspondents, a dihydroxyanthra-
quinone, viz. the quinizarin, is formed as chief product.
Two of the methods of treating anthraquinone in the above defined manner, are
illustrated by the following two examples. The parts are by weight.
EXAMPLE A.
14 parts of sodium nitrite are introduced into 200 parts of carefully cooled
sulphuric acid (66 degrees Baumé), and after the sodium nitrite has dissolved
(whilst stirring the mixture), 10 parts of anthraquinone, and then 10 parts of
crystallised boric acid, are added. The resulting liquid, on continued stirring, is
heated as quickly as possible, to from 220 to 230 degrees centigrade. A reaction
becomes apparent at from 180 to 191 degrees centigrade, and it is complete after
heating, say, during from 3 to hours, at from 220 to 230 degrees centigrade. The
heated mass exhibits a beautiful red color, and when a portion thereof is dissolved
in pure concentrated sulphuric acid, solutions result which show an intense orange-
yellow fluorescence. After cooling, the mass is poured into water, and the resulting
liquid is boiled up. The precipitate is filtered off. It possesses a beautiful orange
red color, whilst the filtrate is but slightly colored.
The product thus obtained dissolves in concentrated sulphuric acid, affording a
yellowish red colored solution, which shows the same spectrum as quinizarin. Its
alkaline solutions exhibit a violet red color.

page_text: EXAMPLE B.
10 parts of anthraquinone are dissolved in 200 parts of sulphuric acid (66 degrees
Baumé), and after adding 10 parts of crystallised boric acid, the liquid mixture is
heated at from 220 to 230 degrees centigrade. Whilst stirring, nitrous acid in
gaseous state is introduced, until the solution has assumed an intense red color, and
a sample, after pouring into water and boiling up, dissolves in alkalies, affording a
solution which shows a violet red color.
The isolation of the hydroxyanthraquinone thus formed, can be effected by the
method described in the above Example A.
The researches of my foreign correspondents have shown, that according to the
conditions under which the said reaction is carried out, small quantities of other
hydroxyanthraquinone derivatives, capable of dyeing with the aid of mordants, are
formed at the same time; for instance, my foreign correspondents have succeeded
in isolating purpurin, which was formed together with quinizarin in the same
process.
In order to convert anthraquinone into hydroxyanthraquinones by means of the
process hereinbefore defined, my foreign correspondents do not limit themselves to
the directions above given in the Examples A and B, as the mode of working can
be varied. For instance, the sodium nitrite used in the above Example A, can be
replaced by the corresponding quantities of other nitrites, the temperature can
vary within wide limits, and accordingly the time of reaction may be a longer or
shorter one.
The boric acid may be replaced by salts of boric acid, or other boron
compounds (as, for instance, boron trichloride), which yield boric acid when used
in the presence of sulphuric acid.
Dated this 16th day of January 1894.
COMPLETE SPECIFICATION.
The Manufacture or Production of Hydroxyanthraquinones.
I HENRY EDWARD NEWTON of The Office for Patents, 6 Bream's Buildings,
Chancery Lane, in the County of London, Patent Agent, 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 :-
My foreign correspondents some time ago discovered a process for producing
hydroxyanthraquinone, derivatives, which consists in treating anthraquinone with
nitric acid, and heating the nitro products with concentrated or fuming sulphuric
acid in the presence of boric acid, or other boron compounds, which, when used
together with sulphuric acid, act in a similar manner (see the Specification of
Letters Patent No. 14345, dated 25 July 1893), and my foreign correspondents
stated at the same time that, when effected in the absence of boric acid, the action
yields products of no value.
The researches of my foreign correspondents have now shown that nitrous acid,
or substances acting in the same or a similar manner, can be used instead of nitric
acid in the aforesaid process.
This process is profitably carried out, for instance, either by introducing nitrous
acid into a heated solution prepared by dissolving anthraquinone and boric acid or
the like in sulphuric acid, or by first mixing the necessary agents, viz., authra-
quinone, horic acid, sulphuric acid, and salts of nitrous acid, or compounds which
yield nitrous acid in the presence of sulphuric acid, and subsequently heating such
mixtures at elevated temperatures.
The presence of boric acid or the like is advantageous in this case also, as

page_text: with the aid of boric acid, or other boron compounds yielding boric acid, when
used together with sulphuric acid, which process consists either in introducing
nitrous acid into a heated liquid containing anthraquinone, boric acid, or the like,
and sulphuric acid, or in heating, at elevated temperatures, mixtures prepared from
anthraquinone, boric acid, or the like, sulphuric acid and salts of nitrous acid, or
other compounds which yield nitrous acid when used together with sulphuric
acid.
Dated 11004
NEWTON & SON,
Agents for the Applicant.