The Manufacture of Blue Colouring Matter Containing Sulphur.
Year: 1893

page_text: Date of Application, 24th Apr., 1893
Complete Specification Left, 22nd Jan., 1894-Accepted; 3rd Mar., 1894
PROVISIONAL SPECIFICATION.
The Manufacture of Blue Colouring Matter Containing Sulphur.
WILLIAM HENRY CLAUS Chemical Manufacturer c/o Claus & Rée Droylsden
Manchester ALFRED REE Chemical Manufacturer c/o Claus & Rée, Droylsden,
Manchester, do hereby declare the nature of this invention to be as follows:-
By the action of sodium thio sulphate and acetic acid upon hydrochlorate of
para nitroso dimethyl aniline in aqueous solution at an elevated temperature a
soluble compound is formed which yields when oxidized in presence of dimethyl
aniline preferably as hydrochlorate in aqueous solution and in presence of chloride
of zinc, blue colouring matter containing sulphur.
As an illustration the manufacture of this blue colouring matter may be carried
out as follows:
About 26 parts of para-nitroso dimethyl aniline hydrochlorate are dissolved in
about 150 parts of hot water and about 120 parts of commercial acetic acid 12°. T.
there is now added quickly a solution of about 75 parts of thiosulphate of soda
dissolved in 350 parts of hot water, the yellow appearance of the liquid is changed
to a partially discoloured solution at this stage, there are then added about 120 parts
of chloride of zinc 102° T. and "a solution of about 15 parts of dimethyl aniline
and" about 17 parts of hydrochloric acid 28° T. and immediately afterwards a hot
solution of about 25 parts of bichromate of soda (or potash) and 5 lbs. of sulphuric
acid 168° T. in 250 parts of hot water is rapidly run in and the liquor agitated
briskly at the same time, the blue colouring matter is formed at once and separates
out as a partly crystalline precipitate it is collected on a filter and washed out with
weak brine and dissolved in about 500 parts of boiling water, filtered from insoluble
matter and precipitated with common salt.
Other salts of thio sulphuric acid may be used, but they have no advantage over
the sodium salt, which can be obtained at a lower cost and greater purity.
Dated this 22nd day of April 1893.
WILLIAM HENRY CLAUS.
ALFRED RÉE.
COMPLETE SPECIFICATION.
The Manufacture of Blue Colouring Matter Containing Sulphur.
WILLIAM HENRY CLAUS ALFRED REE Chemical Manufacturers c/o Claus
& Rée Droylsden Manchester 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 :-
By the action of sodium thio sulphate and acetic acid upon hydrochlorate of para
nitroso-dimethyl aniline in aqueous solution at an elevated temperature a soluble
compound is formed which yields when oxidized in presence of dimethyl aniline
preferably as hydrochlorate in aqueous solution and in presence of chloride of zinc,
blue colouring matters containing sulphur.
As an illustration the manufacture of this blue colouring matter may be carried
out as follows :
About 18 parts of dimethyl aniline are converted in the usual way into para
nitroso-dimethyl aniline bydrochlorate, the latter is collected on a filter and drained
well, the paste left on the filter represents about 26 parts of para nitroso-dimethyl

page_text: aniline bydrochlorate, it is dissolved in about 150 parts of hot water and about
120 parts of acetic acid (12° Twaddle).
This solution is preferably heated to about 75° C. There is now added quickly
a solution of about 75 parts of thiosulphate of soda dissolved in 350 parts of hot
water; the yellow appearance of the liquid is changed after about 10 minutes to a
partially discoloured solution.
At this stage steam is applied to keep the temperature up to about 80° C., and
at the same time there are further added about 120 parts of chloride of zinc
(102 Twaddle) and a solution of about 15 parts of dimethyl aniline and about
17 parts of hydrochloric acid (28 Twaddle). Immediately after this a solution of
about 25 parts of bichromate of soda (or the equivalent in regard to oxidising
power of any other soluble chromate) and 5 parts of vitriol in 250 parts of water
(this solution being at a temperature of about 90° C.) is rapidly run in and the
liquor agitated briskly at the same time.
The time allowed for the running in of the bichromate solution and the oxidation
is about-3-minutes.
The colour is produced at once, it is collected on a filter and purified by
dissolving in boiling water and filtration from impurities and precipitation with
common salt.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :
"
The production of a blue colouring matter known as methylene blue by the action
of para nitroso-dimethyl aniline hydrochlorate upon thiosulphate of soda and
acetic acid and subsequent treatment of the resulting liquor with a solution of
bichromate of soda and sulphuric acid in the presence of dimethyl aniline
hydrochlorate and chloride of zinc at a temperature approaching the boiling point
of water substantially in the manner herein before described.
Dated this 20th day of January 1894.