Process for Separating the Alpha-monosulpho Acid of the Betanaphtol from certain Admixtures.
Year: 1884

page_text: "
Process for Separating the Alpha-monosulpho Acid of the
Betanaphtol from certain Admixtures.
PROVISIONAL SPECIFICATION.
I; HERBERT JOHN HADDAN, of the firm of Herbert and Company, Patent
Agents, of 67, Strand, in the City of Westminster, Civil Engineer, do hereby
declare the nature of said Invention for "PROCESS FOR SEPARATING THE
ALPHA-MONOSULPHO-ACID OF THE BETANAPHTOL FROM CERTAIN ADMIXTURES, &
communication to me from abroad by the Farbenfabriken vorm. Fr. Bayer & Co,
of Elberfeld, Germany, to be as follows:-
The alpha-monosulpho-acid of the betanaphtol produced by the rapid sulpho-
nizing of the finely powdered dry betanaphtol at a low temperature (about 50 to
60 degrees Centigrade) is mixed with the isomer monosulpho-acid of Schäffer and
an other body which is probably also a monosulpho-acid of the betanaphtol. These
admixtures are of comparatively little value and may therefore be considered as
impurities.
".
This invention consists in the separation of the alpha-monosulpho-acid of the
betanaphtol from the sulpho-acids which occur in the same mixture, by causing
tetrazo-diphenyl, its homologues or the sulpho-acids of these bodies to act on au
aqueous solution of the mixture after having been made sufficiently alkaline, a),
either by adding of the tetrazo-compound the quantity necessary for binding the
impurities inclusive of Schäffer's monosulpho-acid occuring in the mixture and
separating the colouring matter produced by this process, b,) or by adding at
first only that quantity of the tetrazo-compound which is necessary to précipitate
and separate as a colouring matter the foreign body which occurs in the mixture,
and subsequently the quantity necessary for the precipitation of Schäffer's acid.

page_text: COMPLETE SPECIFICATION.
I HERBERT JOHN HADDAN, of the firm of Herbert and Company, Patent
Agents, of 67, Strand, in the City of Westminster, Civil Engineer, do hereby
declare the nature of said Invention for "PROCESS FOR SEPARATING THE
ALPHA-MONOSULPHO ACID OF THE BETANAPHTOL FROM CERTAIN ADMIXTURES," &
communication to me from abroad by The Farbenfabriken vorm. Fr Bayer
and Co., Elberfeld, Germany, and in what manner the same is to be për-
formed, to be particularly described and ascertained in and by the following
statement:
When the alphamonosulpho-acid of betanaphtol is prepared by rapidly sulpho-
nising finely ground dry betanaphtol at a low temperature, about 50 to 60° C, it
appears mixed with the isomeric Schäffer monosulpho-acid, and another body which
is also most probably a monosulpho-acid of betanaphtol.
My correspondents have already discovered several processes for freeing the
alpha-acid from theso impurities.
The present invention relates to a new and valuable process for the same purpose,
and consists in the employment of tetrazodiphenyl, tetrazoditolyl, tetrazodixylil and
other tetrazo-compounds derived from homologues of benzidine, as well as the
sulpho-acids of the same.
The inventors have found that the above named compounds bear a similar
relation to the monosulpho-acid mixture of betanaphtol, as they have already shown
regarding diazobenzol and other diazo-compounds. The greatest affinity is also
shown in this case by the foreign body already mentioned, which is the first to
unite with the said compound, then the Schäffer-sulpho-acid unites and thirdly the
alphamonosulpho-acid.
If there is only so much of the said compounds as will unite with these two
bodies and any other impurities, to form azobodies, then the latter are exclusively
derived from comparatively valueless bodies which are all considered as impurities
in the valuable alpha-acid, and the latter is obtained, technically speaking, in a
pure state in the form of an aqueous solution of its salts. The process has the
advantage over the old method of separating by, spirit, as regards cheapness and
rapidity, since the costly spirit and the evaporating process can be dispensed with; it
also possesses the following advantage over the method of separating by means of
diazobenzol and other diazo-compounds; namely, the new dye produced by tetrazo-
diphenyl, and its substitutes, with the separated mixture is a valuable claret-red
body, which, it is known, arises from the combination of tetrazodiphenyl“ with
Schäffer's acid.
It is, however, almost insoluble in water, and therefore, it was useless as a dye.
As soon, however, as the foreign bodies mentioned above are dissolved with
Schäffer's acid, there is obtained the easily-soluble claret-red dye.
This process of separation is, therefore, superior to former ones from an economical
point of view.
The method of producing tetrazodiphenyl and its homologues is known,
Th

page_text: The quantity of tetrazodiphenyl &c required to separate the foreign bodies is
determined by the quantity of Schäffer-, foreign, and alpha-monosulpho-acid
contained in the mixture.
As, however, the mixture is not constant, but the proportions of the parts, on
the contrary, change according to the requirements of the work, the proper quantity
should be ascertained by a small preliminary experiment, as has been previously
shown in the case of diabenzol &c.
.
The preliminary experiment is complete, when the filtrate of the precipitated
dye (the colouring matter precipitated by means of salt) produces with diazobenzol-
monosulpho-acid the pure crocein scarlot.
The calculated quantity of the said tetrazo-compounds is then added to the
aqueous salt mixture of the sulpho-acids which has been sufficiently alkalised.
Previously, however, a considerable portion of the Schäffer monosulpho-acid
may be separated alone from the mixture, as stated in the present patent
specification.
This is also advisable, for, according to this process, the foreign body already
named does not pass off; and is, therefore, present in due proportion to the
Schäffer-acid, in order to form with the tetrazo-compound a useful and easily
soluble dye.
If too little of the tetrazo-compound is taken, the alpha-acid remains somewhat
impure, and the dye made from it shows this impurity; if there is too much, the
valuable alphamonosulpho-acid is partly lost for the fine crocein dyes.
Of course, in this case too, the above named foreign bodies only can be separated
first, and then the Schäffer-acid.
More or less of the new dye formed with the tetrazo-compound is at once
separated, according to the degree of concentration of the mixture.
The residue is precipitated from the solution by means of salt and then separated
mechanically.
The new alphamonosulpho-acid of betanaphtol is found in the residual lye in a
technically pure form.
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
The process of separating the alpha monosulpho-acid of betanaphtol from the
sulpho-acids produced with it in the mixture, by the action of tetrazodiphenyl, its
homologues and sulpho-acids on the aqueous solution of the mixture of salts which
has been rendered sufficiently alkaline
a-either by adding a sufficient quantity of the tetrazo-compound to combine
with the impurities, including Schäffer's monosulpho-acid, then precipitating by
means of salt and separating the dye produced by this process.
bor by adding at first only as much of the tetrazo-compound as will serve to
precipitate and separate as a dye, the foreign body or impurity and, subsequently,
adding enough to precipitate and separate also the Schäffer acid.
Dated this 18th day of February 1885