BAYER The Manufacture or Production of Sulpho Acids of the Naphthalene Series Derived from Naphthalene B 13 Disulpho Acid or Naphthalene B B3 Disulphō Acid.
Year: 1893

page_text: Date of Application, 30th Dec., 1893
Complete Specification Left, 29th Sept., 1894-Accepted, 3rd Nov., 1894
PROVISIONAL SPECIFICATION.
[Communicated from abroad by THE FARBENFABRIKEN, vormals FRIEDRICH
Co., of Elberfeld, in the Empire of Germany.]
BAYER
The Manufacture or Production of Sulpho Acids of the Naphthalene
Series Derived from Naphthalene B₁ 13 Disulpho Acid or
Naphthalene B2 B3 Disulphō Acid.
I HENRY EDWARD NEWTON of The Office for l'atents, 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 described in the Specification of the German
Patent No. 40893, dated 7th December 1886, that the naphthalene tetrasulpho acid
first obtained by Senhofer (see Berichte der Deutschen Chemischen Gesellschaft,
volume 8, page 1486) can be used as the initial material for producing naphthol-
trisulpho acid and dihydroxynaphthalene disulpho acid.
The said naphthalene tetrasulpho acid was obtained by Senhofer by heating
naphthalene with vitriol and phosphoric anhydride in a closed tube, at about
260 degrees centigrade, but the resulting amount of tetrasulpho acid was very slight.
If, according to the directions given in the Specification of the above German
Patent No. 40893, one part of naphthalene is heated with 5 parts of fuming sulphuric
acid (containing 40 per cent. of anhydride), at 160 degrees centigrade, a mixture of
naphthalene tetrasulpho acid and naphthalenetrisulpho acid is formed. It is notice-
able that, by means of the above two methods, not only one naphthalene tetrasulpho
acid, but at least two isomeric naphthalene tetrasulpho acids are formed, as Senhofer
bas observed (see Monatshefte für Chemie, 3, page 111-117, and Berichte der
Deutschen Chemischen Gesellschaft, volume 15, Ref. 1080), and which my foreign
correspondents have proved by experiment.
It is very difficult to isolate from the aforesaid mixtures the naphthalene tetra-
sulpho acids in such a pure state as is desirable for the further technical use of
these acids.
My foreign correspondents have now found a suitable method of obtaining
separately the one and the other of the two naphthalene tetrasulpho acids in a
pure state, riz., by employing, as initial materials, on the one hand, the naphtha-
lene B, B disulpho acid, or the naphthalene 3, ẞ, a, trisulpho acid, obtainable by
sulphonating the last mentioned naphthalene B, 33 disulpho acid; on the other
band, the naphthalene B2 B3 disulpho acid, or the naphthalene ẞ, B3 α, trisulpho
acid, obtainable by sulphonating the last mentioned naphthalene B, B3 disulpho acid.
These naphthalene di- or naphthalene trisulpho acids are treated with sulphonating
agents, and this sulphonation can be effected, for instance, by heating with fuming
sulphuric acid, sulphuric chlorhydrine, or agents acting in the same or a similar
manner, at elevated temperatures.
This process of sulphonation is illustrated by the following examples, which,
however, are merely typical. The parts are by weight.

page_text: (containing 25 per cent. of anhydride), and the resulting mixture is heated at
90 degrees centigrade during 4 hours, a naphthalene trisulpho acid being thus
formed. The vessel containing the sulphonated mass is then closed, in order to
avoid any loss of anhydride, and the temperature is raised to 260 degrees centigrade,
and the mass is heated at this temperature during 6 hours. After cooling, the
mass is full of compact crystals. It is dissolved in water, and the resulting solution
is neutralised by means of slaked lime. After filtering off the calcium sulphate
(gypsum), sodium carbonate is added to the filtrate thus obtained, in order to
convert the calcium salt contained therein into the sodium salt. 'The calcium
carbonate precipitated is filtered off, aud the solution of the sodium salt thus
obtained is evaporated, until the volume is about 300 litres (in case the above-
mentioned parts are kilos. by weight). On adding common salt to the boiling
solution of the sodium salt,-the sodium salt of the naphthalene tetrasulpho acid
separates as a sand like precipitate, which is isolated by filtration. This sodium
salt remains in colorless thick crystals on slowly evaporating its solution in water,
and the crystals then cover the sides of the vessel in the form of crusts.
No decompositions could be observed during this operation. The solutions of
the salts of the produced naphthalene tetrasulpho acids are as clear as water, and the
yields are therefore satisfactory.
- NAPHTHALENE
TETRASULPHO ACID FROM NAPHTHALENE ẞ, B, DISULPHO
ACID.
If the calcium salt of naphthalene ẞ, 3, disulpho acid is replaced by the calciuni
salt of naphthalene B, B3 disulpho acid, and the sulphonation is carried out in the
manner described in the above Example A, the sodium salt of a naphthalene tetra
sulpho acid is obtained, which is much more soluble than the sodium salt of the
naphthalene tetrasulpho acid obtainable as mentioned in the Example A. The
solution of the sodium salt of this new naphthalene tetrasulpho acid profitably is
mixed with barium chloride. The tetra barium salt separates as a white heavy
precipitate on evaporating the solution of the barium salt. It is filtered off.
The formation of by-products does not take place during this operation, and the
new tetrasulpho acid is obtained in good quantities.
My foreign correspondents have further found that the naphthalene tetra sulpho
acid obtainable, as described in the above Example A, from naphthalene B
disulpho acid, is, by melting with alkalies, converted into a naphtholtrisulpho acid,
which process conveniently proceeds and yields a pure product.
a
In order to illustrate the conversion of naphthalenetetrasulpho acid into
naphtholtrisulpho acid, the following example is given, the parts being by
weight.
PRODUCTION OF a NAPHTHOLTRISULPHO ACID BY MELTING WITH ALKALIES
THE NAPHTHALENE TETRA SULPHO ACID OBTAINABLE FROM NAPHTHA-
LENE B B DISULPHO ACID.
100 parts of the sodium salt of the said naphthalenetetrasulpho acid are mixed
with 50 parts of soda and 280 parts of water. The resulting mixture is heated in a
closed vessel capable of withstanding pressure, at 180 degrees centigrade, for, say,
8 hours. The resulting light yellow solution, after adding 125 parts of muriatic
acid (21 degrees Baumé) is evaporated until a saturated solution of common salt
results. The acid sodium salt of the naphtholtrisulpho acid then separates in white
rosettes of compact flat needles.
The soda used in this example can be replaced by potassa, and the operation can

page_text: also be effected in open vessels. In the latter case, alkali lye of a stronger
concentration is profitably employed.
My foreign correspondents have also converted the naphthalene tetrasulpho acid
(obtainable by sulphonating naphthalene ẞ, B3 disulpho acid) into dihydroxyuaph-
thalene disulpho acid, following the directions given in the Specification of the
above German Patent No. 40893, and they have found that the said tetrasulpho
acid, when treated in such a manner, yields two isomeric dihydroxynaphthalene
disulpho acids.
The process for producing these dihydroxynaphthalene disulpho acids is
illustrated by the following example :-
CONVERSION OF NAPHTHALENE TETRA SULPHO ACID (OBTAINABLE FROM
NAPHTHALENE B₁ ẞ3 DISULPHO ACID) INTO TWO ISOMERIC DIHYDROXY-
NAPHTHALENE DISULPHO ACIDS.
100 parts (the parts are by weight) of naphthalenetetrasulphonate of sodium are
mixed with 160 parts of soda lye (containing 60 per cent. of NaOH), and the
resulting mixture is heated in a vessel capable of withstanding pressure, during
8 hours, at 200 degrees centigrade. The melted mass is dissolved in 250 parts of
muriatic acid (21 degrees Baumé), and 150 parts of water. The one of the two
isomerie dihydroxynaphthalene disulpho acids then separates in long hair-like needles.
grouped in the shape of balls. The neutral salts of this dihydroxynaphthalene
disulpho acid, which my foreign correspondents term "red acid," show, when
dissolved in water, a violet fluorescence. The amount of this acid is 30 per cent.
The other of the two isomeric dihydroxynaphthalene disulpho acids, which is
termed by my foreign correspondents "yellow acid," remains dissolved in the mother
liquors. These mother liquors are saturated with potassium chloride, in order to
convert the sodium salt into the potassium salt, which is soluble with slighter
readiness than the sodium salt, and separates in white scales. The amount of the
"yellow acid" thus produced is 70 per cent. The watery solutions of its neutral
salts show a deep yellow color, with an intense green fluorescence.
The soda employed in the preceding Example D can be replaced by potassa;
the temperature of the melted mass can vary within from about 180 to 240 degrees
centigrade; and the operation may also be carried out in open vessels.
The naphthalene tetra sulpho acid can be replaced by a corresponding quantity
of the a naphtholtrisulpho acid, which results as hereinbefore described by melting
this tetrasulpho acid with alkalies.
Dated the 30th day of December 1893.
NEWTON & SON,
Agents for the Applicant.
COMPLETE SPECIFICATION.
The Manufacture or Production of Sulpho Acids of the Naphthalene
Series Derived from Naphthalene Beta, Beta, Disulpho Acid or
Naphthalene Beta, Betaз Disulpho Acid.
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 :-
A description has been given by my foreign correspondents in the Specification
of the German Patent No. 40893, dated 7th December 1886, of the manner in
which the naphthalene tetrasulphonic acid first obtained by Senhofer (see Berichte

page_text: der Deutschen Chemischen Gesellschaft, volume 8, page 1486) can be used in
producing naplitholtrisulphonic acid and dihydroxynaphthalenedisulphonic acid.
The said naphthalenetetrasulphonic acid was prepared by Senhofer by heating
naphthalene with oil of vitriol and phosphoric anhydride in sealed tubes, at
about 260 degrees centigrade, but the amount of tetrasulphonic acid obtained in
this manner was very small.
If, in accordance with the directions given in the Specification of the above
named German Patent No. 40893, one part of naphthalene be heated with 5 parts
of fuming sulphuric acid (containing 40 per cent. of anhydride) at 160 degrees
centigrade, a mixture of naphthalenetetrasulphonic acid and naphthalenetrisulphonic
acid is formed, but it is to be noted that these two methods afford at least two
isomeric naphthalenetetrasulphonic acids, as Senhofer has observed (see Monatshefte
für Chemie, 3, page 111--117, and Berichte der Deutschen Chemischen Gesellschaft,
volume 15, Ref. 1080), and as my foreign correspondents have also ascertained.
It is very difficult to separate the naphthalenetetrasulphonic acids from the
aforesaid mixtures in a state of purity such as is desirable for technical purposes.
My foreign correspondents have now found a suitable method of separately
obtaining both the naphthalenetetrasulphonic acids in a pure state, iz, by using, as
initial materials, on the one hand, either naphthalene beta,-beta,-disulphonic acid,
or the naphthalene beta, beta, alpha, trisulphonic acid obtainable by sulphonating
the said naphthalene beta, betas disulphonic acid, and, on the other hand, either
naphthalene beta, beta, disulphonic acid, or the naphthalene beta, beta, alpha
trisulphonic acid obtainable by sulphonating it.
These naphthalenedi- or naphthalenetri-sulpho acids are acted on by sulphonating
agents. The sulphonation can be effected, for instance, by heating with fuming
sulphuric acid, or agents acting in the same or a similar manner, at elevated
temperatures.
This process of sulphonation is illustrated by the following examples, which,
NAPHTHALENETETRASULPHONIC ACID OBTAINED FROM NAPHTHALENE BETAI
BETA DISULPHONIC ACID.
100 parts of the calcium salt (dried at 200 degrees centigrade) of naphthalene
beta beta, disulphonic acid, are mixed with 300 parts of fuming sulphuric acid
(containing 25 per cent. of anhydride), and the resulting mixture is heated at
90 degrees centigrade, during 4 hours, a naphthalenetrisulphonic acid being thus
formed. The vessel containing the sulphonated mass is then closed, in order to
avoid loss of anhydride during the subsequent heating; the temperature is raised
to 260 degrees centigrade, and maintained at this point during 6 hours. When
cool, the mass is full of compact crystals. It is dissolved in water, and the solution
is neutralised with slaked lime. After filtering off the calcium sulphate (gypsum),
sodium carbonate is added to the filtrate, in order to convert the calcium salt into
the sodium salt. The precipitated calcium carbonate is filtered off, and the solution
of the sodium salt is evaporated until the volume is about 300 litres (in case the
above mentioned parts are kilos. by weight). On adding common salt to the
boiling solution, the sodium salt of the naphthalenetetrasulphonic acid separates
from the bot liquid as a sand-like precipitate, which is separated by filtration.
This sodium salt is obtained in colorless thick crystals on slowly evaporating its
solution in water, the crystals covering the sides of the vessel in the form of crusts.
No decompositions could be observed during this operation. Solutions of the
salts of the naphthalenetetrasulphonic acids thus produced are as clear as water,
and the yields are therefore satisfactory.
The same naphthalenetetrasulphonic acid can be produced by sulphonating
naphthalene beta, beta, alpha, trisulphonic acid, or salts thereof.

page_text: NAPHTHALENETETRASULPHONIC ACID FROM NAPHTHALENE BETA,
DISULPHONIC ACID.
BETA
If, instead of the calcium salt of naphthalene beta, beta, disulphonic acid, the
calcium salt of naphthalene beta, beta, disulphonic acid be used, and the sulphonation
and further treatment be carried out in the manner described in the above first
example, a solution of the sodium salt of a naphthalenetet rasulphonic acid is finally
obtained, the which sodium salt is much more soluble than the sodium salt of the
naphthalenetetrasulphonic acid obtained by following the directions given in the
first example. On adding barium chloride to the solution of the sodium salt of
this new naphthalenetetrasulphonic acid, and on subsequently evaporating the
solution, the barium salt separates as a white heavy precipitate, which can be
separated by filtration.
Bye-products are not formed in the process illustrated by the second example,
the yield of the new tetrasulphonic acid being satisfactory.
The same naphthalenetetrasulphonic acid can be produced by sulphonating
naphthalene beta, beta, alpha, trisulphonic acid, or salts thereof.
My foreign correspondents have further found, that the naphthalenetetrasulphonic
acid obtainable, as described in the preceding first example, from naphthalene beta,
beta, disulphonic acid, is converted by fusion with alkalies into two naphthol-
trisulphonic acids.
In order to illustrate the conversion of this naphthalenetetrasulphonic acid into
naphtholtrisulphonie acids, the following example is given, the parts being by
weight
PRODUCTION OF NAPHTHOLTRISULPHONIC ACIDS BY FUSING WITH ALKALIES
THE NAPHTHALENETETRASULPHONIC ACID OBTAINABLE FROM NAPHTHA-
LENE BETA₁ BETA, DISULPHONIC ACID.
100 parts of the sodium salt of the said naphthalenetetrasulphonic acid are mixed
with 50 parts of soda and 280 parts of water. The mixture is heated in a closed
vessel capable of withstanding pressure at 180 degrees centigrade during about
8 hours. The light yellow solution is then mixed with 125 parts of muriatic acid
(21 degrees Baumé), and evaporated until it becomes a saturated solution of common
salt. The acid sodium salts of the two new naphtholtrisulphonic acids separate at
this point.
In order to separate these two naphtholt risulphonic acids from one another, the
mixture of the acid sodium salts is filtered off, dissolved in water, and the solution
is evaporated until crystallization begins. The acid sodium salt of the one acid
crystallizes out in little white warts. It is filtered off as soon as a crystallization
of compact needles begins. These compact needles consist of the acid sodium salt
of the other acid, which subsequently separates from the filtrate. The compact
needles are separated by filtration as soon as the first mentioned acid sodium salt
again begins to separate in the said form of white warts. On several times
repeating these two processes, viz., crystallization and filtration, the two acids can
be easily separated. As a matter of course, the filtrates are concentrated, if
necessary, in order to facilitate the separation of the said two acid sodium salts."
These two naphtholtrisulphonic acids materially differ from one another, inasmuch
as alkaline solutions of the former show a blue fluorescence, while alkaline solutions
of the latter acid exhibit a green fluorescence.
According to the researches of my foreign correspondents, the naphtholtri-
sulphonic acids obtainable as described in the foregoing third example, differ from
all the naphtholtrisulphonic acids hitherto known.

page_text: Instead of the soda used in this example, potash can be used, and the operation
can also be effected in open vessels. In the latter case, a more concentrated alkali
lye is used with advantage.
My foreign correspondents have also converted the naphthalenetetrasulphonic
acid (obtainable by sulphonating naphthalene beta, beta, disulphonic acid) into
dihydroxynaphthalenedisulphonic acid, following the directions given in the
Specification of the aforementioned German Patent No. 40893, and they have
found that, when so treated, the said. tetrasulphonic acid yields two isomeric
dihydroxynaphthalenedisulphonic acids.
The process for producing these dihydroxynaphthalenedisulphonic acids is
illustrated by the following examble
CONVERSION OF NAPHTHALENETETRASULPHONIC ACID (OBTAINABLE FROM
NAPHTHALENE BETA, BETA, DISULPHONIC ACID) INTO TWO ISOMERIC
DIHYDROXYNAPHTHALENE DISULPПONIC ACIDS.
100 parts (the parts are by weight) of sodium naphthalenetetra sulphonate are
mixed with 160 parts of soda lye (containing 60 per cent. of NaOH), and the
resulting mixture is heated in a vessel capable of withstanding pressure, during
8 hours, at 200 degrees centigrade. The melted mass is dissolved in 250 parts of
muriatic acid (21 degrees Baumé) and 150 parts of water. One of the isomeric
dihydroxynaphthalenedisulphonic acids then separates in long hair-like needles,
grouped in the shape of balls. Aqueous solutions of the nentral salts of this
dihydroxynaphthalenedisulphonic acid, which ny foreign correspondents term
dihydroxynaphthalenedisulphonic acid R," show a violet fluorescence. The
amount formed of this acid is about 30
per cent.
"
The other isomeric dihydroxynaphthalenedisulphonic acid, which is termed by
my foreign correspondents "dihydroxynaphthalenedisulpbonic acid Y," remains
dissolved in the mother liquors. These mother liquors are saturated with potassium
chloride, in order to convert the sodium salt into the potassium salt, the which salt
separates in white scales, as it is less soluble than the sodium salt. The amount of
the "
'dihydroxynaphthalenedisulphonic acid Y" thus produced, is about 70 per
cent. Aqueous solutions of its neutral salts are of a deep yellow color, and show
an intense green fluorescence.
Instead of the soda used in the preceding fourth example, potash can be used;
the temperature during the melting can vary within from about 180 to 210 degrees
centigrade, and the operation may also be carried out in open vessels.
Instead of naphthalenetetrasulphonic acid, a corresponding quantity of the
naphtholtrisulphonic acids formed, as herein before described, by fusing this tetra-
sulphonic acid with alkalies, can be used.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, as communicated to me from
abroad, I declare that what I claim is :-
1. The production of naphthalenetetrasulphonic acids, which process consists in
sulphonating, on the one hand, naphthalene beta, beta, disulphonic acid, or
naphthalene beta, beta, alpha, trisulphonic acid, or salts thereof; on the other
hand, naphthalene beta, beta, disulphonic acid, or naphthalene beta, beta, alpha
trisulphonic acid, or salts thereof.
2. The process for producing two naphtholtrisulphonic acids by the action of
alkalies on the naphthalenetetrasulphonic acid (or salts thereof) which is obtainable
by sulphonating either naphthalene beta, beta, disulphonic acid, or naphthalene
beta, beta, alpha, trisulphonic acid.
3. The production of two isomeric dihydroxynaphthalenedisulphonic acids
(so-called dihydroxynaphthalenedisulphonic acid R and Y), which process consists

page_text: in heating with alkalies, at from about 180 to 240 degrees centigrade, either
naphthalenetetrasulphonic acid (obtainable from naphthalene beta, beta, disulphonic
acid, or naphthalene beta, beta, alpha, trisulphonic acid), or the naphthol-
trisulphonic acids obtainable as described in the preceding second claim, or salts
of the said naphthalenetetrasulphonic acid, or naphthol trisulphonic acids, and in
subsequently separating the two dihydroxynaphthalenedisulphonic acids thus formed,
for instance, by means of the different degrees of solubility in water of the sodium
salts thereof.
4. As new products of manufacture, the new acids prepared by the processes
bereinbefore defined, or by any other means producing the same result.
Dated this 27th day of September 1894.
NEWTON & SON,
Agents for the Applicant.

page_text: Date of Application, 30th Dec., 1893
Complete Specification Left, 29th Sept., 1894-Accepted, 3rd 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 Beta Beta, Dihydroxynaphtha-
lene Beta Beta, Disulphonic Acid.
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: :-
A new dihydroxynaphthalene disulpho acid, derived from naphthalene B₂ B,
disulpho acid, can be produced, according to the researches of my foreign corre-
spondents, by melting with alkalies the B naphthol B2 B3 B4 trisulpho acid which
results from the heating of B, naphthol a 1, B3 ß, tetrasulpho acid, with water or
acids, in order to split off the sulpho group in the position al-
As the naphthol B2 B3 ẞ, trisulpho acid used as initial material, contains all
the substituents in the positions ẞ, it could not be foreseen with certainty which of
the sulpho groups would be replaced during the melting with alkalies. The
researches of my foreign correspondents have shown, that only the sulpho group in
the position to the hydroxylic group in the position ₁ is displaced by the
hydroxylic group, as the new dihydroxynaphthalene disulpho acid possesses the
following formula:
My foreign correspondents have ascertained this formula, as the said dihydroxy-
naphthalene disulpho acid is, by splitting off the sulpho groups, converted
into B B dihydroxynaphthalene.
The following example is given in order to illustrate one method of producing
the new dihydroxynaphthalene disulpho acid. The parts are by weight.
:
PRODUCTION OF B₁ B. DIHYDROXYNAPHTHALENE 3, ẞ, DISULPHO ACID FROM
B, NAPHTHOL ẞ. Ba ẞ, TRISULPHO ACID.
50 parts of naphtholtrisulphonate of sodium are mixed with 100 parts of soda
and 50 parts of water, and the resulting mixture is heated in a closed vessel
capable of withstanding pressure, at from 220 to 300 degrees centigrade, until a hot
acidulated sample (after filtering off the separated dihydroxynaphthalene disulpho
acid), yields a filtrate from which the naphtholtrisulpho acid no longer separates in
little needles, which usually occurs after from 6 to 10 hours. If this stage be
arrived at, the melted mass is acidulated. The acid sodium salt of the so formed
new dihydroxynaphthalene disulpho acid separates as a crystalline powder, even
from the hot solution.
The acid sodium salt easily dissolves in hot water, whilst it is soluble with
difficulty in solutions of common salt, or in alcohol, even at elevated temperatures.
The acid sodium salt of the new dihydroxynaphthalene disulpho acid does not
contain water of crystallization, and possesses the composition corresponding to the

page_text: normal formula, for my foreign correspondents have found, that the sodium salt
contains 13-01 and 12.96 per cent of sodium, whilst the theoretical amount of sodium
is 12.96 per cent, according to the formula CH, (OH), (SO,Na),
The alkaline solutions show a bluish-green fluorescence. The normal potassium
salt very readily crystallises, and in large brilliant needles, on cooling its hot
watery solutions, which needles easily dissolve in hot water. The barium salt is a
precipitate soluble with very great difficulty. The dilute watery solutions of the
alkaline salts, after adding ferric chloride, assume a deep blue color, which
disappears on adding muriatic acid. An addition of a small quantity of chloride of
lime produces an orange color, whilst a brownish color results ou using a greater
quantity of chloride of lime, and a great excess of this reagent renders the liquid
first clear and then cloudy, a white precipitate being separated. Nitrous acid,
when introduced into the acidulated solutions, effects the precipitation of a reddish
yellow nitroso compound soluble with difficulty.
If the new dihydroxynaphthalene disulpho acid is heated with sulphuric acid
(20 per cent.), at 200 degrees centigrade, ẞ, ẞ, dihydroxynaphthalene, melting at
185 degrees centigrade, is readily formed. The new acid can be combined in
solutions rendered alkaline by means of sodium carbonate, with one molecule of
diazo benzene chloride, a brown dye-stuff being thus formed.
The directions given in the above example can be varied; potassa can be used in
place of soda, and the melting process can also be carried out in open vessels.
Dated this 21st day of February 1894.
NEWTON & SON,
Agents for the Applicant.
COMPLETE SPECIFICATION.
The Manufacture or Production of Beta Beta, Dihydroxynaphtha-
lene Beta Beta, Disulphonic Acid.
I HENRY EDWARD NEWTON of The Office for Patents, 6 Bream's Buildings,
Chancery Lane in the County of Lordon, 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 :-
The researches of my foreign correspondents show that beta, beta, dihydroxy-
naphthalene beta, beta, disulphonic acid can be produced by the action of alkalies
on the beta, naphthol beta, beta, beta, trisulphonic acid formed on heating beta,
naphthol alpha, beta, beta, beta, tetrasulphonic acid with diluted acids, whereby the
sulphonic group in the alpha, position is split off.
As beta, naphthol beta, beta, beta, trisulphonic acid contains all its substituents
in beta positions, it could not be foreseen with certainty, which of the sulphonic
groups would be displaced on fusing it with alkalies. The researches of my
foreign correspondents show, that only the sulphonic group in the beta, position
relatively to the hydroxyl group in the beta, position, is displaced by hydroxyl,
and that the dihydroxynaphthalene disulphonic acid which is thus formed, possesses
the following formula :-
My foreign correspondents infer this formula from the fact that the said 45
dihydroxynaphthalene disulphonic acid is converted into beta, beta dihydroxy-
naphthalene when the sulphonic groups are removed from it.

page_text: The following example is given in order to illustrate one method of producing
the said dihydroxynaphthalene disulphonic acid. The parts are by weight:
PRODUCTION OF BETAL BETA, DIHYDROXYNAPHTHALENE BETA, BETA, DISUL-
PHONIC ACID FROM BETA NAPHTHOL BETA, BETA BETA TRISULPHONIC.
ACID.
50 parts of sodium beta naphthol trisulphonate are mixed with 100 parts of
caustic soda and 50 parts of water and the mixture is heated in a closed vessel
capable of withstanding pressure, at from 220 to 300 degrees centigrade, until, on
filtering off the dihydroxynaphthalene disulphonic acid which separates on acidu-
lating a hot solution of a sample, a filtrate is obtained from which, on cooling,
naphtholtrisulphonic acid no longer separates in little needles. This is usually
the case after from 6 to 10 hours. When this stage is arrived at, the melted
mass is mixed with acid. The acid sodium salt of the dihydroxynaphthalene
disulphonic acid thus formed separates as a crystalline powder even from a hot
solution.
This acid sodium salt easily dissolves in hot water, whilst it is with difficulty
soluble in solutions of common salt, or in alcohol, even at elevated temperatures.
It does not contain water of crystallization, but corresponds in composition to the
normal formula CH, (OH), (SO,Na), as it is found to contain 13-01 and
12.96 per cent. of sodium, the theoretical amount being 12.96 per cent.
Its alkaline solutions shew a bluish-green fluorescence. The analogous
potassium salt crystallises very readily on cooling hot aqueous solutions in large
brilliant needles, which easily dissolve in hot water. The barium salt is very
difficultly soluble.
On adding ferric chloride to dilute aqueous solutions of alkaline salts of the
dihydroxynaphthalene disulphonic acid, they assume a deep blue colour, which
disappears on adding muriatic acid. An addition of a small quantity of chloride
of lime produces an orange colour, whilst a brownish colour is produced on using a
greater quantity; a great excess of this agent renders the liquid first clear and
then cloudy, a white precipitate finally separating. On adding nitrous acid to an
acidulated solution, a difficultly soluble reddish-yellow nitroso compound is
precipitated.
As above mentioned, on heating this dihydroxynaphthalene disulphonic acid with
sulphuric acid (20 per cent.) at 200 degrees centigrade, it is transformed into beta,
beta, dihydroxynaphthalene, melting at 185 degrees centigrade. A brown dye
stuff is obtained on combining molecular proportions of the said dihydroxy-
naphthalene disulphonic acid and diazo benzene chloride in a solution rendered
alkaline by means of sodium carbonate.
The directions given in the above example can be varied; for instance, potash
can be used in place of soda, and the melting process can also be carried out in open
vessels.
My foreign correspondents were at first of opinion that the dihydroxynaphthalene
disulphonic acid obtainable as hereinbefore defined was a new dihydroxynaphthalene
disulphonic acid, but their further researches have shewn that it is identical with
the 2-7 dihydroxynaphthalene disulphonic acid (beta, beta, dihydroxynaphthalene
disulphonic acid) which is formed on sulphonating 2-7 dihydroxynaphthalene (beta
beta, dihydroxynaphthalene) described in the Berichte der Deutschen Chemischen
Gesellchaft, volume 13, page 1959, and volume 14, page 2208, and as mentioned in
the Specification of Letters Patent No. 16199, dated 28th August 1893. It is also
clearly ascertained by these researches of my foreign correspondents, that the said
dihydroxynaphthalene disulphonic acid formed by the sulphonation of beta, beta
dihydroxynaphthalene, is beta, beta, dihydroxynaphthalene beta, beta, disulphonic
acid.

page_text: 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, I declare that what I claim is :-
The process for producing beta, beta dihydroxynaphthalene beta, beta,
disulphonic acid, which process consists in heating beta, naphthol beta, beta, beta
trisulphonic acid, or salts thereof, with alkalies, at from 200 to 300 degrees
centigrade.
Dated this 29th day of September 1894.
NEWTON & SON,
Agents for the Applicant.