IMPROVEMENTS IN RED DYE-STUFFS SUITABLE FOR DYEING AND PRINTING
Year: 1883

page_text: LETTERS PATENT to Sydney Pitt of Sutton in the County of Surrey for an
"
Invention of "IMPROVEMENTS IN RED DYE-STUFFS SUITABLE FOR DYEING
AND PRINTING communicated to him from abroad by Verein chemischer
Fabriken of Mannheim in the Empire of Germany
PROVISIONAL SPECIFICATION left by the said Sydney Pitt at the Office
of the Commissioners of Patents on the 2nd May 1883.
"
SYDNEY PITT of Sutton in the County of Surrey "IMPROVEMENTS IN RED
DYE-STUFFS SUITABLE FOR DYEING AND PRINTING [communicated to him
from abroad by Verein chemischer Fabriken of Mannheim in the Empire of
Germany]
This invention has for its object improvements in red dye-stuffs suitable for
dyeing and printing.
These new dye-stuffs form a group of the large class of compounds known to
chemists under the name of azo-compounds. All azo-compounds of a red shade
which have hitherto been prepared are derivatives of B-Naphtol (Beta-Naphtol).
The new dye-stuffs which form the subject of this specification are derived on the
contrary from a Naphtol (alphanaptol).
To prepare these substances we take the salts of alphanaphtolsulfonic acids, the
preparation of which is herein described and we react upon them with the diazo-
derivatives of any or either of the following aromatic bases:-Aniline, Toluidine
either Ortho- or Para-), ortho or Metaxylidine Alpha or Betanaphtylamine,
amidoaethylxylene (prepared by molecular transformation of aethylxylidine)
cumidine, mesidine (the latter both prepared either from coal tar or by mole-
cular transformation) benzidine, amidoazobenzene, amidoazotoluene, amidoazo-
naphtalene.
Instead of these bases, their sulpho derivatives may be used with equal
success.
According to the diazo compounds chosen the shade of the dye-stuff obtained
varies from a red orange to a deep bluish purple. The derivatives of xylidine

page_text: and amidoaethylxylene are the most important ones as they are of a pure scarlet
shade.
The alpha-naphtolmonosulphonic acid which we use for these reactions may be
prepared in the following ways.
1. If a naphtol be sulphorrated at a low temperature a small quantity of the
acid suitable for our purposes is formed and may be extracted by means of alcohol
from the mixture of the crude sodium salts.
2. We prefer however to prepare a suitable naphtolsulfonate by the following
process starting from alpha naphtylamine.
Alphanaphtylamine is transformed into one of its sulfo derivatives either by
heating it with an excess of sulphuric acid or by heating it with only one
molecule of sulphuric acid to 140° or by introducing its hydrochloride into fuming
sulphuric acid In all these cases différent sulpho derivatives are formed all of
which however are equally suitable for our purposes. The acid formed by
heating naphtylamine with a theoretical quantity of sulphuric acid may also be
prepared from nitronaphtalene according to the process described by Piria.
The naphtylaminesulphonic acids prepared by any or either of these methods or
a mixture of them may be transformed into alphanaphtolsulphonic acids suitable
for our purposes in the following manner.
They are first transformed into their diazo compounds, by treating thein with
nitrous acid. These diazo-compounds are boiled with water, acidulated with
sulphuric acid, until all evolution of nitrogen ceases; the solution now contains
the acids sought for which may be converted into sodium salts and acted
upon with the diazo-compounds" already named. The dye-stuffs are formed
immediately and may be salted out, pressed, dryed and delivered into the
market.
The following description is intended as an example of the manner in which we
work.
To prepare the acid we take 143 lbs of alphanaphtylamine and treat it with
98 lbs of sulphuric acid of 100% until the mass is quite soluble in caustic soda.
We then dissolve it in a quantity of caustic soda solution containing 40 lbs of
pure caustic soda. We allow to cool down to the ordinary temperature when we
add, first
200 lbs hydrochloric acid of 36.5%, and then
69 lbs sodium nitrite dissolved in 100 gallons of water. We then collect the
yellow precipitate formed which constitutes the diazo compound referred to, and
introduce it into a boiling mixture of 50 lbs sulphuric acid and 100 gallons of
water.
When no more nitrogen is given off we saturate with quicklime and
transform the lime salt into the sodium salt by double decomposition with sodium
carbonate.
(
To prepare a scarlet dye, we take a solution containing 25 lbs of the sodium
alphanaphtolsulphonate prepared as above, we cool it well and add to it the
solution of 17 lbs diazometaxylene (prepared from metaxylidine in a manner well
known to chemists.
A red precipitate is formed immediately, we facilitate the reaction by keeping
the mixture slightly alcaline and when the formation of the dye-stuff is complete
galt it out press and dry it

page_text: Amidoazonapthalene
or the sulpho acids of any or either of the above named bases.
According to the nature of the diazo compound chosen the shade of the dye-stuff
obtained varies from a reddish orange to a deep bluish purple. The derivatives of
xylidine and amidoaethylxylene are the most important ones as they are of a pure
scarlet shade. As an example we will describe the production of a scarlet from a
naphtolsulphonic acid and xylidine.
In a wooden vat
24-6 lbs of the sodium salt of one of the a naphtolsulphonic acids prepared as
described hereafter are dissolved in 24 gallons of water. A golution of caustic soda
containing 4 lbs of sodic hydrate is then added and the mixture cooled down with
ice to a temperature not exceeding 5° Centigrade. We then add under constant
stirring a solution 16-8 lbs diezoxylene chloride freshly prepared from xyliding in a
manner well known to chemists, The dye-stuff is formed at once, it may after a

page_text: while be precipitated with salt, filtered, pressed, purified by redissolving it in
boiling water and precipitating with salt water, filtering and drying. It is then
ready to be delivered into the market.
The preparation of other dye-stuffs from other bases is exactly similar to the one
described.
The alpha-naphtol-sulphonic acids which we use for these reactions may be
prepared by different methods.
If a naphtol be sulphonated with either ordinary or fuming sulphuric acid
especially at a low temperature several isomerides are formed one of which is
suitable for producing the new red dye-stuffs. To separate it from its isomerides
which are formed at the same time it is necessary to transform the crude acids
into their sodium salts and to treat these with boiling alcohol which dissolves the
compound required while the useless isomerides remain insoluble.
To prepare the
proper compounds in a regular and practical manner The following method is
referred.
First stage.
The necessary alphanaphty laminsulphonic acids may be obtained by three
different methods all of which are practically useful, the three alphanaphtylamin-
sulphonic acids obtained by these three methods are isomeric but not identical;
they are all capable of undergoing the same transformations in the second and
third stage of the process and the three isomeric alphanaphtolsulphonic acids to
which they give rise are all capable of being transformed into red dye-stuffs by
being reacted upon with diazo compounds as above described.
The first of these acids may be prepared by the method described by Nevile and
Winther, viz, heating of naphtylamine with a theoretical quantity of ordinary
sulphuric acid to 150-180° C. It is identical with the acid described by Piria
and obtained by him from the action of ammonium bisulphite upon nitronaphtaline;
for practical work however Nevile and Winther's method is preferable and in using
it we proceed as follows:-
'
143 lbs alphanaphtylamine are intimately mixed with 98 lbs sulphuric acid,
containing 100% sulphuric hydrate (H, SO.)
This mixture is heated in an oven to 150-180° C until a sample drawn from it
is completely soluble in weak caustic soda solution. It is then dissolved in milk
of lime, soda solution or any other suitable alkaline liquid and purified by
crystallization. The sodium salt of the naphtionic acid thus obtained crystallises
in beautiful prisms containing 4 molecules of water of crystallization.
Another acid suitable for these purposes may be obtained in the following
manner:-
100 lbs of alphanaphtylamine are dissolved in 400-500 lbs ordinary sulphuric
acid and heated to 100-120° C until a sample drawn from the mixture is

page_text: perfectly soluble in weak caustic soda solution. It is then poured into an excess
of water when the acid formed separates out and may be collected by filtration.
This acid is different from the one before described. Its calcium salt crystallises
with 7 molecules of water. "Its sodium salt forms lustrous white leaflets containing
5 molecules of crystallization.
TEME
The third acid capable of being used in the process may be prepared in the
following manner; Y
.
143 lbs naphtylamine are transformed into their hydrochloride by mixing them
with 100 lbs bydrochloric acid of 36-5° and drying until all the water is driven
off. The salt thus obtained is then introduced gradually and under constant
stirring and cooling into 400 lbs of fuming sulphuric acid containing 20-22° free
sulphuric anhydride. When all the salt is stirred in, the mixture is poured into
water and the acid which separates out, collected by filtration. The calcium salt
of this acid is similar in outward appearance to the one obtained by the second
process; it contains however 9 molecules of water and I therefore consider it as an
isomeric modification.
The invention is not limited to the exact proportions or temperatures given in
the above examples, nor to the use of any or either of the acids described; they
may be used either pure or mixed as the subsequent treatment to which they are
subiected is identical for all of them.
The alphanaphty laminsulphonic acids obtained by the methods above described
are transformed into their diazo derivatives. Although this is a process well
known to all chemists we will give as an example a description of the manner in
which we proceed :-
223 lbs naphtylaminsulphonic acid (or a corresponding quantity of a salt of the
same together with sufficient of a mineral acid to decompose it) are mixed with
200 gallons of water, taking care to have the acid in a state of the finest division.
An excess of hydrochloric acid, say 200-250 lbs of the ordinary acid of commerce
is then added. The mixture is kept in constant motion by a mechanical stirrer
and a solution of 69 lbs sodic nitrite in 50 gallons of water added gradually and
slowly, taking care that the temperature of the liquid does not exceed 10° C. The
diazo compound separates out after a while in the shape of heavy yellow powder
which may be collected by filtration.
The diazo compound prepared by the above or any other method suitable for
the purpose is introduced gradually into weak boiling sulphuric acid containing
2-5% H. SO, and the boiling continued until all is dissolved and no more
nitrogen gas given off from the boiling liquid.
Or the diazo compound may be mixed with the weak sulphuric acid until a thin
paste is obtained which is then gradually raised to the boil until all evolution of
nitrogen ceases. Or any other of the well known methods for transforming diazo
compounds into their corresponding phenols may be adopted.
The liquid thus obtained is treated with lime in order to remove the sulphuric
acid and obtain the calcium salt of the naphtol sulphonic acid; the calcium salt is
then transformed into the sodium salt by treating it with the necessary quantity
of sodic carbonate. The solution of the sodium salt may either be evaporated to
dryness or used directly for preparing the dye-stuffs as described in the beginning
of this specification.
Having thus described the nature of the said invention and the manner of
performing the same I would bave it understood that I claim :-
First The new dye-stuffs, the preparation of which has been described,

page_text: Second-The manufacture of dye-stuffs from alphanaphtolsulphonic acids and
the diazo derivatives or aromatic bases as herein described.
In witness whereof I the said Sydney Pitt have hereunto set my hand and seal
this twenty seventh day of October in the year of our Lord One thousand eight
hundred and eighty three.