IMPROVEMENTS IN THE MANUFACTURE OF COLOURING MATTERS SUITABLE FOR DYEING AND PRINTING
Year: 1882

page_text: LETTERS PATENT to Joseph Anthony Dixon, of 151, St. Vincent Street,
Glasgow, in the County of Lanark, North Britain, Solicitor, for an Invention
of "IMPROVEMENTS IN THE MANUFACTURE OF COLOURING MATTERS
SUITABLE FOR DYEING AND PRINTING," A communication from abroad
by Carl Rumpff, of Elberfeld, in the Empire of Germany, Manufacturing
Chomist.
PROVISIONAL SPECIFICATION left by the said Joseph Anthony Dixon at
the Office of the Commissioners of Patents on the 30th January 1882.
JOSEPH ANTHONY DIXON of 151 St. Vincent Street, Glasgow, in the County
of Lanark, North Britain, Solicitor. "IMPROVEMENTS IN THE Manufacture of
COLOURING MATTERS SUITABLE FOR DYEING AND PRINTING." [A communication
from abroad by Carl Rumpff, of Elberfeld in the Empire of Germany, Manufacturing
Chemist.]
The Invention hereinafter described rests on the newly discovered fact that the
sulpho acids of the napthylamines, on treatment with nitrous acid in neutral, or
very slightly acid, aqueous solution, yield valuable water soluble brown dyestuffs,
which dye wools and silks fast against soap and light and are distinguished by
their very great dyeing power. It is well known that the amido sulphonic acids
of the napthalene series, by treatment with nitrous acid in acid solution (one
molecule of amido-sulphonic acid and two molecules of any mineral acid), pass over
into the corresponding diazo napthalene sulphonic acids which are wholly colourless
bodies. But the process runs differently if nitrous acid acts in neutral or very
slightly acid (by preference acetic acid) solution on the amido sulphonic acids in
question. In this case the reaction appears to take such a course, that (as with
the napthylamines themselves)-amido-azo bodies (namely, amido-azo napthalene
sulphonic acids) are produced direct, which, like all amido-azo compounds, possess

page_text: colouring properties and may form dyestuffs. The following equation may
illustrate the reaction,-
In the following paragraphs I describe by way of example the preparation
of the colouring matter or dyestuff from alpha-napthylamine sulphonic acid,
namely:
100 lbs. of alpha-naphthylamine sulphonate of soda and 14 lbs. of nitrito of
sodium are dissolved in 800 lbs. of water, and then there is very gradually added
so much of any suitable dilute acid (by preference acetic acid diluted with about
10 parts of water to one of absolute acid) as is necessary for decomposing the
nitrite of sodium. The solution becomes at once coloured deep brown and after
standing for one or two days the reaction is finished.
The dyestuff or colouring matter may be precipitated with diluto sulphuric
acid or hydrochloric acid, or the whole solution may be evaporated down to
dryness.
Instead of the nitrite of sodium free nitrous acid may also be made to react on
the solution of the sodium salt of the amido-napthalene sulphonic acid, or I can
"bring together one molecule of diazo napthalene-sulpho-acid with one.molecule of
amido napthalene sulpho acid in neutral solution.
Within the expressions napthylamine, or the napthylamines, I include in the
most prominent way alpha and beta napthylamine and methyl napthylamine.
The different methods of preparing the amido napthalene sulpho acids are well
known, but I recommend as inost suitable that which is based on the direct
heating of the napthylamine with from two to five parts of oil of vitriol at from
60° to 150° centegrade.
There are formed, according to the temperature and the amount of sulphuric
acid applied, isomeric mono or di sulpho-acids the whole of which yield brown
dyestuffs of different nuances or shades.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Joseph Anthony Dixon in the Great Seal Patent Office on the 24th
June 1882.
JOSEPH ANTHONY DIXON, of 151 St. Vincent Street, Glasgow, in the County
of Lanark, North Britain, Solicitor, "IMPROVEMENTS IN THE MANUFACTURE OF
COLOURING MATTERS SUITable for DyEING AND PRINTING." A communication
from abroad by Carl Rumpff of Elberfeld, in the Empire of Germany, Manufacturing
Chemist,
The Invention hereinafter described consists in the production, by means of a
reaction or combination effected in neutral or very slightly or weakly acid solutions
as hereinafter described, of colouring matters or dyestuff's which may in chemical
language be denominated the sulpho-acids of amido-azo derivatives of the
napthylamines (using napthylamines in the sense hereinafter explained); and the
processes hereinafter described for the production thereof rest on the newly dis-
covered fact that the sulpho-acids of the napthylamines, on treatment with nitrous
acid in neutral or in only very slightly acid aqueous solution, yield sulpho acids of
amido-azo napthaline, which possess great tinctorial powers, and are suited to form
valuable water soluble brown dyestuffs with which to dye wools and silks fast
against soap and light, and on the fact also newly discovered that an analagous
behaviour is exhibited in the case of the napthylamines themselves. It is well
known that the amido sulphonic acids of the napthalene series (to take these as an
instance) when treated with nitrous acid in a strongly acid solution (such as a
solution containing one molecule of amido sulphonic acid and two molecules of any
mineral acid such as sulphuric or bydrochloric acid) pass over into the corre-
sponding diazo napthalene sulpho acids, and diazo amido napthalene sulpho acids,
which are wholly colorless bodies.-But if the nitrous acid acts on the amido
sulphonic acid in a neutral solution or only a very feeble or slightly acid solution
such as the acetic acid solution, or the solution given in the illustration of the
process hereinafter contained, the reaction runs a different course.-If an acetic
acid solution is used (and I prefer to use such a solution) some excess of the acid
does not interfere injuriously with the reaction because acetic acid is a very weak
acid. In the case of a noutral or very slightly acid solution, the reaction appears
to take such a course that amido-azo bodies are produced direct, that is to say, in
the case of an amido sulpho napthalene treated with nitrous acid in neutral or
very weak acid solution the product, which is instantly, or almost instantaneously
formed, and which appears also to be formed immediately and directly (that is to
say without the formation of any intermediate body) is an amido azo napthalene
sulphonic acid.-In the case of the napthylamines or amido-napthalanes themselves,
as well as in that of their sulpho acids, nitrous acid produces the same kind of
reaction, that is to say, in the case of a napthylamine treated with nitrous acid in
neutral or very slightly acid solution, the product is an amido azo napthalene,
which comes or at least appears to come into existence at once without the
formation of any intermediate body. Like all amido-azo bodies, these amido-azo
and sulpho amido-azo derivatives of napthalene possess colouring properties and
may form dyestuffs.-The amido-azo dyestuffs, however, in order to form readily-
water-soluble, fast, and convenient dyestuffs require to be subsequently sulphonated,
or converted into sulpho amido-azo bodies, and it is the production of such sulpho
amido-azo bodies as dyestuffs by means of the new reaction in neutral or very
feebly acid solution, and whether that reaction takes place after or before
sulphonization, or whether the sulphonization partly precedes and partly follow
the reaction, that constitutes the subject of this Invention.

page_text: Taking the case of an amido sulpho napthalene for the sake of illustrating the
reaction by which the said amido-azo bodies, whether sulphonated or not-are
produced, I explain that the action of the nitrous acid in neutral or very weak or
slightly acid solution on a sulpho acid of an amido napthalene-(preferably used
in the form of its sodium salt)gives rise in the first instance by a re-arrangement
of molecules, the type or course of which is familiar to chemists,-to water and to
the sulpho acid of diazo-amido-napthalene (in the form of course of its sodium salt
if the amido sulpho acid has been used in that form.) The course of the process, so
far, is no doubt this, that by the action of the nitrous acid a certain portion of
amido sulphonapthalene is converted into diazo sulpho napthalene, which at once
reacts on and combines with an equivalent of the still unconverted or non-
diazotized amido sulpho napthalene in its presence, and forms a diazo-amido-
napthalene sulpho acid, or more precisely in the case in question, forms diazo-sulpho-
napthalene-amido-sulpho-napthalene. The successive steps of the reaction aro
expressed in the following equations :—
ᏚᏅ 1
(1) 2 (C• H.NH,H)+ ENO=E_O+C% HNN-CHÁNH
(Sulpho acid of amido
napthalene)
(nitrous acid) (water)
(diazo sulpho
napthalene)
H²
(sulpho acid of amido
napthalene)
(3) C₁ H‹Ñ=N_N‹Ñ„ H, SO³ H=C„ H‹Ñ=NC H¸ \N H
(diazo sulphonapthalene amido
sulpho napthalene)
(sulphonapthalene azo sulpho amido
napthalene.)
Of course if the potassium or sodium salts are used instead of the freo sulpho
acids the products will be in the form of the corresponding salts. The course of
the reaction is not affected by the presence or absence of the sulpho group. Non-
sulphonated amido napthalene treated with nitrous acid in a similar solution gives
the diazo-amido-napthalene which transforms itself into the amido-azo body, exactly
as if the sulpho group were present, and, one or more sulpho groups being added
by means well known to chemists, the product will be a sulpho acid of amido-
azo-napthalene of the same general character as the other.
It will be obvious to any chemists from this explanation that the same product
as is obtained from amido sulpho napthalene according to the series of reactions
expressed by the preceding equations will be obtained by bringing together in
neutral or very feeble or slightly acid solution one molecule of a diazo-napthalene-
sulpho acid; or its salt, prepared in one vessel, with one molecule of amido-
napthalene-sulpho acid, or its salt prepared in a separato vessel.
Further from the statement that the napthylamines, as well as their sulpho acids,
behave (as is hereinbefore mentioned) in neutral or very feeble or very slightly
acid solutions in the same way as their sulpho acids, it will be readily understood
by chemists that similar sulpho acids of amido-azo-napthalene may be prepared by
first acting on a napthylamine in such a solution as aforesaid with nitrous acid
and then sulphonating the amido-azo product afterwards-the temperature, amount,
and strength of sulphuric acid employed determining in manner well known to
chemists whether such product bo a mono or disulpho acid. It will be readily
understood that the napthylamine may be diazotised separately, and then
napthylamine may be added to it, and the product sulphonated: and also that in

page_text: the case above mentioned, wherein the diazo-sulpho-napthalene, and the amido-
sulpho-napthalene are prepared in separate vessels and then brought into com-
bination, though either the diazo body or the amido body should be non-sulphonated,
yet if the other be sulphonated, a sulpho acid of amido-azo-napthalene will bo
obtained, and that this product again, if desired, may be further sulphonated. As
both napthylamine and its sulpho acids when treated with nitrous acid in a neutral
or feebly acid solution run the same course of reaction in yielding an amido azo
instead of a diazo-amido body and as it is (except as regards in some cases a slight
modification of shado) immaterial whether the sulpho group or groups be introduced
at an earlier or a later stage of the process for producing the amido azo sulpho acids
which constitute the now dyestuffs the variations of procedure above mentioned
are all substantially equivalent; the main difference being that there may be only
one, or there may be more, sulpho groups in the product, and that, even though tho
number of the sulpho group or groups may be the same, the position or positions
of such sulpho group or groups in the compound produced may or may not be
identical. Similar variations as regards the number and position of the sulpho
group or groups may also arise from the different methods of preparing the
napthylamine sulpho acids as hereinafter mentioned. But these variations do not
alter the substantial identity of the reaction by which the said sulpho acids of
amido-azo-napthalene are produced, as resting on the fact that it takes place in a
neutral or feebly acid solution, nor does it alter the general identity of chemical
character in the products as all sulpho acids of amido azo napthalene. In liko
manner the use of the alpha or the beta napthylamine or methyl-napthylamine as
hereinafter mentioned, though the products will not be identical, does not
materially affect the reaction, nor the nature of its products as amido-azo and not
diazo-amido bodies, nor indeed their general character, and qualities, as suited for
dyeing and printing.
NH
Within the expression napthylamine or the napthylamines in this Specification
I include the N H derivatives of napthalene, whether there be further substitution
of the nucleal hydrogen by other groups or molecules or not, and particularly besides
napthylamine, alpha, and beta, I include methyl-napthylamine (C, H. CH³
and phenyl napthylamine, and like alkyl-substituted napthylamines. Any of the
napthylamines included in this definition may be used in forming the azo coupled
compounds either as the source of the diazo member, or as the amido member, or as
both.
The different methods of preparing the amido napthalene or napthylamine-
sulpho acids are well known as by the direct action of sulphuric acid on
napthylamine; or from nitro napthalene by digestion with sulphite of ammonia; or
by reduction from the nitro napthalene sulpho acids (which again are produced as
well from nitro napthalene as from the napthalenic sulpho acids). The isomeric
amido-sulpho acids obtained by these different methods are well known to vary in
many particulars, but more especially in respect of their various degrees of solubility
in water. I prefer to recommend, as the best and most suitable method, that which
is based on the direct heating of the napthylamine with two to three parts of oil of
vitriol at from 60° to 150° centigrade. According to the temperaturo and the
quantity of sulphuric acid applied isomeric mono-or di-sulpho acids are obtained,
which yield all of them brown colours of various nuances or shades.
According to the variations in the number of sulpho groups in the sulphonated
amido azo bodies produced in manner above mentioned, and in the positions of the
sulpho group or groups in the same, or in the two different members united by the
azo copula, and according also to the different isomeric napthylamines and the
modes of preparing the amido sulpho acids employed,-there will be differences in
the shades of dyestuffs produced. It is not necessary in any case that the solution
should be acid; it is enough that it be neutral though a slight leaning towards
acidity, especially with a weak acid like acetic acid, will not make any appreciable
alteration in the course of the re-action or at all events will not prevent the amido

page_text: -azo body from forming. It is not necessary to use nitrite of sodium-free nitrous
acid may also be used in solutions of the salts of the amido napthalene sulpho
acids.
I shall now describe by way of illustration the process or method of procedure
which I prefer to follow in producing a brown dyestuff from the mono sulphonic
acid of alpha napthylamine, and I take here an example of a neutral solution-
100 lbs of alpha napthylamine sulphonate of soda and 14 lbs: of nitrite of sodium
are dissolved in 800 lbs: of water, and then there is very gradually added
just so much of any suitable dilute acid (by preference acetic acid diluted with
about ten parts of water to one of absolute acid) as is necessary for decom-
posing the nitrite of sodium. The solution becomes at once coloured deep dark
brown, and after standing for one or two days the reaction is finished. The
cooler the solutions are kept the better. The dyestuff or colouring matter may
be precipitated with dilute sulphuric or hydrochloric acid or the whole solution
may be evaporated down to dryness. The composition of this brown dyestuff is
SO³ Na
"SO³ Na
NH
C₁₂ H
N = N – C H
*—It is consequently the sodium salt
of a di-sulpho acid of amido azo napthalene or more precisely the sodium salt of
sulpho-napthalene-azo-sulpho-amido-napthalene.
With reference to the preceding example I may observe that if, instead of a
sulpho acid of napthylamine, I had diazotised napthylamine, and had then poured
the diazotized body into a solution of napthylamine with the view of subsequently
sulphonating the product, I should find it best to form an acid solution of the
napthylamine which is difficult of solution in water. Its salts, as for example, the
hydrochlorate, are much more readily soluble in water, and therefore I should have
taken the solution of the hydrochlorate, or some other similar salt. If I added to
the napthylamine only so much hydrochloric acid as would forin the hydrochlorate,
the solution would be neutral; but I find that some little excess even of a mineral
acid beyond what is needed to effect the formation of the hydrochlorate or other
salt, does not prevent the desired reaction. But especially with mineral acids, it is
requisite to be cautious in guarding against any very considerable excess of free
acid. By an acid solution of napthylamine, I mean a solution of it in water, to
which so much acid is added, to render it (the napthylamine) more readily soluble,
as is required to convert the napthylamine into its corresponding salt, and if a
little more acid be present, it will not be injurions. In any caso of doubt a
preliminary experiment will easily determine whether such an excess of acid bas
been used as to prevent, on addition of the diazotised body, the formation of the
coloured amido azo body, or determine the formation of the colourless diazo amido
body only.
I give another example of the mode of producing another brown dyestuff, or sct
of dyestuffs by the action of diazo napthalene sulphonate of soda on napthylamine
in an acid solution. I take 50 lbs. of alpha- or beta-napthylamine sulphonato
of soda, dissolved in 500 lbs. of water, and cooled down with ice to 3° centigrade.
To this solution I add slowly 75 lbs. of muriatic acid and thereafter 11 lbs. of
sodium nitrito dissolved in 40 lbs. of water. After standing for several
hours the liquid is poured into a solution containing 25 lbs. of napthylamine,
50 lbs. of muriatic acid, and 500 lbs. of water. The brown dyestuff separates
instantly as a voluminous precipitate, which is filtered and dried. This dyestuff
is, from the constituents which enter into it, obviously of the following formula
"SO³ Na
C10 Ho
N = N-C, H, NH,
and is consequently the sodium salt of a mono
sulpho acid of amido-azo-napthalene, or more precisely, of sulpho-napthalene-
azo-amido-napthalene. This product may be further sulphonated, as already
mentioned. The aqueous solution of said dyestuff becomes yellowish brown by
the addition of alkalis, blueish red by addition of concentrated mineral acids, and
the dyestuff separates partially. It dyes silk and wool in an acidulated bath, and

page_text: is fast against soap and light. The solutions however need not be acid; they may
quite as well be kept neutral without any essential difference appearing in the
course of the reaction or process.
Having now described and particularly ascertained the nature of the said
Invention and the manner in which the same is or may be carried into effect, I
would observe in conclusion that what I consider novel and original, and there-
fore claim as the Invention secured to me by the hereinbefore in part recited
Letters Patent, is―
The production of dyestuffs, which may be described as sulpho acids of amido
azo derivatives of the napthylamines, or salts thereof, by causing the diazo
derivatives obtained by the action of nitrous acid from any of the napthylamines,
sulphonated or non-sulphonated, or their salts, to combine with any of the
napthylamines, sulphonated or non-sulphonated, or their salts, in neutral or in
very feebly acid solution; the product of the reaction, when both of the re-agents
are non-sulphonated, being afterwards sulphonated, and the product of the reaction,
when only one of the re-agents is sulphonated, being afterwards further sulphonated
or not as desired-all as herein before described and substantially in the manner,
and by the processes herein before described.
In witness whereof I the said Joseph Anthony Dixon, have hereunto set my
hand and seal this Eighteenth day of May in the year of our Lord Ono
thousand eight hundred and eighty two.