A Process for the Manufacture of Compounds of the Series of the Indoxylic Acids, and of Dye-stuffs of the Indigo-series.
Year: 1896

page_text: Date of Application, 9th Sept., 1896
Complete Specification Left, 9th June, 1897-Accepted, 31st July, 1897
A Process for the Manufacture of Compounds of the Series of the
Indoxylic Acids, and of Dye-stuffs of the Indigo-series.
I, RUBIN BLANK, of 53 Luisen-Ufer, Berlin, in the Empire of Germany, Doctor of
Philosophy and Chemist, do hereby declare the nature of this invention to be as
follows:-
On allowing primary or secondary aromatic (cyclic) amines to act upon bromo- or
chloromalonic acid or upon their esters or salts, aromatic amidomalonic acids or their
esters or salts are produced, while hydrohalogen is separated, according to the
equation.
In this equation: "ar R" is any one aromatic radical, as for instance: phenyl,
10 naphthyl, anthryl and their derivatives; "Y" indicates any single valuable group of
atoms or hydrogen; "X" indicates an atom of halogen; "R" indicates alkyl or
hydrogen or an atom of metal.
The essential feature of the present invention is to be seen in the use of the
aromatic emidomalonic acids, their salts and esters for the manufacture of indoxylic
5 acid and its derivatives.
The reaction takes place according to the following
CO₂R
C. NY.CH
CH
CO₂R
C-NY
-
ROH
=====
C CH. CO₂R,
CO
20 water or alcohol being separated.
This condensing reaction is effected generally by heating with or without condensing
agents.
In this reaction it is unessential which aromatic radical is combined with the
amidomalonic acid or its salts and esters, and further whether the third atom of
hydrogen of the amine is substituted by any one single valuable group of atoms
or not.
5 In an analogous manner aromatic di-and polyamines can be used, two or more
groups of indoxyl being introduced into the molecule.
The indoxylic derivatives thus obtained are easily transformed by oxidation into
the corresponding indigo dye-stuffs.
The transformation of the said indoxylic derivatives into indigo dye-stuffs, can be
30 effected also upon the fibre.

page_text: On allowing sulphuric acid to act upon the indoxylic derivatives
indigo dye stuffs themselves the sulphonic acids of the said dye-stuffs are
obtained.
Dated this 9th day of September 1896
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.
A Process for the Manufacture of Compounds of the Series of the
Indoxylic Acids, and of Dye-stuffs of the Indigo-series.
1, RUBIN BLANK, of 53 Luisen-Ufer, Berlin, in the Empire of Germany, Doctor of
Philosophy and Chemist, 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 :-
On allowing aromatic (cyclic) amines to act upon bromo- or chloromalonic-acid-esters
or upon bromo- or chloroinalonic-acid, aromatic amidomalonic-acid esters or
amidomalonic acids are produced, while hydric-halogenide is separated, according to
the equation:

page_text: The aromatic amidomalonic acid esters and the aromatic amidomalonic acids
possess an eminent capability of forming the indoxyl-ring, this capability is evidently
owing to the properties of the malonic acid; therefore it is unessential which aromatic
radical is combined with the amidomalonic acid, and further whether the third atom
of hydrogen of the amine is substituted by any one monoatomic group of atoms or not,
but it is of course necessary, that in the said radical not both the ortho-places are
occupied by polyatomic groups as for instance alkyl,
If in the process above described di- or polyamines are used, then two or more
indoxyl-groups can be introduced in one molecule.
The members thus obtained of the series of the indoxylic acid esters and indoxylic
acids behave themselves altogether of course analogically as the first members
manufactured by Adolf Bayer in another way of both the same series, and can as
easily as the last mentioned members be transformed, into the corresponding indigo
dye-stuffs and their sulphonic acids.
The transformation of the said indoxylic derivatives into indigo dyestuffs can be
effected also upon the fibre.
EXAMPLES.
A. Manufacture of the aromatic amidomalonic acid esters.
1. Anilidomalonic acid ester.
Ten parts by weight of nonobromomalonic acid-ethyl-ester (one molecule) are
mixed with seven and eight tenths (7, 8) parts aniline (two molecules). This mixture
turns or becomes muddy immediately, and the separation of crystals begins soon after.
Now the mixture is allowed to stand for one or two days, until almost the whole liquid
has congealed or become set, or the mixture is to be heated for about two hours in a
water-bath.
Then about fifty parts of water and some hydrochloric acid are added and the
whole is well shaken. The hydrochlorate of aniline becomes dissolved, while the
anilidomalonic acid ester falls down in the form of oil. The water is now lecanted or
poured off and the oil is brought in a cool place, where it congeals after some time.
Then the crystals are placed upon a filter, washed out with water and pressed
energetically. By dissolving the said crystals in alcohol and then precipitating the
solution by water the ester is obtained in the form of pure colorless crystals, which are
sometimes colored a little red and which melt. at a temperature of forty-five degrees
and are easy soluble to the ordinary organic dissolving agents.
2. Paratoluidomalonic acid ester.
Nine parts of para-toluidine are dissolved in alcohol and then to this solution ten
parts of bromomalonic acid ester are added; as for the rest the proceeding is the same
as described in the Example 1.
The ester crystallizes large in colorless crystals, melts at a temperature of fifty five
degrees and is easy soluble in organic dissolving agents.
3. B-naphtylamidomalonicacid ester.
Twelve parts of naphtylamine are dissolved in hot alcohol, then to this selution ten
parts of bromomalonic acid ester are added and then the whole is heated for about two
hours in a water-bath. After the solution has been cooled some hydrochloric acid is
added, then it is shaken after which the ester is precipitated by a little water. By
recrystallizing the ester out of diluted alcohol it is obtained in the form of white,
feltlike crystals, which melt at a temperature of eighty eight degrees and are easy
soluble in the ordinary organic dissolving agents.
The manufacture of the said esters by means of chloromalonic acid esters instead of
the bromic compound is quite analogical; but in this case the reaction must be
continued a little longer..
B. Examples for the manufacture of the aromatic amidomalonic acids.
The aromatic amidomalonic acids are easily produced from the esters above described
by saponifying the latter by alkalies or alkaline earths. They can however be
manufactured also directly from the chloro- and bromomalonic acid. Then I proceed
in the following manner:

page_text: 1. Anilidomalonic acid,
Seven and four tenths (7-4) parts of chloromalonic acid (one molecule) are dissolved
in a little water, then to this solution ten parts aniline (two molecules) are added
after which the solution is heated for one hour in a water-bath. The solution is
now cooled, mixed with some hydrochloric acid and allowed to stand until the
crystals have been entirely deposited. It is then filtered, washed out with a little
water and dried. The anilidomalonic acid thus obtained crystallizes in colorless
needles, which melt at a temperature of one hundred and fifteen degrees and, if
further heated, are soon decomposed. Exposed to the light they become gradually a
yellow color. They are soluble in alcohol and in water."
2. Paratoluidomalonic acid.
Six and five tenths (6-5) parts of chloromalonic acid are dissolved in alcohol,
then to this solution an alcoholic solution of ten parts para-toluidine is added, the
mixture is then heated for one hour in a water-bath, after which the alcohol is
distilled off and the residuum is then shaken out with water containing hydrochloric
acid, filtered and washed out. By recrystallizing the paratoluidomalonic acid thus
obtained out of diluted alcohol I obtained it pure and in the form of colorless
needles, which melt and decompose at a temperature of one hundred and seventeen
degrees. Exposed to the light the said acid becomes gradually a yellow color. It is
soluble in alochol and in water.
3. 8-naphtylamidomalonic acid,
The process is the same as described under the last heading. The acid melts, while
being decomposed, at the temperature of one hundred and eleven degrees and
it is soluble in alco hol and in water. Exposed to the light it becomes a reddish
color.
In all cases nstead of chloromalonic acid, bromomalonic acid can be used in a
similar manneir.
C. Examples of the indoxyl-condensation of the aromatic anidomalonic acid
esters.
1. Anilidomalonic acid ester.
The said ester is brought into a retort and then the latter is dipped into a paraffine-
bath, which has been previously heated to a temperature of from two hundred and
sixty to two hundred and sixty-five degrees. The said ester melts, and
bubbles of alcohol soon arise out of the molten mass in a violent manner;
after about three minutes the development of the bubbles decreases and is
soon very small; at the same time the molten mass becomes thicker and
assumes a dark color. After five minutes the retort is taken out of the
bath, the molten mass is then boiled in doable weight of alcohol, cooled and allowed
to stand for one half hour, whereby a small quantity of a yellow colored crystalline
substance is separated. This substance is filtered off, and from the clear solution
(filtrate) the indoxylic acid ester is precipitated by water. It is cleaned or purified
by recrystallisation out of dilated alcohol.
The indoxylic acid ester thus obtained possesses the same properties as the indoxylic
acid ester described by Adolf Bayer.
2. Para-toluidomalonic acid ester.
The process is effected in the same manner as described above under the last heading 1,
but I have found it more preferable to use in this case a lower temperature,
namely two hundred and fifty to two hundred and fifty five degrees, that is to say, ten
degrees less.
The paratolylindoxylic acid ester was until now unknown. It crystallizes in colorless
crystals, the melting point of which is from one hundred and fifty five to one hundred
and fifty six degrees. It is insoluble in water and in ligroine, but easy soluble in
alcohol and in benzol. It is dissoluble in alkalies and can be precipitated unaltered
out of the alkaline solution by carbonic acid.
By boiling it a good while with alkalies or alkaline earths, salts of the
paratolylindoxylic acid are produced. By heating the said ester with concentrated

page_text: sulphuric acid in a water-bath it is transformed into sulphonic acids of
paratolylindigo.
3. The B-naphtylamidomalonic acid ester forms the indoxyl-ring still more easily
than the esters first mentioned. The reaction begins at a temperature of two hundred
degrees, but it is however more preferable to effect the reaction at a temperature of
fron two hundred thirty five to two hundred forty degrees. As for the rest it is to
proceed as described under the headings 1 and 2.
In this manner the beta-naphtaline indoxylic acid ester which is also until now
unknown, is obtained in the form of a greenish-yellow powder, which melts at a
temperature of one hundred fifty-eight degrees and coincides in relation to
the remaining properties with both the indoxylic acid esters described at first.
By heating the said ester with concentrated sulphuric acid it is transformed into
sulphonic acids of the B-naphtalineindigo.
The temperatures, which I have above indicated for performing the condensing
reaction, are to be considered only as those, by means of which the best results
have been attained, but the reaction also takes place at considerable lower temperatures;
especially if a condensing agent, as for instance sodium, ethylate of sodium, acetate
of sodium, is added.
D. Examples for the manufacture of the indoxylic acids.
1. Manufacture of (henzol-) indoxylic acid.
a. By saponification of the ester: indoxylic-acid-ester is boiled from two to three
hours in a concentrated watery solution of the fourfold quantity of hydrate of barium
and then it is quickly cooled. The salt thus formed is sucked, then washed first with
water and afterwards with alcohol, it is then brought into diluted hydrochloric acid,
the whole being afterwards thoroughly mixed by stirring. After some time the
indoxylic acid is filtered off and washed with water.
The indoxylic acid thus obtained possesses the same properties as the indoxylic acid
manufactured in another way by Adolf Bayer.
b. Manufacture of the indoxylic acid out of amilidomalonic acid in a direct
manner.
Anilidomalonate of sodium is mixed intimately with the fourfold quantity of hydrate
of sodium, then quickly heated up to three hundred or three hundred and fifty degrees
and then maintained about five minutes at this temperature while continually stirring,
The yellow colored mass thus formed is cooled and brought into cool, very diluted
sulphuric acid, by which the indoxylic acid is precipitated in the form of a white
powder.
can be
2 and 3. Paratolylindoxylic acid and Betanaphtaline-indoxylic-acid
manufactured in a similar manner by proceeding according to one or the other of the
methods above described under the headings a and b.
The paratolylindoxylic acid is obtained in the form of a bluish white powder, which
decomposes and melts at about a temperature of one hundred and seventeen degrees.
It dissolves in alcohol with a blue color; likewise in concentrated sulphuric acid,
whereby it is transformed into sulphonic acids of the paratolylindigo.
The alkaline solution has a greenish color, but soon becomes a blue color, when air
has free access to it, whereby paratolyl indigo is separated, while on the surface of the
liquid the characteristic indigo-skin or cuticle forms, having the reddish metallic
gloss or lustre.
The said acid easily oxidizes also in the air to paratolylindigo.
The B-naphtalineindoxylic acid forms a greenish powder which melts at about a
temperature of one hundred and fifty-six degrees. The said acid is soluble in alcohol
with a green color; in concentrated sulphuric acid it dissolves with a brilliant blue-
green color, while being transformed into sulphonic acide of the ẞ-naphtalineindigo.
Its alkaline solution possesses a faint or feeble green color, which grows inore and more
intense, when air has free access to it, whereby green flocks (ẞ-naphtalineindigo) are
separated gradually, while on the surface a dark green brilliant cuticle is
formed.
E. Transforination of the indoxylicacids into indigo-dye stuffs.

page_text: 1. The transformation of the (benzol-) indoxylic acid indigo is known by Adolf Bayer
and others.
2. The transformation of the para-tolylindoxylic acid into paratolylindigo is effected
in a very similar manner. This indigo possesses in the form of a powder a blue color,
larger pieces of the said indigo show on the surface a red colour. It is soluble in
alcohol, aniline and sulphuric acid, and the solutions show a blue color; its
paraffine-solution possesses when heated a red-violet color, and when cooled a
blue-violet color.
3. The transformation of the B-naphtalineindoxylic-acid into B-naphtalineindigo is
effected in the same manner as the transformation of (benzol-) indoxylic acid into
indigo.
The B-naphtalineindigo is dark green and shows on the surface brilliancy. It is
somewhat soluble in alcohol and aniline; these solutions show a green color, when
light passes through them, but show a blue color, when light falls upon them. The
paraffine-solution is when heated red-violet and when cooled green. The solution in
sulphuric acid possesses a magnificent blue-green color.
For the manufacture of the indigo-dye-stuffs it is of course neither necessary to
isolate the corresponding indoxylic acid ester nor the corresponding indoxylic acid, in
a pure state, but the molten masses can be manufactured directly into indigo.
The formation of the para-tolylindigo and of the B-naphtalineindigo out of the
corresponding indoxylic acids or their salts can be effected also upon the fibre in a
quite analogical manner as that of the proper indigo (benzol-indigo) out of (benzol-)
indoxylic acid.
The transformation of the para-tolylindigo and of the 3-naphtalineindigo into the
corresponding sulphonic acids is effected in the same manner as the sulphuration of
the benzol-indigo.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to he performed, I declare that what I
claim is:-
1. A process for the manufacture of aromatic (cyclic) amidomalonic acids and their
esters of the general formula ar R. NY. CH (CO,R) 2, wherein "ar R" indicates any
one aromatic radical "Y" any one monoatomic group or hydrogen and "R" alkyl or
hydrogen, consisting in allowing aromatic amines to act upon bromo-
chloromalonicacid or upon their esters, in a solution or without a solvent, at ordinary
or higher temperature.
or
2. A process for the transformation of aromatic amidomalonic acids, their esters or
salts into compounds of the series of the indoxylic acids or indoxylic acid esters,
consisting in heating the first mentioned acids, esters or salts with or without a
condensing agent.
3. A process for the transformation of the indoxylic acids or the indoxylic acid
esters after their saponification thus obtained into dye-stuffs of the indigo-series,
consisting in oxidizing the said acids by pressing air through their alkaline solution or
by means of other oxidizing agents.
4. A process for the transformation of the indoxylic acids, indoxylic acid esters,
indigos and their derivatives, obtained according to Claims 2 and 3, into the
corresponding indigo sulphonic acids, consisting in allowing sulphuric acid to act upon
the said compounds.
HASELTINE, LAKE & Co.
45 Southampton Buildings, London, W.C., Agents for the Applicant.