Improvements in or connected with the Manufacture and Production of Unsymmetrical Acid Green.
Year: 1889

page_text: Date of Application, 19th Jan., 1889
Complete Specification Left, 19th Nov., 1889-Accepted, 18th Jan., 1890
.
PROVISIONAL SPECIFICATION.
Improvements in or connected with the Manufacture and Production
of Unsymmetrical Acid Green.
I, BENJAMIN WILLCOX, of 47 Lincoln's Inn Fields, in the County of Middlesex,
Patent Agent, do hereby declare the nature of this invention, which has been com-
municated to me from abroad by the Farbenfabriken vormals Friedrich Bayer & Co.,
of Elberfeld, in the German Empire, to be as follows:-
This Invention relates to the manufacture or production of a new acid green
dyestuff by means of an improved process of manufacture hereinafter described.
In the case of the tetra alkylised products representing green dyestuffs of the oil
of bitter almonds (mirbane oil or nitro benzene) series my foreign correspondents
have discovered that as a general rule the colouring power increases not merely in
inverse but even in hyperbolical or exaggerated proportion to the amount of molecular
weight. This circumstance especially in the case of the commercially valuable
dyestuffs known as acid green obtained by the condensation of benzaldehyde with
ethyl benzyl aniline and methyl benzyl aniline enables lower molecular dyestuffs to
be produced without impairing the valuable colouring properties.
In the first place in order to replace the two benzyl groups by the methyl or ethyl
group one molecule of benzaldehyde is caused to act simultaneously upon one
molecule of dimethyl aniline and upon one molecule of methyl benzyl aniline in the
presence of a dehydrating agent with the result that instead of the dimethyl anilino
first entering in reaction in the sense of forming totra methyl diamido triphenyl
methan and afterwards the methyl benzyl aniline ontering in the sense of forming
symmetrical dimethyl dibenzyl diamido triphenyl methan the intermediate base of
trimethyl benzyl diamido triphenyl methan (hereinafter more briefly referred to as
trimethyl benzyl D) results in preponderating quantity.
The object of the present invention is to provide a process constituting a simple
method of producing the intermediate bases represented by the above mentioned
example by means of benzaldehyde acting upon two different amides simultaneously
in the presence of a dehydrating agent.
Tertiary as well as secondary alkyl aniline or aniline itself may be employed in
this reaction and it is immaterial whether the union or combination of the same takes
place in molecular proportion or not.
The improved process according to the present invention may be concisely stated
as consisting in condensing benzaldehyde with a mixture of two different primary
secondary and tertiary amines in the presence of a dehydrating agent then converting
the unsymmetrical substituted and imperfectly alkylised diamido triphenyl methan
derivative thus obtained into a higher substituted derivative by heating the same in
an alkaline, alcoholic or watery solution with alkyl or benzyl haloids and in further
converting it into leuco-sulpho acids by means of sulphurising agents such as
concentrated sulphuric acid fuming acid or mono chlorhydrin, the resulting
unsymmetrical substituted diamido triphenyl methan sulpho acid being then converted
into the green dyestuff by an oxidizing process.
By sulphonising the bases produced by the new process and oxidising the resulting
sulpho acids valuable new sulpho acids for dyestuffs can be obtained of which the
trimethyl benzyl D derivative and the unsymmetrical dimethyl dibenzyl D derivative
may be taken as examples being the two most important products in a commercial
sense.
Example I. About 220 parts by weight of sulphuric acid at 66 per cent. strength
are gradually formed into an externally cooled enamelled boiler or vessel containing
a mixture of about 121 parts by weight of dimethyl aniline and about 197 parts of

page_text: methyl benzyl aniline and about 106 parts of benzaldehyde are then added at the
ordinary or usual temperature. The enamelled vessel is then placed in an oil bath
and the contents being well stirred the internal temperature is gradually raised to
from 120 to 130 degrees centigrade, and this temperature is maintained for some
hours. The melt thus prepared is dissolved in water and the symmetrical dimethyl
dibenzyl (a small quantity of which is incidentally formed) is thereby separated.
When this has been skimmed off the sulphuric acid solution is mixed with a sulphate
solution in order to remove the tetra methyl D which is also present in a small
quantity. The trimethyl benzyl D is precipitated and the tetra methyl D remains in
solution. After boiling down with water the former forms a resinous mass of a pale
green colour which is dried and dissolved in five times the quantity of 20 per cent.
anhydride without raising the temperature. The resulting sulpho acid is 'treated in
the usual way and converted into the soda salt. The oxidation into a sulpho acid
-dye-stuff is-effected in the manner understood.
The proportions and temperatures specified in the foregoing example may be varied
within certain limits and in place of the sulphuric acid oxalic acid, chloride of zinc
and other like condensing agents may be employed for the condensation.
The soda salt of the leuco sulpho acid is readily soluble in water and is not
precipitated from its watery solution by the action of acetic acid but strong acids
such as sulphuric or hydro chloric acid precipitate the free sulpho acid without
heat although it disappears again when the temperature is raised. The sulpho acid
dye stuff is of a bluish green shade and acts more slowly on wool than does ordinary
acid green a more equal effect being thus obtained.
Example II. A mixture of about 273 parts by weight of dibenzyl aniline and
21 parts dimethyl aniline is condensed with 106 parts of benzaldehyde and the
employment of 220 parts of sulphuric-acid-as-in-the-first example; the subsequent
operations are also conducted in the same way but the separation of the tetra
methyl D is effected by boiling down with dilute sulphuric acid in place of the
sulphate solution the unsymmetrical dimethyl dibenzyl D unlike the trimethyl
benzyl D not being readily soluble.
The new sulpho acid dyestuff is distinguished from the known isomeric sulpho acid
by its extremely blue shade.
Practically useful results are also obtained from the following ĥases namely
unsymmetrical diethyl dibenzyl D.
dimethyl ethyl benzyl D
diethyl methyl benzyl D
triethyl benzyl D.
methyl ethyl dibenzyl D
methyl ethyl methyl benzyl D
methyl ethyl ethyl benzyl D.
Their production and after treatment is analogous to that described in examples I
and 11 or the production may be accomplished by in place of condensing mixtures
of two different tertiary alkyl anilines with benzaldehyde combinations of aniline
employing secondary and tertiary alkyl anilines and converting the condensation
products thereof into the above mentioned bases by methylising, ethylising
benzylising.
or 4
3

page_text: COMPLETE SPECIFICATION.
Improvements in or connected with the Manufacture and Production
of Unsymmetrical Acid Green.
I BENJAMIN WILLCOX of 47 Lincolns Inn Fields in the County of Middlesex,
Patent Agent, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by the Farbenfabriken vormals Friedrich Bayer & Co.
of Elberfeld in the German Empire) and in what manner the same is to be
performed to be particularly described and ascertained in and by the following
statement:-
:-
This Invention relates to the manufacture or production of new acid green
dyestuffs by means of an improved process of manufacture hereinafter described.
My foreign correspondents have discovered the general rule that in the case of the
tetra-alkylised product of the diamido-tri-phenyl-inothane series which are groen
dyestuffs the colouring power increases as the molecular weight is decreased not
merely in an inverse but even in an hyperbolical or exaggerated proportion.
This circumstance justifies the hope, especially in the case of the commercially
valuable dyestuffs, known as acid-greens obtained by the condensation of benzaldehyde
with ethyl benzyl aniline and methyl benzyl aniline, that dyestuffs of lower molecular
weights may be produced without impairing their valuable coloring properties.
For this purpose it was absolutely necessary at first to replace one benzyl group
by the methyl or ethyl group, one molecular proportion of benzaldehydo was
therefore allowed to act simultaneously upon one molecular proportion of dimethyl-
aniline and upon one molecular proportion of methyl-benzyl-aniline in the presence
of a dehydrating agent. Instead of the dimethyl aniline first entering into reaction
in the sense of forming tetra-methyl-diamido-triphenyl-methane and afterwards the
methyl benzyl aniline reacting in the sense of forming symmetrical dimethyl-dibenzyl-
diamido-triphenyl-methane, the intermediate base trimethyl-benzyl-diamido-triphenyl-
methane was obtained (hereinafter more briefly called "D" in preponderating
quantity. The discovery was thus made of the present invention constituting a simple
method of producing the unsymmetrical substituted bases of the diamido triphenyl-
methane series or their nitro compounds by the action of one molecular proportion of
benzaldehyde or meta nitrobenzaldehyde upon a mixture of two different amines in
the presence of a dehydrating agent.
The improved process according to the present invention may be concisely stated
as consisting in condensing benzaldehyde or nitrobenzaldehyde with two different
tertiary amines in the presence of a dehydrating agent, then converting the
unsymmetrical substituted diamido-triphenyl-methane derivatives thus obtained into
leuco sulpho acids by means of sulphonating agents such as concentrated sulphuric
acid, fuming acid or sulphuric mono-chlorhydrine the resulting unsymmetrical
substituted diamido-triphenyl-methane-sulpho-acid-being thon converted into the
green dyestuff by an oxidizing process.
By sulphonating the bases produced by the new process and oxidising the resulting
sulpho-acids, valuable new dyestuff sulpho-acids can be obtained of which the
trimethyl benzyl D) derivative and the unsymmetrical dimethyl-dibenzyl D derivative
are the most important products.
In the following we give for example an exact description of the manufacture
of these dyestuffs, which at the same time describes the nature of the present
invention.
Example I. About 220 parts by weight of sulphuric acid of 66 per cent. strength
are gradually poured into an externally cooled enamelled vessel containing a mixture
of about 121 parts by weight of dimethyl-aniline and about 197 parts of methyl-
benzyl-aniline and to this mixture about 106 parts of benzaldehyde are slowly added
at the ordinary temperature. The enainelled vessel is then placed in an oil bath its
contents are continually stirred and the internal temperature is gradually raised from
120 to 130 degrees Centigrade and this temperature is maintained for some hours.

page_text: The resulting melt is dissolved in water whereupon the symmetrical dimethyl-
dibenzyl D (a small quantity of which is incidentally formed) separates. When this
has been skimmed off, the sulphuric acid solution is mixed with a sulphate of soda
solution in order to remove the tetra-methyl-D which is also present in a small
quantity. The trimethyl-benzyl-D is thereby precipitated whilst the tetra-methyl-D
remains in solution. After repeatedly boiling out with water, the former forms a
resinous mass of a pale green colour which is dried and dissolved in five parts by
weight of fuming sulphuric acid containing 20 per cent. anhydride at a lower
temperature and the solution is allowed to stand at the ordinary temperature until a
sample dissolves in diluted alkali to a clear solution. The product of the reaction is
then poured into water. The resulting sulpho-acid is converted in the well known
manner into the sodium salt. The oxidation into a sulpho-acid-dye-stuff is effected
in the well known manner by the known process with peroxide of lead (Pb. O,) or
other oxidizing agents which act similarly in-an-acid solution, (for example: 10 parts
by weight of the sodium salt of the leuco sulpho acid) are dissolved-in-about 250 parts
by weight of water the calculated quantities of diluted sulphuric acid and peroxide of
lead are then added the resulting dyestuff is filtered off from the precipitated sulphate
of lead and the blue-green solution of the dyestuff is evaporated to dryness.
The proportions and temperatures specified in the foregoing example may be varied
within certain limits and in place of the sulphuric acid, oxalic acid, chloride of tin or
other similar condensing agents may be employed in effecting the condensation.
The sodium salt of the leuco-sulpho-acid is readily soluble in water and is not
precipitated from its watery solution on addition of acetic acid. Strong acids such
as sulphuric-or hydrochloric acid precipitate the free sulpho-acid from a cold watery
solution but the precipitate dissolves-if the temperature is raised. The sulpho-acid-
dye-stuff is of a blueish-green shade and dyes more slowly_on_wool than do the
ordinary acid greens.
-
Example II. A mixture of about 273 parts by weight of dibenzyl-aniline and
21 parts dimethyl-aniline is condensed with 106 parts of benzaldehyde by the.
employment of 220 parts of sulphuric acid exactly as is described in the first
example; the subsequent operations are also conducted in the same way as before
but the separation of the tetra-methyl-D is effected by boiling with dilute sulphuric
acid because the unsymmetrical dimethyl-dibenzyl-D forms a more difficultly-soluble
sulphate than does the trimethyl-benzyl-D. The new sulpho-acid-dyestuff is dis-
tinguished from the known isomeric sulpho-acid by its intensely blue shade.
Practically useful results are also obtained with the following bases namely:

page_text: Second. The process for converting the unsymmetrical substituted diamido-
triphenyl-methane derivative referred to in the preceding claiming clause into leuco-
sulpho-acids by treating with sulphuric acid, fuming acid or monochlorhydrine.
Third. The process for converting the unsymmetrical substituted diamidotriphenyl-
methane-sulpho acids obtained according to the process of the second claiming clause
into green colouring matters or dyestuffs by oxidising the same.
Fourth. As new articles of manufacture the products obtained by the means
herein before described and claimed by the preceding several claiming clauses.
Dated this 10th day of Novemblon 1000
J. H. JOHNSON & Co.,
Agents.