Improvements in the Manufacture of Colouring Matters.
Year: 1893

page_text: Date of Application, 22nd June, 1893
Complete Specification Left, 21st Apr., 1894-Accepted, 25th May, 1894
PROVISIONAL SPECIFICATION.
[Communicated from abroad by Messrs. WIRTH & Co.. of Frankfort-on-the-Main,
in the Empire of Germany, acting as Agents of A. Leonhardt & Co., of
Mühlheim, near Frankfort-on-the-Main, in the Empire of Germany, Aniline
Colour Manufacturers.]
Improvements in the Manufacture of Colouring Matters.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent
Agents, of 45 Southampton Buildings, in the County of Middlesex, do hereby
declare the nature of this invention to be as follows:-
Metaamidoparacresol (CH, NH.: OH = 1:2:4) can be condensed with form-
aldehyde, best in the presence of hydrochloric acid, yielding diamidodioxy-ditolyl-
methan, (melting point about 225° C.). In a similar way other aldehydes, such as
When the resulting
benzaldehyde, can be condensed with metaamidoparacresol.
products of condensation are treated with dehydrating agents, such as sulphuric
acid, a yellowish melt is obtained, which contains new oxides or leucobodies
together with colouring matter, the latter being formed by spontaneous oxidation.
By acting on the lencobodies thus produced with oxidizing agents the whole can be
transformed into colouring matter.
These colouring matters can also be produced in a direct way, if in place of the
aldehydes, acids or acid-chlorides, such as formic acid (or a mixture of glycerine
and oxalic acid) or phthalic acid or succinic acid or benzotrichloride are brought
into reaction with meta-amidocresol in or without the presence of a suitable
condensing agent.
The colouring matters thus obtained are of yellowish red to red shades dissolving
in water or spirit with an intensely green fluorescence.
Dated this 22nd day of June 1893.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Colouring Matters.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45 Southampton Buildings, in the County of Middlesex, 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:-
:
Metaamidoparacresol (CH, NH,: OH=1:2:4) has been found by the communi-
cators to be an excellent raw material for producing colouring matters of the
rhodamine series, dyeing mordanted cotton in yellowish red to red shades and
dissolving in water or spirit with an intense green fluorescence.
Thus formaldehyde can be condensed with metaanidoparacresol yielding
diamidodioxyditolylmethan; and in a similar way other aldehydes, such as
benzaldehyde, can be brought into re-action. When the obtained products of
condensation are treated with dehydrating agents such as concentrated sulphuric
acid, a yellowish red melt is obtained, which contains new leuco-bodies together
with colouring matter, the latter being formed by spontaneous oxidation. By

page_text: acting on the produced leucobodies with oxidizing agents the whole can
transformed into colouring matter.
De
These colouring matters can also be produced in a direct way, if in place of the
aldehydes, acids such as formic acid (or a mixture of glycerine and oxalic acid) or
succinic acid or phthalic acid or its substitutes are brought into re-action with
metaamidocresol best in the presence of a suitable condensing agent.
The best results (as regards yield and purity of colouring matter) are obtained
by acting with formaldehyde or with phthalic acid on metaamidocresol and I now
proceed to an exact description of the manner in which the invention may be
carried out practically, the parts hereinafter given being by weight.
First. The condensation of formaldehyde with metaamidocresol is best effected
in cold aqueous solutions in the presence of mineralic acid. For instance 12 parts
of metaamidocresol are dissolved in 14 parts of hydrochloric acid of 30% and
200 parts of water. To this solution 3.8 parts of a watery solution of formaldehyde
of 40% are added and when after standing in the cold for some time the smell of
formaldehyde has disappeared the solution is heated up to 60° C., any impurities
are removed by fractionally adding carbonate of sodium and the diamidodioxy-
ditolylmethan is precipitated from the filtered liquid by carbonate of sodium.
As another example, a solution of 12.5 parts of metaamidocresol in 300 parts of
water and 25 parts of concentrated sulphuric acid is treated in the cold with
3.8 parts of a watery solution of formaldehyde of 40%. After some time the
sulphate of diamidodioxyditolylmethan, which is nearly insoluble in water separates
from the solution, and when this separation is finished, it is filtered off, pressed and
dried.
Diamidodioxyditolylmethan can also be formed by acting with one molecular
proportion of formaldehyde on two molecular proportions of the sodium salt of
metaamidocresol in cold aqueous solutions and may be isolated by fractionally
precipitating with acetic acid; but as I have stated above it is preferable to operate
in the presence of mineralic acids
The thus obtained ditolylmethan derivative is soluble in dilute mineralic acids
and in alkalies and can be precipitated from such solutions respectively by
carbonate of sodium or by acetic acid. When crystallized out of spirit its melting
point is at about 225° C.
When this diamidodioxyditolylmethan is heated with about five parts of
concentrated sulphuric acid up to about 100° C., a yellowish red melt is obtained
which contains an orange dyestuff together with leucobodies. The end of the
reaction can be tested by pouring a sample into water, oversaturating with caustic
soda lye and filtering; the filtrate by carefully adding acetic acid must not show
any or only an insignificant precipitation.
The melt is then poured into about 20 parts of ice water whereby the greatest
part of the directly formed colouring matter is precipitated. To the mother-lye,
salt water and chloride of zinc solution are added and the oxidation is effected by
adding in the cold a solution of ferric chloride or biebromate of potassium until no
The thus obtained
further formation of colouring manner is to be observed.
colouring matter may be purified by dissolving in water, filtering and repeated
precipitating.
Second. The condensation between phthalic acid and metaamidocresol is best
effected by operating with concentrated sulphuric acid as diluting and condensating
agent.
Example: A mixture of one ko. of phthalic anhydride, two kos. of meta-
amidocresol and eight kos. of concentiated sulphuric acid is heated during several
hours up to about 160° C., until no further formation of colouring matter can be
observed. After cooling, the melt is poured into 100 litres of water and the whole
mass is brought up to boiling and filtered and the residue is again extracted with
boiling water.
The greatest part of the colouring matter crystallizes out of the filtered solution
on cooling, the rest can be precipitated with salt.

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
by my foreign correspondents. I declare that what I claim is :-
1. The production of diamidodioxyditolylmethan by the hereinbefore described
process which consists in combining metaamidocresol (CH, NH,: OH=1:2:4)
with formaldehyde.
:
2. Diamidodioxyditolylmethan produced according to Claim 1.
3. The production of an orange red colouring matter by the herein described
process which consists in heating diamidodioxyditolylmethan with concentrated
sulphuric acid.
4. The production of an orange red colouring matter by the herein described
process which consists in heating diamidodioxyditolylmethan with concentrated
sulphuric acid and treating leucobodies thus formed with oxidizing agents.
5. The production of an orange red colouring matter by the herein described
process which consists in heating phthalic anhydride with metaamidocresol
(CH, NH, OH 1:2:4) in the presence of concentrated sulphuric acid.
:
:
-
6. The orange red colouring matters produced according to Claims 3, 4 and 5.
Dated this 21st der of April 1804
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.