Improvements in and relating to the Production of Coloring Matters and Intermediate Products.
Year: 1897

page_text: Improvements in and relating to the Production of Coloring
Matters and Intermediate Products.
A communication from LA SOCIÉTÉ CHIMIQUE DES USINES DU RHÔNE, Anciennement
Gilliard P. Monnet et Cartier, of Lyons, France, Manufacturers.
I, GEORGE BELOE ELLIS, of the Firm of J. C. Mewburn & Ellis, of 55 and 56,
Chancery Lane, in the County of London, Chartered Patent Agents, do hereby
declare the nature of this invention to be as follows:-
This invention is based upon the discovery that phthalaldehydic acid can be con-
densed with meta-amido-phenols or with their alkyl derivatives.
According to this invention, the leuco bases of the coloring matters are produced,
which leuco compounds may be converted into the dyes as will be readily understood
by chemists.
While aldehydes are very advantageously employed for the production of triphenyl-
methane dyestuffs, for the preparation of the rhodamines of the phtalic series, phtalic
acid has hitherto been employed.
The condensation of phthalaldebydic acid and meta amido phenol or its substitution
products takes place so energetically that the employment of condensation, agents is
unnecessary; in most cases the reaction takes place in aqueous solution.
The preparation of the leuco bases may be divided into two phases.
At a low temperature the aldehyde reacts, very probably in accordance with its
tantamaria formula

page_text: 15 kg. phtalaldehydic acid and 16.5 kg. diethyl-amido-phenol are dissolved in any
suitable solvent of low boiling point, for example ether, and heated for some hours
with a reflux condenser; the solvent is distilled off and the residue crystallized from
alcohol. The phtalide is obtained in the form of white flakes of melting point 152°C.
(uncor.), readily soluble in acids and alkalies. The acid solutions are colorless, the
alkaline are colored a characteristic intense orange.
Carbonate of soda does not dissolve the product in the cold; from this it would
appear that the carboxyl group is not free.
In order to obtain the leuco base of ordinary rhodamine the phtalide is added as
a powder to 20 kg. melted diethyl meta-amido-phenol. The product of the reaction
is powdered and the excess of amido phenol removed by washing with boiling alcohol.
The leuco base is almost insoluble in most organic solvents, readily soluble in
alkalies and acids and has a melting point of about 190°.
Rhodamine is slowly formed in acetic acid solution by the action of the oxygen of
the air. The reaction is complete when oxidizing agents are employed, such as
chloride of iron, persulphate of potassium, or hydrogen peroxide.
The purification of the rhodamines so obtained may be effected by the known
methods.
The dimethyl-amido-phenol-phtalide melts at about 186º.
46 kg. mono-methyl-meta-amido-phenol are dissolved in ether, then there is added
5 kg. phthalaldehydic acid and the mixture is boiled for some hours with a reflux 3
condenser. After evaporation of the ether, the phtalide remains as a bright reddish
mass which can after washing with warm water be crystallized out of ether. It has
a melting point of about 184°. The leuco base of the trimethyl rhodamine is
obtained by heating 9 kg. of this product with 20 kg. dimethyl-meta-amido-phenol
to about 110°C.
The leuco base of dimethyl rhodamine is produced by heating the phtalide with
meta-methyl-amido-phenol.
3

page_text: The phtalides obtained by condensation of phthalaldehydic acid with meta-amido
phenols can also be combined with a phenol or an aromatic amine instead of
further molecule of amido-phenol.
Dated this 7th dan n
1007
•
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.
-Improvements-in-and-relating to the Production of Coloring
Matters and Intermediate Products.
A communication from LA SOCIÉTÉ CHIMIQUE DES USINES DU RHÔNE, anciennement
Gilliard P. Monnet et Cartier, of Lyons, France, Manufacturers.
I, GEORGE BELOE ELLIS, of the Firm of J. C. Mewburn & Ellis, of 55 and 56,
Chancery Lane, in the County of London, Chartered Patent Agents, 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 :―
This invention is based upon the discovery that phthalaldehydic acid can be
condensed with meta-amido-phenols or with their alkyl derivatives.
. According to this invention, the leuco bases of the coloring matters are produced,
which leuco compounds may be converted into the dyes as will be readily understood
by chemists.
While aldehydes are very advantageously employed for the production of triphenyl-
methane dyestuffs, for the preparation of the rhodamine of the phthalic series,
phthalic acid has hitherto been employed.
or its
The condensation of phthalaldehydic acid and meta-amido-phenol
substitution products takes place so energetically that the employment of
condensation agents is unnecessary; in most cases the reaction takes place in aqueous
solution.
.
The preparation of the leuco bases may be divided into two phases.—
At a low temperature the aldehyde reacts, very probably in accordance with its

page_text: C₁₂H₁
OH!
-COOH
CH
The second molecule of the amido phenol can naturally be substituted by any
other amido phenol derivative, so that a series of mixed leuco bases results.
Further, the condensation of two molecules of an amido phenol may be directly
effected with one molecule of a salt of phthalaldehydic acid.
EXAMPLE I.
15 kg. phthalaldehydic acid and 16.5 kg. diethyl-amido-phenol are dissolved
in any suitable solvent of low boiling point, for example ether, and heated
for some hours with a reflux condenser; the solvent is distilled off and the residue
crystallised from alcohol. The phthalide is obtained in the form of white flakes of
melting point 152° C. (uncor.), readily soluble in acids and alkalies. The acid
solutions are colorless, the alkaline are colored a characteristic intense orange.
Carbonate of soda does not dissolve the product in the cold; from this it would
appear that the carboxyl group is not free.
In order to obtain the leuco base of ordinary rhodamine the phthalide is added as
a powder to 20 kg. melted diethyl-meta-amido-phenol. The product of the reaction
is powdered and the excess of amido phenol removed by washing with boiling alcohol.
The leuco base is almost insoluble in most organic solvents, readily soluble in alkalies
and acids and has a melting point of about 190°.
Khodamine is slowly formed in acetic acid solution by the action of the oxygen of
the air. The reaction is complete when oxidizing agents are employed, such as
chloride of iron, persulphate of potassium, or hydrogen peroxide.
The purification of the rhodamine so obtained may be effected by the known
methods.
The dimethyl-amido-phenol-phthalide melts at about 186°.
EXAMPLE II.
4.6 kg. mono-methyl-meta-amido-phenol are dissolved in ether, then there is
added 5 kg. phthalaldehydic acid and the mixture is boiled for some hours with a reflux
condenser. After evaporation of the ether, the phthalide remains as a bright reddish
mass which can after washing with warm water be crystallized out of ether. It has a
melting point of about 184°. The leuco base of the trimethyl rhodamine is obtained
by heating 9 kg. of this product with 20 kg. diamethyl-meta-amido-phenol to
about 110°C.
The leuco base of dimethyl rhodamine is produced by heating the phthalide with
mono-methyl-meta-amido-phenol.
The phthalides obtained by condensation of phthalaldehydic acid with meta-amido-
phenols can also be combined with a phenol or an aromatic amine instead of a further
molecule of amido-phenol.
Having now particularly described and ascertained the nature of the said
invention as communicated to me, and in what manner the same is to be performed,
I declare that what I claim is :-
1. The process of producing condensation products of phthalaldehydic acid and meta-
amido-phenols or their alkyl derivatives by the reaction of one molecule of

page_text: phthalaldehydic acid with one molecule of a meta-amido-phenol or its alkyl derivative
at a low temperature, substantially as herein before described.
2. The process of producing leuco rhodamines or condensation products of
phthalaldehydic acid and meta-amido-phenols or the alkyl derivatives by melting
together one molecule of phthalaldehydic acid with two molecules of a meta-amido-
phenol or its alkyl derivative to a temperature of about 100° to 120°C., substantially
as hereinbefore described.
3. The process of producing new condensation products of phthalaldehydic acid by
melting together with one molecule of the condensation products of phthalaldehydic
acid obtained by the reaction of one molecule of phthalaldehydic acid with one
molecule of a meta-amido-phenol or its alkyl derivative, a second molecule of the
same-or-another-meta-amido-phenol-or-alkyl-derivative, or-with-another-amine-or-
phenol, substantially as described.
4. The process for the manufacture of rhodamines which consists in first producing
the leuco bases in the manner set forth in Claim 2 or Claim 3 and then converting
the said leuco bases into rhodamines by means of oxidising agents, substantially as
set forth.
5. As new products the condensation products such as are obtained by the action of
one molecule of phthalaldehydic acid upon one molecule of a meta-amido-phenol or
its alkyl derivative at a low temperature, substantially as described.
6. As new products, the condensation products such as are obtained by the action
of one molecule of phthalaldehydic acid upon two molecules of a meta-amido-phenol
or its alkyl derivative, or upon one molecule of meta-amido-phenol or its alkyl
derivative and one molecule of another meta-amido-phenol or its alkyl derivative or
another aromatic amine or phenol substantially as described.
Dated this 97th day of Mev 1908
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.