Improvements in the Manufacture of Colouring or Carbinol Matters.
Year: 1897

page_text: Date of Application, 19th June, 1897
Complete Specification Left, 18th Mar., 1898-Accepted, 14th May, 1898
Improvements in the Manufacture of Colouring or Carbinol Matters.
I, MARIUS OTTO, of 18, Avenue de Neuilly, Neuilly (Seine), France, Paris, France,
Doctor of Science, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in the manufacture of colouring matters
and is based on the discovery, which I have just made, that under the influence of
ozone the leucobases are readily converted into corresponding colouring matters.
Thus, for instance, on causing ozone to act upon tetramethyldiaminotriphenyl-
methane, which is the leucobase of malachite green, this leucobase is converted into
malachite green.
The reaction may be expressed by the following equation:
C6H5
CHẶ−CH*N(CH3)2 + O3
C*H*N (CH3)2
C®H5
=
02 +C (HO)
-C³H+N (CH³)²
CH*N (CH³)²
In order practically to prepare malachite green by means of ozone, it is sufficient
to cause a current of ozonized air of about 100° to pass into a solution of hydro-
chlorate of tetramethyldiaminotriphenylmethane. The solution immediately assumes
a cantharides green colour, and when the theoretically determined quantity of ozone
has been fixed, the malachite green is isolated by one of the known methods, it being
precipitated either by means of a solution of chloride of sodium or by means of a
solution of chloride of zinc.
Instead of causing ozone to act upon the hydrochlorate of the leucobase, it may
also be caused to act directly upon the mixture employed for producing the said
leucobase. The latter is then oxidized as it is formed. For example, in the case of
malachite green, ozone may be caused to react directly upon a mixture composed
of 50 parts of dimethylaniline, 22 parts of benzaldehyde, and 134 parts of sulphuric
acid of 66° B.
The method that I have just described by way of example for the preparation of
malachite green, is generally applicable, and I have tried it upon the greater part of
the leucobases and their derivatives. For example, in the preparation of "brilliant
green,"

page_text: I, MARIUS OTTO, of 18, Avenue de Neuilly, Neuilly (Seine), France, Doctor of
Physical Sciences, 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 relates to improvements in the manufacture of colouring matters
and is based on the discovery, which I have made, that under the influence of ozone
the leucobases are readily converted into corresponding colouring matters.
I will consider by way of example the preparation of malachite green. The
manufacture of this substance is ordinarily effected as follows:-
A mixture of benzaldehyde, dimethyl-aniline, and chloride of zinc, in determined
proportions is heated in alcoholic solution and after removing, by means of a current
of water vapour, the substances which have not entered into the reaction, the
leucobases are dissolved in a dilute solution of hydrochloric acid. Acetic acid is added,.
and the CH group of the leucobase converted into a C (OH) group by means of
peroxide of lead (or puce oxide of lead). The mass is then allowed to rest so as to
permit the chloride of lead to separate and the solution is then decanted and precipitated
by means of soda, and finally, according as it is desired to obtain the chloro-zincate or the
oxalate of the leucobase, the said precipitate is dissolved either in hydrochloric acid
and chloride of zinc, or in oxalic acid.
According to my invention by causing ozone to act upon tetra-methyl-diamido-
triphenyl-methane, which is the leucobase of malachite green, this leucobase is
converted into malachite green.
;

page_text: OHN (CHу
In order practically to prepare malachite green by means of ozone, it is sufficient
to cause a current of ozonized air at 100°C. to pass into a solution of hydrochlorate of
tetra-methyl-diamido-triphenyl-methane. The solution immediately assumes a can-
tharides green colour, and when the theoretically determined quantity of ozone, has
been fixed, the malachite green is separated by one of the known methods, as for
example by precipitating it either by means of a solution of chloride of sodium or of
chloride of zinc.
Instead of causing ozone to act upon the hydrochlorate of the leucobase, it may also
be caused to act directly upon the mixture employed for producing the said leucobase.
The latter is then oxidized as it is formed. For example, in the case of malachite
green, ozone may be caused to react directly upon a mixture composed of :-
50 parts by weight of dimethyl-aniline
22 parts by weight of benzaldehyde
13.4,
by weight of sulphuric acid of 66° B.
-
The product formed is separated by the known method and is sold in form of
chloro-zincate or oxalate. This example shows clearly the advantage of employing
ozone. In the old process, as described above, a considerable residue of chloride of
lead is produced, and numerous difficulties as well as a considerable loss of time is
incurred in separating the said residue.
By the use of ozone, these objections are obviated; the ozone being in a gaseous
form reacts instantaneously under the influence of a temperature of 100° to which.
it is raised, and does not leave any residue.
The method which I have described by way of example for the preparation of
malachite green,
is generally applicable, and I have tried it upon the greater number
of the leucobases and their derivatives. For example, in the preparation of "brilliant
green "the reaction is represented as follows:-

page_text: As in the case of malachite green, the products formed are separated by known
methods.
The invention thus comprises the application of the action of ozone to the
group CH for the conversion of the said group into the carbinol group C (OH).
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In the manufacture of colouring matters, the application of ozone to the
leucobases, or to mixtures which serve for the production thereof, for the purpose of
converting the same into their corresponding colouring matters substantially as
described.
2. In the manufacture of colouring or carbinol matters, converting a CH group
into a C (OH) or carbinol group by means of ozone, substantially as described.
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.