IMPROVEMENTS IN THE PREPARATION OF DIPHENYLAMINE AND ANALOGOUS SUBSTANCES
Year: 1866

page_text: LETTERS PATENT to Charles Adam Girard, of 66, Rue des Ecoles, Paris,
Chemist, and George de Laire, of 11, Rue de Sèvres, Paris, Chemist,
for the Invention of "IMPROVEMENTS IN THE PREPARATION OF DIPHENYLAMINE
AND ANALOGOUS SUBSTANCES."
Sealed the 16th October 1866, and dated the 18th April 1866.
PROVISIONAL SPECIFICATION left by the said Charles Adam Girard and
George de Laire at the Office of the Commissioners of Patents, with their
Petition, on the 18th April 1866.
We, CHARLES ADAM GIRARD, of 66, Rue des Ecoles, Paris, Chemist, and
GEORGE DE LAME, of 11, Rue de Sèvres, Paris, Chemist, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE PREPARATION OF
DIPHENYLAMINE AND ANALOGOUS SUBSTANCES," to be as follows:-
We take one part of pure hydrochlorate of aniline and two parts of pure
aniline or thereabouts; we introduce this mixture into a suitable closed
vessel, and we heat it for several hours under a pressure of from three to five
atmospheres, which corresponds to a temperature ranging between 220° and
265° centigrade; under these circumstances the aniline reacts upon its
hydrochlorate producing diphenylamine. In order to purify the diphenyla-
mine thus obtained, we treat the whole mass with strong commercial hydro-
chloric acid, slightly heating it, and we then dilute the imperfect solution
thus obtained with a large quantity of water, say 20 to 30 times the weight

page_text: of the hydrochloric acid employed. The untransformed aniline and certain
colored products remain dissolved in the acid liquor, and the diphenylamine
which had been dissolved by the strong acid is precipitated. After one or
two washings with cold water it is collected and dried. In this state it is
always colored.
To complete its purification, and obtain it quite white, the cheapest and
simplest method is to submit it to the process of distillation, or recourse may
be had to one of its numerous solvents, such as benzole, ether, or petroleum
spirit in which diphenylamine and the impurities which accompany it are
unequally soluble. When purified the diphenylamine is applicable to the
production of colouring matters for dyeing and printing. Ditolylamine may
be similarly obtained by the action of toluidine on its hydrochlorate; or
again, phenyltolylamine by the action of toluidine on the hydrochlorate of
aniline, or of aniline on the hydrochlorate of toluidine.
. Although we believe the employment of pressure to be useful we have
ascertained that it is by no means absolutely necessary. Under ordinary
'pressure and at the temperature of the boiling point of the mixture the
reaction of aniline in excess upon its hydrochlorate also takes place,
but in this case the duration of the operation is greater and the yield less
abundant.
Diphenylamine may also be obtained by employing aniline in excess to
react upon the sulphate, the phosphate, the arseniate, or the nitrate of aniline,
and upon the combinations which aniline forms with the chlorides of zinc and
iron with the bichlorides of tin and mercury, and with the perchloride of
antimony, and upon anologous aniline salts and compounds, and ditolylamine
and phenyltolylamine respectively by a similar employment of toluidine,
and toluidine and aniline respectively. In these cases the results are
'complicated by the formation of various products for the most part colored
but which products we eliminate by processes of purification similar to those
above described. :
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles Adam Girard and George de Laire in the Great Seal
Patent Office on the 18th October 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, CHARLES
ADAM GIRARD, of 66, Rue des Ecoles, Paris, Chemist, and GEORGE DE LAIRE,
of 11, Rue de Sèvres, Paris, Chemist, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of April, in the year of our Lord
One thousand eight hundred and sixty-six, in the twenty-ninth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us;
the said Charles Adam Girard and George de Laire, Her special license that
we, the said Charles Adam Girard and George de Laire, our executors, ad.
ministrators, and assigns, or such others as we, the said Charles Adam Girard
and George de Laire, our executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for "IMPROVE,
MENTS IN THE PREPARATION OF DIPHENYLAMINE AND ANALOGOUS SUBSTANCES," upon
the condition (amongst others) that we, the said Charles Adam Girard and
George de Laire, our exccutors or administrators, by an instrument in writing
under our or their hands and seals, or under the hand and scal of one of us or
them, should particularly describe and ascertain the nature of the said Invention,
and in what manner the same was to be performed, and cause the same to
be filed in the Great Scal Patent Office within six calendar montlis next and
mmediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Charles Adam Girard, on behalf of
myself and the said George de Laire, do hereby declare the nature of the
said Invention, and in wliat manner the same is to be performed, to be
particularly described and ascertained in and by the following statement thereof,
that is to say:-
.
This Invention has for its object improvements in the preparation of
diphenylamine and analogous substances. We mix hydrochlorate of aniline
and aniline in the proportion by preference of one part of the hydrochlorate to
three parts of aniline, a smaller proportion of aniline may be employed, but an
excess facilitates the process. This mixture we place in a strong boiler or
close vessel of copper or bronze; the vessel is set in brickwork with a fire-
place beneath in such manner that the flame from the fire may not play
directly on the vessel, but the highly heated air and products of combustion
from the fire circulate in flues or air spaces surrounding the bottom and sides
of the vessel. The vessel may be of any convenient size, a capacity of 20
gallons is very suitable. It has an opening into it for the introduction of the
materials, and a cover or moveable cap held down by bolts and screws closes
this opening air-tight when the vessel is in use. There is also a safety valve
on the vessel, the lever of which is weighted in such manner that the valve

page_text: may open at a pressure of about five or six atmospheres. A pressure guage
may also be applied to the vessel, but if so its construction should be such as
to enable it to bear the high heat to which it will be subjected when at work.
The vessel is about two-thirds filled with the mixture, and the fire is applied
and is maintained as regularly as possible for about ten hours, so as to main-
tain the pressure at about the point to which the valve is weighted. The
valve should be allowed to blow slightly from time to time as ammonia is
generated in the process which thus escapes. A small quantity of vapour of
aniline escapes at the same time, but if the operation is carefully conducted
this loss is so small that it is not worth while to complicate the apparatus by
the application of a condenser to collect and retain it. The temperature in
the vessel during the process will be about 265° to 280° centigrade. At the
end of the operation, when the vessel is cool, it is opened, and the semi-solid
mass which it contains is removed and is treated with strong commercial
bydrochloric acid in the proportion of rather more than one equivalent of acid
for cach equivalent of aniline originally taken; the mixture is warmed to
about 40° to 60° centigrade, and so an imperfect solution is obtained to which
we then add a quantity of water of twenty or thirty times the weight of the
hydrochloric acid employed. The untransformed aniline and certain colored
products remain dissolved in the acid liquor, and the diphenylamine which
had been dissolved by the strong acid is precipitated. After one or two
washings with cold water it is collected and dried at the ordinary temperature
of the air as it easily fuses. In this state it is always colored..
To obtain it quite white the cheapest and simplest method is to submit it
to a process of distillation, and for this purpose we employ a cast-iron still set
in brickwork with a fire beneath it in the same way as the converting vessel
already described; the temperature required is about 310° to 350° centigrade.
It is not essential to exclude the air from the retort by steam or otherwise.
The purification may also be effected, but less conveniently by dissolving the
diphenylamine in a solvent, such as benzole or petroleum spirit; if the latter
is used it should be such as has been separated by rectification from the
heavier oils with high boiling points, and also (for safety and convenience of
working) from the spirits with very low boiling points. The impurities do
not dissolve readily in these solvents, so that by dissolving the diphenylamine,
filtering, and then driving off the solvent by distillation, it may be obtained
purc.
Ditolylamine may be similarly obtained by the action of toluidine on its
hydrochlorate; or again, phenyltolylamine by the action of toluidine on the
hydrochlorate of aniline, or of aniline on the hydrochlorate of toluidine. In

page_text: the case of ditolylamine the heat in the converting vessel should be continued
for a somewhat longer time, say for 12 in place of 10 hours, or a somewhat
higher pressure may be used with this exception; the processes for the pro-
duction and purification of ditolylamine and phenyltolylamine are identical with
those for the production and purification of diphenylamine. Although the
employment of the high pressure herein directed is advantageous it is not
essential, but by means of it the operation is hastened and a better yield is
obtained. In place of employing the hydrochlorate of aniline, other salts of
aniline may be employed, viz., the sulphate, the phosphate, the arseniate, and
the nitrate (the use of the nitrate is however dangerous); or compounds of
aniline may be employed, viz., such as it forms when mixed with chloride of
zinc, chloride of iron, bichloride of tin, bichloride of mercury, or perchloride
of antimony. A mixture of aniline in excess with chloride of ammonium may
also be used; here, however, there is no doubt a formation of hydrochlorate of
aniline in the process. All these variations of the process (excepting, perhaps,
the use of the chloride of ammonium mixture) are however disadvantageous,
(comparatively) as the yields obtained are very much less and the proportions
of colored impurities simultancously produced aro greatly increased. The
antimony process requires to be worked with care, the action being extremely
violent. Ditolylamine and phenyltolylamine may be similarly produced.
We would observe here that the commercial aniline (which is a mixture
of aniline and toluidinc, together with small and commercially insignificant
quantities of their higher homologues) if treated by the processes detailed
above, yields a mixture of diphenylamine, ditolylamine, and phenyltolylamine,
which we propose
to call commercial diphenylamine, it is this material (purified
as directed) that we prefer for the preparation of coloring matters suitable for
dyeing and printing. To prepare blue coloring matter from commercial
diphenylamine it is preferred to employ a process described in a Provisional
Specification filed by me, the said Charles Adam Girard, on the Seventeenth day
of October, in the present year, that is to say, we introduce into a convenient
distilling apparatus of enamelled iron or other material, two parts (by weight)
of commercial diphenylamine, and three parts of sesquichloride of carbon
(C, Cl), we then heat the mixture, taking care to maintain the temperature
between 140° and 180° centigrade. The sesquichloride of carbon which distils
over is condensed to avoid loss. The blue color is rapidly developed, and at the
cnd of a few hours, say three to five, a sample drawn from the mass will have
a bronzed aspect, and on cooling becomes brittle, the operation is then finished
and the fire is removed. The mass when cold is powdered and then gently
heated with benzole, ether, or petroleum spirit (such as before mentioned).

page_text: The untransformed sesquichloride of carbon and commercial diphenylamine
are thus dissolved and the blue remains undissolved; it is then collected and
dried; in this state after having been dissolved in alcohol or methylated
spirit it may be used in dyeing and printing, but if it is found desirable to
purify it further it should be dissolved in boiling alcohol or methylated
spirit and precipitated by commercial hydrochloric acid in excess (two volumes
of acid for one of spirit).
Although in the preparation of diphenylamine blue the sesquichloride of
carbon unites a number of practical advantages which have induced us to
mention it more particularly, there are a great many other reagents capable
of yielding blue with commercial diphenylamine. An artificial mixture of
diphenylamine and ditolylamine, say two parts of the former, and one of the
latter will produce the blue coloring matter, and so also will a mixture of
phenyltolylamine with diphenylamine and ditolylamine.
We would remark, however, that in practice these substances are extremely
difficult to separate entirely the one from the other, and there is little to gain
commercially by their separation.
Having thus described the nature of our said Invention, and the manner of
performing the
same, we would have it understood that we do not confine our
selves to the exact details described; but what we claim is, the preparation of
diphenylamine, ditolylamine, and phenyltolylamine by the action of the hydro-
chlorate or other salt or compound of aniline or its homologue on aniline or its
homologue, as herein-before described.
In witness whereof, I, the said Charles Adam Girard, have hereunto set
my hand and seal, this Eighteenth day of October, in the year of our
Lord One thousand eight hundred and sixty-six.
ידת! מז
OR. A. GIRARD. (L.S.).