IX.
CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF
HARWARD COLLEGE.
ON TRIBROMTRINITROBENZOL.
By C. Lori Ng JAckson AND John F. WING.
Presented June 15, 1887.
THE following paper contains the description of the first results of
a research on tribromtrinitrobenzol and its derivatives, which we are
obliged to publish now, as on account of the departure of one of us
from Cambridge we cannot go on with the work together. Had it
not been for this, we should have postponed its publication until our
experiments on the reduction of triamidotrinitrobenzol had led to
some definite result. At present we are able to describe only the
tribromtrinitrobenzol, triamidotrinitrobenzol, and trianilidotrinitroben-
zol, with several preliminary experiments on other substances, which
we mention in order to reserve the further study of this subject for
one of us, who will continue it in this laboratory.
The tribromtrinitrobenzol has never been described, for although
Koerner * in 1874 stated that he had obtained it by the action of a
mixture of boiling fuming nitric and sulphuric acids on tribromdinitro-
benzol, he gave no description of it, saying that this must be postponed
till a later paper. Some years afterward (in 1879) Wurster and
Beran,t after many attempts to prepare the substance according to
Koerner, came to the conclusion that it could not be made in this
way, as, even when Koerner's mixture of acids was heated with tri-
bromdinitrobenzol to 220° in a sealed tube, they got only a very
small amount of a substance melting from 200° to 220°, the greater
part of the product being unaltered tribromdinitrobenzol. As this
paper has remained unanswered by Koerner up to the present time,
that is, for eight years, we have assumed that he has abandoned the
subject, and have accordingly taken it up, our attention being called
to it by the results obtained in the study of the action of nitric acid on
t Ber, d. ch. G., 1879, p. 1821.
* Gazz. Chim., 1874, p. 425.


OF ARTS AND SCIENCES. 139
trichlorbenzol described in a previous paper.” Upon treating sym-
metrical tribrombenzol with a mixture of fuming sulphuric acid and a
nitric acid of specific gravity 1.51, but essentially free from nitrous
fumes, we found, as stated in the paper just mentioned, that tribrom-
trinitrobenzol was formed, thus confirming the results of Koerner, in
opposition to those of Wurster and Beran ; and in the same place we
have tried to show that the most probable cause of the failure of these
latter chemists to obtain tribromtrinitrobenzol was the presence of a
large quantity of nitrous fumes in the nitric acid used by them, which
raised its specific gravity without increasing its strength.
Tribromtrinitrobenzol, C.Br. (NO),
Symmetrical tribrombenzol (melting point 119°) was converted
into tribromdinitrobenzol, either by treatment with nitric acid f of spe-
cific gravity 1.51, the mixture being warmed to secure complete ac-
tion, or by boiling it with a mixture of commercial fuming nitric acid
and common sulphuric acid. To convert the tribromdinitrobenzol,
by whichever process prepared, into tribromtrinitrobenzol, 20 grm.
of it were dissolved by the aid of heat in a mixture of about 500 c.c.
of the nitric acid of specific gravity 1.51 mentioned above with one
third of its volume of fuming sulphuric acid, since these proportions
had been found by experiment to give the best result with the least
consumption of acid, and the solution boiled gently in a flask loosely
closed with a glass bulb. As a portion of the nitric acid volatilizes
during the boiling, a little of the solid separates, which can be dis-
solved by the addition of more nitric acid, but this precaution is not
necessary in working on a large scale. When the mixture had boiled
for four to five hours, it was allowed to cool, and then, disregarding
the comparatively large amount of solid which had separated, poured
into snow, and the precipitate washed thoroughly with water and after-
ward purified, - first by extraction with hot alcohol, which removed
the unaltered tribromdinitrobenzol, since the tribromtrinitrobenzol is
but slightly soluble even in hot alcohol, - and then by crystallization
from chloroform, which separated the less soluble tribromtrinitro-
benzol from the tetrabromdinitrobenzol f which was always formed at
* These Proceedings, vol. xxii. p. 372.
t Prepared directly from sulphuric acid and nitre, not pushing the reaction
beyond the formation of acid potassic sulphate. See our previous paper,
these Proceedings, vol. xxii. p. 372.
f The purification and identification of this substance are described at the
end of this paper. If the tribrom trinitrobenzol is to be used in making triami-
N
140 PROCEEDINGS OF THE AMERICAN ACADEMY
the same time. The crystallization from chloroform was continued
until the substance showed the constant melting point of 285°; it was
then dried at 100°, and its composition determined by the following
analyses.*
I. 0.2310 grim. of the substance gave 19.6 c.c. of nitrogen under a
pressure of 765 mm. and a temperature of 21°.
II. 0.1688 grm. of the substance gave, according to the method of
Carius, 0.2128 grm. of argentic bromide.
Calculated for Found.
CeBrs(NO2)3.
Nitrogen 9.33 9.72
Bromine 53.33 gº tº º 53.64
The yield was far from satisfactory, amounting on the average from
about 15 to 20 per cent of the theoretical, although on one occasion
we obtained 40 per cent. As, however, the tribromdinitrobenzol used
in this case was the residue from the alcoholic extracts derived from
previous preparations, we think that a considerable part of this large
yield consisted of tribromtrinitrobenzol from the previous processes,
which had been dissolved by the hot alcohol, since, although nearly
insoluble in hot alcohol, it is not completely so. It follows from this
that it is well to use the tribromdinitrobenzol obtained in purifying
the crude product with alcohol as material for a new preparation.
Properties. – The tribromtrinitrobenzol forms good-sized, well-
developed white crystals, with perhaps a slight yellowish tinge, which
differ in habit according to the solvent from which they have been
crystallized. From benzol, hexagonal prisms terminated by hexag-
onal pyramids are deposited, which look very much like some, forms
of quartz crystal ; from a mixture of benzol and alcohol, long, slender,
tapering prisms are obtained, which under the microscope seem to be
made up of rows of hexagonal pyramids united as in cap quartz, so
that the edges of the prisms are bluntly serrated; crystallized from
chloroform, the prisms are not so slender as from benzol and alcohol,
and the twinning just described is much better marked. These crys-
tals, furrowed by numerous re-entering angles parallel to the basal
plane, are very characteristic. The substance melts at 285° (uncorr.),
and sublimes to a slight extent when heated in an air-bath, even at as
dotrinitrobenzol, it is not necessary to purify it completely from tetrabromdi-
nitrobenzol. See page 143.
* See also page 142.
OF ARTS AND SCIENCES. 141
low a temperature as 175°. It is but slightly soluble in alcohol, even
when boiling, essentially insoluble in it when cold, soluble in chloro-
form, and more easily in ether, benzol, acetone, glacial acetic acid, or
carbonic disulphide. Chloroform, or a mixture of benzol and alcohol,
is the best solvent for it.
The tribromtrinitrobenzol is a decidedly reactive substance, forming
compounds with most of the common reagents; of these compounds
we have been able to study thoroughly only those derived from alco-
holic ammonia and aniline, which will be described later in the paper,
but some preliminary experiments with other reagents may find a
place here. With potassic hydrate, dissolved in alcohol, a yellow
product was formed which gave red potassium and yellow barium
salts, the latter being only slightly soluble, and separating in hair-like
crystals from its hot aqueous solution. It is probable that this pro-
duct is the trinitrophloroglucin of Benedikt,” but to decide this point
the experiment must be repeated with a larger quantity of substance.
With sodic ethylate it gives what appears to be a new compound.
When boiled with an alcoholic solution of potassic sulphocyanate, it
forms a dark red powder, which we have not yet succeeded in obtain-
ing in crystals. When heated in a sealed tube with potassic iodide
and alcohol to 150° for 18 hours, a crystalline compound is formed,
which has a very high melting point and explodes when heated to a
somewhat higher temperature; but the yield is so small that we have
not been able as yet to obtain enough of it sufficiently pure for analy-
sis. All these substances will be more thoroughly studied in this
laboratory, and the behavior of tribromtrinitrobenzol with other re-
agents, especially sodium malonic ester, will be investigated also.
When tribromtrinitrobenzol is heated to 100° with common strong
sulphuric acid, it dissolves, but crystallizes out unaltered as the solu-
tion cools. A boiling solution of argentic nitrate in alcohol has no
action on it, and the same remark applies to argentic nitrite, as was to
be expected. We hope, however, that the triiodtrinitrobenzol may
react with this latter substance, and it was for this reason that we
undertook the study of the action of potassic iodide on the tribromtri-
nitrobenzol.
In the hope of obtaining addition-products similar to those formed
by Hepp's trinitrobenzol with hydrocarbons, we have studied the ac-
tion of tribromtrinitrobenzol on naphthaline. For this purpose benzol
solutions of the two substances were mixed in the proportion of one
* Ber. d. ch. G., xi. 1376.
142 PROCEEDINGS OF THE AMERICAN ACADEMY
molecule of each, but we obtained from the mixed solutions only crys-
tals melting at 285°; as, however, the melting-tubes contained a slight
sublimate, and the habit of the crystals was somewhat different from
that of tribromtrinitrobenzol, we thought it possible, although not
probable, that a compound might have been formed, which decomposed
before it melted, and have accordingly analyzed the crystals, which,
remembering the instability of Hepp's substance, were dried only by
pressing between filter-paper, in order to be certain that the substance
should not be decomposed.
0.1200 grm. of the substance gave, according to the method of Carius,
0.1500 grm. of argentic bromide.
Calculated for Found Calculated for
CoBră(NO2)3. e CeBră(NO2)3C10Hs.
Bromine 53.33 53.20 41.52
It is evident, therefore, that the substance is only tribromtrinitro-
benzol, and that it does not combine with naphthaline under these con-
ditions. The same negative result was obtained when chloroform or
ether was substituted for benzol as the solvent. We may add, too,
that the tribromtrinitrobenzol shows no tendency to unite with benzol,
so far as we could find.
Triamidotrinitrobenzol, C.(NH,)a(NO)s.
When tribrom trinitrobenzol is mixed with cold alcoholic ammonia,
an action sets in almost immediately, as shown by the appearance of
an orange color in the solution; and, if the substances are allowed to
stand for twelve hours in a corked flask at ordinary temperatures, the
reaction proceeds further, but is not complete, as is shown by the
presence of white specks consisting of unaltered tribromtrinitrobenzol
in the undissolved solid. It is necessary, therefore, in order to bring
this small amount of unaltered substance into the reaction, to boil the
mixture in a flask with a return condenser for about half an hour,
adding more alcoholic ammonia as it is needed. The nearly insol-
uble triamidotrinitrobenzol is then filtered hot from the orange liquid,
which has the color of a strong solution of potassic dichromate,” and
the paler yellow solid purified by washing, first with water to remove
ammonic bromide, and afterward with alcohol to get rid of the organic
impurities.
* Our study of the substances contained in this liquid is not complete as
yet, but a description of the results obtained up to this time will be found on
page 145.
OF ARTS AND SCIENCES. 143
The triamidotrinitrobenzol can be made conveniently also from the
mixture of tribrom trinitrobenzol and tetrabromdinitrobenzol obtained
in purifying tribrom trinitrobenzol, thus utilizing directly a secondary
product, which could be separated into its pure constituents only with
a great outlay of time and work. For this purpose, the mixture is
treated with alcoholic ammonia in the manner already described when
speaking of the preparation from pure tribromtrinitrobenzol, and the
product freed from the tetrabromdinitrobenzol, which is not attacked
by alcoholic ammonia under these conditions, by boiling and washing
with benzol or chloroform after the washing with alcohol.
The composition of the substance after being dried at 100° was
determined by the following analyses.
I. 0.2352 grin. of the substance gave on combustion 0.2370 grn. of
carbonic dioxide and 0.0544 grim. of water.
II. 0.2346 grim. of the substance gave 0.2342 grim. of carbonic
dioxide.*
III. 0.2186 grim. of the substance gave 60.4 c.c. of nitrogen under
a pressure of 770 mm. and a temperature of 19°.
IV. 0.1058 grm. of the substance gave 29.6 c.c. of nitrogen under a
pressure of 765 mm. and a temperature of 20°.
Calculated for Found.
Ce(NH2)3(NO2)3. I. II. III. IV.
Carbon 27.90 27.48 27.23
Hydrogen 2.32 2.57
Nitrogen 32.55 tº gº tº e & © 32.19 32.22
Properties.—As obtained from the action of alcoholic ammonia on
the tribromtrinitrobenzol, the triamidotrinitrobenzol forms an amor-
phous powder of an orange or yellow color, according to the conditions
under which it was prepared; crystallized from aniline or nitrobenzol,
it forms small rhombic plates of a pale yellow color. It decomposes
without melting above the boiling point of mercury, and is nearly,
although not completely, insoluble in water, alcohol, ether, benzol,
chloroform, or glacial acetic acid. It dissolves in aniline, or in nitro-
benzol, and, as already stated, can be obtained in crystals from these
solutions. Cold strong sulphuric acid slowly dissolves it, forming a pale
yellow solution, but on dilution the unaltered substance is precipitated.
Dilute sulphuric acid, or dilute or strong nitric or hydrochloric acid,
has no action on it, and when the substance was suspended in alcohol
* The hydrogen of this analysis was lost.
144 PROCEEDINGS OF THE AMERICAN ACADEMY
and hydrochloric acid gas passed into the liquid no change was ob-
served. It is therefore either incapable of forming salts, or can form
them only under unusual conditions. When the solution in strong
sulphuric acid was heated it became charred.
We have made many attempts to convert the triamidotrinitrobenzol
into an acet-compound, but have found that it was not acted on by
glacial acetic acid, acetylchloride, or acetic anhydride, even when
sealed with the substance, and heated to 150°; we infer, therefore, that
the radical acetyl cannot be introduced directly into the molecule.
The reduction of triamidotrinitrobenzol naturally has engaged our
attention, as by this means it might be possible to obtain hexamido-
benzol. Owing to want of material, however, our experiments on this
subject have not been brought to a conclusion, but we think it best to
describe them briefly now, as we shall have no other opportunity to
put them in print, if the future work of one of us on this subject
should not lead to the desired result; and there seems to be only too
much reason to fear that this will be the case, especially since Nietzki
and IIagenbach * have found that ammonia is eliminated in reductions
which should lead to pentamidobenzol. Up to this time we have
tried only three reducing agents, tin and hydrochloric acid, ammonic
sulphydrate in alcoholic solution, and zinc dust and acetic acid. The
first of these, tin and hydrochloric acid, removed ammonia from the
molecule, as was proved by the formation of pink salt and the precip-
itation of ammonic chlorplatinate on adding chlorplatinic acid, the
latter being analyzed for still greater certainty. This was the result
whether tin and hydrochloric acid or stannous chloride and hydro-
chloric acid were used. The alcoholic solution of ammonic sulphy-
drate gave a more promising result; but, as it was evident that the
product was decomposed at a temperature a little above that at which
it was formed, we turned our attention to the third method, which
seemed on the whole the most promising, since zinc dust and 80 per
cent acetic acid acting in an atmosphere of carbonic dioxide seem to
reduce the triamidotrinitrobenzol completely; at any rate, the yellow
color disappears, and the whole goes into solution. This solution, after
being freed from zinc with sulphuretted hydrogen, gave no precipitate
with sodic hydrate, nor did ether extract anything from the alkaline
solution. It was blackened by exposure to the air even more readily
than a solution of a salt of diamidobenzol, and the residue from it was
decomposed easily by heat; chlorplatinic acid gave no precipitate with
* Ber, d. ch. G., 1887, p. 331. See also p. 2114.
OF ARTS AND SCIENCES. 145
it, but chlorauric acid threw down an uninviting precipitate, which
we thought was in part at least a product of oxidation. If the sub-
stance formed was really hexamidobenzol, it is evident that its isola-
tion in a form fit for analysis will be a matter of great difficulty owing
to its extreme instability. The study of this subject will be continued
in this laboratory, however, as soon as a sufficient quantity of material
can be prepared, and the work will be extended also to the action of
other reducing agents, including those which form azo-compounds.
As yet we have been unable to finish the study of the substances
contained in the orange-red filtrate formed in the preparation of the
triamidotrinitrobenzol, because in spite of its marked color the amount
of solid dissolved in it is far from large. It seems, however, to con-
tain at least two compounds, one crystallizing in red needles, frequently
grouped in round masses like chestnut burs, the other a yellow sub-
stance forming flat crystals; but the separation of these two bodies is
a matter of such great difficulty that we have not yet succeeded in
obtaining either of them in a state of purity, nor are we certain that
these are the only secondary products of the reaction.
Trianilidotrinitrobenzol, C. (NHC.H.),(NO.),
This substance was prepared by allowing a mixture of tribromtrini-
trobenzol and aniline, in the proportion of one molecule of the former
to six of the base, to stand at ordinary temperatures, when the re-
action runs slowly, but is complete after the mixture has stood for a
day or two. The product was purified by washing with water, to
which a little hydrochloric acid was added to remove any slight excess
of free aniline, and crystallizing the residue from a mixture of alcohol
and chloroform. It was dried at 100°, and analyzed with the following
results.
I. 0.1468 grim. of the substance gave on combustion 0.3176 grm.
of carbonic dioxide and 0.0516 grim. of water.
II. 0.1830 grm. of the substance gave 28.1 c.c. of nitrogen at 25°
temperature and 755 mm. pressure.
Calculated for Found.
Co(NHCGII5)3(NO2)3. I.
Carbon 59.26 58.99
Hydrogen 3.71 3.90
Nitrogen 17.28 © º & 17.02
If an excess of aniline is used in the preparation, and the mixture
heated, a coloring matter is formed looking like rosaniline; but the
vol. xxi.II. (N. S. xv.) 10
146 PROCEEDINGS OF THE AMERICAN ACADEMY
purification of this substance was attended with such great difficulties
that we have abandoned for the present the further study of this re-
action, in which the nitro groups undoubtedly play a part.
Properties. – The trianilidotrinitrobenzol forms an orange powder,
crystallizing from alcohol or chloroform in fine red needles, which
melt at 238°. It is essentially insoluble in water, soluble with diffi-
culty in alcohol, but easily in chloroform, soluble in ether, benzol,
glacial acetic acid, or acetone. The best solvent for it is a mixture of
alcohol and chloroform. Hydrochloric acid has no action on it, and
in general it shows no more tendency to form salts than the corre-
sponding amido compound. Strong nitric acid produces no change of
color when added to it.
Tetrabromdinitrobenzol, C.Br. (NO),
As has been already stated, during the preparation of the tribrom-
trinitrobenzol from tribromdinitrobenzol by the action of nitric acid
and fuming sulphuric acid there was formed invariably another sub-
stance which melted in the crude state at about 230°, and was left
behind with the tribrom trinitrobenzol after the tribromdinitrobenzol
was removed with alcohol, and was separated partially from it by
crystallizing the residue from chloroform, in which the trinitro com-
pound is less soluble than the other substance. In this way it is
easy to get the trinitro compound in a state of purity; but to purify
completely the other substance it is necessary to submit the residue
from the evaporation of the chloroform mother-liquors to systematic
fractional crystallization from a mixture of alcohol and benzol, which
removes a small quantity of tribromtrinitrobenzol. These crystalliza-
tions lowered the melting point instead of raising it, as is usual, and
after it had been brought down from about 230° to 224° it remained
constant, and then the substance, dried at 100°, was analyzed with the
following results.
I. 0.3526 grm. of the substance gave 18.7 c.c. of nitrogen at 24°
temperature and 764 mm. pressure.
II. 0.1690 grim. of the substance gave, by the method of Carius,’
0.2606 grim. of argentic bromide.
Calculated for Found.
CoBrA(NO2)2. I. II.
Nitrogen 5.78 5.97
Bromine 66.11 © tº ge 65.62
OF ARTS AND SCIENCES. 147
These analyses and the melting point 224° prove that the substance
is the tetrabromdinitrobenzol melting point 227–228°, discovered by
Von Richter.”
The following experiments were tried to throw light upon the
manner in which the tetrabromdinitrobenzol was formed. In the
first place, to prove that it was not formed from an impurity (tetrabrom-
benzol) in our tribrombenzol, we have prepared it from an analyzed
sample of tribromdinitrobenzol. This experiment was hardly neces-
sary, as the tribrombenzol and tribromdinitrobenzol used by us in
working on the large scale showed the correct melting points within
two degrees; but we felt that absolute certainty on this point was im-
portant, and accordingly prepared some perfectly pure tribromdinitro-
benzol, melting point 190° (Von Richterf gives 191°, Koernerf 192°),
which gave on analysis the following result.
0.1658 grim. of the substance gave, according to the method of Carius,
0.2314 grim. of argentic bromide.
Calculated for
CoBraſ NO2).H.
Bromine 59.26 59.39
Found.
This was treated with a mixture of nitric acid and fuming sulphu-
ric acid, precisely as in the preparation of tribromtrinitrobenzol, and
yielded a product which, after removing the unattacked tribromdinitro-
benzol, consisted of tribromtrinitrobenzol and tetrabromdinitrobenzol
in about equal parts, thus proving that the tetrabromdinitrobenzol is
not derived from an impurity, but is formed during the process.
A second experiment had for its object to determine whether the
conversion of the tribromdinitrobenzol into tetrabromdinitrobenzol
was due to the fuming sulphuric acid, which might well be the case,
since Bâssmann Š has observed that symmetrical tribrombenzol is con-
verted in part into pentabrombenzol, when heated with fuming sul-
phuric acid to 100° from a week to a fortnight. We accordingly
heated another quantity of the pure tribromdinitrobenzol with an
excess of fuming sulphuric acid in a sealed tube to 100° for twelve
hours, but no tetrabromdinitrobenzol was formed, and, as the tempera-
ture of our mixture during the manufacture of the tribromtrinitroben-
zol could have been little, if at all, above 100°, and that process was
carried on for only five hours, we are inclined to ascribe the formation
of the tetrabrom compound to the nitric rather than the sulphuric acid.
* Ber. d. ch. G., 1875, p. 1427. f Gazz. Chim., 1874, p. 425.
f Ber. d. ch. G., 1875, p. 1426. § Ann. Chem., cxci. 208.
ITY OF MICHIGAN
Hill
148 PROCEEDINGS OF THE AMERICAN ACADEMY
In a third experiment the mixture of tribromdinitrobenzol with
nitric and fuming sulphuric acids was boiled for only a quarter of an
hour, instead of for the usual five hours, and the proportion of tetra-
bromdinitrobenzol formed was comparatively small, it would seem,
therefore, that it is formed chiefly in the later part of the boiling; but
it is not advantageous in preparing tribromtrinitrobenzol to diminish
the length of the boiling, as the superior purity of the product does
not compensate for the much smaller yield. We may add, that
another experiment showed that it was impossible to convert tribrom-
trinitrobenzol into tetrabromdinitrobenzol by boiling it with the mix-
ture of nitric acid and fuming sulphuric acid.
Von Richter, the discoverer of tetrabromdinitrobenzol, gave the
melting point 227–228°, whereas our substance showed a constant
melting point of 224°. We are of the opinion, however, that Von
Richter's melting point is more correct than ours, as it might well be
that a small quantity of tribromtrinitrobenzol, sufficient to lower the
melting-point 4°, could not be removed by crystallization, and in fact
our analysis seems to indicate the presence of such an impurity; but
as our object was to identify the substance rather than study its prop-
erties, we did not think it worth while to sacrifice the large amount of
time and labor which would undoubtedly have been necessary to
settle this point thoroughly. Von Richter also states that it is soluble
in alcohol or benzol, and Bodewig “ has published a thorough descrip-
tion of its crystalline form. The following properties, which we have
had occasion to study, have not been published heretofore, so far as we
can find. It begins to sublime at about 175°, and is soluble in me-
thylalcohol, ether, acetone, glacial acetic acid, or carbonic disulphide;
the best solvent for it is a mixture of alcohol and benzol, in the
former of which it is but sparingly soluble. It dissolves in cold sul-
phuric acid, but is precipitated unchanged on dilution. When heated
over a free flame with sulphuric acid, it is destroyed. The bromine
in it is much more firmly attached to the molecule than in the tri-
bromtrinitrobenzol, as it is not removed when the substance is boiled
with alcoholic ammonia in open vessels. It is also very hard to effect
its complete decomposition in its analysis according to Carius.
Finally, we may remark that it is highly probable that the substance
melting above 200° obtained by Wurster and Beran by heating tri-
bromdinitrobenzol to 220° in a sealed tube with a mixture of fuming
nitric and sulphuric acids was the tetrabromdinitrobenzol.
* Zeitschr. Kryst., iii. 398.
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