OH ]
/ ]
C[C₆H₃ ]
/ \ \ ]
/ O OH ]2
/ /
Cal. for C₆H₃——SO₂
\
NO₂
Found
I II III IV V
C = 52.66 52.18 52.42 52.67 —— ——
H = 3.46 3.76 3.27 3.66 —— ——
S = 7.39 —— —— —— 7.57 7.48
An effort to obtain the anhydride was unsuccessful. Some loss of weight
was observed, but the compound underwent decomposition before this loss
amounted to much.
6. The Action of Pyrogallol upon the Symmetrical Chloride of
Paranitroorthosulphobenzoic Acid.
The product of this action dissolves readily in dilute sodium hydroxide
without residue, producing a very deep purple-black color when
concentrated, passing to grayish-violet as the solution is diluted. On
adding hydrochloric acid, precipitation occurs, as in most of these
reactions. On attempting to filter off this precipitate, it forms a
sticky, black mass on the filter with which little can be done. It is
best to evaporate to dryness before filtration and powder the residue.
This powder can then be washed fairly clean from alkali salts and
acid.
Nothing to suggest the formation of an etherial salt was observed.
Analysis of this product for sulphur showed that in this galleïn, as
in the case of the hydroquinone phthaleïn more than two pyrogallol
residues had entered the acid residue. The indications were that
six had entered into one of the chloride. This also agrees with the
observation of Lyman[23], who describes a hexapyrogallol galleïn of
orthosulphoparatoluic acid.
Probably a mixture of varying composition was obtained, and little
importance was attached to the results save as they showed that no
etherial salt is formed in the reaction.
[23] Am. Ch. Journ. XVI-527.
7. The Action of β-Naphthol upon the Symmetrical Chloride of
Paranitroorthosulphobenzoic Acid.
It was hoped that here, as in the case of the monohydroxy phenols an
etherial salt would be obtained. It was found, however, that very
little action occurred, save such as was indicated by the development
of a bright carmine color in the melted mixture, until a temperature of
about 160° was reached. At this point hydrochloric acid was evolved,
but the chloride itself undergoes decomposition. Nothing definite could
be isolated among the reaction products, save unchanged β-Naphthol.
VIII. The Action of Aniline upon the Symmetrical Chloride of
Paranitroorthosulphobenzoic Acid.
As has been pointed out in the Introduction, it was in connection
with the aniline derivatives of orthosulphobenzoic acid, that the
isomerism of the chlorides was first noticed, two anilids being
obtained. Accordingly, when Gray began his study of the chlorides
of paranitroorthosulphobenzoic acid, his first effort was to obtain
evidence of the existence of two anilids. These were not obtained,
however, until after the chlorides themselves had been isolated, as
their properties made their isolation and preparation a matter of
difficulty.
Some points still remained in doubt after Gray’s study, and a further
investigation was thought to be desirable to clear these up.
Some time was spent in an endeavor to obtain a method by which a good
yield of fusible, or symmetrical, anilid could be obtained. The yield
in all cases tried, is not a good one. The presence of the nitro group
appears to complicate the reaction, leading to secondary reactions
whose course could not be followed. Upon bringing aniline and the
chloride together, a very vivid red color was always observed, and the
same was true when it was necessary to employ alkali. The fact that
such colors develop when nitro compounds are treated with alkali has
been noticed in many instances and some progress has been made in the
study of these compounds. Jackson and Ittner[24] have lately reviewed
this subject.
If a solution of the symmetrical chloride in ether is slowly added to a
similar solution of aniline, no appreciable amount of heat is evolved.
If the resulting solution is allowed to stand at ordinary temperatures,
action proceeds very slowly, aniline hydrochloride being precipitated
as the reaction proceeds. This can be filtered off from time to time
and the rate of action so observed. In such a way it was found that
five grams of chloride required about fifty hours time to react
completely with an excess of aniline. Similar results were obtained
with chloroform as the solvent. By boiling the solution for an hour or
more the reaction is complete.
[24] Am. Chem. Journ. XIX-199
The method employed was to bring the chloride and an excess of
aniline—somewhat more than four molecules—together in chloroform
solution. The flask was then boiled for about an hour, when the
chloroform was distilled off. During the boiling as well as the
distillation more or less bumping occurs in consequence of the aniline
hydrochloride which separates, and constant shaking of the flask is
sometimes necessary. The residue which is in a thick, gummy condition
in consequence of the presence of an excess of aniline, was digested
with water acidulated with hydrochloric acid. The excess of aniline
is thus removed, and the reaction product obtained as a reddish-brown
solid substance. This was treated with dilute sodium hydroxide, all
lumps being broken up with a stirring rod. The undissolved substance
is largely anil, which was filtered off. The anilid was then regained
by acidifying the alkaline solution, in which it was dissolved. It
separates immediately as a curdy colorless precipitate, though it is
frequently colored pink by impurity. It was found that this color could
be removed, in case not much was present, by redissolving the anilid in
alkali, and slowly pouring the solution into an excess of dilute acid.
In all cases a considerable amount of anil was obtained, even when the
substances were employed in the molecular ratios of 1:10. The reactions
involved, so far as the formation of anilid and anil are concerned are,
COCl CO.NH.C₆H₅
/ /
C₆H₃——SO₂Cl + 4C₆H₅NH₂ = C₆H₃——SO₂.NH.C₆H₅ + C₆H₅NH₃Cl
\ \
NO₂ NO₂
CO
/ \
COCl / N.C₆H₅
/ / /
C₆H₃——SO₂Cl + 3C₆H₅NH₂ = C₆H₃——SO₂ + 2C₆H₅NH₃Cl
\ \
NO₂ NO₂
On the whole the reaction seemed to be the most satisfactory in
chloroform solution, the main objection being, that, owing to the
simultaneous presence of chloroform, alkali, an a trace of aniline,
phenyl isocyanide is always formed, and renders the work more or less
unpleasant.
A number of experiments were also made to see if the yield could
be increased be employing a modification of the “Schotten-Baumann
Reaction”[25] for the formation of anilids. For this purpose an etherial
solution of the chloride was added to a like solution of aniline in
which was suspended finely powdered anhydrous potassium carbonate. The
proportions of the substances were those demanded by the equation
COCl CO.NH.C₆H₅
/ /
C₆H₃——SO₂Cl + 2C₆H₅NH₂ + 2K₂Cl₃ = C₆H₃——SO₂NH.C₆H₅ + 2KCl + 2KHCO₃
\ \
NO₂ NO₂
Very little anilid was, however obtained, but in its place a
substance soluble in water, of acid reaction capable of forming salts
and yielding several well characterized derivatives. I hope to
investigate this reaction more fully at some future time.
[25] Ber. XVII-2545; XXIII, 3430.
* * * * *
The anilid is rather sparingly soluble in alcohol, from which it is
deposited on cooling in very small needles. These melt, as stated by
Gray, at 222°. It is also soluble in chloroform and glacial acetic
acid, but does not form well defined crystals from any solvent. It
dissolves in dilute alkali from which solution acids precipitate it
unchanged.
* * * * *
The anil is also soluble in alcohol, glacial acetic acid etc. It
crystallizes in much better-formed crystals than does the anilid. These
melt at 188°.
On boiling the anil with aniline for a time, it is converted into the
anilid
CO
/ \
/ N.C₆H₅ CO.NH.C₆H₅
/ / /
C₆H₃——SO₂ + C₆H₅NH₂ = C₆H₃——SO₂NH.C₆H₅
\ \
NO₂ NO₂
In none of these reactions was any infusible anilid observed.