COOC₆H₅
/
Cal. for C₆H₃——SO₂OC₆H₅
\
NO₂ Found.
I II III
C = 57.14 56.97 57.03 ——
H = 3.26 3.47 3.33 ——
S = 8.02 —— —— 8.09
This substance melts at 119° (uncorr).
It possesses properties similar to those of the diphenyl etherial
salt of orthosulphobenzoic acid described by Saunders. It is
insoluble in water, and is unaffected by hydrochloric acid or aqueous
alkali. On heating for a short time with alcoholic potash, the
needles were transformed into a voluminous precipitate. This was
filtered off, dissolved in water, and hydrochloric acid was added.
On cooling, characteristic crystals of the acid potassium salt of
paranitroorthosulphobenzoic separated.
Analysis.
0.1392 gram lost 0.009 gram at 150° and gave 0.0385 gram K₂SO₄.
COOH
/
Cal. for C₆H₃——SO₂OK + H₂O
\
NO₂
Found.
H₂O = 5.95 H₂O = 6.51
K = 13.65 K = 13.35
No attempt was made to isolate the corresponding intermediate
chlor-etherial salt of the composition
COOC₆H₅
/
C₆H₃——SO₂Cl
\
NO₂
or its acid as was done by McKee[21] in his work on the analogous
etherial salt of orthosulphobenzoic acid.
[21] Am. Ch. Journ. XVIII-799
On evaporating the aqueous extract from the original melt almost to
dryness on the water-bath, there was a deposit on the sides of thedish
of scales possessing a beautiful bronze-green metallic lustre They
formed a deep purple solution in alkalis, or magenta, if the solution
was very dilute, and orange-yellow in acids. On acidifying the alkaline
extract with hydrochloric acid, this same substance was precipitated
as a brownish flocculent precipitate. It was, however, found to be
impossible to obtain this substance in pure condition. The amount
formed in the reaction is small, and its properties were such as to
render work with it very difficult. The method of precipitation is not
satisfactory because, owing to the fact that the substance is soluble
in acid solutions to an unusual extent for substances of this class,
the solution had to be concentrated to such a degree as to render the
precipitated substance very impure from acids and alkali salts. These
could not be removed by washing, obviously, without again dissolving
the substance. From its properties however, and its color reactions,
there can be little doubt that the substance is a sulphonphthaleïn,
and that it is always formed in considerable quantities in the
reaction of phenol upon the symmetrical chloride.
It was noticed that the aqueous extract of the mass left after fusion
was almost always decidedly acid in reaction, and it was thought that
this might be due to the formation of an acid etherial salt, whose
formation would be expressed by the equations:
COCl COOC₆H₅
/ /
C₆H₃——SO₂Cl + C₆H₅OH = C₆H₃——SO₂Cl + HCl.
\ \
NO₂ NO₂
COOC₆H₅ COOC₆H₅
/ /
C₆H₃——SO₂Cl + H₂O = C₆H₃——SO₂OH + HCl.
\ \
NO₂ NO₂
Accordingly, the solution was saturated with barium carbonate, the
excess of carbonate removed by filtration, the filtrate concentrated,
and allowed to cool. Crystals in the form of pearly scales separated,
which upon analysis proved to be the neutral barium salt of
paranitroorthosulphobenzoic acid.
0.2291 gram anhydrous salt gave 0.1386 gram BaSO₄.
COO
/ \
/ Ba
/ /
Cal. for C₆H₃——SO₂O
\
NO₂
Found
Ba = 35.85 35.57
This would seen to indicate that the reaction is an incomplete one even
in the presence of excess of phenol. No indications of the formation of
an acid etherial salt was observed.
2. The Action of Orthocresol upon the Symmetrical Chloride of
Paranitroorthosulphobenzoic Acid.
With orthocresol the reaction proceeds with more difficulty. A higher
temperature was required (135°-145°), and quite an amount of tarry
material was obtained from which very little could be extracted. The
product was warmed repeatedly with dilute alkali, the solution so
obtained neutralized with hydrochloric acid, and distilled with steam
for several hours to free it from cresol. The resulting solution was
then evaporated to small volume, and acidified with hydrochloric acid.
A considerable precipitate was thrown down, which was easily filtered
off and dried. In this condition it is a dark purple-red powder, lumps
of which possessed a yellowish-bronze metallic lustre. In dilute
alkaline solution it forms a deep-bluish purple solution, while in
acids it is crimson, or light yellow if the solution is dilute. It is a
excellent indicator, especially with ammonia.
In the insoluble tarry substance the etherial salt was sought for
and obtained in small quantity only. As this substance is soluble in
alcohol, and separates again on cooling in much the same condition,
the etherial salt could not be isolated be crystallization from this
solvent. By boiling the substance with benzene, purifying the filtrate
with boneblack, and allowing the benzene to evaporate, an almost
colorless gummy substance was obtained, which when dissolved in
alcohol, crystallizes in small colorless needles which melt at 89°-90°.
They were not obtained in quantity sufficient for analysis, but there
was little doubt that they were crystals of the diorthocresol etherial
salt.
Apparently much more decomposition occurred in this reaction than
when paracresol was employed, probably in consequence of the higher
temperature required for the reaction.
3. The Action of Paracresol upon the Symmetrical Chloride of
Paranitroorthosulphobenzoic Acid.
This reaction was conducted in the same manner as with phenol. No
hydrochloric acid was evolved until a temperature of about 110° was
reached, although after melting, the solution had steadily darkened to
a deep reddish-brown color. At 130°, after heating for several hours,
hydrochloric acid ceased to be evolved. The product was treated as in
the last experiment. The alkaline extract did not exhibit any marked
color reactions, such as were observed in most of these experiments,
being dull reddish-brown in both acid and alkaline solution.
The insoluble residue crystallized from alcohol in light brown
transparent crystals, which did not lose their color by repeated
crystallization, and boiling with boneblack, and melted sharply at
117°. From benzene they crystallized in colorless needles or flat,
narrow plates. These become opaque on exposure to the air, apparently
through loss of benzene of crystallization.
Analysis of the needles from alcohol gave the following results:
I. 0.2372 gram of substance gave 0.5137 gram CO₂ and
0.0965 gram H₂O.