Part 6

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 in his work on the analogous etherial salt of orthosulphobenzoic acid.

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.

II. 0.2223 gram gave 0.1203 gram BaSO₄.

COOC₆H₄.CH₃ / Cal. for C₆H₃——SO₂OC₆H₄.CH₃ \ NO₂ Found. I II C = 59.08 59.06 H = 3.98 4.52 S = 7.49 7.43

4. The Action of Hydroquinone upon the Symmetrical Chloride of Paranitroorthosulphobenzoic Acid.

Action with hydroquinone occurs at 120°-135°, the mixture at the same time becoming dark colored and viscous.