Part 4

When the reaction was complete, the resulting product was isolated and purified in accordance with the directions given by Hollis. Repeated trials showed that, as in the case of the unsymmetrical chloride, only one phenyl group could be introduced by this method. The resulting compound, paranitroorthobenzoylbenzenesulphon chloride, was identical with that derived from the unsymmetrical chloride. Owing, however, to the fact that so much more decomposition occurs in the reaction with the symmetrical chloride, in paranitroorthobenzoylbenzene sulphon chloride could not be obtained in perfectly pure condition. In appearance it agreed closely with that described by Hollis, forming very characteristic greenish, rhombic crystals. These melted, not very sharply, at 174° instead of 177° as observed by Hollis.

Accordingly, to establish the identity of the two compounds beyond any doubt, the material on hand was converted into the barium salt of paranitroorthobenzoylbenzene sulphonic acid. This was done by boiling the sulphon chloride with dilute hydrochloric acid until complete solution had been effected; evaporating to dryness on a water-bath; dissolving the residue in hot water, and neutralizing with barium carbonate. On filtering the hot solution from the excess of carbonate, and allowing it to cool, the barium salt separated.

The solution was somewhat colored by impurities, and the long needles in which the salt crystallized were also somewhat colored. They were analysed with the expectation that they would prove to be specimens of the salt described by Hollis as having three, or three and a half molecules of water of crystallization, in as much as the conditions under which they were formed were favorable to the formation of salts with these ratios of water of crystallization. Hollis found that this salt could be obtained with at least four different ratios of water of crystallization viz. three, three and a half, six and seven molecules respectively. The analysis was as follows, the amount of barium being calculated on the basis of the anhydrous salt.

0.3087 gram lost 0.064 gram at 210°, and gave 0.0759 gram BaSO₄.

Cal. for (C₁₃H₈O₆NS)₂Ba + 11H₂O Found. H₂O = 20.90 20.73 Ba = 18.29 18.23

The mother-liquor, in which the crystals remaining from analysis were redissolved, was warmed, but not boiled, with boneblack, to remove impurities. When filtered, the solution was perfectly colorless, and on standing for some time, well formed colorless, rhombic crystals appeared. On analysis they gave results as follows.

0.2804 gram lost 0.0405 gram at 210°, and gave 0.0759 gram BaSO₄.

Cal. for (C₁₃H₈O₆NS)₂Ba + 7H₂O. Found. H₂O = 14.40 14.44. Ba = 18.29 18.03.

In making a further supply of the salt it was found that if the solution, after filtering from the barium carbonate, was diluted to such an extent that no crystals separated on cooling, then on slow evaporation under a bell-jar the first crystals to appear were very long slender needles. As evaporation proceeded, these needles became much thicker assuming prismatic proportions, and corresponded in appearance to the salt described by Hollis as having six molecules of crystal water.

As growth proceeded, the crystals became dark in color, and the mother-liquor correspondingly clearer, the crystals evidently absorbing the impurity in their growth.

When the solution had become quite colorless, rhombic crystals of the salt containing seven molecules of water of crystallization appeared. The larger prismatic crystals were carefully removed, and redissolved in water in order to see if the same phenomena would repeat themselves. This in fact was the case, crystals of both types appearing in the same way as described. Without separating the crystals in this second experiment, water was added, and the crystals dissolved. The solution was then warmed briskly with boneblack, and filtered. From the filtrate, which was colorless, nothing but rhombic crystals having seven molecules of water of crystallization could be obtained, although a great many variations in the conditions were tried. Analysis of these last crystals was as follows:

0.2400 gram lost 0.035 gram at 210°, and gave 0.0637 gram BaSO₄.

Cal. for (C₁₃H₈O₆NS)₂Ba + 7H₂O. Found. H₂O = 14.40 14.58 Ba = 18.29 18.27

Hollis states that treatment with boneblack decomposes this salt, and hence he did not purify it prior to crystallization. From the experiments just described it seems probable that the impurities present affect the crystalline habit, and the degree of hydration of this salt in a very striking manner. By careful warming with boneblack no decomposition was observed, and the crystals so obtained have constantly seven molecules of crystal water.

VI. The Action of Alcohols upon the Symmetrical Chloride of Paranitroorthosulphobenzoic Acid.

Kastle found that when the chlorides of paranitroorthosulphobenzoic acid (which he supposed to be an individual) were dissolved in alcohol, and the solution boiled for some time, the acid etherial salt of paranitroorthosulphobenzoic acid was the final product. The reactions were shown to be:

COCl COOC₂H₅ / / I. C₆H₃——SO₂Cl + C₂H₅OH = C₆H₃——SO₂Cl + HCl. \ \ NO₂ NO₂

COOC₂H₅ COOC₂H₅ / / II. C₆H₃——SO₂Cl + C₂H₅OH = C₆H₃——SO₂OC₂H₅ + HCl \ \ NO₂ NO₂

COOC₂H₅ COOC₂H₅ / / III. C₆H₃——SO₂OC₂H₅ + C₂H₅OH = C₆H₃——SO₂OH + (C₂H₅)₂O \ \ NO₂ NO₂

Am. Ch. Journ. XI--281.

Kastle, it will be observed, gave the symmetrical formula to this mixture of chlorides. Several acid etherial salts were made, and a series of the neutral salts of various metals described by him.

The action of pure symmetrical chloride was studied in the same general manner to see if the resulting products would be the same as those formed from the mixed chlorides.

1. Action of Methyl Alcohol upon the Symmetrical chloride.

A portion of the chloride was dissolved in methyl alcohol, and the solution boiled until a drop added to cold water gave no precipitate, of unchanged chloride. The alcohol was then distilled off, and the thick syrup remaining, diluted with water. This solution was neutralized with barium carbonate and filtered. On cooling, the barium salt crystallized in shining mica-like plates, or in yellowish needles corresponding accurately with those described by Kastle. They gave the following analytical results.

0.2664 gram lost 0.0211 gram at 150°, and gave 0.0870 gram BaSO₄.

2. In like manner the barium ethyl salt was made. It also agreed perfectly with Kastle’s description, crystallizing in fine, colorless needles, forming in tufts from a not too concentrated solution. In case it is necessary to concentrate these solutions, it is of advantage to add a small quantity of alcohol to the solution as this prevents any great amount of saponification, which otherwise takes place to a noticeable extent.

Analysis.

I. 0.2824 gram lost 0.0276 gram at 180°, and gave 0.0860 gram BaSO₄.