Part 5

II. 0.2655 gram lost 0.0262 gram at 190°, and gave 0.0815 gram BaSO₄.

Kastle also found that by dissolving the mixed chlorides in alcohol in the cold, and allowing the solution to evaporate, there separated after a time, crystals of the chloride of the acid etherial salt of paranitroorthosulphobenzoic acid whose formation and composition are represented in equation I.

This same product was sought for when pure symmetrical chloride was employed, but without success. In every case, crystals of unchanged chloride separated, or else it was found that it had been completely converted into the acid etherial salt. In another trial cold water was carefully added in small portions, since Kastle found that such treatment facilitated the separation of the substance; the chloride alone appeared. Still other attempts were made to obtain the substance by adding a large amount of water to the solution of the chloride in alcohol, after it had stood for some time. In this way, quite a precipitate was thrown down, and this was filtered off and crystallized from ether. It always proved to be the symmetrical chloride, and none of the other substance was obtained.

Karslake in working with the symmetrical chloride of orthosulphobenzoic acid, was unable to isolate the analogous compound, although from the mixed chlorides, by the action of alcohols, Remsen and Dohme had obtained chloro-etherial salts.

Inaug. Diss. J. H. Univ. 1895.

Am. Ch. Journ. XI, 341.

In as much as the pure symmetrical chloride is relatively stable in cold alcohol (it can be crystallized from warm alcohol with very little loss), it is possible that it is more stable than the chloro etherial salt, and that in consequence the latter, when formed, yields more readily to the further action of alcohol than does the unacted on chloride. Hence when the action begins, it at once proceeds to the limit. The fact that the symmetrical chloride is rather sparingly soluble in cold alcohol, making the use of concentrated solutions impossible, may also be a factor in the case. Whatever may be the cause, this substance could not be obtained under any conditions that were devised.

Having in my possession a very small specimen of crystallized unsymmetrical chloride, it was submitted to the action of ethyl alcohol, under as nearly as possible the conditions employed by Kastle. Crystals of a colorless substance were obtained, which in every respect agreed with Kastle’s description of the chloride of the acid ethyl etherial salt of paranitroorthosulphobenzoic acid. Crystallized from ether they melted at 68°.

The conditions employed by Kastle in preparing the chloride would undoubtedly lead to a relatively large proportion of unsymmetrical chloride, and it is to this chloride that the formation of the chloro etherial salt is apparently due.

VII. The Action of Phenols upon the Symmetrical Chloride of Paranitroorthosulphobenzoic Acid.

Remsen and Saunders in their investigation of the chlorides of orthosulphobenzoic acid, studied the action of phenol upon these substances, and from both the symmetrical chloride and the mixed chlorides, they obtained a normal diphenyl ether together with a red substance which was not further studied. It was formed in small quantity and was probably the corresponding sulphonphthalein. Later McKee obtained these same substances from both the symmetrical and the unsymmetrical chlorides. R. Meyer obtained analogous substances by the action of various phenols upon phthalyl chloride. It seemed probable, therefore, that the chlorides of paranitroorthosulphobenzoic acid would yield similar derivatives, and a study was accordingly made of the reaction of the symmetrical chloride with a series of phenols. The products in some instances were exceedingly difficult to deal with, possessing properties that made it impossible to prepare them for analysis, but even in such cases there could be little doubt as to the general nature of the reactions which had occurred.

Am. Chem. Journ. XVII, 347.

Ibid. XVIII, 798.

Ber. XXVI, 204.

1. The Action of Phenol upon the Symmetrical Chloride of Paranitroorthosulphobenzoic Acid.

A portion of the symmetrical chloride was brought together with somewhat more than double the molecular amount of phenol. The mixture was placed in a good-sized test-tube and the temperature gradually raised by means of a sulphuric acid bath.

As soon as the phenol melts, some slight action occurs, as is indicated by the fact that the mixture assumes a bright red color. No appreciable amount of hydrochloric acid gas is evolved however, until the liquid mixture has reached a temperature of about 115°. At this point the gas is freely evolved, and the action is complete at a temperature of 125°. The temperature observations were made by means of a thermometer used as a stirring rod in the mixture. During the heating, the color of the liquid becomes a much more intense red, growing darker in shade, and the liquid itself becomes somewhat viscous but does not solidify while hot.

When cool, the melt was repeatedly extracted with boiling water, the aqueous solution being very deep purple in color. The colored matter was removed very slowly in this manner, and so the process was continued with dilute alkali. A solid insoluble residue was thus obtained, of a light-brownish color. This was dissolved in alcohol, boiled with boneblack and filtered. On cooling, needles of a straw yellow color were deposited from the alcoholic solution.

This proved to be the normal diphenyl etherial salt of paranitroorthosulphobenzoic acid, the formation of this substance being expressed by the equation:

COCl COOC₆H₅ / / C₆H₃——SO₂Cl + 2C₆H₅OH = C₆H₃——SO₂OC₆H₅ + 2HCl. \ \ NO₂ NO₂

Analysis of the substance gave the following results:

I. 0.1627 gram gave 0.3398 gram CO₂ and 0.0510 gram H₂O.

II. 0.1999 gram gave 0.4180 gram CO₂ and 0.0600 gram H₂O.

III. 0.2649 gram gave 0.1561 gram BaSO₄.

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.